本研究評估本院放射科之醫療用移動式X 光機在無鉛屏蔽條件下，所站位置至X 光管之平行距離1 公尺，兩個禮拜累積的劑量約為0.044 mSv，相當於年劑量0.528 mSv，此值遠低於職業年限度值50 mSv。而在有鉛屏蔽的狀況下，鉛屏蔽後方之醫護人員輻射劑量為0.021 mSv，換算成年累積劑量約為0.2514 mSv。X 光管管套表面附近，劑量最大值位於X 光管下方之X 光射出窗附近，劑量值為0.327 mSv；而X 光管上方因有外殼所以其輻射劑量偏低，僅為下方射出窗周遭的約二十五分之一。X 光管左右二端相差大，右端劑量值為0.0676 mSv 約為左端的五倍，主要可能為陽極跟效應所導致。使用游離腔計數器評估醫用移動式X 光機周圍空間的輻射劑量，包括實際現場的照射及模擬空間。在醫用移動式X 光機周圍做游離腔計數器的放置，經實際照射病房現場累積約兩個禮拜的輻射劑量；空間的模擬則以醫用移動式X 光機、假體、病床、計數器3D 空間的放置，曝射50 次以模擬現場照射及輻射劑量評估。於X 光室內空間曝露之模擬，鉛屏蔽離X 光管球1.6 公尺，鉛屏蔽前方劑量平均值為0.0211 mSv；而後方平均值為0.0112 mSv，鉛屏蔽約阻擋減少53%的輻射曝露。鉛屏蔽後方平均值0.0112 mSv 應可作為50 次醫用移動
式X 光照射曝露參考之保守值。而距離X 光管0.5 公尺、1.0 公尺的劑量分別為0.05044 mSv、0.01643 mSv，距離越遠輻射劑量越低。

The ion chamber dosimeter (Vitoreen 450P) was adopted to assess radiation dose that were resulted from exposure of medical portable X-ray machine. The study includes two parts, a field study and a laboratory experiment. The ion chamber dosimeter (Vitoreen 450P) the surface of an X-ray machine that was actually performed in the hospital and exposed to X-ray in one month. Besides, that a portable X-ray machine, a body phantom, and a table were assembled to setup on a clinical room and exposed 50 times to simulate the field study and investigate exposure strength.The maximum accumulated dose around the surface of X-ray tube was 0.327mSv that was found beneath the X-ray tube, near the window. But the dose that located upper the tube was low, a twenty-fifths of the maximum dose. Doses on the sides of the tube were rather different as a result of heel effect. The dose, 0.0676mSv, on the right side is five times of that on the left side. The dose with a distance of 1.0 m from X-ray tube without any lead shield was 0.021 mSv for two weeks.It is equivalent to 0.55 mSv for a year that is lower than annual occupational dose limit, 20 mSv. The exposure behind the lead shield was 0.021mSv for two weeks. It is equivalent to 0.2514mSv for a year.The laboratory experiment was performed to simulate and assess space exposure around an X-ray machine. After fifty exposures, doses before and behind of lead shield were 0.0211 mSv and 0.0112 mSv, respectively. Lead shield prevents 53% X-ray exposure. The space exposures at the altitude of 1.0 m and was higher that at the altitude of 0.5 m. The exposures with a distance of 0.5 m and 1.0 m from the place to X-ray tube were 0.054mSv and 0.0164mSv, respectively. The data showed longer distance lower exposure.