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Sample records for knife fryburg mondak

  1. Reducing Chatter in Knife-Edge Scanning Microscopy 

    E-Print Network [OSTI]

    Shah, Raj Sunil


    , at different knife vibration frequencies. External sinusoidal wave vibrations were introduced in the KESM knife from a signal generator throughout the sectioning process. These electrical signals were converted to mechanical waves at the tip of the KESM knife...

  2. A knife-edge array field emission cathode

    SciTech Connect (OSTI)

    Lee, B.


    many cathode applications require a new type of cathode that is able to produce short pulsed electron beams at high emission current. Gated field emitter arrays of micrometer size are recognized as candidates to meet this need and have become the research focus of vacuum microelectronics. Existing fabrication methods produce emitters that are limited either in frequency response or in current emission. One reason is that the structure of these emitters are not sufficiently optimized. In this study, the author investigated the factors that affect the performance of field emitters. An optimum emitter structure, the knife-edge field emitter array, was developed from the analysis. Large field enhancement factor, large effective emission area, and small emitter capacitance are the advantages of the structure. The author next explored various options of fabricating the knife-edge emitter structure. He proposed a unique thin film process procedure and developed the fabrication techniques to build the emitters on (110) silicon wafers. Data from the initial cathode tests showed very low onset voltages and Fowler-Nordheim type emission. Emission simulation based on the fabricated emitter structure indicated that the knife-edge emitter arrays have the potential to produce high performance in modulation frequency and current emission. Several fabrication issues that await further development are discussed and possible solutions are suggested.

  3. Rotating and static sources for gamma knife radiosurgery systems: Monte Carlo studies

    E-Print Network [OSTI]

    Yu, Peter K.N.

    Rotating and static sources for gamma knife radiosurgery systems: Monte Carlo studies J. Y. C of the 201 static sources Leksell gamma knife, LGK . The rotating sources of RGSs simulate an infinite number by the surrounding normal brain tissues, which is a resultant of 201 static 60 Co sources. Each individual beam

  4. Size reduction of high- and low-moisture corn stalks by linear knife grid system

    SciTech Connect (OSTI)

    Womac, A.R. [University of Tennessee; Igathinathane, C. [Mississippi State University (MSU); Sokhansanj, Shahabaddine [ORNL; Narayan, S. [First American Scientific Co.


    High- and low-moisture corn stalks were tested using a linear knife grid size reduction device developed for first-stage size reduction. The device was used in conjunction with a universal test machine that quantified shearing stress and energy characteristics for forcing a bed of corn stalks through a grid of sharp knives. No published engineering performance data for corn stover with similar devices are available to optimize performance; however, commercial knife grid systems exist for forage size reduction. From the force displacement data, mean and maximum ultimate shear stresses, cumulative and peak mass-based cutting energies for corn stalks, and mean new surface area-based cutting energies were determined from 4 5 refill runs at two moisture contents (78.8% and 11.3% wet basis), three knife grid spacings (25.4, 50.8, and 101.6 mm), and three bed depths (50.8, 101.6, and 152.4 mm). In general, the results indicated that peak failure load, ultimate shear stress, and cutting energy values varied directly with bed depth and inversely with knife grid spacing. Mean separation analysis established that high- and low-moisture conditions and bed depths 101.6 mm did not differ significantly (P < 0.05) for ultimate stress and cutting energy values, but knife grid spacing were significantly different. Linear knife grid cutting energy requirements for both moisture conditions of corn stalks were much smaller than reported cutting energy requirements. Ultimate shear stress and cutting energy results of this research should aid the engineering design of commercial scale linear knife gird size reduction equipment for various biomass feedstocks.

  5. Gamma Knife Radiosurgery for the Treatment of Cystic Cerebral Metastases

    SciTech Connect (OSTI)

    Ebinu, Julius O.; Lwu, Shelly; Monsalves, Eric; Arayee, Mandana; Chung, Caroline; Laperriere, Normand J.; Kulkarni, Abhaya V.; Goetz, Pablo; Zadeh, Gelareh


    Purpose: To assess the role of Gamma Knife radiosurgery (GKRS) in the treatment of nonsurgical cystic brain metastasis, and to determine predictors of response to GKRS. Methods: We reviewed a prospectively maintained database of brain metastases patients treated at our institution between 2006 and 2010. All lesions with a cystic component were identified, and volumetric analysis was done to measure percentage of cystic volume on day of treatment and consecutive follow-up MRI scans. Clinical, radiologic, and dosimetry parameters were reviewed to establish the overall response of cystic metastases to GKRS as well as identify potential predictive factors of response. Results: A total of 111 lesions in 73 patients were analyzed; 57% of lesions received prior whole-brain radiation therapy (WBRT). Lung carcinoma was the primary cancer in 51% of patients, 10% breast, 10% colorectal, 4% melanoma, and 26% other. Fifty-seven percent of the patients were recursive partitioning analysis class 1, the remainder class 2. Mean target volume was 3.3 mL (range, 0.1-23 mL). Median prescription dose was 21 Gy (range, 15-24 Gy). Local control rates were 91%, 63%, and 37% at 6, 12, and 18 months, respectively. Local control was improved in lung primary and worse in patients with prior WBRT (univariate). Only lung primary predicted local control in multivariate analysis, whereas age and tumor volume did not. Lesions with a large cystic component did not show a poorer response compared with those with a small cystic component. Conclusions: This study supports the use of GKRS in the management of nonsurgical cystic metastases, despite a traditionally perceived poorer response. Our local control rates are comparable to a matched cohort of noncystic brain metastases, and therefore the presence of a large cystic component should not deter the use of GKRS. Predictors of response included tumor subtype. Prior WBRT decreased effectiveness of SRS for local control rates.


    E-Print Network [OSTI]

    . McCormick Department of Computer Science Texas A&M University College Station, TX ABSTRACT Recent process. One vertical lift stage is used to adjust the level of the specimen relative to the knife

  7. Experience with the CyberKnife for intracranial stereotactic radiosurgery: Analysis of dosimetry indices

    SciTech Connect (OSTI)

    Floriano, Alejandro, E-mail:; Santa-Olalla, Iciar; Sanchez-Reyes, Alberto


    We evaluated coverage, dose homogeneity, dose conformity, and dose gradient in CyberKnife VSI treatment plans. Several dosimetric indices were calculated, and the results were compared with those of previous publications. The effect of target volume on the radiosurgical treatment indices selected was also investigated. The study population comprised the first 40 patients treated at our department from March 2011 to September 2012. Dosimetric indices were calculated and compared with published results for other frame-based and frameless intracranial stereotactic radiotherapy techniques. A comparison of the indices confirmed the ability of the CyberKnife VSI system to provide very high-quality dosing plans. The results were independent of target volume for coverage, homogeneity, and dose conformity. However, a dependence on target volume was observed for the dose-gradient indices analyzed. Based on the indices proposed, CyberKnife provides very good treatment plans and compares favorably with other techniques in most cases. However, greater consensus on the radiosurgery indices calculated would be desirable to facilitate comparison of the various techniques or the same techniques when applied by different users.

  8. In situ tomography of femtosecond optical beams with a holographic knife-edge 

    E-Print Network [OSTI]

    Strohaber, James; Kaya, G; N, Kay; Hart, Nathan; Kolomenskii, Alexander; Paulus, Gerhard; Schuessler, Hans


    ? that are mechanically difficult or impossible to reproduce. We test our method by holographically knife-edging and tomographically reconstructing both continuous wave and broadband radiation in transverse optical modes. ?2011 Optical Society of America OCIS codes..., and C. J. G. J. Uiterwaal, ?Ultrashort intense-field optical vortices produced with laser-etched mirrors,? Appl. Opt. 46(36), 8583?8590 (2007). #146202 - $15.00 USD Received 19 Apr 2011; revised 2 Jul 2011; accepted 2 Jul 2011; published 12 Jul 2011...

  9. Electromagnetic Casimir forces of parabolic cylinder and knife-edge geometries

    SciTech Connect (OSTI)

    Graham, Noah [Department of Physics, Middlebury College, Middlebury, Vermont 05753 (United States); Shpunt, Alexander; Kardar, Mehran [Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Emig, Thorsten [Laboratoire de Physique Theorique et Modeles Statistiques, CNRS UMR 8626, Bat. 100, Universite Paris-Sud, 91405 Orsay cedex (France); Rahi, Sahand Jamal [Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Center for Studies in Physics and Biology, The Rockefeller University, 1230 York Street, New York, New York 10065 (United States); Jaffe, Robert L. [Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Center for Theoretical Physics and Laboratory for Nuclear Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)


    An exact calculation of electromagnetic scattering from a perfectly conducting parabolic cylinder is employed to compute Casimir forces in several configurations. These include interactions between a parabolic cylinder and a plane, two parabolic cylinders, and a parabolic cylinder and an ordinary cylinder. To elucidate the effect of boundaries, special attention is focused on the 'knife-edge' limit in which the parabolic cylinder becomes a half-plane. Geometrical effects are illustrated by considering arbitrary rotations of a parabolic cylinder around its focal axis, and arbitrary translations perpendicular to this axis. A quite different geometrical arrangement is explored for the case of an ordinary cylinder placed in the interior of a parabolic cylinder. All of these results extend simply to nonzero temperatures.

  10. SU-E-T-542: Comparison of Stereotactic Radiosurgery (SRS) of Brain Lesions Using Gamma Knife, VMAT, IMRT, and Conformal Arcs

    SciTech Connect (OSTI)

    Li, S; Charpentier, P; Chan, P; Neicu, T; Miyamoto, C


    Purpose: To compare dose distributions in stereotactic radiation surgery of brain lesions using gamma Knife, VMAT, conformal arcs, and IMRT in order to provide an optimal treatment. Methods: Dose distributions from single shot of 4C model of Gamma Knife at the helmet collimation sizes of 4, 8, 14, and 18 mm in diameter were compared with full arcs with the square shapes of 4×4 (or 5×5), 8×8 (or 10×10), and spherical shapes of 16 or 20 mm in diameter using EDR3 films in the same gamma knife QA phantom. Plans for ten SRS cases with single and multiple lesions were created in gamma knife plans and Pinnacle plans. The external beam plans had enlarged field size by 2-mm and used single conformal full circle arc for solitary lesion and none coplanar arcs/beams for multiple lesions. Coverage, conformity index, dose to critical organs, and integral dose to the brain and nearby critical structures were compared on all plans. Structures and dose matrices were registered in a Velocity deformable image registration system. Results: Single full circle arc from Elekta beam-modulate MLC (4-mm leaf thickness) and agility MLC (5-mm leaf thickness) have larger penumbra and less flatness than that of Gamma Knife single shot. None-coplanar arcs or beams were required to achieve similar dose distribution. In general, Gamma Knife plans provided significant less integral dose than that of linac-based plans. Benefits of IMRT and VMAT versus gamma Knife and conformal arcs were not significant. Conclusion: Our dose measurement and treatment planning evaluation clearly demonstrated dose distribution differences amount current popular SRS modalities for small solitary and multiple brain lesions. The trend of using MLC shape beams or arcs to replace conventional cones should be revisited in order to keep lower integral dose if the late correlates with some radiation-induced side effects. Pilot grant from Elekta LLC.

  11. Establishing a process of irradiating small animal brain using a CyberKnife and a microCT scanner

    SciTech Connect (OSTI)

    Kim, Haksoo; Welford, Scott; Fabien, Jeffrey; Zheng, Yiran; Yuan, Jake; Brindle, James; Yao, Min; Lo, Simon; Wessels, Barry; Machtay, Mitchell; Sohn, Jason W.; Sloan, Andrew


    Purpose: Establish and validate a process of accurately irradiating small animals using the CyberKnife G4 System (version 8.5) with treatment plans designed to irradiate a hemisphere of a mouse brain based on microCT scanner images. Methods: These experiments consisted of four parts: (1) building a mouse phantom for intensity modulated radiotherapy (IMRT) quality assurance (QA), (2) proving usability of a microCT for treatment planning, (3) fabricating a small animal positioning system for use with the CyberKnife's image guided radiotherapy (IGRT) system, and (4)in vivo verification of targeting accuracy. A set of solid water mouse phantoms was designed and fabricated, with radiochromic films (RCF) positioned in selected planes to measure delivered doses. After down-sampling for treatment planning compatibility, a CT image set of a phantom was imported into the CyberKnife treatment planning system—MultiPlan (ver. 3.5.2). A 0.5 cm diameter sphere was contoured within the phantom to represent a hemispherical section of a mouse brain. A nude mouse was scanned in an alpha cradle using a microCT scanner (cone-beam, 157 × 149 pixels slices, 0.2 mm longitudinal slice thickness). Based on the results of our positional accuracy study, a planning treatment volume (PTV) was created. A stereotactic body mold of the mouse was “printed” using a 3D printer laying UV curable acrylic plastic. Printer instructions were based on exported contours of the mouse's skin. Positional reproducibility in the mold was checked by measuring ten CT scans. To verify accurate dose delivery in vivo, six mice were irradiated in the mold with a 4 mm target contour and a 2 mm PTV margin to 3 Gy and sacrificed within 20 min to avoid DNA repair. The brain was sliced and stained for analysis. Results: For the IMRT QA using a set of phantoms, the planned dose (6 Gy to the calculation point) was compared to the delivered dose measured via film and analyzed using Gamma analysis (3% and 3 mm). A passing rate of 99% was measured in areas of above 40% of the prescription dose. The final inverse treatment plan was comprised of 43 beams ranging from 5 to 12.5 mm in diameter (2.5 mm size increments are available up to 15 mm in diameter collimation). Using the Xsight Spine Tracking module, the CyberKnife system could not reliably identify and track the tiny mouse spine; however, the CyberKnife system could identify and track the fiducial markers on the 3D mold.In vivo positional accuracy analysis using the 3D mold generated a mean error of 1.41 mm ± 0.73 mm when fiducial markers were used for position tracking. Analysis of the dissected brain confirmed the ability to target the correct brain volume. Conclusions: With the use of a stereotactic body mold with fiducial markers, microCT imaging, and resolution down-sampling, the CyberKnife system can successfully perform small-animal radiotherapy studies.

  12. SU-E-T-104: Development of 3 Dimensional Dosimetry System for Gamma Knife

    SciTech Connect (OSTI)

    Yoon, K; Kwak, J; Cho, B; Lee, D; Ahn, S


    Purpose: The aim of this study was to develop a new 3 dimensional dosimetry system to verify the dosimetric accuracy of Leksell Gamma Knife-Perfexion™ (LGK) (Elekta, Norcross, GA). Methods: We designed and manufactured a lightweight dosimetry instrument to be equipped with the head frame to LGK. It consists of a head phantom, a scintillator, a CCD camera and a step motor. The 10×10 cm2 sheet of Gd2O3;Tb phosphor or Gafchromic EBT3 film was located at the center of the 16 cm diameter hemispherical PMMA, the head phantom. The additional backscatter compensating material of 1 cm thick PMMA plate was placed downstream of the phosphor sheet. The backscatter plate was transparent for scintillation lights to reach the CCD camera with 1200×1200 pixels by 5.2 um pitch. With This equipment, 300 images with 0.2 mm of slice gap were acquired under three collimator setups (4mm, 8mm and 16mm), respectively. The 2D projected doses from 3D distributions were compared with the exposured film dose. Results: As all doses normalized by the maximum dose value in 16 mm setup, the relative differences between the equipment dose and film dose were 0.2% for 4mm collimator and 0.5% for 8mm. The acquisition of 300 images by the equipment took less than 3 minutes. Conclusion: The new equipment was verified to be a good substitute to radiochromic film, with which required more time and resources. Especially, the new methods was considered to provide much convenient and faster solution in the 3D dose acquisition for LGK.

