數位放射醫療影像系統的演進使得常規X光攝影的成像原理與流程有了革命性的改變，隨著影像儲存傳輸系統(PACS)的普及，直接式數位X光系統(Direct Radiography)，簡稱DR，也逐漸受到各醫院的青睞，本研究的目的，是利用DR高效能的偵測平版轉換技術與可調整影像亮度對比的特性，在不影響影像品質的情況下，降低X光的輸出量，找出骨骼攝影的適當劑量，作爲DR設定攝影條件時的參考依據，我們利用一具模擬真人的假體，進行人體各部位骨骼的攝影研究，依比例降低攝影條件中mAs值，再請三位專科醫師進行影像的評分，評估出符合臨床需求影像的攝影條件，並利用熱發光劑量計(TLD)的計測，比較人體吸收劑量上的變化。根據實驗結果。我們得知利用DR操作骨骼攝影時，因爲軟硬體的進步，強化了各部位的影像品質，使X光的輸出量幾乎可以降低至傳統輸出量的50~60%，而受檢者接受的輻射劑量也減少了35%~40%，因此讓我們更能達到合理抑低的目的。

Due to the development of digitalization in medical imaging, the technique and process of conventional radiography have a lot of revolutionary changes. Following the popularization of the PACS, Direct Radiography becomes more important in hospitals. The purpose of this study is to reduce and optimize the radiation doses of X-ray in orthopedic radiography without image quality losses, by means of applying the high efficacy of plane detective and converted characteristics, and the techniques with the flexibility in contrast and density adjustment of DR system. The Rando phantom and TLD are used in this study, various mAs were choose to create images, these images were then evaluated by three radiologists and make judgments about the satisfactions in image quality. Finally, by the results of this study, we can reduce the output (mAs) of X-ray unit up to 50~60% comparing with the conditions of conventional radiography without image quality losses, patient's absorbed dose also reduced 35-40% to achieve the spirit of ALARA.