分析診斷用X光機於高能量輸出時平面劑量分布

Analyzing diagnostic X-ray machine for plane dose distribution at high energy output

彭嘉俊(Chia-Chun Peng) ； 趙樹禮(Shu-Li Chao) ； 高敬堯(Jing-Yao Gao) ； 劉惟汶(Wei-Wen Liu) ； 鍾孟廷(Meng-Ting Zhong) ； 王亞飛(Ya-Fei Wang) ； 陳楷浩(Ckai-Hao Chen) ； 黃韋寧(Wei-Ning Huang) ； 楊詠鈊(Yung-Shin Yang) ； 蕭文田(Wen-Tien Hsiao)

《加馬》 52期 (2021/12) Pp. 31-37

摘要

在臨床檢查時，常有行動不便甚至是無法配合受檢姿勢的成人患者，此時則需患者家屬在檢查室內協助患者受檢，同時也接受到輻射照射。本研究採用成人腹部X光攝影參數（74kVp、20mAs），以X光中心射線對應檢查台為中心，距離50公分、100公分與150公分，往左、右與向前延伸共28個測量點，分為未蓋鉛皮與覆蓋鉛皮兩組進行輻射照射，使用輻射偵檢儀測其背景輻射劑量率（μSv/hr），每一測量點均偵測三次，取其平均值，繪製平面劑量分布圖進行分析。在高能量輸出時，分析未覆蓋與覆蓋鉛皮兩種情形時，可發現輻射劑量率在100公分內隨著距離而減少，但卻在150公分處輻射劑量率卻有升高的情況。造成此劑量率分布情形推測是由康普吞效應所造成。而覆蓋鉛皮所測得的劑量率除X光中心外，其餘測量點均高於未覆蓋鉛皮所測得之輻射劑量率，此現象為輻射散射所造成。高能輻射造成光電效應外，亦伴隨著康普吞效應的影響，在輻射防護當中，不得不將此因素納入考量，則可提供未來協助患者之人員更完備的防護措施。

關鍵字

X光 ； 輻射劑量率 ； 光電效應 ； 康普吞效應

並列摘要

During clinical examinations, adult patients who is mobility impairment or even cannot cooperate with the position under examination. At this time, the patient's family members are required to assist the patient in the examination room and receive radiation exposure at the same time. We use adult abdominal X-ray parameters (74 kVp, 20 mAs), centered on the X-ray center ray corresponding to the examination table, at a distance of 50 cm, 100 cm, and 150 cm, extending to the left, right, and forward with a total of 28 measurement points. Divide into two groups of uncovered lead skin and covered lead skin for radiation exposure. Use a radiation detector to measure the background radiation dose rate (μSv/hr). Each measurement point is detected three times, and the average value is used to draw the plane dose. Distribution map for analysis. In the high energy X-ray output, when analyzing the two situations of uncovered and covered lead, it can be found that the radiation dose rate decreases with distance within 100 cm, but the radiation dose rate increases at 150 cm. The distribution of this dose rate is presumed to be caused by the Compton effect. Except for the X-ray center, the dose rate measured by the covered lead sheet is higher than the radiation dose rate measured by the uncovered lead sheet. This phenomenon is caused by radiation scattering. In addition to the photoelectric effect caused by high-energy radiation, it is also accompanied by the impact of the Compton effect. In the radiation protection, this factor has to be taken into consideration, which can provide more complete protection measures for personnel assisting patients in the future.

並列關鍵字

X-ray ； radiation dose rate ； photoelectric effect ； Compton effect