医疗照射是全民所受电离辐射的最大人为因素 ,Ｘ射线诊断医疗照射剂量水平又是整个医疗照射调查的重要组成部分〔1〕。结合受照频率情况 ,它对于公众集体剂量负担的估算与评价 ,施行Ｘ射线诊断正当性判断和最优化分析以及搞好医用辐射防护具有重要意义。为此 ,我们选自Ｘ射线中 Medical exposure is the biggest human factor of ionizing radiation for all. X-ray diagnosis of medical radiation dose level is an important part of the whole medical radiation investigation [1]. Combined with the frequency of exposure, it is of great significance for estimating and evaluating the public collective dose burden, performing X-ray diagnosis justification and optimization analysis, and improving medical radiation protection. For this purpose we are selected from X-rays