  13. Long-Term Results for Trigeminal Schwannomas Treated With Gamma Knife Surgery

    SciTech Connect (OSTI)

    Hasegawa, Toshinori, E-mail:; Kato, Takenori; Iizuka, Hiroshi; Kida, Yoshihisa


    Purpose: Surgical resection is considered the desirable curative treatment for trigeminal schwannomas. However, complete resection without any complications remains challenging. During the last several decades, stereotactic radiosurgery (SRS) has emerged as a minimally invasive treatment modality. Information regarding long-term outcomes of SRS for patients harboring trigeminal schwannomas is limited because of the rarity of this tumor. The aim of this study was to evaluate long-term tumor control and functional outcomes in patients harboring trigeminal schwannomas treated with SRS, specifically with gamma knife surgery (GKS). Methods and Materials: Fifty-three patients harboring trigeminal schwannomas treated with GKS were evaluated. Of these, 2 patients (4%) had partial irradiation of the tumor, and 34 patients (64%) underwent GKS as the initial treatment. The median tumor volume was 6.0 cm{sup 3}. The median maximum and marginal doses were 28 Gy and 14 Gy, respectively. Results: The median follow-up period was 98 months. On the last follow-up image, 7 patients (13%) had tumor enlargement, including the 2 patients who had partial treatment. Excluding the 2 patients who had partial treatment, the actuarial 5- and 10-year progression-free survival (PFS) rates were 90% and 82%, respectively. Patients with tumors compressing the brainstem with deviation of the fourth ventricle had significantly lower PFS rates. If those patients with tumors compressing the brainstem with deviation of the fourth ventricle are excluded, the actuarial 5- and 10-year PFS rates increased to 95% and 90%, respectively. Ten percent of patients had worsened facial numbness or pain in spite of no tumor progression, indicating adverse radiation effect. Conclusions: GKS can be an acceptable alternative to surgical resection in patients with trigeminal schwannomas. However, large tumors that compress the brainstem with deviation of the fourth ventricle should be surgically removed first and then treated with GKS when necessary.

  14. A kinetic model of tumor growth and its radiation response with an application to Gamma Knife stereotactic radiosurgery

    E-Print Network [OSTI]

    Watanabe, Yoichi; Leder, Kevin Z; Hui, Susanta K


    We developed a mathematical model to simulate the growth of tumor volume and its response to a single fraction of high dose irradiation. We made several key assumptions of the model. Tumor volume is composed of proliferating (or dividing) cancer cells and non-dividing (or dead) cells. Tumor growth rate (or tumor volume doubling time, Td) is proportional to the ratio of the volumes of tumor vasculature and the tumor. The vascular volume grows slower than the tumor by introducing the vascular growth retardation factor, theta. Upon irradiation the proliferating cells gradually die over a fixed time period after irradiation. Dead cells are cleared away with cell clearance time, Tcl. The model was applied to simulate pre-treatment growth and post-treatment radiation response of rat rhabdomyosarcoma tumor and metastatic brain tumors of five patients who were treated by Gamma Knife stereotactic radiosurgery (GKSRS). By selecting appropriate model parameters, we showed the temporal variation of the tumors for both th...

  15. SU-E-T-476: Quality Assurance for Gamma Knife Perfexion Using the Exradin W1 Plastic Scintillation Detector

    SciTech Connect (OSTI)

    Pino, R; Therriault-Proulx, F; Yang, J; Beddar, S


    Purpose: To perform dose profile and output factor measurements for the Exradin W1 plastic scintillation detector (PSD) for the Gamma Knife Perfexion (GKP) collimators in a Lucy phantom and to compare these values to an Exradin A16 ion chamber, EBT3 radiochromic film and treatment planning system (TPS) data. Methods: We used the Exradin W1 PSD which has a small volume, near-water equivalent sensitive element. It has also been shown to be energy independent. This new detector is manufactured and distributed by Standard Imaging, Inc. Measurements were performed for all three collimators (4 mm, 8 mm and 16 mm) for the GKP. The Lucy phantom with the PSD inserted was moved in small steps to acquire profiles in all three directions. EBT3 film was inserted in the Lucy phantom and exposed to a single shot for each collimator. Relative output factors were measured using the three detectors while profiles acquired with the PSD were compared to the ones measured with EBT3 radiochromic film. Results: Measured output factors relative to the largest collimator are as followsCollimator PS EBT3 A1616mm 1.000 1.000 1.0008mm 0.892 0.881 0.8834mm 0.795 0.793 0.727 The nominal (vendor) OFs for GKP are 1.000, 0.900, and 0.814, for collimators 16 mm, 8 mm and 4 mm, respectively. There is excellent agreement between all profiles measured with the PSD and EBT3 as well as with the TPS data provided by the vendor. Conclusion: Output factors measured with the W1 were consistent with the ones measured with EBT3 and A16 ion chamber. Measured profiles are in excellent agreement. The W1 detector seems well suited for beam QA for Gamma Knife due to its dosimetric characteristics. Sam Beddar would like to disclose a NIH/NCI SBIR Phase II grant (2R44CA153824-02A1) with Standard Imaging, Title: “Water-Equivalent Plastic Scintillation Detectors for Small Field Radiotherapy”.

  16. Percentage depth dose distributions in inhomogeneous phantoms with lung and bone equivalent media for small fields of CyberKnife

    E-Print Network [OSTI]

    Lee, Chung Il; Yoon, Sei-Chul; Suh, Tae Suk; Hong, Seung-Woo; Min, Kyung Joo; Lee, Sang Deok; Chung, Su Mi; Jung, Jae-Yong


    The percentage depth dose distributions in inhomogeneous phantoms with lung and bone equivalent media are studied. For lung equivalent media a Balsa wood is used, and for a soft bone equivalent media a compound material with epoxy resin, hardener and calcium carbonate is used. Polystyrene slabs put together with these materials are used as an inhomogeneous phantom. Dose measurements are performed with Gafchromic EBT film by using photon beams from 6MV CyberKnife at the Seoul Uridul Hospital. The cone sizes of the photon beams are varied from 5, 10 to 30 mm. As a simulation tool GEANT4 Monte Carlo code v9.4.p02 is used. When the Balsa wood is inserted in the phantom, the dose measured with EBT film is found to be significantly different from the dose without the EBT film in and beyond the Balsa wood region, particularly for small field sizes. On the other hand, when the soft bone equivalent material is inserted in the phantom, discrepancy between the dose measured with EBT film and the dose without EBT film ca...

  17. Characterization of radiation beams used to determinate the correction factor for a CyberKnife® unit reference field using ionization chambers

    SciTech Connect (OSTI)

    Aragón-Martínez, Nestor Massillon-JL, Guerda; Gómez-Muñoz, Arnulfo


    This paper aimed to characterize a 6 MV x-ray beam from a Varian® iX linear accelerator in order to obtain the correction factors needed by the IAEA/AAPM new formalism{sup 1}. The experiments were performed in a liquid water phantom under different irradiation conditions: a) Calibration of the reference field of 10 cm × 10 cm at 90 cm SSD and 10 cm depth was carried out according to the TRS-398 protocol using three ionization chambers (IC) calibrated in different reference laboratory and b) Measurement of the absorbed dose rate at 70 cm SSD and 10 cm depth in a 10 cm × 10 cm and 5.4 cm × 5.4 cm fields was obtained in order to simulate the CyberKnife® conditions where maximum distance between the source and the detector is equal to 80 cm and the maximum field size is 6 cm diameter. Depending where the IC was calibrated, differences between 0.16% and 2.24% in the absorbed dose rate measured in the 10 cm × 10 cm field at 90 cm SSD were observed, while for the measurements at 70 cm SSD, differences between 1.27% and 3.88% were obtained. For the 5.4 cm × 5.4 cm field, the absorbed dose measured with the three ICs varies between 1.37% and 3.52%. The increase in the difference on the absorbed dose when decreasing the SSD could possibly be associated to scattering radiation generated from the collimators and/or the energy dependence of the ionization chambers to low-energy radiation. The results presented in this work suggest the importance of simulating the CyberKnife® conditions using other linear accelerator for obtaining the correction factors as proposed by the IAEA/AAPM new formalism in order to measure the absorbed dose with acceptable accuracy.

  18. Semiquantitative Analysis Using Thallium-201 SPECT for Differential Diagnosis Between Tumor Recurrence and Radiation Necrosis After Gamma Knife Surgery for Malignant Brain Tumors

    SciTech Connect (OSTI)

    Matsunaga, Shigeo; Shuto, Takashi; Takase, Hajime; Ohtake, Makoto; Tomura, Nagatsuki; Tanaka, Takahiro; Sonoda, Masaki


    Purpose: Semiquantitative analysis of thallium-201 chloride single photon emission computed tomography ({sup 201}Tl SPECT) was evaluated for the discrimination between recurrent brain tumor and delayed radiation necrosis after gamma knife surgery (GKS) for metastatic brain tumors and high-grade gliomas. Methods and Materials: The medical records were reviewed of 75 patients, including 48 patients with metastatic brain tumor and 27 patients with high-grade glioma who underwent GKS in our institution, and had suspected tumor recurrence or radiation necrosis on follow-up neuroimaging and deteriorating clinical status after GKS. Analysis of {sup 201}Tl SPECT data used the early ratio (ER) and the delayed ratio (DR) calculated as tumor/normal average counts on the early and delayed images, and the retention index (RI) as the ratio of DR to ER. Results: A total of 107 tumors were analyzed with {sup 201}Tl SPECT. Nineteen lesions were removed surgically and histological diagnoses established, and the other lesions were evaluated with follow-up clinical and neuroimaging examinations after GKS. The final diagnosis was considered to be recurrent tumor in 65 lesions and radiation necrosis in 42 lesions. Semiquantitative analysis demonstrated significant differences in DR (P=.002) and RI (P<.0001), but not in ER (P=.372), between the tumor recurrence and radiation necrosis groups, and no significant differences between metastatic brain tumors and high-grade gliomas in all indices (P=.926 for ER, P=.263 for DR, and P=.826 for RI). Receiver operating characteristics analysis indicated that RI was the most informative index with the optimum threshold of 0.775, which provided 82.8% sensitivity, 83.7% specificity, and 82.8% accuracy. Conclusions: Semiquantitative analysis of {sup 201}Tl SPECT provides useful information for the differentiation between tumor recurrence and radiation necrosis in metastatic brain tumors and high-grade gliomas after GKS, and the RI may be the most valuable index for this purpose.

  19. Gamma Knife Stereotactic Radiosurgery as Salvage Therapy After Failure of Whole-Brain Radiotherapy in Patients With Small-Cell Lung Cancer

    SciTech Connect (OSTI)

    Harris, Sunit; Chan, Michael D.; Lovato, James F.; Ellis, Thomas L.; Tatter, Stephen B.; Bourland, J. Daniel; Munley, Michael T.; Guzman, Allan F. de; Shaw, Edward G.; Urbanic, James J.; McMullen, Kevin P.


    Purpose: Radiosurgery has been successfully used in selected cases to avoid repeat whole-brain irradiation (WBI) in patients with multiple brain metastases of most solid tumor histological findings. Few data are available for the use of radiosurgery for small-cell lung cancer (SCLC). Methods and Materials: Between November 1999 and June 2009, 51 patients with SCLC and previous WBI and new brain metastases were treated with GammaKnife stereotactic radiosurgery (GKSRS). A median dose of 18 Gy (range, 10-24 Gy) was prescribed to the margin of each metastasis. Patients were followed with serial imaging. Patient electronic records were reviewed to determine disease-related factors and clinical outcomes after GKSRS. Local and distant brain failure rates, overall survival, and likelihood of neurologic death were determined based on imaging results. The Kaplan-Meier method was used to determine survival and local and distant brain control. Cox proportional hazard regression was performed to determine strength of association between disease-related factors and survival. Results: Median survival time for the entire cohort was 5.9 months. Local control rates at 1 and 2 years were 57% and 34%, respectively. Distant brain failure rates at 1 and 2 years were 58% and 75%, respectively. Fifty-three percent of patients ultimately died of neurologic death. On multivariate analysis, patients with stable (hazard ratio [HR] = 2.89) or progressive (HR = 6.98) extracranial disease (ECD) had worse overall survival than patients without evidence of ECD (p = 0.00002). Concurrent chemotherapy improved local control (HR = 89; p = 0.006). Conclusions: GKSRS represents a feasible salvage option in patients with SCLC and brain metastases for whom previous WBI has failed. The status of patients' ECD is a dominant factor predictive of overall survival. Local control may be inferior to that seen with other cancer histological results, although the use of concurrent chemotherapy may help to improve this.

  20. SU-E-T-587: Monte Carlo Versus Ray-Tracing for Treatment Planning Involving CNS Tumors On the MultiPlan System for CyberKnife Radiosurgery

    SciTech Connect (OSTI)

    Forbang, R Teboh


    Purpose: MultiPlan, the treatment planning system for the CyberKnife Robotic Radiosurgery system offers two approaches to dose computation, namely Ray-Tracing (RT), the default technique and Monte Carlo (MC), an option. RT is deterministic, however it accounts for primary heterogeneity only. MC on the other hand has an uncertainty associated with the calculation results. The advantage is that in addition, it accounts for heterogeneity effects on the scattered dose. Not all sites will benefit from MC. The goal of this work was to focus on central nervous system (CNS) tumors and compare dosimetrically, treatment plans computed with RT versus MC. Methods: Treatment plans were computed using both RT and MC for sites covering (a) the brain (b) C-spine (c) upper T-spine (d) lower T-spine (e) L-spine and (f) sacrum. RT was first used to compute clinically valid treatment plans. Then the same treatment parameters, monitor units, beam weights, etc., were used in the MC algorithm to compute the dose distribution. The plans were then compared for tumor coverage to illustrate the difference if any. All MC calculations were performed at a 1% uncertainty. Results: Using the RT technique, the tumor coverage for the brain, C-spine (C3–C7), upper T-spine (T4–T6), lower T-spine (T10), Lspine (L2) and sacrum were 96.8%, 93.1%, 97.2%, 87.3%, 91.1%, and 95.3%. The corresponding tumor coverage based on the MC approach was 98.2%, 95.3%, 87.55%, 88.2%, 92.5%, and 95.3%. It should be noted that the acceptable planning target coverage for our clinical practice is >95%. The coverage can be compromised for spine tumors to spare normal tissues such as the spinal cord. Conclusion: For treatment planning involving the CNS, RT and MC appear to be similar for most sites but for the T-spine area where most of the beams traverse lung tissue. In this case, MC is highly recommended.

  1. Predictive Parameters of CyberKnife Fiducial-less (XSight Lung) Applicability for Treatment of Early Non-Small Cell Lung Cancer: A Single-Center Experience

    SciTech Connect (OSTI)

    Bahig, Houda; Campeau, Marie-Pierre; Vu, Toni; Doucet, Robert; Béliveau Nadeau, Dominic [Radiation Oncology Department, Centre Hospitalier de l'Université de Montréal, Montréal, Quebec (Canada); Fortin, Bernard [Radiation Oncology Department, Maisonneuve-Rosemont Hospital, Montréal, Quebec (Canada); Roberge, David; Lambert, Louise; Carrier, Jean-François [Radiation Oncology Department, Centre Hospitalier de l'Université de Montréal, Montréal, Quebec (Canada); Filion, Edith, E-mail: [Radiation Oncology Department, Centre Hospitalier de l'Université de Montréal, Montréal, Quebec (Canada)


    Purpose: To determine which parameters allow for CyberKnife fiducial-less tumor tracking in stereotactic body radiation therapy (SBRT) for early-stage non-small cell lung cancer. Methods and Materials: A total of 133 lung SBRT patients were preselected for direct soft-tissue tracking based on manufacturer recommendations (peripherally located tumors ?1.5 cm with a dense appearance) and staff experience. Patients underwent a tumor visualization test to verify adequate detection by the tracking system (orthogonal radiographs). An analysis of potential predictors of successful tumor tracking was conducted looking at: tumor stage, size, histology, tumor projection on the vertebral column or mediastinum, distance to the diaphragm, lung-to-soft tissue ratio, and patient body mass index. Results: Tumor visualization was satisfactory for 88 patients (66%) and unsatisfactory for 45 patients (34%). Median time to treatment start was 6 days in the success group (range, 2-18 days) and 15 days (range, 3-63 days) in the failure group. A stage T2 (P=.04), larger tumor size (volume of 15.3 cm{sup 3} vs 6.5 cm{sup 3} in success and failure group, respectively) (P<.0001), and higher tumor density (0.86 g/cm{sup 3} vs 0.79 g/cm{sup 3}) were predictive of adequate detection. There was a 63% decrease in failure risk with every 1-cm increase in maximum tumor dimension (relative risk for failure = 0.37, CI=0.23-0.60, P=.001). A diameter of 3.6 cm predicted a success probability of 80%. Histology, lung-to-soft tissue ratio, distance to diaphragm, patient's body mass index, and tumor projection on vertebral column and mediastinum were not found to be predictive of success. Conclusions: Tumor size, volume, and density were the most predictive factors of a successful XSight Lung tumor tracking. Tumors >3.5 cm have ?80% chance of being adequately visualized and therefore should all be considered for direct tumor tracking.


