Abstract
The radiation doses measured by Electric Personal Dosimeter (EPD) were compared with those by Radio-Photoluminescence Dosimeter (RPLD) in natural radiation environment. These two values were almost agreed and have a linear relationship with high correlation. However, the dose by EPD was higher than that by RPLD. The regression expression shows that the slope is a little higher than one, and this line does not pass through the zero dose point. In order to investigate the cause, the gamma ray irradiation was conducted. The result shows that the sensitivity of the EPDs were 4-11% higher than the expected dose. On the other hand, the dose rates varied from 0.019μSv/h to 0.028μSv/h in the lead box which has 10cm thickness. As a result, it would be necessary that the sensitivity of each EPD is calibrated in order to obtain an accurate dose.