Development of multichannel readout electronics system for MWPC of heavy ion radiotherapy

Abstract

A customized Multi-Wire Proportional Chamber (MWPC) was developed for beam monitoring in heavy ion radiotherapy at West China Hospital of Sichuan University. We designed a miniaturized readout electronics module to ensure the device is compact and lightweight enough to fit into the treatment head. Each module is equipped with 13 DDC316 chips and a Field Programmable Gate Array (FPGA) to process 200-channel signals from the MWPC, including charge integration, digital-to-analog conversion, beam spot localization, and an optical module to enable 100-meter signal transmission from the module to the Irradiation Control System (ICS). Test results show that the linearity of the readout data is better than 1% over the dynamic range of charge input from 60 fC–12 pC. The relative energy resolution of electronics is about 4.87% at a minimum input charge of 60 fC. The test results illustrate that the positional resolution is better than 0.1 mm after channel conformance correction with a MWPC, utilizing a 30 mm diameter X-ray beam at an energy of 19.5 keV.