    E-Print Network [OSTI]

    Palanker, Daniel

    ,* ARND GANDORFER, MD,* DANIEL PALANKER, PHD, ANSELM KAMPIK, MD* Purpose: To evaluate the advantages and/or "hot" coagulation, thus improving the precision, safety, and ergonomics of vitreoretinal

  3. Giovanni Battista Bracelli. Knife Grinders. 1624.

    E-Print Network [OSTI]

    " deep. Pop Art Conceptual Art Joseph Kosuth One and Three Hammers (English occur from the 17th century onward. Kinetic Art History Prelude Changes in art in the 20th, in 1923. It is probably the largest single project in modern art and may also

  4. Casimir force at a knife's edge

    SciTech Connect (OSTI)

    Graham, Noah [Department of Physics, Middlebury College, Middlebury, Vermont 05753 (United States); Shpunt, Alexander; Rahi, Sahand Jamal; Kardar, Mehran [Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Emig, Thorsten [Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Institut fuer Theoretische Physik, Universitaet zu Koeln, Zuelpicher Strasse 77, 50937 Koeln (Germany); Laboratoire de Physique Theorique et Modeles Statistiques, CNRS UMR 8626, Batiment 100, Universite Paris-Sud, 91405 Orsay cedex (France); Jaffe, Robert L. [Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Center for Theoretical Physics and Laboratory for Nuclear Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)


    The Casimir force has been computed exactly for only a few simple geometries, such as infinite plates, cylinders, and spheres. We show that a parabolic cylinder, for which analytic solutions to the Helmholtz equation are available, is another case where such a calculation is possible. We compute the interaction energy of a parabolic cylinder and an infinite plate (both perfect mirrors), as a function of their separation and inclination, H and {theta}, and the cylinder's parabolic radius R. As H/R{yields}0, the proximity force approximation becomes exact. The opposite limit of R/H{yields}0 corresponds to a semi-infinite plate, where the effects of edge and inclination can be probed.

  5. Knife-Edge Scanning Microscope Mouse Brain Atlas In Vector Graphics For Enhanced Performance 

    E-Print Network [OSTI]

    Choi, Jinho


    loading time. Furthermore, we employed an open-source mapping JavaScript library, OpenLayers API [12], to visualize the KESM data sets on the web in place of the Google Maps API. Just like Google Maps API, OpenLayers API provides essential functions... and implemented the graphical user interface (GUI) using Flash, Java and AJAX (dHTML and JavaScript). As a result, they provide rapid web-based 19 navigation and visualization, aiming to provide a virtual microscopy service. They also provide 3D visualization...

  6. Acquisition and reconstruction of brain tissue using knife-edge scanning microscopy 

    E-Print Network [OSTI]

    Mayerich, David Matthew


    . This required developing and implementing processes for stage motion control, alignment, focusing, illumination, and image acquisition. I was able to retrieve high- resolution data sets from both Nissl and Golgi stained tissue to show the alignment... ....................................................................................................4 A. Data Acquisition.................................................................................................4 B. Reconstruction....................................................................................................5...

  7. Automated Neurovascular Tracing and Analysis of the Knife-Edge Scanning Microscope India Ink Data Set 

    E-Print Network [OSTI]

    Yang, Wenjie


    the large volume of data. To solve these issues, a novel automated neurovascular tracing and data analysis method with less processing time and high accuracy is developed in this thesis. First, an automated seed point selection algorithm was described in my...

  8. Real-Time Image Error Detection in Knife-Edge Scanning Microscope 

    E-Print Network [OSTI]

    Zhang, Wencong


    Research about the microstructure of the brain provides important information to help understand the functions of the brain. In order to investigate large volume, high-resolution data of mouse brains, researchers from Brain ...

  9. Knife-Edge Scanning Microscopy: High-throughput Imaging and Analysis of

    E-Print Network [OSTI]

    Choe, Yoonsuck

    : High-throughput Imaging and Analysis of Massive Volumes of Biological Microstructures Author 1 Yoonsuck Choe Author 1 - Address Department of Computer Science, Texas A&M Univ. 3112 TAMU, College Station, TX, 77843-3112, USA Author 1 - Email Author 1 - Tel +1 979 845 5466 Author 2 Louise C. Abbott

  10. SU-E-T-476: Quality Assurance for Gamma Knife Perfexion Using...

    Office of Scientific and Technical Information (OSTI)

    phantom and to compare these values to an Exradin A16 ion chamber, EBT3 radiochromic film and treatment planning system (TPS) data. Methods: We used the Exradin W1 PSD which has...

  11. Semi-Automated Reconstruction of Vascular Networks in Knife-Edge Scanning Microscope Mouse Brain Data 

    E-Print Network [OSTI]

    Dileepkumar, Ananth


    , vascular reconstruction techniques focus either on tracing vessels at the macro-level in a whole brain or tracing micro vessels in a small section of the brain. In this thesis, I attempt to develop a new, more targeted approach to semi-automatically trace a...

  12. SU-E-T-476: Quality Assurance for Gamma Knife Perfexion Using...

    Office of Scientific and Technical Information (OSTI)

    States); Therriault-Proulx, F; Yang, J; Beddar, S University of Texas MD Anderson Cancer Center, Houston, TX (United States) 07 ISOTOPES AND RADIATION SOURCES; COLLIMATORS;...

  13. Choice of phantom materials for dosimetry of Leksell Gamma Knife unit: A Monte Carlo study

    E-Print Network [OSTI]

    Yu, Peter K.N.

    .74% of hydrogen by mass , perspex (density 1.19 g/cm3 , 59.98% of carbon, 31.96% of oxygen and 1.19% of hydrogen by mass , water, and water with a skull bone bone density 1.85 g/cm3 , 6.40% of hydrogen, 27.80% of carbon equivalent material,2 with an attenuation coefficient 0.0063 mm 1 at the energy 1.25 MeV, in all calculations

  14. SU-E-T-476: Quality Assurance for Gamma Knife Perfexion Using the Exradin

    Office of Scientific and Technical Information (OSTI)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of NaturalDukeWakefield MunicipalTechnical Report:Speeding accessby aLEDSpeeding FINAL2-4260Earth784216W1 Plastic Scintillation

  15. SU-E-T-476: Quality Assurance for Gamma Knife Perfexion Using the Exradin

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 Outreach Home RoomPreservation of Fe(II) byMultidayAlumni > The2/01/12 PageInformation DoE PagesW1 Plastic

  16. Alternative and Emerging Technologies for an Energy-Efficient, Water-Efficient, and Low-Pollution Textile Industry

    E-Print Network [OSTI]

    Hasanbeigi, Ali


    are: horizontal padders, kiss roller coating, knife-over-roller coating, knife on air, and slot applicators.

  17. The Materiality and ‘Enchantment’ of the Gebel el-Arak Knife and the Gerzean Flint Blade Production

    E-Print Network [OSTI]

    Kim, Patricia E.


    a similar reading of the design of the blade as a landscape.structure, the design of the flint blade has a high valueof the design and the color of the blade (Figure 11) appear

  18. Exploration, Registration, and Analysis of High-Throughput 3D Microscopy Data from the Knife-Edge Scanning Microscope 

    E-Print Network [OSTI]

    Sung, Chul


    resolution methods like diffusion MRI [8, 27, 76, 94] on the one hand and small- scale, higher resolution methods like SBF-SEM [18] on the other hand. So, mapping our KESM data sets to a standard coordinate system for the mouse brain provides deeper... . . . . . . . . . . . . . . . . . . . . . . . . 71 6.1.5 Data Transmission and Visualization . . . . . . . . . . . . . . 71 6.2 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 6.3 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 7...


    E-Print Network [OSTI]

    Fay, Noah

    ), knife, fork, spoon, bowl ____ Sunscreen (SPF 15 or greater) and protective lip balm ____ Toiletries

  20. Cell Detection in Knife-Edge Scanning Microscopy Images of Nissl-stained Mouse and Rat Brain Samples Using Random Forests 

    E-Print Network [OSTI]

    Lal Das, Shashwat


    of images, use heuristics that are time consuming to develop, or do not generalize well to three dimensional data. In this thesis, I propose two methods based on random forests for detecting neuron bodies in the rat and mouse brain KESM data. The proposed...

  1. Hartz, fieldsafety, East Greenland 19-05-06 6 EXAMPLES OF WHAT TO BRING

    E-Print Network [OSTI]

    Hartz, Ebbe

    personal washing gear sunscreen: skin and lips knife sunglasses 2 sleeping bags (-10oC) Pillow cover (fill

  2. Savings Project: Insulate and Air Seal Floors Over Unconditioned...

    Broader source: (indexed) [DOE]

    insulation Wire fasteners Tape measure Sharp utility knife Caulk and foam sealant Caulk gun Stepladder Straightedge Respirator or dust mask Eye protection Protective clothing,...


    E-Print Network [OSTI]

    Authors, Various


    injection molding and roll coating. Since this aspect of thecoating Curtain Coating Roll coating, reverse and direct·important, Knife and roll coating have difficulty building

  4. Synthesis of arginine, tyrosine, and phenylalanine by Lactobacillus arabinosus 

    E-Print Network [OSTI]

    Ory, Robert Louis


    .1 %, respectively. Carcass yields were 65.4% knife separable lean, 7.6% knife separable fat, and 23.6% bone. Ten muscles were designated as major subprimals and constituted 48.2% of the hot carcass. Total aerobic plate counts of steaks ii-increased with ii...

  5. Visualization of individual DNA molecules in a small-scale coating flow

    E-Print Network [OSTI]

    Natelson, Douglas

    Visualization of individual DNA molecules in a small- scale coating flow Rajat Duggal and Matteo roll and a stationary glass knife. The roll picks up a thin layer of liquid from a pool and drags it to the knife, establishing a bead delineated by two menisci. At low roll speed the flow is premetered

  6. Non-reclosing pressure relief device for vacuum systems

    DOE Patents [OSTI]

    Swansiger, W.A.


    A non-reclosing overpressure protection device such as a rupture disc provides a non-reclosing opening upon forcible contact with a knife blade. A bellows, having an inlet capable of being sealably connected to a source of pressure (the vacuum system) and an outlet containing the rupture disc, transmits the pressure in the system to the disc. The bellows maintains the disc away from the knife when the pressure is below an overpressure amount, and carries the disc to a position when the pressure is above an overpressure amount where the disc is ruptured by the knife. 6 figures.


    E-Print Network [OSTI]

    is prohibited. · Weapons (knife, gun, etc) are not permitted on the property at any time. FACILITY RULES of equipment beyond its designed purpose are prohibited. · Chalk is prohibited in the facility. · Spitting

  8. The Get Girl

    E-Print Network [OSTI]

    Cataluna, Lee Dorothy Alohakeao


    the hula show’s resident coconut tree climber. I guess sheMokihana said. “Besides, the coconuts were just props. Heplastic knife. No way a coconut tree can make a new coconut

  9. Core-Shell Nanopillar Array Solar Cells using Cadmium Sulfide Coating on Indium Phosphide Nanopillars

    E-Print Network [OSTI]

    Tu, Bor-An Clayton


    using roll-to-roll methods: Knife-over- edge coating, slot-die coating and screen printing,” Solar Energy Materials andCells using Cadmium Sulfide Coating on Indium Phosphide

  10. A numerical study of compressible flow in labyrinth seals with rub grooves 

    E-Print Network [OSTI]

    Adams, Richard Gordon


    A labyrinth sea] uses a series of knife blades and cavities to create a high frictional flow path that turns a pressure potential into kinetic energy, which is then dissipated as heat. An existing numerical model is extended ...

  11. Automated counting of cell bodies using Nissl stained cross-sectional images 

    E-Print Network [OSTI]

    D'Souza, Aswin Cletus


    segments, counts, and helps visualize the various cell bodies present in a sample mouse brain, by analyzing the images produced by the Knife-Edge Scanning Microscope (KESM) at the Brain Networks Laboratory. The process is described essentially in five...

  12. SMA Actuator Tutorial Prof. Carmel Majidi

    E-Print Network [OSTI]

    , pliers, an Exacto knife, and/or access to a CO2 laser (e.g. Epilog laser in the MechE Machine Shop of 4950. With an Exacto knife or CO2 laser, cut the outline of the actuator as shown. Step 3 ­ Using-stick substrate on which to pattern the 4950 foam adhesive. Step 2 ­ Cover the non-stick substrate with a sheet

  13. 3D Printing Prof. Hank Dietz

    E-Print Network [OSTI]

    Dietz, Henry G. "Hank"

    #12;Our 3D Printer It's a MakerGear M2, cost about $1700 We extrude 1.75mm diameter PLA filament3D Printing Prof. Hank Dietz TCMS, March 14, 2014 University of Kentucky Electrical & Computer/Craft: paper moves in Y, knife in X EDM/Laser: X/Y bed, vaporizes material #12;Subtractive 3D CNC: Computer

  14. Method Of Making An Ultracapacitor Electrode

    DOE Patents [OSTI]

    Wei, Chang (Niskayuna, NY); Jerabek, Elihu Calvin (Glenmont, NY); DeJager, Katherine Dana (BJ Goes, NL); LeBlanc, Jr., Oliver Harris (Schenectady, NY)


    A paste of organic solvent with dissolved organic salt and active carbon is formed and a uniform film of the paste is applied onto a substrate by casting the paste into a clearance between a knife blade and the substrate. The paste is evaporated to form a paste electrode for an ultracapacitor.

  15. Method of making an ultracapacitor electrode

    DOE Patents [OSTI]

    Wei, Chang (Niskayuna, NY); Jerabek, Elihu Calvin (Glenmont, NY); DeJager, Katherine Dana (BJ Goes, NL); LeBlanc, Jr., Oliver Harris (Schenectady, NY)


    A paste of organic solvent with dissolved organic salt and active carbon is formed and a uniform film of the paste is applied onto a substrate by casting the paste into a clearance between a knife blade and the substrate. The paste is evaporated to form a paste electrode for an ultracapacitor.

  16. Lesson Summary In this activity, students build and decorate their own

    E-Print Network [OSTI]

    Mojzsis, Stephen J.

