Establishment of medium-hard X-ray reference fields for performance tests of radiation measuring instruments based on national standard

Shimizu, Shigeru; Sawahata, Tadahiro; Kajimoto, Yoichi; Shikaze, Yoshiaki ; Yoshihara, Yasuaki*; Tatebe, Yosuke

In the Japanese Industrial Standard, JIS Z 4511 sets the condition of X-ray reference fields to be used for the performance test of radiation measuring instruments for radiation protection. We renewed a X-ray tube of the medium-hard X-ray irradiation device that was damaged in the Facility of Radiation Standards in Nuclear Science Research Institute. Therefore, we established four series of medium-hard X-ray reference fields with quality index of 0.6, 0.7, 0.8 and 0.9 based on JIS Z 4511. In this process, quality of the X-ray fields, X-ray spectra, conversion coefficients to the dose equivalents from Air-kerma were evaluated in the medium-hard X-ray fields produced with X-ray tube voltage ranging from 20kV to 300kV. As a result, medium-hard X-ray reference fields were established that can provide the dose equivalent standard with good precision and wide range of test energy points and dose rates. We clarified these detailed data.