透視攝影輻射劑量空間分佈研究

原能會大力推行透視品保的工作，在透視下，醫師及放射師無可避免的將接受到輻射劑量，但其劑量多寡，可因其所站立位置、使用不同儀器操作及輻射劑量條件組合而有所不同。若能理解於透視檢查室內，矩陣空間進行透視攝影時，其所遭受到的輻射劑量分佈，並提供一個友善的等劑量曲線，可讓檢查的醫事同仁安心。本研究以中部某醫院血管攝影室X光機進行，選用TLD-100H（Harshaw，美國）之熱發光劑量計（Thermoluminescent dosimeter，TLD）置入已編號的夾鏈袋中並懸吊於細繩上，此細繩兩端連接並用支架作為支撐點固定，而TLD位置的佈點以X光中心射束為中心軸，設定長300公分、寬180公分的平面空間，以每30公分為一個間隔放置TLD，再分別以85公分、95公分、125公分、155公分以及175公分高作量測，如此形成一個立體空間的劑量分佈曲線。為增加臨床醫事人員可能干擾的散射劑量，在本研究設置三個人形假體，並穿上鉛衣以模擬散射及互相干擾情形。讀取TLD手動參數劑量，觀察5分鐘透視攝影的平均劑量，由下往上分五層分別測得的劑量結果為1.46 ± 0.45 mGy、1.54 ± 0.69 mGy、2.12 ± 0.82 mGy、1.42 ± 0.56mGy、1.36 ± 0.38 mGy。從結果發現，在五層數據中125公分處測量到最高平均劑量，但即使是最高劑量也低於法規的限值，甚至低於背景劑量，因此可以認定在透視攝影室作業都在安全範圍內。此外，從研究中發現醫事人員在臨床上都會穿著鉛衣為病人診療，無形中亦增加彼此輻射劑量，建議距離至少30公分以上，以達到合理抑低之原則。

關鍵字

透視劑量；空間矩陣；熱發光劑量計

並列摘要

Taiwan Atomic Energy Council developed a scheme to monitor the fluoroscopic x-ray machines nation-wide since 2002. Medical staffs include radiologists, radiographers, nurses, interns exposed to radiation undergoing fluoroscopic examination is inevitable. The post, type of x-ray machine, exposure protocol, and backscatter radiation decide the radiation dose delivery to staffs. 77 TLDs-100H (Harshaw, USA) were allocated in the matrix of space of 300×180 cm^2, 30 cm separated each apart. Five heights from floor respectively at 80cm, 95cm, 125cm, 155cm, and 175cm were also marked to represent the radio-sensitive organs. Three models wore leaded aprons to simulate the medical staffs post in the examination room. 90kV, 250mA, 0.1s, FOV set at 40×40 cm^2, SID at 100 cm, all data were calculated. The results from 80cm to 175cm were respectively 1.46±0.45mGy, 1.54±0.69 mGy, 2.12±0.82 mGy, 1.42±0.56 mGy and 1.36±0.38 mGy. The highest dose at the level 125cm but still lower than the regulation limit, it is understood that the angio-room is a well-controlled one to perform patient examinations. From the result to depict that scatter radiation could occur from leaded apron from staff to each other, it is advised to keep each other at least 30cm could reduce the scatter radiation.

並列關鍵字

fluoroscopy ； radiation dose measurement ； TLDs

國際替代計量

透視攝影輻射劑量空間分佈研究

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