    Materials Each Student Needs: · 1- 7 inch Oatmeal container · 1- 3 x 5 Index card · 1 Exact-o knife · 1 Construction paper · Masking tape · 1 Incandescent light bulb · Thick black markers · Markers, aluminum foil or atmosphere. #12;Group Size 1 Expendable Cost per Group $4 Engineering Connection Spectrographs are used both

  17. Laser EYE SURGERY LASIK and Excimer Lasers

    E-Print Network [OSTI]

    Hansma, Paul

    Laser EYE SURGERY LASIK and Excimer Lasers Michael Hutchins #12;The PROBLEM opia - near sightedness - Laser Assisted in SItu Keratomileusis atomileusis is the procedure of opening the eye and ring the cornea. SIK uses an excimer laser to perform the alterations an er a knife or a femtosecond laser

  18. CRIME IN FLORIDA University of Central Florida PD Florida Department of

    E-Print Network [OSTI]

    Wu, Shin-Tson

    Property Values Change Total Index 428 Total Stolen Murder 0 0 Total Violent 26 262992 Firearm 0 0 Total 00 PRIMARY OFFENSE 2011 2012 Change Firearm 0 0 KnifeCutting Instr 0 0 Murder 0 0 HandsFistsFeet 2 2

  19. brief communications nature methods | VOL.12 NO.4 | APRIL2015 | 319

    E-Print Network [OSTI]

    Cai, Long

    brief communications nature methods | VOL.12 NO.4 | APRIL2015 | 319 these characteristics, allowing blades, was likely considerable. To assess what quality of surface could be obtained if `hot (Supplementary Fig. 1). Using oil for knife lubrication dramatically reduced stick-slip (the periodic sticking

  20. SWS 5716C -Pedology -Spring Semester, 2015 Syllabus for Distance Education (DE)

    E-Print Network [OSTI]

    Ma, Lena

    that will be needed are digging implements (shovels and spades or a hand auger, depending upon the situation faced in exposing the soil profile) and a metric tape measure. A dull knife for digging in the soil and a rag). Some laboratories for on-campus students may be recorded as well, and made accessible to DE students

  1. Evaluation of Perforated Carbonate Cores Under Acid Stimulation 

    E-Print Network [OSTI]

    Diaz, Nerwing Jose


    charge ........................................................................ 5 Fig. 2?Perforating gun and detonation sequence (Economides et al. 1994) ........... 6 Fig. 3?Sources of pressure drop in a perforated system (Bell et al.... 1995) ............. 7 Fig. 4?Mechanical knife perforator (Bell et al. 1995) ............................................. 9 Fig. 5?Bullet gun perforating (Allen and Worzel. 1956) ........................................ 10...

  2. The impact of the threat of violence on selected school districts in Texas 

    E-Print Network [OSTI]

    Neeley, Martha Ann


    assault, robbery, and aggravated assault. Statistics have remained consistent at seven percent to eight percent for students who have been injured or threatened with a weapon such as a gun, knife, or club since 1993. At the middle and high school levels... Design.................................................. 53 Data Collection........................................................... 56 Analysis and Design Techniques................................. 58 vii CHAPTER Page IV RESULTS OF THE STUDY...

  3. The Ohio State University University Policies Page 1 of 4 Workplace Violence, 7.05

    E-Print Network [OSTI]

    , and designed or specially adapted for use as a weapon, or possessed, carried or used as a weapon including, etc.), knife, club, brass knuckles, martial arts weapon, or stun gun. Prohibited items shall. Definitions Term Definition Deadly weapon Any instrument, device or thing capable of inflicting death

  4. East Carolina University Anonymous Crime Reporting Form

    E-Print Network [OSTI]

    Gopalakrishnan, K.

    of weapon used (gun, knife, baseball bat, etc.) _______________________ Was the victim physically injured Part 668 This form is to be completed whenever a designated Campus Security Authority becomes aware, religion, sexual orientation, ethnicity, or disability.) Was a weapon used? Yes No If yes, name the type

  5. Photoperiodic Control of Oestrous Cycles in Syrian Hamsters: Mediation by the Mediobasal Hypothalamus

    E-Print Network [OSTI]

    Zucker, Irving

    Hypothalamus D. Lewis,* D. A. Freeman,* J. Dark,* K. E. Wynne-Edwards and I. Zucker* Departments of *Psychology. Abstract To assess whether the mediobasal hypothalamus (MBH) is necessary for photoperiodic control) of the hypothalamus are critical for the control of pineal-dependent ovarian function (14, 15). Knife cuts ventral

  6. Dynamic Interactions in the Western United States Electricity Spot Markets Christine A. Jerko

    E-Print Network [OSTI]

    are balanced on a knife-edge with weather grid reliability, grid dynamics, transmission dynamicsDynamic Interactions in the Western United States Electricity Spot Markets Christine A. Jerko Economic Research Analyst at Tractebel Electricity & Gas International, Houston, TX James W. Mjelde

  7. The mirror effect: Virginia Woolf's war writings 

    E-Print Network [OSTI]

    Murchison, Marcia Wilkens


    reproach, one that causes her to doubt herself and to revisit her decision to marry Dalloway. As Clarissa watches Peter play with his knife, a symbol of aggression and violence, she reflects on his effect on her. Woolf describes her experience using...

  8. Imaging and Computational Methods for Exploring Sub-cellular Anatomy 

    E-Print Network [OSTI]

    Mayerich, David


    . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.2. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 II KNIFE-EDGE SCANNING MICROSCOPY : : : : : : : : : : : : : 7 2.1. Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2.1.1. KESM Design... . . . . . . . . . . . . . 128 Compression Characteristics . . . . . . . . . . 128 Volume Splatting . . . . . . . . . . . . . . . . 130 Independent-Axis Iteration . . . . . . . . . . . 131 Perspective Projection . . . . . . . . . . . . . 132 6...

  9. The value of ureterocolostomy in the male Felis domestica 

    E-Print Network [OSTI]

    Beamer, Russell James


    , and milk. No dietary supplement was added to the food. Water was availabls at all times. The following instruments were packed and sterilised for each operation: Oae Sard parker knife snd No. 15 blade pour Gaefe fixation forceps Two mosquito forceps...

  10. U.S. Department of the Interior U.S. Geological Survey

    E-Print Network [OSTI]

    Torgersen, Christian

    -based assessment of conventional and continuous oil and gas resources of the Devonian Three Forks Formation fracturing, which stimulates movement of hydrocarbons in tight-oil reservoirs. Approximately 450 million bar Basin Province boundary Bakken TPS Middle Bakken Conventional AU Nesson-Little Knife Continuous Oil AU

  11. Electric plugs--repair or replace The problem

    E-Print Network [OSTI]

    need s New plug­if your old one cannot be used. (Buy one with a UL label) s A screwdriver s A knife How to 1. Cut the cord off at the damaged part (Fig. 1). 2. Slip the plug back on the cord (Fig. 2). 3

  12. 3D Printing Prof. Hank Dietz & Paul Eberhart

    E-Print Network [OSTI]

    Dietz, Henry G. "Hank"

    3D Printing Prof. Hank Dietz & Paul Eberhart September 28, 2013 University of Kentucky Electrical/Craft: paper moves in Y, knife in X EDM/Laser: X/Y bed, vaporizes material #12;Subtractive 3D CNC: Computer "The whole is greater than the sum of its parts." ­ Aristotle #12;Additive 3D Building Material

  13. Supporting Information Cody et al. 10.1073/pnas.1015913108

    E-Print Network [OSTI]

    polymer are embedded in molten sulfur (mp ¼ 117 °C) that is then quenched to solid providing a sample that may be readily microtomed using a diamond knife with samples captured on standard SiO coated TEM grids. The sulfur-embed- ding matrix is removed completely through sublimation. 13C Solid-State Nuclear Magnetic

  14. SCIENCE VOL 304 25 JUNE 2004 1885 1 8 9 2 1 8 9 4 1 8 9 9

    E-Print Network [OSTI]

    billion effort to har- ness energy from nuclear fusion was teeter- ing on a knife edge earlier this week equally determined to play host, more technical studies were car- ried out, followed by a series body, committed it- self on 16 June to creating a new funding body that will support fundamental

  15. Apparatus and method for measuring critical current properties of a coated conductor

    DOE Patents [OSTI]

    Mueller, Fred M. (Los Alamos, NM); Haenisch, Jens (Dresden, DE)


    The transverse critical-current uniformity in a superconducting tape was determined using a magnetic knife apparatus. A critical current I.sub.c distribution and transverse critical current density J.sub.c distribution in YBCO coated conductors was measured nondestructively with high resolution using a magnetic knife apparatus. The method utilizes the strong depression of J.sub.c in applied magnetic fields. A narrow region of low, including zero, magnetic field in a surrounding higher field is moved transversely across a sample of coated conductor. This reveals the critical current density distribution. A Fourier series inversion process was used to determine the transverse J.sub.c distribution in the sample.

  16. Micromachined electrical cauterizer

    DOE Patents [OSTI]

    Lee, A.P.; Krulevitch, P.A.; Northrup, M.A.


    A micromachined electrical cauterizer is disclosed. Microstructures are combined with microelectrodes for highly localized electro cauterization. Using boron etch stops and surface micromachining, microneedles with very smooth surfaces are made. Micromachining also allows for precision placement of electrodes by photolithography with micron sized gaps to allow for concentrated electric fields. A microcauterizer is fabricated by bulk etching silicon to form knife edges, then parallelly placed microelectrodes with gaps as small as 5 {mu}m are patterned and aligned adjacent the knife edges to provide homeostasis while cutting tissue. While most of the microelectrode lines are electrically insulated from the atmosphere by depositing and patterning silicon dioxide on the electric feedthrough portions, a window is opened in the silicon dioxide to expose the parallel microelectrode portion. This helps reduce power loss and assist in focusing the power locally for more efficient and safer procedures. 7 figs.

  17. A high precision, compact electromechanical ground rotation sensor

    SciTech Connect (OSTI)

    Dergachev, V., E-mail: [LIGO Laboratory, California Institute of Technology, MS 100-36, Pasadena, California 91125 (United States); DeSalvo, R. [LIGO Laboratory, California Institute of Technology, MS 100-36, Pasadena, California 91125 (United States) [LIGO Laboratory, California Institute of Technology, MS 100-36, Pasadena, California 91125 (United States); University of Sannio, Garibaldi 107, Benevento 82100 (Italy); Asadoor, M. [Mayfield Senior School, 500 Bellefontaine Street, Pasadena, California 91105 (United States) [Mayfield Senior School, 500 Bellefontaine Street, Pasadena, California 91105 (United States); Oklahoma State University, 219 Student Union, Stillwater, Oklahoma 74074 (United States); Bhawal, A. [Arcadia High School, 180 Campus Drive, Arcadia, California 91007 (United States) [Arcadia High School, 180 Campus Drive, Arcadia, California 91007 (United States); Carnegie Mellon University, 5000 Forbes Ave, Pittsburgh, Pennsylvania 15213 (United States); Gong, P. [Department of Precision Instrument, Tsinghua University, Beijing 100084 (China) [Department of Precision Instrument, Tsinghua University, Beijing 100084 (China); School of Industrial and System Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0205 (United States); Kim, C. [California Institute of Technology, Pasadena, California 91125 (United States)] [California Institute of Technology, Pasadena, California 91125 (United States); Lottarini, A. [Department of Computer Science, University of Pisa, Largo B. Pontecorvo 3, 56127 Pisa (Italy) [Department of Computer Science, University of Pisa, Largo B. Pontecorvo 3, 56127 Pisa (Italy); Department of Computer Science, Columbia University, 1214 Amsterdam Avenue, New York, New York 10027 (United States); Minenkov, Y. [Sezione INFN Tor Vergata, via della Ricerca Scientifica  1, 00133 Roma (Italy)] [Sezione INFN Tor Vergata, via della Ricerca Scientifica  1, 00133 Roma (Italy); Murphy, C. [School of Physics, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, Western Australia 6009 (Australia) [School of Physics, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, Western Australia 6009 (Australia); University of Melbourne Grattan Street, Parkville VIC 3010 (Australia); O'Toole, A. [University of California, Los Angeles, 405 Hilgard Ave, Los Angeles, California 90095 (United States) [University of California, Los Angeles, 405 Hilgard Ave, Los Angeles, California 90095 (United States); Michigan Technological University, 1400 Townsend Dr, Houghton, Michigan 49931 (United States); Peña Arellano, F. E. [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)] [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); and others


    We present a mechanical rotation sensor consisting of a balance pivoting on a tungsten carbide knife edge. These sensors are important for precision seismic isolation systems, as employed in land-based gravitational wave interferometers and for the new field of rotational seismology. The position sensor used is an air-core linear variable differential transformer with a demonstrated noise floor of 1 × 10{sup ?11}m/?( Hz ). We describe the instrument construction and demonstrate low noise operation with a noise floor upper bound of 5.7 × 10{sup ?9} rad /?( Hz ) at 10 mHz and 6.4 × 10{sup ?10} rad /?( Hz ) at 0.1 Hz. The performance of the knife edge hinge is compatible with a behaviorur free of noise from dislocation self-organized criticality.


    E-Print Network [OSTI]

    .1. Treatment of hemp fibres at varied pH levels. Fibre sliver produced by alignment of hemp fibres was mixed with water at varied pH levels in the range pH = 1-7. The suspensions with fibres were incubated for 1 h in a knife mill and passed through a 1 mm sieve. Consecutively, degradation and extraction of wax, water

  19. Coating and curing apparatus and methods

    DOE Patents [OSTI]

    Brophy, Brenor L; Maghsoodi, Sina; Neyman, Patrick J; Gonsalves, Peter R; Hirsch, Jeffrey G; Yang, Yu S


    Disclosed are coating apparatus including flow coating and roll-coating that may be used for uniform sol-gel coating of substrates such as glass, solar panels, windows or part of an electronic display. Also disclosed are methods for substrate preparation, flow coating and roll coating. Lastly systems and methods for skin curing sol-gel coatings deposited onto the surface of glass substrates using a high temperature air-knife are disclosed.

  20. Broiler Chicken Deboning. 

    E-Print Network [OSTI]

    Denton, J.H.; Mellor, D.B.


    made through cartilage or connective tissue where bones and muscles are attached. There is no need to cut any bones except for some small ribs. Use a sharp, 5- to 6-inch, rigid blade knife for these procedures. Use a cutting board that provides...). After the end of the thigh bone has been dislocated, continue to apply pressure to that joint until the ends ofthe thigh bone begin to protrude from the thigh muscle. The thigh bone should now be free from the hip socket, the muscle attachments...

  1. Variable diameter wind turbine rotor blades

    DOE Patents [OSTI]

    Jamieson, Peter McKeich; Hornzee-Jones, Chris; Moroz, Emilian M.; Blakemore, Ralph W.


    A system and method for changing wind turbine rotor diameters to meet changing wind speeds and control system loads is disclosed. The rotor blades on the wind turbine are able to adjust length by extensions nested within or containing the base blade. The blades can have more than one extension in a variety of configurations. A cable winching system, a hydraulic system, a pneumatic system, inflatable or elastic extensions, and a spring-loaded jack knife deployment are some of the methods of adjustment. The extension is also protected from lightning by a grounding system.

  2. Watson Gourmet (2nd edition)

    E-Print Network [OSTI]


    baking. Bake in a moderately hot oven (325°), 10 minutes. EASY DIVINITY MIS. Fay Talley 1 pkg. flavored gelatin 1 c. chopped nuts 1/2 c. grated coconut 3 c. sugar 3/4 c. light com sytup 3/4 c. water 2 egg whites Grease a 9 inch square pan thoroughly... in the nuts and coconut. Quickly pour into pan. Divinity cuts more satisfactorily if you keep dipping your knife into hot water during the cutting process. Makes 5 dozen pieces. OKLAHOMA POPCORN BALLS Shit ley Hastings 3/4 tsp. salt 1/4 c. butter or oleo 3...

