Comparison And Analysis Of The Dose Conversion Coefficients Of External Photon Irradiation

Objective This study aims to compare the current national standards GBZ/T 144 and ICRP publication NO.116,summarizes the differences in the dose conversion coefficients of the major organs or tissues and the related influencing factors.Explore and analyze the limitations of the current national standard GBZ/T 144 in order to provide some reference for its update.Methods This paper consulted GBZ/T 144-2002,ICRP publication No.74 and No.116,overall analyzed and summarized data,consulted the ICRU Report No.47 conversion coefficients formula of air kerma(Ka),photon fluence(Φ)and exposure(X)of mono-energetic photon,converted organ dose conversion coefficients DT/Φ of ICRP publication No.116 to DT/Ka,then compaired GBZ/T 144 DT/Ka to ICRP publication No.116 DT/Ka.Results The dose conversion coefficients of the GBZ/T 144 were changed with the increase of photon energies,and the change trends of the organ dose conversion coefficients of the ICRP publication No.116 were basically consistent.The relative changes of some organs under some irradiation conditions were more obvious: under the condition of AP irradiation,energy in the 2Me V~10Me V,the eye crystal dose conversion coefficients of the GBZ/T 144 were higher than the ICRP publication No.116,when the energy was higher than 6Me V,the relative changes were more than 100%;when the energy was higher than 4Me V,the breast dose conversion coefficients of the GBZ/T 144 were higher than the ICRP publication No.116,the relative change were more than 100%;when energy in the 0.15 Me V~10Me V,the thyroid dose conversion coefficients of the GBZ/T 144 were higher than the female and male of the ICRP publication NO.116,the relative changes were 4% ~ 42%,5% ~ 31%.Under the condition of PA irradiation,energy in the 0.03 Me V~0.1Me V,the eye crystal dose conversion coefficients of the GBZ/T 144 were lower than the ICRP publication No.116,the lower energy,the greater relative change,when the energy was lower than 0.05 Me V,the relative changes were more than 50%;the testicular dose conversion coefficients of the GBZ/T 144 were lower than the ICRP publication No.116,when the energy was lower than 0.08 Me V,the relative changes could be more than 30%.Under the condition of LLAT irradiation,the liver dose conversion coefficients of the GBZ/T 144 were lower than the ICRP publication No.116,the lower energy,the greater relative change,when the energy below 0.06 Me V,the relative changes were more than 50%.Conclusions Under different position irradiation conditions,the overall trends of changes of the organ dose conversion coefficients of the GBZ/T 144-2002 and ICRP publication NO.116 are consistent with the increase of photon energy.However,under the same position exposure conditions,when the reference to the human body model(such as model structure,organ location,organ composition and size and so on),the reference person(such as reference to gender,physical parameters and organ quality and so on)and the organ dose calculation method(such as Kerma approximation)are different,the variances of the organ dose conversion coefficients of the GBZ/T 144-2002 and ICRP publication No.116 are obvious.So in above cases,application of the organ dose coefficients of the current national standard GBZ/T 144 may need to be slightly adjusted.We recommend GBZ/T 144 need to timely update.