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Title: Integral radiation dose to normal structures with conformal external beam radiation

Abstract

Background: This study was designed to evaluate the integral dose (ID) received by normal tissue from intensity-modulated radiotherapy (IMRT) for prostate cancer. Methods and Materials: Twenty-five radiation treatment plans including IMRT using a conventional linac with both 6 MV (6MV-IMRT) and 20 MV (20MV-IMRT), as well as three-dimensional conformal radiotherapy (3DCRT) using 6 MV (6MV-3DCRT) and 20 MV (20MV-3DCRT) and IMRT using tomotherapy (6MV) (Tomo-IMRT), were created for 5 patients with localized prostate cancer. The ID (mean dose x tissue volume) received by normal tissue (NTID) was calculated from dose-volume histograms. Results: The 6MV-IMRT resulted in 5.0% lower NTID than 6MV-3DCRT; 20 MV beam plans resulted in 7.7%-11.2% lower NTID than 6MV-3DCRT. Tomo-IMRT NTID was comparable to 6MV-IMRT. Compared with 6MV-3DCRT, 6MV-IMRT reduced IDs to the rectal wall and penile bulb by 6.1% and 2.7%, respectively. Tomo-IMRT further reduced these IDs by 11.9% and 16.5%, respectively. The 20 MV did not reduce IDs to those structures. Conclusions: The difference in NTID between 3DCRT and IMRT is small. The 20 MV plans somewhat reduced NTID compared with 6 MV plans. The advantage of tomotherapy over conventional IMRT and 3DCRT for localized prostate cancer was demonstrated in regard to dose sparing ofmore » rectal wall and penile bulb while slightly decreasing NTID as compared with 6MV-3DCRT.« less

Authors:
 [1];  [2];  [3];  [4];  [4];  [2];  [4];  [3];  [4];  [3];  [3];  [3];  [4];  [3];  [3]
  1. Department of Human Oncology, University of Wisconsin, Madison, WI (United States) and Department of Radiology, Hokkaido University Graduate School of Medicine, Sapporo (Japan). E-mail: hao@radi.med.hokudai.ac.jp
  2. Department of Medical Physics, University of Wisconsin, Madison, WI (United States)
  3. Department of Human Oncology, University of Wisconsin, Madison, WI (United States)
  4. (United States)
Publication Date:
OSTI Identifier:
20793371
Resource Type:
Journal Article
Resource Relation:
Journal Name: International Journal of Radiation Oncology, Biology and Physics; Journal Volume: 64; Journal Issue: 3; Other Information: DOI: 10.1016/j.ijrobp.2005.11.005; PII: S0360-3016(05)02946-9; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
62 RADIOLOGY AND NUCLEAR MEDICINE; BEAMS; CARCINOMAS; COMPUTERIZED TOMOGRAPHY; INTEGRAL DOSES; LINEAR ACCELERATORS; PATIENTS; PROSTATE; RADIOTHERAPY

Citation Formats

Aoyama, Hidefumi, Westerly, David Clark, Mackie, Thomas Rockwell, Department of Medical Physics, University of Wisconsin, Madison, WI, TomoTherapy Inc., Madison, WI, Olivera, Gustavo H., TomoTherapy Inc., Madison, WI, Bentzen, Soren M., Department of Medical Physics, University of Wisconsin, Madison, WI, Patel, Rakesh R., Jaradat, Hazim, Tome, Wolfgang A., Department of Medical Physics, University of Wisconsin, Madison, WI, Ritter, Mark A., and Mehta, Minesh P. Integral radiation dose to normal structures with conformal external beam radiation. United States: N. p., 2006. Web. doi:10.1016/J.IJROBP.2005.1.
Aoyama, Hidefumi, Westerly, David Clark, Mackie, Thomas Rockwell, Department of Medical Physics, University of Wisconsin, Madison, WI, TomoTherapy Inc., Madison, WI, Olivera, Gustavo H., TomoTherapy Inc., Madison, WI, Bentzen, Soren M., Department of Medical Physics, University of Wisconsin, Madison, WI, Patel, Rakesh R., Jaradat, Hazim, Tome, Wolfgang A., Department of Medical Physics, University of Wisconsin, Madison, WI, Ritter, Mark A., & Mehta, Minesh P. Integral radiation dose to normal structures with conformal external beam radiation. United States. doi:10.1016/J.IJROBP.2005.1.
