TY - JOUR
T1 - Dose prescription in carbon ion radiotherapy
T2 - A planning study to compare NIRS and LEM approaches with a clinically-oriented strategy
AU - Fossati, Piero
AU - Molinelli, Silvia
AU - Matsufuji, Naruhiru
AU - Ciocca, Mario
AU - Mirandola, Alfredo
AU - Mairani, Andrea
AU - Mizoe, Junetsu
AU - Hasegawa, Azusa
AU - Imai, Reiko
AU - Kamada, Tadashi
AU - Orecchia, Roberto
AU - Tsujii, Hirohiko
PY - 2012/11/21
Y1 - 2012/11/21
N2 - In carbon ion radiotherapy there is an urgent clinical need to develop objective tools for the conversion of relative biological effectiveness (RBE)-weighted doses based on different models. In this work we introduce a clinically oriented method to compare NIRS-based and LEM-based GyE systems, minimizing differences in physical dose distributions between treatment plans. Carbon ion plans were optimized on target volumes of cubic and spherical shapes, for RBE-weighted dose prescription levels ranging from 3.6 to 4.4 GyE. Plans were calculated for target sizes from 4 to 12cm defining three beam geometries: single beam, opposed beam and orthogonal beam configurations. The two treatment planning systems currently employed in clinical practice were used, providing the NIRS-based and LEM-based GyE calculations. Physical dose distributions of NIRS-based and LEM-based treatment plans were compared. LEM-based prescription doses that minimize differences in physical dose distributions between the two systems were found. These doses were compared with the mean RBE-weighted dose obtained with a Monte Carlo code (FLUKA) interfaced with LEM I. In the investigated dose range, LEM-based RBE-weighted prescription doses, that minimize differences with NIRS plans, should be higher than NIRS reported prescription doses. The optimal dose depends on target size, shape and position, number of beams and dose level. The opposed beam configuration resulted in the smallest average prescription dose difference (0.45 ± 0.09 GyE). The second approach of recalculating NIRS RBE-weighted dose with a Monte Carlo code interfaced with LEM resulted in no significant difference with the results obtained from the planning study. The delivery of a voxel by voxel iso-effective plan, if different RBE models are employed, is not feasible; it is however possible to minimize differences in a treatment plan with the simple approach presented here. Dose prescription ultimately represents a clinical task under the responsibility of the radiation oncologist, the presented analysis intends to be a quantitative and objective way to assist the clinical decision.
AB - In carbon ion radiotherapy there is an urgent clinical need to develop objective tools for the conversion of relative biological effectiveness (RBE)-weighted doses based on different models. In this work we introduce a clinically oriented method to compare NIRS-based and LEM-based GyE systems, minimizing differences in physical dose distributions between treatment plans. Carbon ion plans were optimized on target volumes of cubic and spherical shapes, for RBE-weighted dose prescription levels ranging from 3.6 to 4.4 GyE. Plans were calculated for target sizes from 4 to 12cm defining three beam geometries: single beam, opposed beam and orthogonal beam configurations. The two treatment planning systems currently employed in clinical practice were used, providing the NIRS-based and LEM-based GyE calculations. Physical dose distributions of NIRS-based and LEM-based treatment plans were compared. LEM-based prescription doses that minimize differences in physical dose distributions between the two systems were found. These doses were compared with the mean RBE-weighted dose obtained with a Monte Carlo code (FLUKA) interfaced with LEM I. In the investigated dose range, LEM-based RBE-weighted prescription doses, that minimize differences with NIRS plans, should be higher than NIRS reported prescription doses. The optimal dose depends on target size, shape and position, number of beams and dose level. The opposed beam configuration resulted in the smallest average prescription dose difference (0.45 ± 0.09 GyE). The second approach of recalculating NIRS RBE-weighted dose with a Monte Carlo code interfaced with LEM resulted in no significant difference with the results obtained from the planning study. The delivery of a voxel by voxel iso-effective plan, if different RBE models are employed, is not feasible; it is however possible to minimize differences in a treatment plan with the simple approach presented here. Dose prescription ultimately represents a clinical task under the responsibility of the radiation oncologist, the presented analysis intends to be a quantitative and objective way to assist the clinical decision.
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U2 - 10.1088/0031-9155/57/22/7543
DO - 10.1088/0031-9155/57/22/7543
M3 - Article
C2 - 23104051
AN - SCOPUS:84869006755
VL - 57
SP - 7543
EP - 7554
JO - Physics in Medicine and Biology
JF - Physics in Medicine and Biology
SN - 0031-9155
IS - 22
ER -