The Research On Calorimetry Of Electron Beams Absorbed Dose Measurement

With the development of various types of electron accelerators in the nuclear medicine, radiation biology and nuclear radiation technology of civilian industries areas, how to measure and evaluate the important physical quantities of electron beams radiation, especially the accurate measurement of electron beams absorbed dose is becoming a very essential task. Absorbed dose is directly related to product quality control in the radiation processing field, and success or failure of radiotherapy in nuclear medicine, radiation biology fields. Therefore it is necessary to regulate the measurement methods of electron beams absorbed dose in order to improve the level of our electron beams applications.Calorimetry, chemical method and ionization chamber method are three common electron beams absorbed dose measurement methods, in which calorimetry method is the only way to measure the energy of material given by ionizing radiation directly. Select calorimeter as the research object of electron beams absorbed dose measurement, compare the chemical dosimeter (potassium (silver) dichromate dosimeter) with calorimeter (graphite calorimeter and polystyrene calorimeter), and use EGSnrc program for the Monte Carlo method.Use Monte Carlo program EGSnrc to simulate the percentage depth dose distribution of water, graphite and polystyrene in the 9.53MeV electron beams irradiation conditions. Simulation result shows calorimeter absorber's average absorbed dose ratio in the in the 9.53MeV electron beams irradiation conditions. Simulate practical range of electron beamss in polystyrene material under four different energy conditons, and compare it with practical extrapolated electron range. Conversion factor of graphite and polystyrene absorbed dose changed into the water absorbed dose is given according to the simulated percentage depth dose distribution (PDD). Use Frike dosimeter to calibrate ceric sulphate-cerous sulphate dosimeter and potassium (silver) dichromate dosimeter in 60Co radiation field, and then compare to eerie sulphate-cerous sulphate dosimeter and graphite calorimeter in the 9.53MeV electron beams condition.Measure graphite and polystyrene calorimeters'absorbed dose under the conveyor irradiation conditon and make comparison after changed into water absorbed dose.Simulation and experimental results show that:the difference of simulated actual range and practical extrapolation range of electron beams in the polystyrene material is less than 1.5%; the radiation chemical yield (G(x)) of the potassium (silver) dichromate dosimeter under the electron beams and y-rays conditions are of less than 1.85% difference; Graphite and polystyrene calorimeters'absorbed dose under the conveyor irradiation conditon less than 1.1% difference.