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Title: Dosimetric study and in-vivo dose verification for conformal avoidance treatment of anal adenocarcinoma using helical tomotherapy

Abstract

This study evaluated the efficacy of using helical tomotherapy for conformal avoidance treatment of anal adenocarcinoma. We retrospectively generated step-and-shoot intensity-modulated radiotherapy (sIMRT) plans and helical tomotherapy plans for two anal cancer patients, one male and one female, who were treated by the sIMRT technique. Dose parameters for the planning target volume (PTV) and the organs-at-risk (OARs) were compared between the sIMRT and the helical tomotherapy plans. The helical tomotherapy plans showed better dose homogeneity in the PTV, better dose conformity around the PTV, and, therefore, better sparing of nearby OARs compared with the sIMRT plans. In-vivo skin dose measurements were performed during conformal avoidance helical tomotherapy treatment of an anal cancer patient to verify adequate delivery of skin dose and sparing of OARs.

Authors:
 [1];  [2];  [3];  [4];  [3];  [4];  [2]
  1. Department of Radiation Physics, City of Hope National Medical Center, Duarte, CA (United States) and Division of Radiation Oncology, City of Hope National Medical Center, Duarte, CA (United States). E-mail: chan@coh.org
  2. Division of Radiation Oncology, City of Hope National Medical Center, Duarte, CA (United States)
  3. Department of Radiation Physics, City of Hope National Medical Center, Duarte, CA (United States)
  4. (United States)
Publication Date:
OSTI Identifier:
20975199
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Dosimetry; Journal Volume: 32; Journal Issue: 1; Other Information: DOI: 10.1016/j.meddos.2006.10.004; PII: S0958-3947(06)00168-3; Copyright (c) 2007 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:
61 RADIATION PROTECTION AND DOSIMETRY; CARCINOMAS; COMPUTERIZED TOMOGRAPHY; DOSIMETRY; IN VIVO; PATIENTS; PLANNING; RADIATION DOSES; RADIOTHERAPY; SKIN; VERIFICATION