  3. Nondestructive evaluation of distributed damage in graphite/epoxy beams using modal parameters 

    E-Print Network [OSTI]

    Kim, Young Ik


    the knife edges on the extensometer. The mechanical testing for each of the eight specimens was performed using a hydraulic closed-loop MTS material test system. The specimens were subjected to quasi-static ramp loading and unloading rate of 150 lbs..., the current values of the internal variables &n each finite element. The values of the internal state variables (IS%) &ndicate the extent and the location of damage. Using a j0/90sj, laminate specimen, mechanical testing and modal test&ng are performed...

  4. The plasma focus as a thruster 

    E-Print Network [OSTI]

    Hardy, Richard Lee


    picture of the TAMU DPF. The length of the center electrode in Figure 2.2 is 30 cm. The axis labeled on Figure 2.1 will be used throughout the rest of this work. 5 Cathode Anode Insulator Knife Edge Capacitor Bank r z Figure 2. 1 Plasma Focus... for the mega amp range. The cathode is the outer electrode. The original plasma focuses in the 1950?s and 1960?s used solid cylinder outer electrodes. A solid outer electrode is problematic because a portion of the gas is pushed out of the way by the moving...

  5. The Caterpillar Coal Gasification Facility 

    E-Print Network [OSTI]

    Welsh, J.; Coffeen, W. G., III



  6. Municipal waste processing apparatus

    DOE Patents [OSTI]

    Mayberry, John L. (Idaho Falls, ID)


    Municipal waste materials are processed by crushing the materials so that pieces of noncombustible material are smaller than a selected size and pieces of combustible material are larger than the selected size. The crushed materials are placed on a vibrating mesh screen conveyor belt having openings which pass the smaller, noncombustible pieces of material, but do not pass the larger, combustible pieces of material. Consecutive conveyors may be connected by an intermediate vibratory plate. An air knife can be used to further separate materials based on weight.

  7. Field application of EMI coatings investigation of coating materials and stylus electroplating protocols for shielded facilities. Final report

    SciTech Connect (OSTI)

    Stephenson, L.D.; Donoho, L.H.


    To maintain reliable electromagnetic interference (EMI) shielding for electronic equipment shelter interfaces, mating surfaces such as doors and interfaces must provide low contact resistances and be resistant to excessive amounts of corrosion and mechanical wear that would tend to degrade their shielding integrity. The objective of this research was to establish the efficacy of stylus electroplating as a potentially viable field maintenance/repair technique for application of corrosion resistant, wear resistant coatings in order to help maintain the shielding integrity of those interfaces. Aluminum alloy (6061-T6) knife-edge and channel test pieces were stylus electroplated with tin or tin-lead coatings with nickel or copper underlayers. A custom-designed electroplating tool developed for electroplating the complex geometry of a knife-edge substrate appears to provide better control of the plating process and circumvents possible interference with previously deposited areas. This research has resulted in an optimized procedure for producing coatings that exhibit greater adherence, better uniformity, less scarring, and fewer blisters and ridges compared to those previously reported. An optimum electroplating strategy is suggested, which includes applying tin or tin-lead top layers over a thick layer of copper and a thin nickel strike.

  8. An experimental apparatus for diffraction-limites soft x-ray nanofocusing

    SciTech Connect (OSTI)

    Merthe, Daniel; Goldberg, Kenneth; Yashchuk, Valeriy; Yuan, Sheng; McKinney, Wayne; Celestre, Richard; Mochi, Iacopo; Macdougall, James; Morrison, Gregory; Rakawa, Senajith; Anderson, Erik; Smith, Brian; Domning, Edward; Warwick, Tony; Padmore, Howard


    Realizing the experimental potential of high-brightness, next generation synchrotron and free-electron laser light sources requires the development of reflecting x-ray optics capable of wavefront preservation and high-resolution nano-focusing. At the Advanced Light Source (ALS) beamline 5.3.1, we are developing broadly applicable, high-accuracy, in situ, at-wavelength wavefront measurement techniques to surpass 100-nrad slope measurement accuracy for diffraction-limited Kirkpatrick-Baez (KB) mirrors. The at-wavelength methodology we are developing relies on a series of wavefront-sensing tests with increasing accuracy and sensitivity, including scanning-slit Hartmann tests, grating-based lateral shearing interferometry, and quantitative knife-edge testing. We describe the original experimental techniques and alignment methodology that have enabled us to optimally set a bendable KB mirror to achieve a focused, FWHM spot size of 150 nm, with 1 nm (1.24 keV) photons at 3.7 mrad numerical aperture. The predictions of wavefront measurement are confirmed by the knife-edge testing.The side-profiled elliptically bent mirror used in these one-dimensional focusing experiments was originally designed for a much different glancing angle and conjugate distances. This work demonstrates that high-accuracy, at-wavelength wavefront-slope feedback can be used to optimize the pitch, roll, and mirror-bending forces in situ, using procedures that are deterministic and repeatable.

  9. Experimental determination of radiated internal wave power without pressure field data

    SciTech Connect (OSTI)

    Lee, Frank M.; Morrison, P. J. [Physics Department and Institute for Fusion Studies, The University of Texas at Austin, Austin, Texas 78712–1192 (United States)] [Physics Department and Institute for Fusion Studies, The University of Texas at Austin, Austin, Texas 78712–1192 (United States); Paoletti, M. S.; Swinney, Harry L. [Physics Department, The University of Texas at Austin, Austin, Texas 78712–1192 (United States)] [Physics Department, The University of Texas at Austin, Austin, Texas 78712–1192 (United States)


    We present a method to determine, using only velocity field data, the time-averaged energy flux (J) and total radiated power P for two-dimensional internal gravity waves. Both (J) and P are determined from expressions involving only a scalar function, the stream function ?. We test the method using data from a direct numerical simulation for tidal flow of a stratified fluid past a knife edge. The results for the radiated internal wave power given by the stream function method agree to within 0.5% with results obtained using pressure and velocity data from the numerical simulation. The results for the radiated power computed from the stream function agree well with power computed from the velocity and pressure if the starting point for the stream function computation is on a solid boundary, but if a boundary point is not available, care must be taken to choose an appropriate starting point. We also test the stream function method by applying it to laboratory data for tidal flow past a knife edge, and the results are found to agree with the direct numerical simulation. The supplementary material includes a Matlab code with a graphical user interface that can be used to compute the energy flux and power from two-dimensional velocity field data.

  10. Systematic measurements of whole-body dose distributions for various treatment machines and delivery techniques in radiation therapy

    SciTech Connect (OSTI)

    Haelg, Roger A.; Besserer, Juergen; Schneider, Uwe


    Purpose: Contemporary radiotherapy treatment techniques, such as intensity-modulated radiation therapy and volumetric modulated arc therapy, could increase the radiation-induced malignancies because of the increased beam-on time, i.e., number of monitor units needed to deliver the same dose to the target and the larger volume irradiated with low doses. In this study, whole-body dose distributions from typical radiotherapy patient plans using different treatment techniques and therapy machines were measured using the same measurement setup and irradiation intention. Methods: Individually calibrated thermoluminescent dosimeters were used to measure absorbed dose in an anthropomorphic phantom at 184 locations. The dose distributions from 6 MV beams were compared in terms of treatment technique (3D-conformal, intensity-modulated radiation therapy, volumetric modulated arc therapy, helical TomoTherapy, stereotactic radiotherapy, hard wedges, and flattening filter-free radiotherapy) and therapy machine (Elekta, Siemens and Varian linear accelerators, Accuray CyberKnife and TomoTherapy). Results: Close to the target, the doses from intensity-modulated treatments (including flattening filter-free) were below the dose from a static treatment plan, whereas the CyberKnife showed a larger dose by a factor of two. Far away from the treatment field, the dose from intensity-modulated treatments showed an increase in dose from stray radiation of about 50% compared to the 3D-conformal treatment. For the flattening filter-free photon beams, the dose from stray radiation far away from the target was slightly lower than the dose from a static treatment. The CyberKnife irradiation and the treatment using hard wedges increased the dose from stray radiation by nearly a factor of three compared to the 3D-conformal treatment. Conclusions: This study showed that the dose outside of the treated volume is influenced by several sources. Therefore, when comparing different treatment techniques, the dose ratios vary with distance to the isocenter. The effective dose outside the treated volume of intensity-modulated treatments with or without flattening filter was 10%-30% larger when compared to 3D-conformal radiotherapy. This dose increase is much lower than the monitor unit scaled effective dose from a static treatment.

  11. Microfabricated high-bandpass foucault aperture for electron microscopy

    DOE Patents [OSTI]

    Glaeser, Robert; Cambie, Rossana; Jin, Jian


    A variant of the Foucault (knife-edge) aperture is disclosed that is designed to provide single-sideband (SSB) contrast at low spatial frequencies but retain conventional double-sideband (DSB) contrast at high spatial frequencies in transmission electron microscopy. The aperture includes a plate with an inner open area, a support extending from the plate at an edge of the open area, a half-circle feature mounted on the support and located at the center of the aperture open area. The radius of the half-circle portion of reciprocal space that is blocked by the aperture can be varied to suit the needs of electron microscopy investigation. The aperture is fabricated from conductive material which is preferably non-oxidizing, such as gold, for example.

  12. Schlieren technique applied to the arc temperature measurement in a high energy density cutting torch

    SciTech Connect (OSTI)

    Prevosto, L.; Mancinelli, B.; Artana, G.; Kelly, H.


    Plasma temperature and radial density profiles of the plasma species in a high energy density cutting arc have been obtained by using a quantitative schlieren technique. A Z-type two-mirror schlieren system was used in this research. Due to its great sensibility such technique allows measuring plasma composition and temperature from the arc axis to the surrounding medium by processing the gray-level contrast values of digital schlieren images recorded at the observation plane for a given position of a transverse knife located at the exit focal plane of the system. The technique has provided a good visualization of the plasma flow emerging from the nozzle and its interactions with the surrounding medium and the anode. The obtained temperature values are in good agreement with those values previously obtained by the authors on the same torch using Langmuir probes.

  13. Design and initial characterization of a compact, ultra high vacuum compatible, low frequency, tilt accelerometer

    SciTech Connect (OSTI)

    O’Toole, A. E-mail:; Peña Arellano, F. E.; Rodionov, A. V.; Kim, C.; Shaner, M.; Asadoor, M.; Sobacchi, E.; Dergachev, V.; DeSalvo, R. E-mail:; Bhawal, A.; Gong, P.; Lottarini, A.; Minenkov, Y.; Murphy, C.


    A compact tilt accelerometer with high sensitivity at low frequency was designed to provide low frequency corrections for the feedback signal of the Advanced Laser Interferometer Gravitational Wave Observatory active seismic attenuation system. It has been developed using a Tungsten Carbide ceramic knife-edge hinge designed to avoid the mechanical 1/f noise believed to be intrinsic in polycrystalline metallic flexures. Design and construction details are presented; prototype data acquisition and control limitations are discussed. The instrument's characterization reported here shows that the hinge is compatible with being metal-hysteresis-free, and therefore also free of the 1/f noise generated by the dislocation Self-Organized Criticality in the metal. A tiltmeter of this kind will be effective to separate the ground tilt component from the signal of horizontal low frequency seismometers, and to correct the ill effects of microseismic tilt in advanced seismic attenuation systems.

  14. SU-E-T-492: Implementing a Method for Brain Irradiation in Rats Utilizing a Commercially Available Radiosurgery Irradiator

    SciTech Connect (OSTI)

    Cates, J; Drzymala, R


    Purpose: The purpose of the study was to implement a method for accurate rat brain irradiation using the Gamma Knife Perfexion unit. The system needed to be repeatable, efficient, and dosimetrically and spatially accurate. Methods: A platform (“rat holder”) was made such that it is attachable to the Leskell Gamma Knife G Frame. The rat holder utilizes two ear bars contacting bony anatomy and a front tooth bar to secure the rat. The rat holder fits inside of the Leskell localizer box, which utilizes fiducial markers to register with the GammaPlan planning system. This method allows for accurate, repeatable setup.A cylindrical phantom was made so that film can be placed axially in the phantom. We then acquired CT image sets of the rat holder and localizer box with both a rat and the phantom. Three treatment plans were created: a plan on the rat CT dataset, a phantom plan with the same prescription dose as the rat plan, and a phantom plan with the same delivery time as the rat plan. Results: Film analysis from the phantom showed that our setup is spatially accurate and repeatable. It is also dosimetrically accurate, with an difference between predicted and measured dose of 2.9%. Film analysis with prescription dose equal between rat and phantom plans showed a difference of 3.8%, showing that our phantom is a good representation of the rat for dosimetry purposes, allowing for +/- 3mm diameter variation. Film analysis with treatment time equal showed an error of 2.6%, which means we can deliver a prescription dose within 3% accuracy. Conclusion: Our method for irradiation of rat brain has been shown to be repeatable, efficient, and accurate, both dosimetrically and spatially. We can treat a large number of rats efficiently while delivering prescription doses within 3% at millimeter level accuracy.

  15. SU-E-T-409: Intensity Modulated Robotic Radiotherapy

    SciTech Connect (OSTI)

    Wang, B; Jin, L; Li, J; Chen, L; Ma, C; Fan, J; Zhang, C


    Purpose: As compared with the IRIS-based models, the MLC-based CyberKnife system allows more efficient treatment delivery due to its improved coverage of large lesions and intensity modulation. The treatment delivery efficiency is mainly determined by the number of selected nodes. This study aimed to demonstrate that relatively small sets of optimally selected nodes could produce high-quality plans. Methods: The full body path of the CyberKnife system consists of 110 nodes, from which we selected various sets for 4 prostate cancer cases using our in-house beamselection software. With the selected nodes we generated IMRT plans using our in-house beamlet-based inverse-planning optimization program. We also produced IMRT plans using the MultiPlan treatment planning system (version 5.0) for the same cases. Furthermore, the nodes selected by MultiPlan were used to produce plans with our own optimization software so that we could compare the quality of the selected sets of nodes. Results: Our beam-selection program selected one node-set for each case, with the number of nodes ranging from 23 to 34. The IMRT plans based on the selected nodes and our in-house optimization program showed adequate target coverage, with favorable critical structure sparing for the cases investigated. Compared with the plans using the nodes selected by MultiPlan, the plans generated with our selected beams provided superior rectum/bladder sparing for 75% of the cases. The plans produced by MultiPlan with various numbers of nodes also suggested that the plan quality was not compromised significantly when the number of nodes was reduced. Conclusion: Our preliminary results showed that with beamletbased planning optimization, one could produce high-quality plans with an optimal set of nodes for MLC-based robotic radiotherapy. Furthermore, our beam-selection strategy could help further improve critical structure sparing.

  16. Mirror monochromator

    SciTech Connect (OSTI)

    Mankos, Marian; Shadman, Khashayar


    In this SBIR project, Electron Optica, Inc. (EOI) is developing a mirror electron monochromator (MirrorChrom) attachment to new and retrofitted electron microscopes (EMs) for improving the energy resolution of the EM from the characteristic range of 0.2-0.5 eV to the range of 10-50 meV. This improvement will enhance the characterization of materials by imaging and spectroscopy. In particular, the monochromator will refine the energy spectra characterizing materials, as obtained from transmission EMs [TEMs] fitted with electron spectrometers, and it will increase the spatial resolution of the images of materials taken with scanning EMs (SEMs) operated at low voltages. EOI’s MirrorChrom technology utilizes a magnetic prism to simultaneously deflect the electron beam off the axis of the microscope column by 90° and disperse the electrons in proportional to their energies into a module with an electron mirror and a knife-edge. The knife-edge cuts off the tails of the energy distribution to reduce the energy spread of the electrons that are reflected, and subsequently deflected, back into the microscope column. The knife-edge is less prone to contamination, and thereby charging, than the conventional slits used in existing monochromators, which improves the reliability and stability of the module. The overall design of the MirrorChrom exploits the symmetry inherent in reversing the electron trajectory in order to maintain the beam brightness – a parameter that impacts how well the electron beam can be focused downstream onto a sample. During phase I, EOI drafted a set of candidate monochromator architectures and evaluated the trade-offs between energy resolution and beam current to achieve the optimum design for three particular applications with market potential: increasing the spatial resolution of low voltage SEMs, increasing the energy resolution of low voltage TEMs (beam energy of 5-20 keV), and increasing the energy resolution of conventional TEMs (beam energy of 80-120 keV). Specialized software packages that have been developed by MEBS, Ltd. were used to calculate the electron optical properties of the key monochromator components: namely, the magnetic prism, the electron mirror, and the electron lenses. In the final step, these results were folded into a model describing the key electron-optical parameters of the complete monochromator. The simulations reveal that the mirror monochromator can reduce the energy spread of a Schottky electron source, an established electron emitter used widely in EMs, to 10 meV for practical beam current values and that further reduction of the energy spread down to 3 meV is possible for low current applications with a Cold Field Emitter (an electron source with 10x the brightness of a Schottky source). MirrorChroms can be designed and built to attach to different types of TEMs and SEMs, thus making them suitable for enhancing the study of the structure, composition, and bonding states of new materials at the nanoscale to advance material science research in the field of nanotechnology as well as biomedical research.

