Radiation Calculations for Advanced Proton Therapy Facility

The shielding calculations of bulk shielding for Advanced Proton Therapy Facility (APTRON) which is under design in Shanghai were carried out. The thickness of radiation shielding walls for the accelerator and treatment rooms of APTRON were determined by Monte Carlo simulation and empirical methods [1~3]. Assumptions of beam loss scenarios and workloads of different energy at LINAC, synchrotron, transport and treatment line are given for the calculations. The calculations were carried out for the proton energy of 150MeV, 220MeV and 250MeV, and the targets of iron and equivalent tissue material. Source terms and attenuation length were calculated with different angles by the simulation using FLUKA code. Based on the source terms and the attenuation length, the thickness of the bulk walls were determined by the empirical formula to ensure the dose rate outside the shielding walls’ surface less than 1μSv/h. Local shielding and maze design were also concerned. INTRODUCTION The Advanced Proton Therapy Facility (APTron), which will be built at Jiading district of Shanghai, is a hospital-based facility designed by Shanghai Institute of Applied Physics. The layout of APTron is shown in Fig.1. It consist of a 7 MeV LINAC injector, a 24.6m circumference synchrotron capable of accelerating protons up to 250MeV, two horizontal fixed beam line and an isocentric gantry beam line in phase I, and can upgrade total 3 gantry beam lines in phase II. Some main parameters of the accelerator are list below: Injection energy: 7MeV; Extraction energy: 70~250MeV; Extraction current: 12.8nC (8.