Study Of Planar Radiation Dosimeter Detection And Transmission Circuit

Planar radiation dosimeter, which is used for dose verification to ensure patients’ safety and IMRT curative effect, generally consists of three parts:two-dimensional detector, detection & transmission circuit, and data processing software. The thesis carries out the research on the detection & transmission circuit, and undertakes the design of continuous acquisition and real-time transmission dose measurement circuit using two-dimensional ionization chamber array.The design includes two aspects:detection circuit and transmission circuit. Analysis is made on circuit performance requirement, and specifications are determined. Through comparison among different micro current detection methods and research on dosimeter transmission modes, DDC232--based digital detection scheme and W5300-based network transmission scheme are adopted. In terms of FPGA-based hardware design,256-channel synchronous data acquisition is implemented with the two-route paralling struction in which each route contains 4 pieces of DDC232 chip, and WIZ830MJ transmission module which based on W5300 is used for network communication. And digital logic design of the circuit is implemented by Verilog program,which introduces the thought of modularization.Experiments have been made to test performance of the designed circuit and system. According to the results, transmission stability and accuracy are validated, and independent linearity of the detection circuit is about ±0.2%,which achieves the design specification. After connected with the two-dimensional ionization chamber array detector, the measurement system proves to have good linearity and reproducibility, which meet the application requirements for IMRT dose verification and are all accord with the regulation in IEC 60731.