TY  - JOUR
AU  - Ulrich, Silke
AU  - Wieser, Hans-Peter
AU  - Cao, Wenhua
AU  - Mohan, Radhe
AU  - Bangert, Mark
TI  - Impact of respiratory motion on variable relative biological effectiveness in 4D-dose distributions of proton therapy.
JO  - Acta oncologica
VL  - 56
IS  - 11
SN  - 0284-186X
CY  - Abingdon
PB  - Taylor & Francis Group
M1  - DKFZ-2017-06251
SP  - 1420 - 1427
PY  - 2017
AB  - Organ motion during radiation therapy with scanned protons leads to deviations between the planned and the delivered physical dose. Using a constant relative biological effectiveness (RBE) of 1.1 linearly maps these deviations into RBE-weighted dose. However, a constant value cannot account for potential nonlinear variations in RBE suggested by variable RBE models. Here, we study the impact of motion on recalculations of RBE-weighted dose distributions using a phenomenological variable RBE model.4D-dose calculation including variable RBE was implemented in the open source treatment planning toolkit matRad. Four scenarios were compared for one field and two field proton treatments for a liver cancer patient assuming (α∕β)x = 2 Gy and (α∕β)x = 10 Gy: (A) the optimized static dose distribution with constant RBE, (B) a static recalculation with variable RBE, (C) a 4D-dose recalculation with constant RBE and (D) a 4D-dose recalculation with variable RBE. For (B) and (D), the variable RBE was calculated by the model proposed by McNamara. For (C), the physical dose was accumulated with direct dose mapping; for (D), dose-weighted radio-sensitivity parameters of the linear quadratic model were accumulated to model synergistic irradiation effects on RBE.Dose recalculation with variable RBE led to an elevated biological dose at the end of the proton field, while 4D-dose recalculation exhibited random deviations everywhere in the radiation field depending on the interplay of beam delivery and organ motion. For a single beam treatment assuming (α∕β)x = 2 Gy, D95
LB  - PUB:(DE-HGF)16
C6  - pmid:28828913
DO  - DOI:10.1080/0284186X.2017.1354131
UR  - https://inrepo02.dkfz.de/record/131619
ER  -