[Mammography -a guidance level and the present situation of mammographic dose-]

Mammography practiced for the detection of breast carcinomas requires an appropriate X-ray equipment which can meet the performance standard. Also it is necessary to meet the requirements for the exposure dose as well as image quality. Factors affecting the exposure dose are X ray equipment, especially target-filter combination, recording systems, compression of breast, structural characteristics of breast and etc. The current guidance for the mammography adopts 3mGy as a dose level for standard breast for a direction which is recommended by IAEA. However, the average glandular dose for the mammography was 1.5mGy according to the image evaluation survey of medical institution as of December, 2001. This figure is almost equal to the result given by the national survey conducted from 1997 to 1998. The exposure reduction depends on the technique of radiological technologists. It is needed for them to optimize affecting factors. When reducing breast thickness by at least 1cm, the exposure does can be reduced by 50%.