Aoyama, Hidefumi, Westerly, David Clark, Mackie, Thomas Rockwell, Department of Medical Physics, University of Wisconsin, Madison, WI, TomoTherapy Inc., Madison, WI, Olivera, Gustavo H., TomoTherapy Inc., Madison, WI, Bentzen, Soren M., Department of Medical Physics, University of Wisconsin, Madison, WI, Patel, Rakesh R., Jaradat, Hazim, Tome, Wolfgang A., Department of Medical Physics, University of Wisconsin, Madison, WI, Ritter, Mark A., and Mehta, Minesh P. Wed . "Integral radiation dose to normal structures with conformal external beam radiation". United States. doi:10.1016/J.IJROBP.2005.1.
@article{osti_20793371,
title = {Integral radiation dose to normal structures with conformal external beam radiation},
author = {Aoyama, Hidefumi and Westerly, David Clark and Mackie, Thomas Rockwell and Department of Medical Physics, University of Wisconsin, Madison, WI and TomoTherapy Inc., Madison, WI and Olivera, Gustavo H. and TomoTherapy Inc., Madison, WI and Bentzen, Soren M. and Department of Medical Physics, University of Wisconsin, Madison, WI and Patel, Rakesh R. and Jaradat, Hazim and Tome, Wolfgang A. and Department of Medical Physics, University of Wisconsin, Madison, WI and Ritter, Mark A. and Mehta, Minesh P.},
abstractNote = {Background: This study was designed to evaluate the integral dose (ID) received by normal tissue from intensity-modulated radiotherapy (IMRT) for prostate cancer. Methods and Materials: Twenty-five radiation treatment plans including IMRT using a conventional linac with both 6 MV (6MV-IMRT) and 20 MV (20MV-IMRT), as well as three-dimensional conformal radiotherapy (3DCRT) using 6 MV (6MV-3DCRT) and 20 MV (20MV-3DCRT) and IMRT using tomotherapy (6MV) (Tomo-IMRT), were created for 5 patients with localized prostate cancer. The ID (mean dose x tissue volume) received by normal tissue (NTID) was calculated from dose-volume histograms. Results: The 6MV-IMRT resulted in 5.0% lower NTID than 6MV-3DCRT; 20 MV beam plans resulted in 7.7%-11.2% lower NTID than 6MV-3DCRT. Tomo-IMRT NTID was comparable to 6MV-IMRT. Compared with 6MV-3DCRT, 6MV-IMRT reduced IDs to the rectal wall and penile bulb by 6.1% and 2.7%, respectively. Tomo-IMRT further reduced these IDs by 11.9% and 16.5%, respectively. The 20 MV did not reduce IDs to those structures. Conclusions: The difference in NTID between 3DCRT and IMRT is small. The 20 MV plans somewhat reduced NTID compared with 6 MV plans. The advantage of tomotherapy over conventional IMRT and 3DCRT for localized prostate cancer was demonstrated in regard to dose sparing of rectal wall and penile bulb while slightly decreasing NTID as compared with 6MV-3DCRT.},
doi = {10.1016/J.IJROBP.2005.1},
journal = {International Journal of Radiation Oncology, Biology and Physics},
number = 3,
volume = 64,
place = {United States},
year = {Wed Mar 01 00:00:00 EST 2006},
month = {Wed Mar 01 00:00:00 EST 2006}
}
  • Purpose: To determine the feasibility of combined long-term luteinizing hormone-releasing hormone agonist-based androgen suppressive therapy (AST) and dose escalation with high-dose-rate (HDR) brachytherapy for high-risk (HRPC) or very-high-risk prostate cancer (VHRPC). Methods and Materials: Between January 2001 and October 2006, 134 patients (median age, 70 years) with either National Comprehensive Cancer Network criteria-defined HRPC (n = 47, 35.1%) or VHRPC (n = 87, 64.9%) were prospectively enrolled in this Phase II trial. Tumor characteristics included a median pretreatment prostate-specific antigen level of 14.6 ng/mL, a median clinical stage of T2c, and a median Gleason score of 7. Three-dimensional conformal radiotherapymore » (54 Gy in 30 fractions) was followed by HDR brachytherapy (19 Gy in 4 b.i.d. treatments). Androgen suppressive therapy started 0-3 months before three-dimensional conformal radiotherapy and continued for 2 