[Consideration on the Influence of the Direction Dependence of the Lens Dosimeter at the Attaching Position on the Equivalent Dose Management of the Lens].

Since International Commission on Radiological Protection's 2011 statement on tissue reaction was released, our hospital recommends wearing radioprotection glasses for radiation workers. The introduction of the lens dosimeter is examined in order to grasp the equivalent dose of the lens; however, the lens dosimeter was guessed to have influence on the equivalent dose management of the lens based on the characteristics and the attaching position. In this study, the validity of the lens dosimeter was verified by examining the characteristics and simulating the attaching position. In the simulation of rotating the human equivalent phantom, the indicated value of the lens was 0.18 mGy in condition as the human equivalent phantom confronted the radiation field, and the indicated value of the lens dosimeter at the corner of the eye was 0.17 mGy. By rotation, the indicated value of the lens proximal to the radiation field became higher compared to the distal value. The values indicated at the distal corner of the eye were below the indicated value of proximal lens, except for 180° rotation. The indicated value of the lens proximal to the radiation field became higher compared to the distal value, except for 180° rotation, and the maximal difference was 2.97 times at 150 degrees to the left. These results suggest the necessity of management of the lens proximal to the radiation field and attaching the lens dosimeter to the proximal corner of eye, since overestimation ensures safety at radiation management.

[Accuracy estimation of non-invasive X-ray output analyzer].

This study estimated the accuracy of an X-ray analyzer by comparing it with an ionization chamber and a tube voltage current meter, and investigated whether it was usable as a substitute for a reference meter for output measurements for quality control purposes. The X-ray output analyzer used was a Piranha (RTI Electronics), a non-invasive instrument. The two subjects of measurements were as follows: the tube voltage, exposure, and half-value layer used in ordinary X-ray radiographic system equipment, and the exposure and half-value layer in X-ray equipment for mammographic systems. The results for a conventional radiographic system showed the error rates for tube voltage, exposure, and half value layer to be within ±1.0%, ±1.8%, and ±4.3%, respectively. The Piranha is not influenced by the dependence of the beam quality in a range of the tube voltage in clinical use. In X-ray equipment for mammographic system results, error rates for exposure and half value layer were ±2.2% and within ±4.0%, respectively. We conclude that it is possible to use the Piranha as an alternative reference meter for quality control of X-ray equipment for typical radiographic and mammographic systems.