A Study on the Image Quality of Mammography and the Average Glandular Dose

맘모그래피의 화질과 평균유선조직선량에 관한 검토

We came to the following conclusion as the results of experiment on the image quality of mammography and the average glandular dose using 4 apparatuses at 3 hospitals in Seoul. 1. Whereas the measurement of half value layer showed no differences among the apparatuses, the measurement by an attenuation curve method showed some differences by 5.9%. There were 9.1% differences in the measurement by aluminum conversion method. 2. The basic density of an automatic exposure control unit must be D = 1.40, but there was no automatic exposure unit adjusted precisely at any hospitals. The unit at the B hospital exceeded the allowable limit by ${\pm}0.15$. 3. In the photographing using an automatic exposure control unit and the management of an automatic film processor using a sensitometer, most automatic film processors were well kept. But in some cases the mean value of a fluctuation coefficient exceeded the allowable limit. There is a need for more cautious management. 4. The image quality of breast phantom photography was affected by the screen/film system among the hospitals. 5. The average glandular dose at a breast of 4.2 cm thickness depended on the tube voltage, In the case of Mo/Mo, it was measured $0.26{\sim}1.39\;mGy$ less than ACR standard 3.0 mGy.

유방촬영에 대한 화질과 평균유선조직선량에 대하여 실험한 결과 반가층은 장치마다 큰 차이를 나타내지 않았으며, 자동노출기구를 사용할 경우 정확성에 문제가 있으므로 확인이 필요하다. 유방촬영에 사용되는 자동현상기 또한 꼭 관리가 필요하며, 유방촬영 시 사용되는 증감지/필름에 따라서 팬톰 촬영 식별능에 많은 영향을 받고 있으므로 선택 시 신중을 기해야 한다. 유방두께 4.2 cm에 대한 평균유선조직 선량은 관전압에 따라 달라지며, ACR기준인 3.0 mGy보다 훨씬 적은 $0.26{\sim}1.39\;mGy$로 나타났다. 이상에서 알 수 있듯이 유방촬영에서는 촬영장치의 성능뿐만 아니라 HVL, AEC, 자동현상기 관리, 증감지/필름 등 모두 관리가 되어야 하며, 이로 인해 평균유선조직선량은 더 줄일 수 있을 것이다.