years. Results: One implant was repositioned with a new procedure (0.7%). Five patients (3.7%) discontinued AST at a median of 13 months (range, 6-18 months) because of disease progression (n = 1), hot flashes (n = 2), fatigue (n = 1), and impotence (n = 1). After a median follow-up of 37.4 months (range, 24-90 months), the highest Radiation Therapy Oncology Group-defined late urinary toxicities were Grade 0 in 47.8%, Grade 1 in 38.1%, Grade 2 in 7.5%, and Grade 3 in 6.7% of patients. Maximal late gastrointestinal toxicities were Grade 0 in 73.1%, Grade 1 in 16.4%, Grade 2 in 7.5%, and Grade 3 in 2.9% of patients. There were no Grade 4 or 5 events. Conclusions: Intermediate-term results show that dose escalation with HDR brachytherapy combined with long-term AST is feasible and has a toxicity profile similar to that reported by previous HDR brachytherapy studies.« less
  • Purpose: To determine whether intensity-modulated radiotherapy (IMRT) treatment increases the total integral dose of nontarget tissue relative to the conventional three-dimensional conformal radiotherapy (3D-CRT) technique for high-grade gliomas. Methods and Materials: Twenty patients treated with 3D-CRT for glioblastoma multiforme were selected for a comparative dosimetric evaluation with IMRT. Original target volumes, organs at risk (OAR), and dose-volume constraints were used for replanning with IMRT. Predicted isodose distributions, cumulative dose-volume histograms of target volumes and OAR, normal tissue integral dose, target coverage, dose conformity, and normal tissue sparing with 3D-CRT and IMRT planning were compared. Statistical analyses were performed to determinemore » differences. Results: In all 20 patients, IMRT maintained equivalent target coverage, improved target conformity (conformity index [CI] 95% 1.52 vs. 1.38, p < 0.001), and enabled dose reductions of normal tissues, including brainstem (D{sub mean} by 19.8% and D{sub max} by 10.7%), optic chiasm (D{sub mean} by 25.3% and D{sub max} by 22.6%), right optic nerve (D{sub mean} by 37.3% and D{sub max} by 28.5%), and left optic nerve (D{sub mean} by 40.6% and D{sub max} by 36.7%), p {<=} 0.01. This was achieved without increasing the total nontarget integral dose by greater than 0.5%. Overall, total integral dose was reduced by 7-10% with IMRT, p < 0.001, without significantly increasing the 0.5-5 Gy low-dose volume. Conclusions: These results indicate that IMRT treatment for high-grade gliomas allows for improved target conformity, better critical tissue sparing, and importantly does so without increasing integral dose and the volume of normal tissue exposed to low doses of radiation.« less
  • Purpose: Several accelerated partial breast irradiation (APBI) techniques are described in the literature, and apparently, the three-dimensional (3D)-conformal technique is being used increasingly. Nonetheless, the optimal radiation dose is not yet known. Here, we report feasibility and early toxicities of APBI delivering 40 Gy over 5 days, in a phase II trial. Methods and Materials: From October 2007 to September 2008, 25 patients with pT1N0 cancer received 3D-conformal APBI. The prescribed radiation dose was 40 Gy in 4-Gy fractions given twice daily. This technique used two minitangents and an 'en face' electron field. Toxicities were systematically assessed at 1, 2,more » and 6 months and then once every 6 months. Results: The planning tumor volume for evaluation (PTV{sub E}VAL) coverage was adequate: the mean dose to the PTV{sub E}VAL was 41.8 Gy (range, 41-42.4 Gy). Mean doses to the ipsilateral lung and heart were 1.6 Gy (range, 1.0-2.3 Gy) and 1.2 Gy (range, 1.0-1.6 Gy), respectively. One and two months after completion of APBI, most patients had no or mild erythema (n = 16 patients at 1 month; n = 25 patients at 2 months); none of these patients developed moist desquamation. After a median follow-up of 12 months, only 1 patient had a significant moderate field contracture (grade 2). Other reported late toxicities were grade 1. Conclusions: 3D-conformal APBI (with two minitangents and an 'en face' electron field) using a total dose of 40 Gy in 10 fractions twice daily over 5 days achieved appropriate PTV{sub E}VAL coverage and offered significant sparing of normal tissue. Early tolerance was excellent.« less