  17. Salvage Treatment for Recurrent Intracranial Germinoma After Reduced-Volume Radiotherapy: A Single-Institution Experience and Review of the Literature

    SciTech Connect (OSTI)

    Hu, Yu-Wen [Cancer Center, Taipei Veterans General Hospital, Taipei, Taiwan (China) [Cancer Center, Taipei Veterans General Hospital, Taipei, Taiwan (China); Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan (China); Huang, Pin-I [Cancer Center, Taipei Veterans General Hospital, Taipei, Taiwan (China) [Cancer Center, Taipei Veterans General Hospital, Taipei, Taiwan (China); Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan (China); Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan (China); Wong, Tai-Tong [Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan (China) [Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan (China); Division of Pediatric Neurosurgery, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan (China); Ho, Donald Ming-Tak [Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan (China) [Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan (China); Department of Pathology, Taipei Veterans General Hospital, Taipei, Taiwan (China); Chang, Kai-Ping [Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan (China) [Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan (China); Department of Pediatrics, Taipei Veterans General Hospital, Taipei, Taiwan (China); Guo, Wan-Yuo; Chang, Feng-Chi [Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan (China) [Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan (China); Department of Radiology, Taipei Veterans General Hospital, Taipei, Taiwan (China); Shiau, Cheng-Yin [Cancer Center, Taipei Veterans General Hospital, Taipei, Taiwan (China) [Cancer Center, Taipei Veterans General Hospital, Taipei, Taiwan (China); Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan (China); Liang, Muh-Lii; Lee, Yi-Yen [Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan (China) [Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan (China); Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan (China); Division of Pediatric Neurosurgery, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan (China); and others


    Purpose: Intracranial germinomas (IGs) are highly curable with radiotherapy (RT). However, recurrence still occurs, especially when limited-field RT is applied, and the optimal salvage therapy remains controversial. Methods and Materials: Between January 1989 and December 2010, 14 patients with clinically or pathologically diagnosed recurrent IGs after RT were reviewed at our institution. Of these, 11 received focal-field RT, and the other 3 received whole-brain irradiation, whole-ventricle irradiation, and Gamma Knife radiosurgery as the respective first course of RT. In addition, we identified from the literature 88 patients with recurrent IGs after reduced-volume RT, in whom the details of salvage therapy were recorded. Results: The median time to recurrence was 30.3 months (range, 3.8-134.9 months). One patient did not receive further treatment and was lost during follow-up. Of the patients, 7 underwent salvage with craniospinal irradiation (CSI) plus chemotherapy (CT), 4 with CSI alone, 1 with whole-brain irradiation plus CT, and 1 with Gamma Knife radiosurgery. The median follow-up time was 105.1 months (range, 24.2-180.9 months). Three patients died without evidence of disease progression: two from second malignancies and one from unknown cause. The others remained disease free. The 3-year survival rate after recurrence was 83.3%. A total of 102 patients from our study and the literature review were analyzed to determine the factors affecting prognosis and outcomes. After recurrence, the 5-year survival rates were 71% and 92.9% for all patients and for those receiving salvage CSI, respectively. Univariate analysis showed that initial RT volume, initial RT dose, initial CT, and salvage RT type were significant prognostic predictors of survival. On multivariable analysis, salvage CSI was the most significant factor (p = 0.03). Conclusions: Protracted follow-up is recommended because late recurrence is not uncommon. CSI with or without CT is an effective salvage treatment for recurrence after reduced-volume RT.

  18. Core based stress measurements: A guide to their application. Topical report, July 1991--June 1993

    SciTech Connect (OSTI)

    Warpinski, N.R.; Teufel, L.W.; Lorenz, J.C.; Holcomb, D.J.


    This report is a summary and a guide to core-based stress measurements. It covers anelastic strain recovery, circumferential velocity anistropy, differential strain curve analysis, differential wave velocity analysis, petrographic examination of microcracks, overcoring of archieved core, measurements of the Kaiser effect, strength anisotropy tests, and analysis of coring-induced fractures. The report begins with a discussion of the stored energy within rocks, its release during coring, and the subsequent formation of relaxation microcracks. The interogation or monitoring of these microcracks form the basis for most of the core-based techniques (except for the coring induced fractures). Problems that can arise due to coring or fabric are also presented, Coring induced fractures are discussed in some detail, with the emphasis placed on petal (and petal-centerline) fractures and scribe-knife fractures. For each technique, a short description of the physics and the analysis procedures is given. In addition, several example applications have also been selected (where available) to illustrate pertinent effects. This report is intended to be a guide to the proper application and diagnosis of core-based stress measurement procedures.

  19. X-ray tests of a two-dimensional stigmatic imaging scheme with variable magnifications

    SciTech Connect (OSTI)

    Lu, J.; Bitter, M.; Hill, K. W.; Delgado-Aparicio, L. F.; Efthimion, P. C.; Pablant, N. A.; Beiersdorfer, P.; Caughey, T. A.; Brunner, J.


    A two-dimensional stigmatic x-ray imaging scheme, consisting of two spherically bent crystals, one concave and one convex, was recently proposed [M. Bitter et al., Rev. Sci. Instrum. 83, 10E527 (2012)]. The Bragg angles and the radii of curvature of the two crystals of this imaging scheme are matched to eliminate the astigmatism and to satisfy the Bragg condition across both crystal surfaces for a given x-ray energy. In this paper, we consider more general configurations of this imaging scheme, which allow us to vary the magnification for a given pair of crystals and x-ray energy. The stigmatic imaging scheme has been validated for the first time by imaging x-rays generated by a micro-focus x-ray source with source size of 8.4 ?m validated by knife-edge measurements. Results are presented from imaging the tungsten L?1 emission at 8.3976 keV, using a convex Si-422 crystal and a concave Si-533 crystal with 2d-spacings of 2.21707 Å and 1.65635 Å and radii of curvature of 500 ± 1 mm and 823 ± 1 mm, respectively, showing a spatial resolution of 54.9 ?m. This imaging scheme is expected to be of interest for the two-dimensional imaging of laser produced plasmas.

  20. High resolution transmission electron microscopy of melamine-formaldehyde aerogels and silica aerogels

    SciTech Connect (OSTI)

    Ruben, G.C. (Dartmouth Coll., Hanover, NH (United States). Dept. of Biological Sciences)


    The goal of the high resolution transmission electron microscopy (HRTEM) was to image the structure of two tetramethyl orthosilicate (TMOS) and two melamine-formaldehyde (MF) aerogels at the single polymer chain level{sup 1,2}. With this level of structural resolution we hoped to interrelate each aerogel's structure with its physical properties and its method of synthesis. Conventional single-step base catalysed TMOS aerogels show strings of spheroidal particles linked together with minimal necking. The spheroidal particles range from 86--132 {Angstrom} and average 113{plus minus}10 {Angstrom} in diameter{sup 2}. In contrast the TMOS aerogels reported on here were made by a two step method. After extended silica chains are grown in solution under acidic conditions with a substoichiometric amount of water, the reaction is stopped and the methanol hydrolysed from TMOS is removed. Then base catalysis and additional water are added to cause gel formation is a nonalcoholic solvent. The MF aerogels were prepared for HRTEM by fracturing them on a stereo microscope stage with razor knife so that fractured pieces with smooth flat surfaces could be selected for platinum-carbon replication. The two silica (TMOS) aerogels were both transparent and difficult to see. These aerogels were fractured on a stereo microscope stage with tweezers. 6 refs., 4 figs.

  1. Fail safe controllable output improved version of the Electromechanical battery

    DOE Patents [OSTI]

    Post, Richard F. (Walnut Creek, CA)


    Mechanical means are provided to control the voltages induced in the windings of a generator/motor. In one embodiment, a lever is used to withdraw or insert the entire stator windings from the cavity where the rotating field exists. In another embodiment, voltage control and/or switching off of the output is achievable with a variable-coupling generator/motor. A stator is made up of two concentric layers of windings, with a larger number of turns on the inner layer of windings than the outer layer of windings. The windings are to be connected in series electrically, that is, their voltages add vectorially. The mechanical arrangement is such that one or both of the windings can be rotated with respect to the other winding about their common central axis. Another improved design for the stator assembly of electromechanical batteries provides knife switch contacts that are in electrical contact with the stator windings. The operation of this embodiment depends on the fact that an abnormally large torque will be exerted on the stator structure during any short-circuit condition.

  2. Fail safe controllable output improved version of the electromechanical battery

    DOE Patents [OSTI]

    Post, R.F.


    Mechanical means are provided to control the voltages induced in the windings of a generator/motor. In one embodiment, a lever is used to withdraw or insert the entire stator windings from the cavity where the rotating field exists. In another embodiment, voltage control and/or switching off of the output is achievable with a variable-coupling generator/motor. A stator is made up of two concentric layers of windings, with a larger number of turns on the inner layer of windings than the outer layer of windings. The windings are to be connected in series electrically, that is, their voltages add vectorially. The mechanical arrangement is such that one or both of the windings can be rotated with respect to the other winding about their common central axis. Another improved design for the stator assembly of electromechanical batteries provides knife switch contacts that are in electrical contact with the stator windings. The operation of this embodiment depends on the fact that an abnormally large torque will be exerted on the stator structure during any short-circuit condition. 4 figs.

  3. Radiosurgery for Craniopharyngioma

    SciTech Connect (OSTI)

    Niranjan, Ajay, E-mail: niranjana@upmc.ed [Department of Neurological Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA (United States); Department of Radiation Oncology, University of Pittsburgh School of Medicine, Pittsburgh, PA (United States); Kano, Hideyuki [Department of Neurological Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA (United States); Department of Radiation Oncology, University of Pittsburgh School of Medicine, Pittsburgh, PA (United States); Mathieu, David [Department of Neurological Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA (United States); Department of Radiation Oncology, University of Pittsburgh School of Medicine, Pittsburgh, PA (United States); Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC (Canada); Kondziolka, Douglas; Flickinger, John C.; Lunsford, L. Dade [Department of Neurological Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA (United States); Department of Radiation Oncology, University of Pittsburgh School of Medicine, Pittsburgh, PA (United States); Center for Image-Guided Neurosurgery, University of Pittsburgh Medical Center, Pittsburgh, PA (United States)


    Purpose: To analyze the outcomes of gamma knife stereotactic radiosurgery (SRS) for residual or recurrent craniopharyngiomas and evaluate the factors that optimized the tumor control rates. Methods and Materials: A total of 46 patients with craniopharyngiomas underwent 51 SRS procedures at University of Pittsburgh between 1988 and 2007. The median tumor volume was 1.0 cm{sup 3} (range, 0.07-8.0). The median prescription dose delivered to the tumor margin was 13.0 Gy (range, 9-20). The median maximal dose was 26.0 Gy (range, 20-50). The mean follow-up time was 62.2 months (range, 12-232). Results: The overall survival rate after SRS was 97.1% at 5 years. The 3- and 5-year progression-free survival rates (solid tumor control) were both 91.6%. The overall local control rate (for both solid tumor and cyst control) was 91%, 81%, and 68% at 1, 3, and 5 years, respectively. No patients with normal pituitary function developed hypopopituitarism after SRS. Two patients developed homonymous hemianopsia owing to tumor progression after SRS. Among the factors examined, complete radiosurgical coverage was a significant favorable prognostic factor. Conclusion: SRS is a safe and effective minimally invasive option for the management of residual or recurrent craniopharyngiomas. Complete radiosurgical coverage of the tumor was associated with better tumor control.

  4. In-depth survey report: control technology for falling solids at Cincinnati Paint and Varnish, Cincinnati, Ohio

    SciTech Connect (OSTI)

    Heitbrink, W.A.


    A visit was made to the Cincinnati Paint and Varnish Company, Cincinnati, Ohio, to determine the effectiveness of control measures used to contain dust generated during the manufacturing of custom coatings. Dust arose when 50 pound bags of different powdered materials, titanium dioxide, talc, and crystalline silica, were emptied into 600-gallon mixing tanks by a worker. The worker slit the bags with a knife, lifted the bag, poured the contents into the mixer, and returned the empty bags to the floor. Exterior surfaces of the bags were dusty; handling them released some dust into the atmosphere. A slot hood was used to capture dust generated during the operation. Air velocity toward th slot hood along the lip of the tank where the bags were emptied ranged from 50 to 100 feet per minute. The total dust concentrations determined for crystalline silica during this operation averaged 3.0mg/cum. During a revisit to the site this worker's exposure was below 0.15mg/cum for a time-weighted average of less than 0.004 mg/m/sup 3/. The difference in liquid level in the tank at the time each powdered ingredient was added may have significantly affected the amount of dust released. Measurements of the actual process indicated that the silica had to fall almost 1 meter before reaching any liquid in the mixing tank whereas the talc had to fall only 25 centimeters.

  5. Error analysis in cross-correlation of sky maps: application to the ISW detection

    E-Print Network [OSTI]

    Anna Cabre; Pablo Fosalba; Enrique Gaztanaga; Marc Manera


    Constraining cosmological parameters from measurements of the Integrated Sachs-Wolfe effect requires developing robust and accurate methods for computing statistical errors in the cross-correlation between maps. This paper presents a detailed comparison of such error estimation applied to the case of cross-correlation of Cosmic Microwave Background (CMB) and large-scale structure data. We compare theoretical models for error estimation with montecarlo simulations where both the galaxy and the CMB maps vary around a fiducial auto-correlation and cross-correlation model which agrees well with the current concordance LCDM cosmology. Our analysis compares estimators both in harmonic and configuration (or real) space, quantifies the accuracy of the error analysis and discuss the impact of partial sky survey area and the choice of input fiducial model on dark-energy constraints. We show that purely analytic approaches yield accurate errors even in surveys that cover only 10% of the sky and that parameter constraints strongly depend on the fiducial model employed. Alternatively, we discuss the advantages and limitations of error estimators that can be directly applied to data. In particular, we show that errors and covariances from the Jack-Knife method agree well with the theoretical approaches and simulations. We also introduce a novel method in real space that is computationally efficient and can be applied to real data and realistic survey geometries. Finally, we present a number of new findings and prescriptions that can be useful for analysis of real data and forecasts, and present a critical summary of the analyses done to date.

