実効エネルギーに基づく患者表面吸収線量推定式

抄録

We propose a new equation to estimate patient surface absorbed dose from effective x-ray energy. The equation is represented as follows : D(skin absorbed dose)=Ds×mAs×FSF×F×DST, where Ds indicates basic exposure, mAs is additional x-ray tube current and exposure time, FSF is a factor used to count additional scattered exposure, F is a conversion coefficient to convert from exposure to absorbed dose, and DST is distance compensation. For Ds, the value of the exposure dose without aluminum in the half-value layer(HVL)measurement for 1 mAs was used(C/kg/mAs). FSF is a ratio of exposure containing scattered radiation that corresponds to field size to basic exposure. F was calculated using reported values of attenuation coefficients in the data book. Then approximation function curves for Ds, FSF, and F were success-fully created, with an excellent correlation coefficient(R^2=0.997), using effective x-ray energy as a variable.