  • Purpose: To compare dose-volume histograms (DVH) in patients with non-small-cell lung cancer (NSCLC) treated by photon or proton radiotherapy. Methods and Materials: Dose-volume histograms were compared between photon, including three-dimensional conformal radiation therapy (3D-CRT), intensity-modulated radiation therapy (IMRT), and proton plans at doses of 66 Gy, 87.5 Gy in Stage I (n = 10) and 60-63 Gy, and 74 Gy in Stage III (n 15). Results: For Stage I, the mean total lung V5, V10, and V20 were 31.8%, 24.6%, and 15.8%, respectively, for photon 3D-CRT with 66 Gy, whereas they were 13.4%, 12.3%, and 10.9%, respectively, with proton withmore » dose escalation to 87.5 cobalt Gray equivalents (CGE) (p = 0.002). For Stage III, the mean total lung V5, V10, and V20 were 54.1%, 46.9%, and 34.8%, respectively, for photon 3D-CRT with 63 Gy, whereas they were 39.7%, 36.6%, and 31.6%, respectively, for proton with dose escalation to 74 CGE (p = 0.002). In all cases, the doses to lung, spinal cord, heart, esophagus, and integral dose were lower with proton therapy even compared with IMRT. Conclusions: Proton treatment appears to reduce dose to normal tissues significantly, even with dose escalation, compared with standard-dose photon therapy, either 3D-CRT or IMRT.« less
  • Purpose: Investigating the impact of tumor regression on the dose within cervical tumors and surrounding organs, comparing conventional, conformal, and intensity-modulated radiotherapy (IMRT) and the need for repeated treatment planning during irradiation. Methods and Materials: Fourteen patients with cervical cancer underwent magnetic resonance (MR) imaging before treatment and once during treatment, after about 30 Gy. Target volumes and critical organs were delineated. First conventional, conformal, and IMRT plans were generated. To evaluate the impact of tumor regression, we calculated dose-volume histograms for these plans, using the delineations of the intratreatment MR images. Second conformal and IMRT plans were made basedmore » on the delineations of the intratreatment MR images. First and second plans were compared. Results: The average volume receiving 95% of the prescribed dose (43 Gy) by the conventional, conformal, and IMRT plans was, respectively, for the bowel 626 cc, 427 cc, and 232 cc; for the rectum 101 cc, 90 cc, and 60 cc; and for the bladder 89 cc, 70 cc, and 58 cc. The volumes of critical organs at this dose level were significantly reduced using IMRT compared with conventional and conformal planning (p < 0.02 in all cases). After having delivered about 30 Gy external beam radiation therapy, the primary gross tumor volumes decreased on average by 46% (range, 6.1-100%). The target volumes on the intratreatment MR images remained sufficiently covered by the 95% isodose. Second IMRT plans significantly diminished the treated bowel volume, if the primary gross tumor volumes decreased >30 cc. Conclusions: Intensity-modulated radiation therapy is superior in sparing of critical organs compared with conventional and conformal treatment, with adequate coverage of the target volumes. Intensity-modulated radiation therapy remains superior after 30 Gy external beam radiation therapy, despite tumor regression and internal organ motion. Repeated IMRT planning can improve the sparing of the bowel and rectum in patients with substantial tumor regression.« less