Investigation on using high-energy proton beam for total body irradiation (TBI).

Investigation on using high-energy proton beam for total body irradiation (TBI).
J Appl Clin Med Phys. 2016;17(5):6223
Authors: Zhang M, Qin N, Jia X, Zou WJ, Khan A, Yue NJ
Abstract
This work investigated the possibility of using proton beam for total body irradia-tion (TBI). We hypothesized the broad-slow-rising entrance dose from a monoen-ergetic proton beam can deliver a uniform dose to patient with varied thickness. Comparing to photon-based TBI, it would not require any patient-specific com-pensator or beam spoiler. The hypothesis was first tested by simulating 250 MeV, 275 MeV, and 300 MeV protons irradiating a wedge-shaped water phantom in a paired opposing arrangement using Monte Carlo (MC) method. To allow ± 7.5% dose variation, the maximum water equivalent thickness (WET) of a treatable patient separation was 29 cm for 250 MeV proton, and > 40 cm for 275 MeV and 300 MeV proton. The compared 6 MV photon can only treat patients with up to 15.5 cm water-equivalent separation. In the second step, we simulated the dose deposition from the same beams on a patient's whole-body CT scan. The maximum patient separation in WET was 23 cm. The calculated whole-body dose variations were ± 8.9%, ± 9.0%, ± 9.6%, and ± 14% for 250 MeV proton, 275 MeV proton, 300 MeV proton, and 6 MV photon. At last, we tested the current machine capability to deliver a monoenergetic proton beam with a large uniform field. Experiments were perfo...

Source: Journal of Applied Clinical Medical Physics - September 30, 2016 Category: Physics Authors: Zhang M, Qin N, Jia X, Zou WJ, Khan A, Yue NJ Tags: J Appl Clin Med Phys Source Type: research