- 學位論文
建立奇美醫院柳營分院醫療X光之診斷參考水平及其相關影像與劑量參數
Establishment of diagnostic reference levels and related imaging and dose index for X-ray examinations in Chi Mei Hospital, Liouying
摘要
本論文於奇美醫療財團法人奇美醫院柳營分院進行，經人體試驗委員會核可，針對臨床常做的放射線檢查之劑量參數制定診斷參考水平(DRLs, 75%)，用以提供該醫院自我檢核的依據；同時也收集分析臨床劑量參數50%數值，可提供政府單位制訂國家級的NDRL，或區域醫院的LDRL。攝影部位選擇是臨床最常執行的部位。包括一般X光攝影(chest與KUB)、移動式X光(chest與KUB)、電腦斷層(brain、sinus、chest、low dose與abdomen)、血管攝影(TAE)與乳房攝影。利用劑量模擬軟體(PCXMC)評估照射條件得到一般X光、移動式X光與血管攝影的有效劑量。電腦斷層使用CTDIvol (volume computed tomography dose index)與DLP (dose length product)、乳房攝影則使用平均乳腺劑量(average glandular dose, AGD)當作DRL的參考指標。制定DRL的目的並非當成病人的輻射劑量限值，而是提供臨床放射師一個再確認的機制，以避免採用錯誤的攝影程序以及自我優化的工具。 另外，我們也利用假體建立部分DRL對應之影像品質，以供日後機器更新等造成影像變動，一個可比較或參考的標準。我們記錄了一般與移動式X光的影像雜訊、可辨識灰階寬度、低對比物質可辨識度及調變轉換函數(modulation transfer function, MTF)；電腦斷層的影像雜訊、對比雜訊比(contrast to noise ratio, CNR)與對比解析度，並利用目測法與圈選ROI的方法保留了影像品質數據。 此外也藉由風險評估軟體透過器官劑量分布，利用BEIR VII委員會建議的風險評估模型（BEIR 2006），建立DRL劑量對應的曝露引發致死癌症風險 (Risk of exposure-induced cancer death, REID) 值。
並列摘要
This study was conducted in Chi Mei Hospital, Liouying, after being approved by the Institutional Review Board (IRB). The purpose is to establish diagnostic reference levels (DRLs, 75%) for the dose parameters of clinical radiological examinations, which can be used as the standard for repeated confirmation of radiological procedures. We had also collected and analyzed the median (50%) of clinical dose parameters, which can be made to establish national or local DRL. The choice of exposure protocols is determined by the most frequently performed clinically. Data analysis includes routine X-ray photography (chest and KUB), mobile X-ray (chest and KUB), computed tomography (brain, sinus, chest, low-dose and abdomen), angiography (TAE) and mammography. The dose simulation software (PCXMC) was used to evaluate the effective doses of routine X-ray, portable X-ray and angiography. Computed tomography uses CTDIvol and DLP, and mammography use average glandular dose(AGD) as reference indicators for DRL. The purpose of establish DRLs is not a limitation of patient’s dose, but provide a double-check mechanism for radiographers to avoid the use of the wrong protocol, and is a self-optimization tool. In addition, we use image phantoms to establish image quality corresponding to some DRLs. It will serve as a comparable or reference standard for image changes caused by machine will upgrade in the future. Image quality records the noise, dynamic range, extent of identifiable in low contrast and modulation transfer function (MTF) of routine and portable X-ray. For CT, it includes image noise, contrast to noise ratio (CNR) and contrast resolution. We use visual inspection and circle ROI method to retain image quality data. This study used the risk assessment model recommended by the BEIR VII report to assess risk of exposure-induced cancer death(REID) value corresponding to the DRL doses.