IPを用いる甲状腺I-131 in vivoモニタリングシステムの計数効率及び検出限界の改善

Abstract

The effects of three kinds of techniques on the performance of an in vivo thyroid I-131 monitoring system using an imaging plate (IP) were estimated. These counts were increased by using a probe consisting of four sheets of IP, repeatedly measuring the residual image of IP up to 10 times and lengthening the exposure time up to 60 min, respectively. In the probe method, the counting efficiency increased with an increased number of IP, and a detection limit showed the minimum value when four IPs were used. In the repeat measurement method, the counting efficiency increased up 300 percent with an increased number of reading times, and the detection limit decreased down to 78 percent. In the long exposure method, the counting efficiency was approximately constant regardless of the period of measuring time, and the detection limit decreased down to 30 percent when lengthening the exposure time. The long exposure time method was effective for decreasing the detection limit. The probe method and the repeat measurement method were effective for both increasing the counting efficiency and decreasing the detection limit.