  A set of nozzle equipment for proton therapy is now being developed at China
Institute of Atomic Energy. To facilitate the off-line commissioning of the
whole equipment, a set of ionization chamber signal generation system, the test
electronics, is designed. The system uses ZYNQ SoC as the main control unit and
outputs the beam dose analog signal through DAC8532. The dual SPDT analog
switch, DG636, is used to simulate the beam position signals according to
Gaussian distribution. The results show that the system can simulate the beam
position, dose, and other related analog signals generated by the proton beam
when passing through the ionization chamber. Moreover, the accuracy of the
simulated beam position is within +/-0.33mm, and the accuracy of the simulated
dose signal is within +/-1%. At the same time, it can output analog signals
representing environmental parameters. The test electronics meets the design
requirements, which can be used to commission the nozzle system as well as the
treatment control system without the proton beam.
