Study On The Tracing Method Of Water Absorbed Dose In (10-300kV) X-ray

In dosimetry,the absorbed dose of radiation,which is a export volume of the international unit system,is a very important physical quantity.It is meaningful to use physical methods to measure the expansion of a physical unit.With the development of X-rays research,the application fields of X-rays are expanding.In the medical field of radiotherapy,radiotherapy has achieved remarkable curative effect in the cancer treatment.However,because the X-rays is exponential decay and the range of X-rays is without control,the damage of shallow tissue and normal tissue is relatively large.Therefore,it is necessary for us to know exactly about the absorbed dose of human tissue,which is extremely important to assessing the effects and side effects of radiation therapy.There are many physical methods to measure the X-rays water absorbed dose,such as calorimetry,ionization method,heat release and so on.In this paper,the treatment of X-rays reference radiations were established by the reference verification regulation,at the same time the semi-value layer,effective energy and radiation field were measured.Based on the TRS-398 report which was published by the International Atomic Energy Organization,the X-rays water absorbed dose was measured and studied by means of ionization method.In measurement,the PTW 30013 ionization chamber and the PTW 23344 ionization chamber were calibrated respectively in the middle and low energy X-rays reference device,and we obtained the ionization chamber air kerma calibration factors.Secondly,we have look up the material to obtain the ratio of the mass energy absorption coefficient of water and air and the disturbance factor.At last,the X-ray water absorbed dose was obtained by calculation formula and the relative standard uncertainty was below 3%,which met the requirement of the measurement standard.Above all,we have established X-rays water absorbed dose measurement methods,and completed the measurement of X ray absorbed dose of water.Finally,we have laid a solid foundation for the traceability of X-ray water absorbed dose in china and international key comparison of X-ray water absorbed dose.