Radiation and Cancer Physics
PD 06 - Physics 2 - Poster Discussion - Treatment Delivery
1048 - Analysis of Beam Delivery Times and Dose Rates for the Treatment of Mobile Tumors Using Real Time Image Gated Spot-Scanning Proton Beam Therapy
Monday, October 22
11:03 AM - 11:09 AM
Location: Room 217 C/D
Shinichi Shimizu, MD, PhD
Hitachi Ltd.: Research Grants
Charged particle beam system, US 14/524,495: Patent/License Fees/Copyright; Radiotherapy control apparatus and radiotherapy control program, US9616249 B2: Patent/License Fees/Copyright
Analysis of Beam Delivery Times and Dose Rates for the Treatment of Mobile Tumors Using Real Time Image Gated Spot-Scanning Proton Beam Therapy
S. Shimizu1,2, T. Yoshimura3, N. Katoh1,4, T. Inoue4, T. Hashimoto5, K. Nishioka2, S. Takao4, T. Matsuura1,6, N. Miyamoto4, Y. M. Ito7, K. Umegaki6, and H. Shirato1,5; 1Global Station for Quantum Medical Science and Engineering, Global Institution for Collaborative Research and Education (GI-CoRE), Hokkaido University, Sapporo, Japan, 2Department of Radiation Oncology, Faculty of Medicine, Hokkaido University, Sapporo, Japan, 3Proton Beam Therapy Center, Hokkaido University Hospital, Sapporo, Japan, 4Department of Radiation Oncology, Hokkaido University Hospital, Sapporo, Japan, 5Department of Radiation Medicine, Faculty of Medicine, Hokkaido University, Sapporo, Japan, 6Division of Quantum Science and Engineering, Faculty of Engineering, Hokkaido University, Sapporo, Japan, 7Department of Biostatistics, Hokkaido University Faculty of Medicine, Sapporo, Japan
Spot-scanning technique ensures the precise delivery of a dose to the clinical target volume (CTV); however, the existence of interplay effects in proton scanning must be considered. One method for mitigating the influence of organ motion is the use of real-time image gating. The use of gating during beam delivery may prolong the treatment time. In this study, we analyzed the clinical feasibility of a real-time-image gated proton beam therapy (RGPT) system regarding beam delivery times and dose rates for the treatment of mobile tumors.
Thirty-six patients were treated using the RGPT system from October 2016 to October 2017, and their data were included in this analysis. The locations of the targets for treatment were obtained through Au fiducial markers of either 1.5 or 2.0 mm diameter inserted around the CTV. The coordinates of the fiducial marker were calculated using the system at a frequency of either 30 or 15 Hz, and the proton beam was automatically controlled and delivered according to the pre-set gating window of ±2 mm. The parameters for beam delivery and nominal dose rates for each treatment port were also examined and analyzed.
Among the patients treated using the RGPT system, 33 liver cases and 3 lung cases were evaluated. The doses delivered to 99% of the CTV were 76 GyE/20Fr (n = 8), 74 GyE/37Fr (n = 6), 72.6 GyE/22Fr (n = 15), and 66 GyE/10Fra (n = 4) for the liver cases, whereas a dose of 70 GyE/10Fr (n = 3) was administered for the lung cases. The number of treatment ports and dose rates for each treatment plan, according to the disease, were as follows: liver, two ports (n = 28): 0.60 ± 0.45 GyE/min, three ports (n = 4): 0.49 ± 0.13 GyE/min, and four ports (n = 1): 0.94 ± 0.06 GyE/min, and lung, three ports (n = 3): 0.92 ± 0.38 GyE/min. The ratio of the treatment time for the delivery of the therapeutic proton beam using RGPT to each port against the QA mode beam delivery time required for non-gating beam delivery were 2.21 ± 1.08 (two ports: 2.34 ± 1.83, three ports: 2.04 ± 1.08, and four ports: 1.63 ± 0.33) for liver cases, and 1.88 ± 0.83 for lung cases. Irradiation of the mobile target with gating function was possible within a reasonable time for clinical usage using RGPT.
The use of RGPT for mobile tumors can deliver a treatment beam within reasonable treatment time using a +/- 2 mm gating window.
| || Without Gating (Data from QA) || RGPT || Time Ratio |
| || Port no. (n) || Min || GyE/min || Min || GyE/min || [Gate/Non-gate] |
| Liver || 2 (27) || 2.15 || 1.18 || 4.71 || 0.60 ± 0.45 || 2.34 ± 1.83 |
| 3 ( 4) || 1.50 || 0.89 || 2.62 || 0.49 ± 0.13 || 2.04 ± 1.08 |
| 4 ( 1) || 1.15 || 1.50 || 1.83 || 0.94 ± 0.06 || 1.63 ± 0.33 |
| Lung || 3 ( 3) || 1.74 || 1.50 || 3.36 || 0.92 ± 0.38 || 1.88 ± 0.83 |
Author Disclosure: S. Shimizu: Research Grant; Hitachi Ltd. Patent/License Fees/Copyright; Radiotherapy control apparatus and radiotherapy control program, US9616249 B2, Charged particle beam system, US 14/524,495. T. Yoshimura: None. N. Katoh: None. K. Nishioka: None. S. Takao: Patent/License Fees/Copyright; Radiotherapy control apparatus and radiotherapy control program, US9616249 B2. T. Matsuura: Patent/License Fees/Copyright; Radiotherapy control apparatus and radiotherapy control program, US9616249 B2. H. Shirato: Research Grant; Hitachi Ltd, Shimadzu Corporation. Patent/License Fees/Copyright; Moving body pursuit irradiating device and positioning method using this device, Charged particle beam system, US 14/524,495.