  6. SU-E-T-563: A Fast and Quantative Picket-Fence Test of a Submillimeter Patient Positioning System for Stereotactic Radiosurgery

    SciTech Connect (OSTI)

    Ma, L; Perez-Andujar, A; Chiu, J; McGuinness, C


    Purpose: Picket-fence test is a qualitative TG142-recommended quality assurance (QA) test for multileaf collimators. In study, we adopted the same concept and developed a fast but quantatitive QA test for an automatic patient positioning system that requires submilleter accuracy for a radiosurgical treatment. Methods: A piece of radiochromic film was first placed inside a spherical solid water phantom and then irradiated with a sequenence of linearly placed shots of same collimator size (e.g. 4-mm) via the Leskell Gamma Knife Perfexion system (PFX). The shots were positioned with either equal or non-equal gaps of approximately 4 mm to 8 mm depending on the location of the region of interest. A pattern recognization program was developed and then applied to measure the gap spacing between two adjacent shots. The measured distance was then compared with the initial preset values for the test. Results: By introducing variable systematic and random shifts of 0.1 mm to 0.5 mm to the shot sequence, the maximum gap variation from the described test was found to be 0.35 mm or less. On average the positioning uncertainty for the PFX delivery system was found to be 0.1±0.2 mm. No significant difference in the positioning uncertainty was noted for the centrally aligned shot sequence locations versus the peripherally aligned shot sequence locations. Conclusion: A new quantitative picket-fence type test was developed and demonstrated for routine QA of the submillimeter PFX patient positioning sytem. This test also enables independent verification of any patient-specific shot positioning for a critical treatment such as a tumor in brainstem. Dr Ma is currently on the board of international society of stereotactic Radiosurgery.

  7. TU-F-BRE-04: Development of a High-Resolution EPID Based Dosimetry Strategy for Radiosurgery QA

    SciTech Connect (OSTI)

    Han, B; Ding, A; Xing, L; Wang, L


    Purpose: To systematically investigate a high spatial-resolution (0.2mm) electronic portal imaging device (EPID) for CyberKnife (CK) based radiosurgery system quality assurance (QA). Methods: An EPID-based dosimetric measurement technique is applied to CK output measurement and field size verification. A Monte Carlo (MC) simulated pixel-to-pixel EPID response specific to CK is used to convert a raw EPID-measured image of a radiosurgery field into water-based dose distribution. The output factors are measured using EPID for radiosurgery fields formed by fixed and variable aperture (Iris) cones. Circular fields of 5, 7.5, 10, 15, 30 and 60mm diameters are measured and compared with diode measurements. The equivalent diameters are determined by analyzing the area received dose greater than half maximum. Results: For both fixed and Iris cones, the EPID measured output factors of circular fields of 5mm to 60mm diameters are in good agreement with the radiosurgery diode measurements. The mean output differences are 1.0% and 1.5% for fixed and Iris cone respectively. The max differences are 2.2% for the 15mm fixed cone, and 1.8% for the 10mm Iris field. The equivalent diameters derived from the EPID measurements are in good agreement comparing to the water scan result with mean differences of 0.21±0.09mm and 0.02±0.22mm for fixed and Iris cone, respectively. The high detector density EPID is able to measure the whole radiation field and identify the field edge and center. Therefore, there is no need to align the detector center perfectly at field center and the setup time is greatly reduced for QA. Conclusion: The high spatial-resolution EPID is proved to be an accurate and efficient dosimetric tool for radiosurgery QA and especially useful in Cyberknife QA for variable aperture collimators.

  8. A micron resolution optical scanner for characterization of silicon detectors

    SciTech Connect (OSTI)

    Shukla, R. A.; Dugad, S. R. Gopal, A. V.; Gupta, S. K.; Prabhu, S. S.; Garde, C. S.


    The emergence of high position resolution (?10 ?m) silicon detectors in recent times have highlighted the urgent need for the development of new automated optical scanners of micron level resolution suited for characterizing microscopic features of these detectors. More specifically, for the newly developed silicon photo-multipliers (SiPM) that are compact, possessing excellent photon detection efficiency with gain comparable to photo-multiplier tube. In a short time, since their invention the SiPMs are already being widely used in several high-energy physics and astrophysics experiments as the photon readout element. The SiPM is a high quantum efficiency, multi-pixel photon counting detector with fast timing and high gain. The presence of a wide variety of photo sensitive silicon detectors with high spatial resolution requires their performance evaluation to be carried out by photon beams of very compact spot size. We have designed a high resolution optical scanner that provides a monochromatic focused beam on a target plane. The transverse size of the beam was measured by the knife-edge method to be 1.7 ?m at 1 ? ? level. Since the beam size was an order of magnitude smaller than the typical feature size of silicon detectors, this optical scanner can be used for selective excitation of these detectors. The design and operational details of the optical scanner, high precision programmed movement of target plane (0.1 ?m) integrated with general purpose data acquisition system developed for recording static and transient response photo sensitive silicon detector are reported in this paper. Entire functionality of scanner is validated by using it for selective excitation of individual pixels in a SiPM and identifying response of active and dead regions within SiPM. Results from these studies are presented in this paper.

  9. Long-term elemental dry deposition fluxes measured around Lake Michigan with an automated dry deposition sampler

    SciTech Connect (OSTI)

    Shahin, U. Yi, S.M.; Paode, R.D.; Holsen, T.M.


    Long-term measurements of mass and elemental dry deposition (MG, Al, V, Cr, Mn, Ni, Co, Cu, Zn, As, Sr, Mo, Cd, Sb, Ba, and Pb) were made with an automated dry deposition sampler (Eagle II) containing knife-edge surrogate surfaces during the Lake Michigan Mass Balance/Mass Budget Study. Measurements were made over a roughly 700-day period in Chicago, IL; in South Haven and Sleeping Bear Dunes, MI; and over Lake Michigan on the 68th Street drinking water intake cribs from December 1993 to October 1995. Average mass fluxes in Chicago, South Haven, Sleeping Bear Dunes, and the 68th Street crib were 65, 10, 3.6, and 12 mg m{sup {minus}2} day{sup {minus}1}, respectively. Primarily crustal elemental fluxes were significantly smaller than the mass fluxes but higher than primarily anthropogenic elemental fluxes. For example, the average elemental flux of Al in Chicago, South Haven, Sleeping Bear Dunes, and the 68th Street crib were 1.0, 0.34, 0.074, and 0.34 mg m{sup {minus}2}day{sup {minus}1}, respectively. The average Pb fluxes in Chicago, South Haven, Sleeping Bear Dunes, and the 68th Street crib were 0.038, 0.023, 0.035, and 0.032 mg m{sup {minus}2}day{sup {minus}1}, respectively. The measured fluxes at the various sites were used to calculate the dry deposition loadings to the lake. These estimated fluxes were highest for Mg and lowest for Cd.

  10. SU-E-T-480: Radiobiological Dose Comparison of Single Fraction SRS, Multi-Fraction SRT and Multi-Stage SRS of Large Target Volumes Using the Linear-Quadratic Formula

    SciTech Connect (OSTI)

    Ding, C; Hrycushko, B; Jiang, S; Meyer, J; Timmerman, R [UT Southwestern Medical Center, Dallas, TX (United States)


    Purpose: To compare the radiobiological effect on large tumors and surrounding normal tissues from single fraction SRS, multi-fractionated SRT, and multi-staged SRS treatment. Methods: An anthropomorphic head phantom with a centrally located large volume target (18.2 cm{sup 3}) was scanned using a 16 slice large bore CT simulator. Scans were imported to the Multiplan treatment planning system where a total prescription dose of 20Gy was used for a single, three staged and three fractionated treatment. Cyber Knife treatment plans were inversely optimized for the target volume to achieve at least 95% coverage of the prescription dose. For the multistage plan, the target was segmented into three subtargets having similar volume and shape. Staged plans for individual subtargets were generated based on a planning technique where the beam MUs of the original plan on the total target volume are changed by weighting the MUs based on projected beam lengths within each subtarget. Dose matrices for each plan were export in DICOM format and used to calculate equivalent dose distributions in 2Gy fractions using an alpha beta ratio of 10 for the target and 3 for normal tissue. Results: Singe fraction SRS, multi-stage plan and multi-fractionated SRT plans had an average 2Gy dose equivalent to the target of 62.89Gy, 37.91Gy and 33.68Gy, respectively. The normal tissue within 12Gy physical dose region had an average 2Gy dose equivalent of 29.55Gy, 16.08Gy and 13.93Gy, respectively. Conclusion: The single fraction SRS plan had the largest predicted biological effect for the target and the surrounding normal tissue. The multi-stage treatment provided for a more potent biologically effect on target compared to the multi-fraction SRT treatments with less biological normal tissue than single-fraction SRS treatment.

  11. SU-E-T-568: Improving Normal Brain Sparing with Increasing Number of Arc Beams for Volume Modulated Arc Beam Radiosurgery of Multiple Brain Metastases

    SciTech Connect (OSTI)

    Hossain, S; Hildebrand, K; Ahmad, S; Larson, D; Ma, L; Sahgal, A


    Purpose: Intensity modulated arc beams have been newly reported for treating multiple brain metastases. The purpose of this study was to determine the variations in the normal brain doses with increasing number of arc beams for multiple brain metastases treatments via the TrueBeam Rapidarc system (Varian Oncology, Palo Alto, CA). Methods: A patient case with 12 metastatic brain lesions previously treated on the Leksell Gamma Knife Perfexion (GK) was used for the study. All lesions and organs at risk were contoured by a senior radiation oncologist and treatment plans for a subset of 3, 6, 9 and all 12 targets were developed for the TrueBeam Rapidarc system via 3 to 7 intensity modulated arc-beams with each target covered by at least 99% of the prescribed dose of 20 Gy. The peripheral normal brain isodose volumes as well as the total beam-on time were analyzed with increasing number of arc beams for these targets. Results: All intensisty modulated arc-beam plans produced efficient treatment delivery with the beam-on time averaging 0.6–1.5 min per lesion at an output of 1200 MU/min. With increasing number of arc beams, the peripheral normal brain isodose volumes such as the 12-Gy isodose line enclosed normal brain tissue volumes were on average decreased by 6%, 11%, 18%, and 28% for the 3-, 6-, 9-, 12-target treatment plans respectively. The lowest normal brain isodose volumes were consistently found for the 7-arc treatment plans for all the cases. Conclusion: With nearly identical beam-on times, the peripheral normal brain dose was notably decreased when the total number of intensity modulated arc beams was increased when treating multiple brain metastases. Dr Sahgal and Dr Ma are currently serving on the board of international society of stereotactic radiosurgery.

  12. Development of Pneumatic Aerodynamic Devices to Improve the Performance, Economics, and Safety of Heavy Vehicles

    SciTech Connect (OSTI)

    Robert J. Englar


    Under contract to the DOE Office of Heavy Vehicle Technologies, the Georgia Tech Research Institute (GTRI) is developing and evaluating pneumatic (blown) aerodynamic devices to improve the performance, economics, stability and safety of operation of Heavy Vehicles. The objective of this program is to apply the pneumatic aerodynamic aircraft technology previously developed and flight-tested by GTRI personnel to the design of an efficient blown tractor-trailer configuration. Recent experimental results obtained by GTRI using blowing have shown drag reductions of 35% on a streamlined automobile wind-tunnel model. Also measured were lift or down-load increases of 100-150% and the ability to control aerodynamic moments about all 3 axes without any moving control surfaces. Similar drag reductions yielded by blowing on bluff afterbody trailers in current US trucking fleet operations are anticipated to reduce yearly fuel consumption by more than 1.2 billion gallons, while even further reduction is possible using pneumatic lift to reduce tire rolling resistance. Conversely, increased drag and down force generated instantaneously by blowing can greatly increase braking characteristics and control in wet/icy weather due to effective ''weight'' increases on the tires. Safety is also enhanced by controlling side loads and moments caused on these Heavy Vehicles by winds, gusts and other vehicles passing. This may also help to eliminate the jack-knifing problem if caused by extreme wind side loads on the trailer. Lastly, reduction of the turbulent wake behind the trailer can reduce splash and spray patterns and rough air being experienced by following vehicles. To be presented by GTRI in this paper will be results developed during the early portion of this effort, including a preliminary systems study, CFD prediction of the blown flowfields, and design of the baseline conventional tractor-trailer model and the pneumatic wind-tunnel model.

  13. Phase II Trial of Radiosurgery to Magnetic Resonance Spectroscopy-Defined High-Risk Tumor Volumes in Patients With Glioblastoma Multiforme

    SciTech Connect (OSTI)

    Einstein, Douglas B.; Wessels, Barry; Bangert, Barbara; Fu, Pingfu; Nelson, A. Dennis; Cohen, Mark; Sagar, Stephen; Lewin, Jonathan; Sloan, Andrew; Zheng Yiran; Williams, Jordonna; Colussi, Valdir; Vinkler, Robert; Maciunas, Robert


    Purpose: To determine the efficacy of a Gamma Knife stereotactic radiosurgery (SRS) boost to areas of high risk determined by magnetic resonance spectroscopy (MRS) functional imaging in addition to standard radiotherapy for patients with glioblastoma (GBM). Methods and Materials: Thirty-five patients in this prospective Phase II trial underwent surgical resection or biopsy for a GBM followed by SRS directed toward areas of MRS-determined high biological activity within 2 cm of the postoperative enhancing surgical bed. The MRS regions were determined by identifying those voxels within the postoperative T2 magnetic resonance imaging volume that contained an elevated choline/N-acetylaspartate ratio in excess of 2:1. These voxels were marked, digitally fused with the SRS planning magnetic resonance image, targeted with an 8-mm isocenter per voxel, and treated using Radiation Therapy Oncology Group SRS dose guidelines. All patients then received conformal radiotherapy to a total dose of 60 Gy in 2-Gy daily fractions. The primary endpoint was overall survival. Results: The median survival for the entire cohort was 15.8 months. With 75% of recursive partitioning analysis (RPA) Class 3 patients still alive 18 months after treatment, the median survival for RPA Class 3 has not yet been reached. The median survivals for RPA Class 4, 5, and 6 patients were 18.7, 12.5, and 3.9 months, respectively, compared with Radiation Therapy Oncology Group radiotherapy-alone historical control survivals of 11.1, 8.9, and 4.6 months. For the 16 of 35 patients who received concurrent temozolomide in addition to protocol radiotherapeutic treatment, the median survival was 20.8 months, compared with European Organization for Research and Treatment of Cancer historical controls of 14.6 months using radiotherapy and temozolomide. Grade 3/4 toxicities possibly attributable to treatment were 11%. Conclusions: This represents the first prospective trial using selective MRS-targeted functional SRS combined with radiotherapy for patients with GBM. This treatment is feasible, with acceptable toxicity and patient survivals higher than in historical controls. This study can form the basis for a multicenter, randomized trial.

  14. Delayed Complications in Patients Surviving at Least 3 Years After Stereotactic Radiosurgery for Brain Metastases

    SciTech Connect (OSTI)

    Yamamoto, Masaaki; Department of Neurosurgery, Tokyo Women's Medical University Medical Center East, Tokyo ; Kawabe, Takuya; Department of Neurosurgery, Kyoto Prefectural University of Medicine Graduate School of Medical Sciences, Kyoto ; Higuchi, Yoshinori; Sato, Yasunori; Nariai, Tadashi; Barfod, Bierta E.; Kasuya, Hidetoshi; Urakawa, Yoichi


    Purpose: Little is known about delayed complications after stereotactic radiosurgery in long-surviving patients with brain metastases. We studied the actual incidence and predictors of delayed complications. Patients and Methods: This was an institutional review board-approved, retrospective cohort study that used our database. Among our consecutive series of 2000 patients with brain metastases who underwent Gamma Knife radiosurgery (GKRS) from 1991-2008, 167 patients (8.4%, 89 women, 78 men, mean age 62 years [range, 19-88 years]) who survived at least 3 years after GKRS were studied. Results: Among the 167 patients, 17 (10.2%, 18 lesions) experienced delayed complications (mass lesions with or without cyst in 8, cyst alone in 8, edema in 2) occurring 24.0-121.0 months (median, 57.5 months) after GKRS. The actuarial incidences of delayed complications estimated by competing risk analysis were 4.2% and 21.2% at the 60th month and 120th month, respectively, after GKRS. Among various pre-GKRS clinical factors, univariate analysis demonstrated tumor volume-related factors: largest tumor volume (hazard ratio [HR], 1.091; 95% confidence interval [CI], 1.018-1.154; P=.0174) and tumor volume {<=}10 cc vs >10 cc (HR, 4.343; 95% CI, 1.444-12.14; P=.0108) to be the only significant predictors of delayed complications. Univariate analysis revealed no correlations between delayed complications and radiosurgical parameters (ie, radiosurgical doses, conformity and gradient indexes, and brain volumes receiving >5 Gy and >12 Gy). After GKRS, an area of prolonged enhancement at the irradiated lesion was shown to be a possible risk factor for the development of delayed complications (HR, 8.751; 95% CI, 1.785-157.9; P=.0037). Neurosurgical interventions were performed in 13 patients (14 lesions) and mass removal for 6 lesions and Ommaya reservoir placement for the other 8. The results were favorable. Conclusions: Long-term follow-up is crucial for patients with brain metastases treated with GKRS because the risk of complications long after treatment is not insignificant. However, even when delayed complications occur, favorable outcomes can be expected with timely neurosurgical intervention.

