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Title: SU-F-T-200: Dosimetric Variation of Organs at Risk for Recurrent Nasopharyngeal Carcinoma (rNPC) Patients Treated by Carbon Ion Beams

Abstract

Purpose: Investigate the factors which affect the doses of organs at risk (OARs) for head and neck carbon ion therapy. Methods: Ten locally recurrent nasopharyngeal carcinoma cases with similar prescriptions were selected. All patients’ organs at risk (OARs) as well as CTVs were contoured by an experienced physician. Carbon ion treatment plans were created using a Syngo treatment planning system (Siemens, Germany). The CTVs were expanded to make optimized target volumes (OTVs) by considering treatment uncertainties and OAR protections. All plans were reviewed by this physician to be clinically acceptable. The OTV was expanded an additional 3mm to define the volume where beam spots could be put. A volume was also drawn 6 mm around the OTV to approximate the 50 % dose volume. The volumes where the OARs overlapped the OTV + 3 mm and OTV + 6 mm volumes, termed residual volumes, were then calculated. Results: The residual volumes within OTV + 3 mm were directly related to the OAR maximum dose. The percentage of the residual volume within the OTV + 6 mm with respect to the OAR volume was strongly related to the OAR mean doses. OAR mean doses also were affected by the beam setups.more » For example, if the OARs were in the beam entrance, the superior beams would sharply decrease the mean doses of the OARs hit by the lateral beams while increasing the mean doses of the OARs hit by the superior beam; the mean dose of the OARs which were hit by higher weight beams would be higher than the OARs hit by lower weight beams. Conclusion: Physicians should be cautious when contouring OARs, especially those close to CTVs and sensitive to large doses. Planners should set the OTV and beam parameters properly in order to save the OARs.« less

Authors:
; ;  [1]
  1. Shanghai proton and heavy ion center, Shanghai, Shanghai (China)
Publication Date:
OSTI Identifier:
22648817
Resource Type:
Journal Article
Journal Name:
Medical Physics
Additional Journal Information:
Journal Volume: 43; Journal Issue: 6; Other Information: (c) 2016 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0094-2405
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; 61 RADIATION PROTECTION AND DOSIMETRY; CARBON IONS; CARCINOMAS; HAZARDS; ION BEAMS; ORGANS; PATIENTS; PLANNING; RADIOTHERAPY

Citation Formats

Wang, W, Sheng, Y, and Shahnazi, K. SU-F-T-200: Dosimetric Variation of Organs at Risk for Recurrent Nasopharyngeal Carcinoma (rNPC) Patients Treated by Carbon Ion Beams. United States: N. p., 2016. Web. doi:10.1118/1.4956337.
Wang, W, Sheng, Y, & Shahnazi, K. SU-F-T-200: Dosimetric Variation of Organs at Risk for Recurrent Nasopharyngeal Carcinoma (rNPC) Patients Treated by Carbon Ion Beams. United States. doi:10.1118/1.4956337.
Wang, W, Sheng, Y, and Shahnazi, K. Wed . "SU-F-T-200: Dosimetric Variation of Organs at Risk for Recurrent Nasopharyngeal Carcinoma (rNPC) Patients Treated by Carbon Ion Beams". United States. doi:10.1118/1.4956337.
@article{osti_22648817,
title = {SU-F-T-200: Dosimetric Variation of Organs at Risk for Recurrent Nasopharyngeal Carcinoma (rNPC) Patients Treated by Carbon Ion Beams},
author = {Wang, W and Sheng, Y and Shahnazi, K},
abstractNote = {Purpose: Investigate the factors which affect the doses of organs at risk (OARs) for head and neck carbon ion therapy. Methods: Ten locally recurrent nasopharyngeal carcinoma cases with similar prescriptions were selected. All patients’ organs at risk (OARs) as well as CTVs were contoured by an experienced physician. Carbon ion treatment plans were created using a Syngo treatment planning system (Siemens, Germany). The CTVs were expanded to make optimized target volumes (OTVs) by considering treatment uncertainties and OAR protections. All plans were reviewed by this physician to be clinically acceptable. The OTV was expanded an additional 3mm to define the volume where beam spots could be put. A volume was also drawn 6 mm around the OTV to approximate the 50 % dose volume. The volumes where the OARs overlapped the OTV + 3 mm and OTV + 6 mm volumes, termed residual volumes, were then calculated. Results: The residual volumes within OTV + 3 mm were directly related to the OAR maximum dose. The percentage of the residual volume within the OTV + 6 mm with respect to the OAR volume was strongly related to the OAR mean doses. OAR mean doses also were affected by the beam setups. For example, if the OARs were in the beam entrance, the superior beams would sharply decrease the mean doses of the OARs hit by the lateral beams while increasing the mean doses of the OARs hit by the superior beam; the mean dose of the OARs which were hit by higher weight beams would be higher than the OARs hit by lower weight beams. Conclusion: Physicians should be cautious when contouring OARs, especially those close to CTVs and sensitive to large doses. Planners should set the OTV and beam parameters properly in order to save the OARs.},
doi = {10.1118/1.4956337},
journal = {Medical Physics},
issn = {0094-2405},
number = 6,
volume = 43,
place = {United States},
year = {2016},
month = {6}
}