核医学検査における患者側面から接した場合の被ばく低減効果

抄録

During examinations using radionuclide methods, technicians sometimes need to interact directly with patients. The initial point of contact is when they assist patients onto the examination table, the second is when the patients are positioned for radionuclide examination, and the third occurs if the patients experience a sudden change in condition and assistance is deemed necessary. The dose of radiation increases proportionately to the size of the area being treated. Therefore, we verified that the lateral area received a lower dose of radiation than the anterior areas because of their smaller surface area. The doses in the anterior and lateral areas of the patients were measured following administration of ^99mTc-hydroxymethyl enebisphosphonic acid (HMDP), ¹³¹I, ¹⁸F-fluoro-2-deoxy-d-glucose (¹⁸F-FDG), and ^99mTc-galactosyl-human serum albumin-diethylenetriamine-pentaacetic acid (GSA). The lateral/anterior (L/A) ratio was defined as an approximation of the ratio of measured values of the lateral and anterior areas; it was calculated as follows: L/A (%)=[(lateral dose–BG)/(anterior dose–BG)]×100. In all patients, the radiation dose rate from the lateral areas was lower than from the anterior areas. L/A was 52% with ^99mTc-HMDP, 51% with ¹³¹I, 58% with ¹⁸F-FDG, and 33% with ^99mTc-GSA, and radiation doses were found to be reduced by approximately 50% when interaction with patients was from the lateral side rather than the anterior side. Therefore, we confirmed that when interacting closely with patients undergoing radionuclide examinations, it is best to approach the patients from the lateral side in order to reduce radioactive exposure of the technicians.