Influence of Temperature on Lower Detection Limits of Thyroid 131IMonitoring System Using Imaging Plates

摘要

Effect of temperature and shielding on fading rates and detection limits of an imaging plate (IP) wasanalyzed by using an incubator and a shielding box. The Ips were fixed on a neck-thyroid phantom ladedwith 120 to 390 kBq, and stored in the incubator at 0, 25, and 40°C after exposure to the 131I photons for 10min. The Ips were taken out of the incubator from 5 min to 3 days after, and their latent images were readout by using an image analyzer. The shielding box reduced the detection limits by 33% compared with nobox, but did not reduce fading rates. The fading rate was reduced by 27% by lowering the temperature from40 to 0°C. The lower detection limits at 0°C with shielding and at 40°C without shielding were 1.15 and2.51 kBq, respectively. All lower detection limits were lower than a screening level of 30 kBq. Storing theIps in a shielding box at low temperature is effective for decreasing the lower detection limits of the IPmonitoring system.