Citation Formats

Han Chunhui, Chen Yijen, Liu An, Division of Radiation Oncology, City of Hope National Medical Center, Duarte, CA, Schultheiss, Timothy E., Division of Radiation Oncology, City of Hope National Medical Center, Duarte, CA, and Wong, Jeffrey Y.C. Dosimetric study and in-vivo dose verification for conformal avoidance treatment of anal adenocarcinoma using helical tomotherapy. United States: N. p., 2007. Web.
Han Chunhui, Chen Yijen, Liu An, Division of Radiation Oncology, City of Hope National Medical Center, Duarte, CA, Schultheiss, Timothy E., Division of Radiation Oncology, City of Hope National Medical Center, Duarte, CA, & Wong, Jeffrey Y.C. Dosimetric study and in-vivo dose verification for conformal avoidance treatment of anal adenocarcinoma using helical tomotherapy. United States.
Han Chunhui, Chen Yijen, Liu An, Division of Radiation Oncology, City of Hope National Medical Center, Duarte, CA, Schultheiss, Timothy E., Division of Radiation Oncology, City of Hope National Medical Center, Duarte, CA, and Wong, Jeffrey Y.C. Sun . "Dosimetric study and in-vivo dose verification for conformal avoidance treatment of anal adenocarcinoma using helical tomotherapy". United States. doi:.
@article{osti_20975199,
title = {Dosimetric study and in-vivo dose verification for conformal avoidance treatment of anal adenocarcinoma using helical tomotherapy},
author = {Han Chunhui and Chen Yijen and Liu An and Division of Radiation Oncology, City of Hope National Medical Center, Duarte, CA and Schultheiss, Timothy E. and Division of Radiation Oncology, City of Hope National Medical Center, Duarte, CA and Wong, Jeffrey Y.C.},
abstractNote = {This study evaluated the efficacy of using helical tomotherapy for conformal avoidance treatment of anal adenocarcinoma. We retrospectively generated step-and-shoot intensity-modulated radiotherapy (sIMRT) plans and helical tomotherapy plans for two anal cancer patients, one male and one female, who were treated by the sIMRT technique. Dose parameters for the planning target volume (PTV) and the organs-at-risk (OARs) were compared between the sIMRT and the helical tomotherapy plans. The helical tomotherapy plans showed better dose homogeneity in the PTV, better dose conformity around the PTV, and, therefore, better sparing of nearby OARs compared with the sIMRT plans. In-vivo skin dose measurements were performed during conformal avoidance helical tomotherapy treatment of an anal cancer patient to verify adequate delivery of skin dose and sparing of OARs.},
doi = {},
journal = {Medical Dosimetry},
number = 1,
volume = 32,
place = {United States},
year = {Sun Apr 01 00:00:00 EDT 2007},
month = {Sun Apr 01 00:00:00 EDT 2007}
}
  • The American College of Radiology practice guideline for total body irradiation (TBI) requires a back-up treatment delivery system. This study investigates the development of helical tomotherapy (HT) for delivering TBI and compares it with conventional extended source-to-surface distance (X-SSD) technique. Four patients' head-to-thigh computed tomographic images were used in this study, with the target defined as the body volume without the left and right lungs. HT treatment plans with the standard TBI prescription (1.2 Gy/fx, 10 fractions) were generated and verified on phantoms. To compare HT plans with X-SSD treatment, the dose distribution of X-SSD technique was simulated using themore » Eclipse software. The average dose received by 90% of the target volume was 12.3 Gy (range, 12.2-12.4 Gy) for HT plans and 10.3 Gy (range, 10.08-10.58 Gy) for X-SSD plans (p < 0.001). The left and right lung median doses were 5.44 Gy and 5.40 Gy, respectively, for HT plans and 8.34 Gy and 8.95 Gy, respectively, for X-SSD treatment. The treatment planning time was comparable between the two methods. The beam delivery time of HT treatment was longer than X-SSD treatment. In conclusion, HT-based TBI plans have better dose coverage to the target and better dose sparing to the lungs compared with X-SSD technique, which applies dose compensators, lung blocks, and electron boosts. This study demonstrates that HT is possible for delivering TBI. Clinical validation of the feasibility of this approach would be of interest in the future.« less
  • To describe a dosimetric method using an anterior dose avoidance structure (ADAS) during the treatment planning process for intensity-modulated radiation therapy (IMRT) for patients with anal canal and rectal carcinomas. A total of 20 patients were planned on the Elekta/CMS XiO treatment planning system, version 4.5.1 (Maryland Heights MO) with a superposition algorithm. For each patient, 2 plans were created: one employing an ADAS (ADAS plan) and the other replanned without an ADAS (non-ADAS plan). The ADAS was defined to occupy the volume between the inguinal nodes and primary target providing a single organ at risk that is completely outsidemore » of the target volume. Each plan used the same beam parameters and was analyzed by comparing target coverage, overall plan dose conformity using a conformity number (CN) equation, bowel dose-volume histograms, and the number of segments, daily treatment duration, and global maximum dose. The ADAS and non-ADAS plans were equivalent in target coverage, mean global maximum dose, and sparing of small bowel in low-dose regions (5, 10, 15, and 20 Gy). The mean difference between the CN value for the non-ADAS plans and ADAS plans was 0.04 ± 0.03 (p < 0.001). The mean difference in the number of segments was 15.7 ± 12.7 (p < 0.001) in favor of ADAS plans. The ADAS plan delivery time was shorter by 2.0 ± 1.5 minutes (p < 0.001) than the non-ADAS one. The ADAS has proven to be a powerful tool when planning rectal and anal canal IMRT cases with critical structures partially contained inside the target volume.« less
