とう骨骨密度測定における被曝線量測定 走査ビーム線量測定

Abstract

Effective doses in radius bone mineral density measurements using dual energy X-ray absorptiometry (DEXA) were assessed with entrance beam intensity and X-ray absorption rate in organs. The X-ray entrance beam intensity was calculated from an energy fluence rate, and we demonstrated how to assess beam intensity by using thermoluminescent dosimeters (TLDs). The entrance beam energies were calculated from X-ray beam intensity in regard to beam sizes, scan areas, and scan times. The X-ray absorption rates were calculated by using X-ray absorption curves at bone mineral density measurements. The average tissue doses were determined by using reference female and men. Skin entrance intensity was 4×10-4 [J/(m2·s)]. Skin entrance energies were 1-2×10-3 [J] in proportion to wrist width. The effective dose was approximately 5nSv.