TY - JOUR
T1 - Fixed- versus Variable-RBE Computations for Intensity Modulated Proton Therapy
AU - Yepes, Pablo
AU - Adair, Antony
AU - Frank, Steven J.
AU - Grosshans, David R.
AU - Liao, Zhongxing
AU - Liu, Amy
AU - Mirkovic, Dragan
AU - Poenisch, Falk
AU - Titt, Uwe
AU - Wang, Qianxia
AU - Mohan, Radhe
N1 - Funding Information:
Sources of support: Supported by the Cancer Research Institute of Texas ( RP160232 ), the National Cancer Institute at the National Institutes of Health ( 2U19CA021239-35 ), and Cancer Center Support [Core] Grant CA016672 to The University of Texas MD Anderson Cancer Center.
Funding Information:
Conflicts of interest: Dr Frank reports grants from Hitachi, personal fees from Varian, and grants from the National Cancer Institute at the National Institutes of Health outside the submitted work. All other authors have no conflicts of interest to disclose.
Publisher Copyright:
© 2018 The Authors
PY - 2019/1/1
Y1 - 2019/1/1
N2 - Purpose: To evaluate how using models of proton therapy that incorporate variable relative biological effectiveness (RBE) versus the current practice of using a fixed RBE of 1.1 affects dosimetric indices on treatment plans for large cohorts of patients treated with intensity modulated proton therapy (IMPT). Methods and Materials: Treatment plans for 4 groups of patients who received IMPT for brain, head-and-neck, thoracic, or prostate cancer were selected. Dose distributions were recalculated in 4 ways: 1 with a fast-dose Monte Carlo calculator with fixed RBE and 3 with RBE calculated to 3 different models—McNamara, Wedenberg, and repair-misrepair-fixation. Differences among dosimetric indices (D02, D50, D98, and mean dose) for target volumes and organs at risk (OARs) on each plan were compared between the fixed-RBE and variable-RBE calculations. Results: In analyses of all target volumes, for which the main concern is underprediction or RBE less than 1.1, none of the models predicted an RBE less than 1.05 for any of the cohorts. For OARs, the 2 models based on linear energy transfer, McNamara and Wedenberg, systematically predicted RBE >1.1 for most structures. For the mean dose of 25% of the plans for 2 OARs, they predict RBE equal to or larger than 1.4, 1.3, 1.3, and 1.2 for brain, head-and-neck, thorax, and prostate, respectively. Systematically lower increases in RBE are predicted by repair-misrepair-fixation, with a few cases (eg, femur) in which the RBE is less than 1.1 for all plans. Conclusions: The variable-RBE models predict increased doses to various OARs, suggesting that strategies to reduce high-dose linear energy transfer in critical structures should be developed to minimize possible toxicity associated with IMPT.
AB - Purpose: To evaluate how using models of proton therapy that incorporate variable relative biological effectiveness (RBE) versus the current practice of using a fixed RBE of 1.1 affects dosimetric indices on treatment plans for large cohorts of patients treated with intensity modulated proton therapy (IMPT). Methods and Materials: Treatment plans for 4 groups of patients who received IMPT for brain, head-and-neck, thoracic, or prostate cancer were selected. Dose distributions were recalculated in 4 ways: 1 with a fast-dose Monte Carlo calculator with fixed RBE and 3 with RBE calculated to 3 different models—McNamara, Wedenberg, and repair-misrepair-fixation. Differences among dosimetric indices (D02, D50, D98, and mean dose) for target volumes and organs at risk (OARs) on each plan were compared between the fixed-RBE and variable-RBE calculations. Results: In analyses of all target volumes, for which the main concern is underprediction or RBE less than 1.1, none of the models predicted an RBE less than 1.05 for any of the cohorts. For OARs, the 2 models based on linear energy transfer, McNamara and Wedenberg, systematically predicted RBE >1.1 for most structures. For the mean dose of 25% of the plans for 2 OARs, they predict RBE equal to or larger than 1.4, 1.3, 1.3, and 1.2 for brain, head-and-neck, thorax, and prostate, respectively. Systematically lower increases in RBE are predicted by repair-misrepair-fixation, with a few cases (eg, femur) in which the RBE is less than 1.1 for all plans. Conclusions: The variable-RBE models predict increased doses to various OARs, suggesting that strategies to reduce high-dose linear energy transfer in critical structures should be developed to minimize possible toxicity associated with IMPT.
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U2 - 10.1016/j.adro.2018.08.020
DO - 10.1016/j.adro.2018.08.020
M3 - Article
C2 - 30706024
AN - SCOPUS:85054845222
SN - 2452-1094
VL - 4
SP - 156
EP - 167
JO - Advances in Radiation Oncology
JF - Advances in Radiation Oncology
IS - 1
ER -