  15. Cone Beam Computed Tomography Image Guidance System for a Dedicated Intracranial Radiosurgery Treatment Unit

    SciTech Connect (OSTI)

    Ruschin, Mark; Radiation Medicine Program, Princess Margaret Hospital, Toronto, Ontario ; Komljenovic, Philip T.; Ansell, Steve; Menard, Cynthia; Radiation Medicine Program, Princess Margaret Hospital, Toronto, Ontario ; Bootsma, Gregory; Cho, Young-Bin; Chung, Caroline; Jaffray, David; Radiation Medicine Program, Princess Margaret Hospital, Toronto, Ontario


    Purpose: Image guidance has improved the precision of fractionated radiation treatment delivery on linear accelerators. Precise radiation delivery is particularly critical when high doses are delivered to complex shapes with steep dose gradients near critical structures, as is the case for intracranial radiosurgery. To reduce potential geometric uncertainties, a cone beam computed tomography (CT) image guidance system was developed in-house to generate high-resolution images of the head at the time of treatment, using a dedicated radiosurgery unit. The performance and initial clinical use of this imaging system are described. Methods and Materials: A kilovoltage cone beam CT system was integrated with a Leksell Gamma Knife Perfexion radiosurgery unit. The X-ray tube and flat-panel detector are mounted on a translational arm, which is parked above the treatment unit when not in use. Upon descent, a rotational axis provides 210 Degree-Sign of rotation for cone beam CT scans. Mechanical integrity of the system was evaluated over a 6-month period. Subsequent clinical commissioning included end-to-end testing of targeting performance and subjective image quality performance in phantoms. The system has been used to image 2 patients, 1 of whom received single-fraction radiosurgery and 1 who received 3 fractions, using a relocatable head frame. Results: Images of phantoms demonstrated soft tissue contrast visibility and submillimeter spatial resolution. A contrast difference of 35 HU was easily detected at a calibration dose of 1.2 cGy (center of head phantom). The shape of the mechanical flex vs scan angle was highly reproducible and exhibited <0.2 mm peak-to-peak variation. With a 0.5-mm voxel pitch, the maximum targeting error was 0.4 mm. Images of 2 patients were analyzed offline and submillimeter agreement was confirmed with conventional frame. Conclusions: A cone beam CT image guidance system was successfully adapted to a radiosurgery unit. The system is capable of producing high-resolution images of bone and soft tissue. The system is in clinical use and provides excellent image guidance without invasive frames.

  16. Automated treatment planning for a dedicated multi-source intra-cranial radiosurgery treatment unit accounting for overlapping structures and dose homogeneity

    SciTech Connect (OSTI)

    Ghobadi, Kimia; Ghaffari, Hamid R.; Aleman, Dionne M.; Institute of Health Policy, Management and Evaluation, University of Toronto, Ontario M5T 3M6; Techna Institute, University Health Network, Ontario M5G 1P5 ; Jaffray, David A.; Department of Radiation Oncology, University of Toronto, Ontario M5S 3E2; Department of Medical Biophysics, University of Toronto, Ontario M5G 2M9; Institute of Biomaterial and Biomedical Engineering, University of Toronto, Ontario M5S 2J7; Techna Institute, University Health Network, Ontario M5G 1P5; Ontario Cancer Institute, Ontario M5G 0A3 ; Ruschin, Mark; Department of Radiation Oncology, University of Toronto, Toronto, Ontario M5S 3E2


    Purpose: The purpose of this work is to advance the two-step approach for Gamma Knife{sup ®} Perfexion™ (PFX) optimization to account for dose homogeneity and overlap between the planning target volume (PTV) and organs-at-risk (OARs).Methods: In the first step, a geometry-based algorithm is used to quickly select isocentre locations while explicitly accounting for PTV-OARs overlaps. In this approach, the PTV is divided into subvolumes based on the PTV-OARs overlaps and the distance of voxels to the overlaps. Only a few isocentres are selected in the overlap volume, and a higher number of isocentres are carefully selected among voxels that are immediately close to the overlap volume. In the second step, a convex optimization is solved to find the optimal combination of collimator sizes and their radiation duration for each isocentre location.Results: This two-step approach is tested on seven clinical cases (comprising 11 targets) for which the authors assess coverage, OARs dose, and homogeneity index and relate these parameters to the overlap fraction for each case. In terms of coverage, the mean V{sub 99} for the gross target volume (GTV) was 99.8% while the V{sub 95} for the PTV averaged at 94.6%, thus satisfying the clinical objectives of 99% for GTV and 95% for PTV, respectively. The mean relative dose to the brainstem was 87.7% of the prescription dose (with maximum 108%), while on average, 11.3% of the PTV overlapped with the brainstem. The mean beam-on time per fraction per dose was 8.6 min with calibration dose rate of 3.5 Gy/min, and the computational time averaged at 205 min. Compared with previous work involving single-fraction radiosurgery, the resulting plans were more homogeneous with average homogeneity index of 1.18 compared to 1.47.Conclusions: PFX treatment plans with homogeneous dose distribution can be achieved by inverse planning using geometric isocentre selection and mathematical modeling and optimization techniques. The quality of the obtained treatment plans are clinically satisfactory while the homogeneity index is improved compared to conventional PFX plans.

  17. Implementing Strategies for Drying and Pressing Wood Without Emissions Controls

    SciTech Connect (OSTI)

    Sujit Banerjee; Terrance Conners


    Drying and pressing wood for the manufacture of lumber, particleboard, oriented strand board (OSB), veneer and medium density fiberboard (MDF) release volatile organic compounds (VOCs) into the atmosphere. These emissions require control equipment that are capital-intensive and consume significant quantities of natural gas and electricity. The objective of our work was to understand the mechanisms through which volatile organic compounds are generated and released and to develop simple control strategies. Of the several strategies developed, two have been implemented for OSB manufacture over the course of this study. First, it was found that increasing final wood moisture by about 2-4 percentage points reduced the dryer emissions of hazardous air pollutants by over 70%. As wood dries, the escaping water evaporatively cools the wood. This cooling tapers off wood when the wood is nearly dry and the wood temperature rises. Thermal breakdown of the wood tissue occurs and VOCs are released. Raising the final wood moisture by only a few percentage points minimizes the temperature rise and reduces emissions. Evaporative cooling also impacts has implications for VOC release from wood fines. Flaking wood for OSB manufacture inevitable generates fines. Fines dry out rapidly because of their high surface area and evaporative cooling is lost more rapidly than for flakes. As a result, fines emit a disproportionate quantity of VOCs. Fines can be reduced in two ways: through screening of the green furnish and through reducing their generation during flaking. The second approach is preferable because it also increased wood yield. A procedure to do this by matching the sharpness angle of the flaker knife to the ambient temperature was also developed. Other findings of practical interests are as follows: Dielectric heating of wood under low-headspace conditions removes terpenes and other extractives from softwood; The monoterpene content in trees depend upon temperature and seasonal effects; Method 25A emissions from lumber drying can be modeled from a knowledge of the airflow through the kiln; A heat transfer model shows that VOCs released during hot-pressing mainly originate from the surface of the board; and Boiler ash can be used to adsorb formaldehyde from air streams.

  18. SU-E-T-224: Is Monte Carlo Dose Calculation Method Necessary for Cyberknife Brain Treatment Planning?

    SciTech Connect (OSTI)

    Wang, L; Fourkal, E; Hayes, S; Jin, L; Ma, C


    Purpose: To study the dosimetric difference resulted in using the pencil beam algorithm instead of Monte Carlo (MC) methods for tumors adjacent to the skull. Methods: We retrospectively calculated the dosimetric differences between RT and MC algorithms for brain tumors treated with CyberKnife located adjacent to the skull for 18 patients (total of 27 tumors). The median tumor sizes was 0.53-cc (range 0.018-cc to 26.2-cc). The absolute mean distance from the tumor to the skull was 2.11 mm (range - 17.0 mm to 9.2 mm). The dosimetric variables examined include the mean, maximum, and minimum doses to the target, the target coverage (TC) and conformality index. The MC calculation used the same MUs as the RT dose calculation without further normalization and 1% statistical uncertainty. The differences were analyzed by tumor size and distance from the skull. Results: The TC was generally reduced with the MC calculation (24 out of 27 cases). The average difference in TC between RT and MC was 3.3% (range 0.0% to 23.5%). When the TC was deemed unacceptable, the plans were re-normalized in order to increase the TC to 99%. This resulted in a 6.9% maximum change in the prescription isodose line. The maximum changes in the mean, maximum, and minimum doses were 5.4 %, 7.7%, and 8.4%, respectively, before re-normalization. When the TC was analyzed with regards to target size, it was found that the worst coverage occurred with the smaller targets (0.018-cc). When the TC was analyzed with regards to the distance to the skull, there was no correlation between proximity to the skull and TC between the RT and MC plans. Conclusions: For smaller targets (< 4.0-cc), MC should be used to re-evaluate the dose coverage after RT is used for the initial dose calculation in order to ensure target coverage.

  19. SU-E-J-258: Inter- and Intra-Fraction Setup Stability and Couch Change Tolerance for Image Guided Radiation Therapy

    SciTech Connect (OSTI)

    Teboh, Forbang R; Agee, M; Rowe, L; Creasy, T; Schultz, J; Bell, R; Wong, J; Armour, E


    Purpose: Immobilization devices combine rigid patient fixation as well as comfort and play a key role providing the stability required for accurate radiation delivery. In the setup step, couch re-positioning needed to align the patient is derived via registration of acquired versus reference image. For subsequent fractions, replicating the initial setup should yield identical alignment errors when compared to the reference. This is not always the case and further couch re-positioning can be needed. An important quality assurance measure is to set couch tolerances beyond which additional investigations are needed. The purpose of this work was to study the inter-fraction couch changes needed to re-align the patient and the intra-fraction stability of the alignment as a guide to establish the couch tolerances. Methods: Data from twelve patients treated on the Accuray CyberKnife (CK) system for fractionated intracranial radiotherapy and immobilized with Aquaplast RT, U-frame, F-Head-Support (Qfix, PA, USA) was used. Each fraction involved image acquisitions and registration with the reference to re-align the patient. The absolute couch position corresponding to the approved setup alignment was recorded per fraction. Intra-fraction set-up corrections were recorded throughout the treatment. Results: The average approved setup alignment was 0.03±0.28mm, 0.15±0.22mm, 0.06±0.31mm in the L/R, A/P, S/I directions respectively and 0.00±0.35degrees, 0.03±0.32degrees, 0.08±0.45degrees for roll, pitch and yaw respectively. The inter-fraction reproducibility of the couch position was 6.65mm, 10.55mm, and 4.77mm in the L/R, A/P and S/I directions respectively and 0.82degrees, 0.71degrees for roll and pitch respectively. Intra-fraction monitoring showed small average errors of 0.21±0.21mm, 0.00±0.08mm, 0.23±0.22mm in the L/R, A/P, S/I directions respectively and 0.03±0.12degrees, 0.04±0.25degrees, and 0.13±0.15degrees in the roll, pitch and yaw respectively. Conclusion: The inter-fraction reproducibility should serve as a guide to couch tolerances, specific to a site and immobilization. More patients need to be included to make general conclusions.

  20. Final Report on "Development and Testing of Advanced Accelerator Structures and Technologies at 11.424 GHz"

    SciTech Connect (OSTI)

    Gold, Steven H.


    This is the final report on the research program ?Development and Testing of Advanced Accelerator Structures and Technologies at 11.424 GHz,? which was carried out by the Naval Research Laboratory (NRL) under Interagency Agreement DE?AI02?01ER41170 with the Department of Energy. The period covered by this report is 15 July 2010 ? 14 July 2013. The program included two principal tasks. Task 1 involved a study of the key physics issues related to the use of high gradient dielectric-loaded accelerating (DLA) structures in rf linear accelerators and was carried out in collaboration with Argonne National Laboratory (ANL) and Euclid Techlabs LLC. Task 2 involved a study of high power active microwave pulse compressors and was carried out in collaboration with Omega-P, Inc. and the Institute of Applied Physics of the Russian Academy of Sciences in Nizhny Novgorod. The studies under Task 1 were focused on rf-induced multipactor and breakdown in externally driven DLA structures at the 200-ns timescale. Suppression of multipactor and breakdown are essential to the practical application of dielectric structures in rf linear accelerators. The structures that were studied were developed by ANL and Euclid Techlabs and their performance was evaluated at high power in the X-band Magnicon Laboratory at NRL. Three structures were designed, fabricated, and tested, and the results analyzed in the first two years of the program: a clamped quartz traveling-wave (TW) structure, a externally copper-coated TW structure, and an externally copper-coated dielectric standing-wave (SW) structure. These structures showed that rf breakdown could be largely eliminated by eliminating dielectric joints in the structures, but that the multipactor loading was omnipresent. In the third year of the program, the focus of the program was on multipactor suppression using a strong applied axial magnetic field, as proposed by Chang et al. [C. Chang et al., J. Appl. Phys. 110, 063304 (2011).], and a successful experiment was carried out that demonstrated suppression of multipactor in the uniform-field region of a TW DLA structure. However, in accordance with theory, the multipactor was enhanced in regions of the structure with lower values of axial magnetic field. Under Task 2, there were two two-month experimental runs at NRL that were used to characterize the performance of high power two-channel dual-mode active microwave pulse compressor configurations that used electron-beam triggered switch cavities. The pulse compressors were designed and fabricated by Omega-P, Inc. and the Russian Institute of Applied Physics and tested in the Magnicon Laboratory at NRL. These pulse compressors made use of an electron beam discharge from a cylindrical knife-edged Mo cathode coated with a CVD diamond film that was driven by a ?100 kV, 100 ns high voltage pulse. The electron beam was used to change the resonant frequency of the switch cavities in order to create the output microwave pulse. The compressor channels included a TE01 input and output section and a TE02 energy storage cavity, followed by a switch assembly that controlled the coupling between the TE01 and TE02 modes. In the initial state, the switch cavity was in resonance, the reflection from the cavity was out of phase, and the mode conversion was only ~2-3%, allowing the energy storage cavity to fill. When the electron beam was discharged into the switch cavity, the cavity was shifted out of resonance, causing the phase of the reflection to change by ~?. As a result of the change in the reflection phase, the mode coupling in the conical taper was greatly increased, and could approach ~100%, permitting the energy storage cavity to empty in one cavity round trip time of the TE02 mode to produce a high power output pulse. The second experiment runs demonstrated a 190 MW, ~20 ns compressed pulse at 25.7 gain and ~50% efficiency, using a 7.4 MW, 1 ?s drive pulse from the magnicon. The success of this experiment suggests a path to future high gain active versions of the SLED 2 pulse compressor at SLAC.