低劑量電腦斷層用於腹部掃描品質與劑量探討

The Discussion of Image Quality and Radiation Dose in Abdominal Low Dose Computed Tomography

林孟萱(MENG-XUAN LIN)

指導教授 ： 鄭凱元

中臺科技大學/健康科學院/醫學影像暨放射科學系暨研究所/碩士(2020年)

摘要

本次研究利用成人擬人假體針對腹部電腦斷層掃描，改採低劑量電腦斷層掃描模式，評估不同掃描模式之影像訊雜比與曝露劑量。
利用假體進行不同參數掃描，設定條件參數為管電壓80 kVp、120 kVp，管電流100 mAs、200 mAs。影像分別圈選固定之感興趣區域，並比較訊雜比及其胃、脾、肝、腎、膀胱、睪丸、小腸之曝露劑量。
評估影像的訊雜比，影像整體平均訊雜比為0.734，而標準劑量120 kVp, 200 mAs平均訊雜比為1.37，若調降管電壓與管電流為80 kVp, 100 mAs，則平均訊雜比下降為0.283，且影像呈現非常粗糙；若管電壓固定為120 kVp調降管電流為100 mAs則平均訊雜比為0.753，影像訊雜比最佳；測量其曝露劑量後發現，無論管電壓調降與否，在100 mA時睪丸的曝露劑量為0.342 mGy、1.495 mGy都是最高的，而在200 mA時則胃的曝露劑量為2.598 mGy、0.955 mGy，亦為最高暴露劑量之器官。研究發現將電腦斷層掃描參數修改，可獲得比整體平均訊雜比較佳的影像，且曝露劑量最多可以下降67 %，因此使用120 kVp, 100 mAs的掃描參數將可獲的最佳之結果。

關鍵字

腹部電腦斷層掃描 ； 低劑量電腦斷層掃描 ； 暴露劑量

並列摘要

In this study, an adult anthropomorphic phantom was used for abdominal computed tomography, and low-dose computed tomography was adopted to evaluate the signal-to-noise ratio and exposure dose of different scanning modes.
Different parameters were used to scan the phantom, The parameters were 80 kVp, 120 kVp, 100 mAs, and 200 mAs. The fixed region of interest was circled in the four groups of images, and the signal-to-noise ratio and exposure doses of the stomach, spleen, liver, kidney, bladder, testis, and small intestine were compared. The average signal-to-noise ratio of the four groups of images was 0.734, and the average signal-to-noise ratio of 120 kVp and 200 mAs was 1.37. If the voltage and current were adjusted to 80 kVp and 100 mAs, then the average signal-to-noise ratio dropped to 0.283, and the image became very rough. When the tube voltage was fixed at 120 kVp and the tube current adjusted 100 mAs, the average signal-to-noise ratio was 0.753, which was the best image signal-to-noise ratio of the four groups. After measuring the exposure dose, it was found that no matter the tube voltage was reduced or not, the exposure doses of the testis were 0.342 mGy and 1.495 mGy at 100 mA, which were the highest in the four groups, while at 200 mA, the exposure doses of the stomach were 2.598 mGy and 0.955 mGy, which were also the highest exposure dose in the four groups .

並列關鍵字

abdominal computed tomography ； low dose computed tomography ； exposure dose

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