TY - JOUR
T1 - Effect of DIR uncertainty on prostate passive-scattering proton therapy dose accumulation
AU - Abe, Yoshitomo
AU - Kadoya, Noriyuki
AU - Arai, Kazuhiro
AU - Takayama, Yoshiki
AU - Kato, Takahiro
AU - Kimura, Kanako
AU - Ono, Takashi
AU - Nakamura, Tatsuya
AU - Wada, Hitoshi
AU - Kikuchi, Yasuhiro
AU - Jingu, Keiichi
N1 - Publisher Copyright:
© 2017 Associazione Italiana di Fisica Medica
PY - 2017/7
Y1 - 2017/7
N2 - Deformable image registration (DIR) is important in dose accumulation. Currently, the impact of DIR-algorithm-associated uncertainties in proton therapy is unclear. Here, we quantify the effect of DIR uncertainties on prostate passive-scattering proton therapy (PSPT) dose accumulation. Ten patients with an intermediate risk for prostate cancer formerly treated by PSPT (PTV D95 = 78 GyE) were studied. Dose distributions from all verification CT images (five images per patient) were warped and accumulated in the planning CT geometries with DIR. The dose-volume histogram parameters (Dmean, V40, and V70) for rectum and bladder were calculated. Two commercially available DIR software packages were employed: Velocity AI (Varian Medical Systems) and RayStation (RaySearch Laboratories). The dice similarity coefficient (DSC) and surface distance, which were calculated between planning CT contours and deformed contours, were used for DIR validation, with the relationship between the dose parameter and DIR uncertainty ultimately investigated. On average, when using RayStation, the DSC increased by 0.14 and surface distance decreased by 6.4 mm, as compared to Velocity. For Dmean, V40, and V70 to the rectum, the average differences between the RayStation and Velocity were 3.9 GyE, 5.5%, and 3.2%, respectively. For the bladder, the differences were 5.2 GyE, 5.8%, and 5.4%, respectively. The maximum differences in V40 between RayStation and Velocity were 14.4% and 22.8% for the rectum and bladder, respectively, when the average DSC and surface distance differences were more than 0.14 and 6.4 mm, respectively. Such results suggest that DIR uncertainties might significantly affect prostate PSPT dose accumulations.
AB - Deformable image registration (DIR) is important in dose accumulation. Currently, the impact of DIR-algorithm-associated uncertainties in proton therapy is unclear. Here, we quantify the effect of DIR uncertainties on prostate passive-scattering proton therapy (PSPT) dose accumulation. Ten patients with an intermediate risk for prostate cancer formerly treated by PSPT (PTV D95 = 78 GyE) were studied. Dose distributions from all verification CT images (five images per patient) were warped and accumulated in the planning CT geometries with DIR. The dose-volume histogram parameters (Dmean, V40, and V70) for rectum and bladder were calculated. Two commercially available DIR software packages were employed: Velocity AI (Varian Medical Systems) and RayStation (RaySearch Laboratories). The dice similarity coefficient (DSC) and surface distance, which were calculated between planning CT contours and deformed contours, were used for DIR validation, with the relationship between the dose parameter and DIR uncertainty ultimately investigated. On average, when using RayStation, the DSC increased by 0.14 and surface distance decreased by 6.4 mm, as compared to Velocity. For Dmean, V40, and V70 to the rectum, the average differences between the RayStation and Velocity were 3.9 GyE, 5.5%, and 3.2%, respectively. For the bladder, the differences were 5.2 GyE, 5.8%, and 5.4%, respectively. The maximum differences in V40 between RayStation and Velocity were 14.4% and 22.8% for the rectum and bladder, respectively, when the average DSC and surface distance differences were more than 0.14 and 6.4 mm, respectively. Such results suggest that DIR uncertainties might significantly affect prostate PSPT dose accumulations.
KW - Adaptive radiotherapy
KW - Deformable image registration
KW - Dose accumulation
KW - Prostate cancer
KW - Proton therapy
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U2 - 10.1016/j.ejmp.2017.06.005
DO - 10.1016/j.ejmp.2017.06.005
M3 - Article
C2 - 28625473
AN - SCOPUS:85020787910
VL - 39
SP - 113
EP - 120
JO - Physica Medica
JF - Physica Medica
SN - 1120-1797
ER -