評估不同機構電腦斷層劑量參考水平制定之經驗分享

Local Diagnostic Reference Level Evaluation in Different Sites of Computed Tomography- Experience Sharing

曾淑玲(Shu-Lin Tsang) ； 顏家文(Chia-Wen Yan) ； 蕭亦蕙(Yi-Hui Hsiao) ； 范佐賓(Tso-Pin Fan) ； 邱慧鈴(Hui-Ling Chiu) ； 錢信德(Hsin-Te Chian) ； 林造民(Tsao-Min Lin) ； 賴彥君(Yen-Jun Lai) ； 曾旭明(Ah-Ming Tsang)

《中華放射線技術學雜誌》 40卷3期 (2016/09) Pp. 169-173

摘要

國際間普遍使用診斷參考水平 （diagnostic reference level, DRL）做為電腦斷層掃描的劑量指標，行政院衛生福利部也於2012 年開始，針對電腦斷層掃描儀成立國家型診斷參考水平（national diagnostic reference level, NDRL）委員會，以提升電腦斷層掃描儀輻射醫療曝露品質，輔導各醫療院所建立機構診斷劑量參考水平（local diagnostic reference level, LDRL），做為放射診斷檢查之參考劑量。在電腦斷層描使用的劑量指標為體積電腦斷層劑量指標（volume computed tomography dose index, CTDI_(vol)）、劑量長度乘積（dose lengthproduct, DLP）。我們收集標準體型65±5 kg 的劑量指標數值，每間電腦斷層檢查室收集常規成人頭部掃描、成人胸腔掃描以及成人腹部（含骨盆腔）掃描三種檢查程序。參與的醫院有某醫學中心（A 醫院）、區域醫院（B 醫院）及地區醫院（C 醫院），本研究將建立其LDRL，並參考英國於2014 年發布的國家診斷參考水平。三家醫院的常規成人頭部LDRL 初始值：CTDI_(vol) 分別為58、62 和67 mGy，DLP 為1003、1112 和956 mGy．cm；常規成人腹部包含骨盆腔檢查為11 mGy、11 mGy 和10 mGy，DLP 為509、458 和466 mGy．cm；常規成人胸腔檢查分別為9、13 和6 mGy，DLP 為337、428 和244 mGy．cm。雖然DRL 與劑量限值無關，不適合用以判斷檢查優劣，然而本研究所列出的劑量指標雖不能做為機構或是檢查的劑量優劣比較，但可以做為長期追蹤的指標，並提供給其他機構參考之用。

關鍵字

電腦斷層 ； 劑量指標 ； 診斷參考水平

並列摘要

The diagnostic reference level (DRL) is commonly used as a dose index for computed tomography (CT). The Ministry of Health and Welfare had also set up a committee of national diagnostic reference level (NDRL) from 2012. In the purpose of increasing the quality of CT radiation exposure and maintaining the image quality, one could establish the local diagnostic reference level (LDRL) as the reference for radiologic examinations. The volume computed tomography dose index (CTDI_(vol)) and dose length product (DLP) are used as dose indices for CT. We collected the dose indices for routine adult head, chest, and abdomen protocols in each CT scan room. The reference patient weight was 65±5 kg. We established the LDRLs for three hospitals and compared them with the NDRL of United Kingdom. The initial LDRL values of CTDI_(vol) in three hospitals were 58, 62 and 67 mGy for adult head protocol; 11 mGy, 11 mGy and 10 mGy for adult abdomen and pelvis protocol; 9 mGy, 13 mGy and 6 mGy for adult chest protocol. The DLP values for three hospitals were 1003, 1112, 956 mGy．cm for adult head protocol; 509, 458 and 466 mGy．cm for adult abdomen and pelvis protocol; 337, 428 and 244 mGy．cm for adult chest protocol. Although this index does not refer as dose limits or to determine the quality of CT exam, the DRL could be used to long-term monitor of CT dose in your facility and provide the references as compared with the other hospitals.

並列關鍵字

computed tomography ； dose index ； diagnostic reference level