乳房放大攝影之影像品質及平均乳腺劑量的評估

Ealuation of Image Quality and Dose in Film-Screen Magnification Mammography

郭瓊文(Chiung-Wen Kuo) ； 葉淑芳(Seu-Fang Ye) ； 詹光裕(Kwan-Yee Chan) ； 陳力慎(Li-Shen Chen) ； 邱鈺蘋(Yu-Ping Chou) ； 詹淑婷(Shu-Tin Jan) ； 張東浩(Tong-Hao Chang)

《中華放射線醫學雜誌》 29卷2期 (2004/04) Pp. 81-86

摘要

乳房X光攝影對於偵測隱藏的乳癌觸診發現的腫塊，可高達70%-90%的準確度。儘管乳房放大攝影的平均乳腺劑量比一般乳房攝影為高，但基於進一步的檢查與確認，乳房放大攝影提供了較高的解析度和病灶的鮮銳度。本實驗之目的為評估放大攝影之平均乳腺劑量及影像品質。
使用的乳房攝影機以鉬及銠為陽極靶，鉬、銠、鋁為濾片材料。以光密度計測量標準乳房假體的光密度值，而影像品質的評定方式，以影像的解析度及對比度為限。隨著峰壓值由26kVp增加到35kVp，得知暴露時間會由1秒降到0.25秒，平均乳腺劑量會由1.95mGy降到1.20mGy;對於鈣化點會因為管電壓的增加而影響辨別的能力。針對鈣化點做診斷時，應避免使用高管電壓。但是，除了鈣化點之外，利用高管電壓的乳房放大攝影技術，不但可減少病人移動之機會，亦可有效降低平均乳腺劑量，並且由影像品質方面來探討，也不會造成影像品質明顯降低，值得臨床使用

關鍵字

影像品質 ； 乳房放大攝影 ； 平均乳腺劑量 ； 管電壓

並列摘要

Background and purpose: Mammography is one of the most reliable techniques for early detection of nonpalpable breast cancer. Magnification mammography offers better resolution than conventional one in spite of increasing patient dose. The goals of this study were to evaluate the mean glandular dose, exposure time and image quality in magnification mammography.
Methods: All measurements were performed on a mammography unit with a molybdenum target and a filter combination of molybdenum, rhodium and aluminum. Gross optical densities of phantom images were measured using a densitometer. Image quality was quantified by image detail detection and image contrase.
Results: Increasing x-ray tube potential from 26 kVp to 35 kVp reduces the exposure time from 1s to 0.25s and mean glandular dose from 1.95 mGy to 1.20 mGy. In evaluation of the image quality, the detection of fibers and masses does not vary with the increasing x-ray tube voltage, but the detection of specks does.
Conclusion: It is concluded that magnification mammography at high kVp similar capability in detecting fibers and masses to that at low kVp. But the detect ability of calcification at 35 kVp may significantly worsend than that performing at 26 kVp. It is our recommendation that the elevation of high kVp (up to 35 kVp) in the study of lesions with fibers and masses might be helpful, but not in the survey of calcified specks.

並列關鍵字

Image quality ； Magnification mammography ； Mean glandular dose ； Tube potential