Development Of Digital And Portable Diagnostic X-ray Dosimeter

Diagnostic X-ray examination is one of the most important methods in modern medicine. But also it is the most source of man-made ionizing radiation in public. So the radiologist and radioprotection expert have a duty to limit the radiation as low as reasonable and reduce the potential damage by X-ray examination for patients and personnal. The most efficient way to do this is to perform quality control (QC) technology on X-ray equipments, The most important parameters tested in QC are patient dose, kVp,exposure time, etc, measuring and evaluating the patient dose is the key work of QC.The paper describes the development of a digital and portable diagnostic X-ray dosimeter based on the progress of diagnostic X-ray dose testing technology. The dosimeter can test the exposure dose and dose rate in real time by using semiconductor detector, a new PIN silicon photodiode made by high purification technics. The research work includes three parts. the first is about the measurement theory and how to make it come true; the second is studying the characteristic of PIN detector by experiment and choosing the best working for X-ray dose measurement; the last is the electric circuit and software system. The measuring range can be changed automatically with microcomputer technique and by using a novel amplifier. The result and radiation wave can be storaged,displayed and printed. The method to transfer the response of the meter into dose or dose rate and the calibration procedure are also discussed in detail.The test shows that the energy response of detector from (60～150kV) is less than 5%. It can measure X-ray dose from 0.01mGy to 9999mGy and dose rate from 0.01mGy/s to 9999mGy/s with a good precision±0.071%(SD) and stability±0.18%(SD) ,suiting for quality control (QC) examination in general Diagnostic X-ray field of hospital.