  • The partial-breast irradiation (PBI) technique, an alternative to whole-breast irradiation, is a beam delivery method that uses a limited range of treatment volume. The present study was designed to determine the optimal PBI treatment modalities for 8 different tumor locations. Treatment planning was performed on computed tomography (CT) data sets of 6 patients who had received lumpectomy treatments. Tumor locations were classified into 8 subsections according to breast quadrant and depth. Three-dimensional conformal radiation therapy (3D-CRT), electron beam therapy (ET), and helical tomotherapy (H-TOMO) were utilized to evaluate the dosimetric effect for each tumor location. Conformation number (CN), radical dosemore » homogeneity index (rDHI), and dose delivered to healthy tissue were estimated. The Kruskal-Wallis, Mann-Whitney U, and Bonferroni tests were used for statistical analysis. The ET approach showed good sparing effects and acceptable target coverage for the lower inner quadrant—superficial (LIQ-S) and lower inner quadrant—deep (LIQ-D) locations. The H-TOMO method was the least effective technique as no evaluation index achieved superiority for all tumor locations except CN. The ET method is advisable for treating LIQ-S and LIQ-D tumors, as opposed to 3D-CRT or H-TOMO, because of acceptable target coverage and much lower dose applied to surrounding tissue.« less
  • Purpose: We investigated whether treatment-planning system (TPS)-calculated dose accurately reflects skin dose received for patients receiving adjuvant breast radiotherapy (RT) with standard three-dimensional conformal RT (3D-CRT) or skin-sparing helical tomotherapy (HT). Methods and Materials: Fifty patients enrolled in a randomized controlled trial investigating acute skin toxicity from adjuvant breast RT with 3D-CRT compared to skin-sparing HT, where a 5-mm strip of ipsilateral breast skin was spared. Thermoluminescent dosimetry or optically stimulated luminescence measurements were made in multiple locations and were compared to TPS-calculated doses. Skin dosimetric parameters and acute skin toxicity were recorded in these patients. Results: With HT theremore » was a significant correlation between calculated and measured dose in the medial and lateral ipsilateral breast (r = 0.67, P<.001; r = 0.44, P=.03, respectively) and the medial and central contralateral breast (r = 0.73, P<.001; r = 0.88, P<.001, respectively). With 3D-CRT there was a significant correlation in the medial and lateral ipsilateral breast (r = 0.45, P=.03; r = 0.68, P<.001, respectively); the medial and central contralateral breast (r = 0.62, P=.001; r = 0.86, P<.001, respectively); and the mid neck (r = 0.42, P=.04, respectively). On average, HT-calculated dose overestimated the measured dose by 14%; 3D-CRT underestimated the dose by 0.4%. There was a borderline association between highest measured skin dose and moist desquamation (P=.05). Skin-sparing HT had greater skin homogeneity (homogeneity index of 1.39 vs 1.65, respectively; P=.005) than 3D-CRT plans. HT plans had a lower skin{sub V50} (1.4% vs 5.9%, respectively; P=.001) but higher skin{sub V40} and skin{sub V30} (71.7% vs 64.0%, P=.02; and 99.0% vs 93.8%, P=.001, respectively) than 3D-CRT plans. Conclusion: The 3D-CRT TPS more accurately reflected skin dose than the HT TPS, which tended to overestimate dose received by 14% in patients receiving adjuvant breast RT.« less
  • Purpose: To describe a novel and straightforward conformal avoidance intensity-modulated radiation therapy (IMRT) technique for coverage of pelvis and inguinal/femoral nodes and to compare the dosimetry of the new method with that of other traditional methods of radiation treatment. Methods and Materials: Data of 2 patients with anal cancer were used as example cases to illustrate details and advantages of conformal avoidance IMRT technique. Conventional photons with enface electrons design was created first, thereby providing 'outermost boundaries' defined as planning target volume (PTV) for subsequent conformal avoidance IMRT design. Organs at risk (OARs), including femoral head and neck and externalmore » genitalia, were contoured as conformal avoidance structures. A step-and-shoot inverse IMRT planning was subsequently generated. For dosimetric comparison, a recently published technique by modified segmental boost was also generated. These treatment techniques were evaluated by dose-volume histogram (DVH) of PTV and OARs. Dose profiles at four different depths from each treatment planning were generated for comparison. Results: The DVH of PTV showed that coverage of the PTV was comparable among three treatment techniques. Percent volume of PTV receiving more than 90% prescription dose was in the range 94-98% for the three treatment techniques, and all had only 0-2% of PTV receiving more than 110% of prescription dose. The DVH of OARs confirmed that both femoral head and neck and external genitalia could be spared well by conformal avoidance IMRT as compared with the other two techniques. Although greater inhomogeneity of dose distribution within the PTV was noted by conformal avoidance IMRT technique, as shown by dose profiles at four different depths, the maximum doses at different depths were less than 115%, which was comparable to those planned by modified segmental boost technique. Planning by photons and enface electrons technique, however, showed a greater dose variation up to 134% of the prescription dose at 1.5 cm depth along photon-electron match-line. Conclusions: To cover pelvis and inguinal/femoral nodes, conformal avoidance IMRT is technically simple to simulate, plan, and execute. Dosimetric study has demonstrated that it achieves comparable PTV coverage compared with other approaches while at the same time significantly sparing the surrounding OARs.« less