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Objective To understand the allocation of radiological diagnostic equipment and the frequency of medical radiation exposure in the medical institutions in Ningxia region,in order to provide the basis for the reasonable application of medical radiation technology.Methods The general survey in the form of the questionnaires was used to investigate and analyze the medical radiation usage of medical X-ray diagnostics,interventional radiology,nuclear medicine and radiotherapy in Ningxia region medical institutions.Results The frequency of X-ray diagnostic radiography in Ningxia region was 727.9 per 1 000 population in 2014.The frequency of X-ray photography examination was the highest,525.2 per 1 000 population,followed bv the frequency of CT scanning,147.9 per 1 000.For others,the frequency was radiotherapy 6.0 per 1 000 population,nuclear medicine 1.8 per 1 000 and interventional radiology 3.8 per 1 000,respectively.These differences were of statistical significance in frequency of X-ray diagnostic examination in five cities' medical institutions in Ningxia (X2 =162 280.7,P ＜ 0.05),also in all medical institutions at different levels (x2 =902 485.2,P ＜ 0.05) and for both frequency of X-ray photography examination and CT scanning in these institutions (x2 =471 574.9,181 887.1,P ＜ 0.05).Conclusions Of the X-ray diagnostic radiography,the CT scanning has becoine a major means next only to the X-ray photography examination.There are differences in frequency of X-ray diagnostic examination in the medical institutions at different levels in different cities of the region.The related regulatory authorities should strengthen the supervision and management of radiation protection in mnedical institutions,to ensure the justification of diagnostic radiology and radiotherapy.

Objective To primarily investigate the indoor radon concentrations in the urban and rural dwellings in Yinchuan, China, and to estimate the effective dose. Methods A total of 67 dwellings, which included 49 urban households and 18 rural households in Yinchuan, were selected to cumulatively measure the indoor radon concentrations for more than 3 months using solid state nuclear track detection. Results The arithmetic mean, geometric mean, median, and range of indoor radon concentrations in urban and rural areas in Yinchuan were 64 Bq/m³, 59 Bq/m³, 57 Bq/m³, and 25-172 Bq/m³, respectively. Surveillance sites with an indoor radon concentration higher than 100 Bq/m³ accounted for 7.5%. Indoor radon concentrations in rural areas were higher than those in urban areas. Indoor radon concentrations were highest in winter and lowest in summer. The effective dose of indoor radon exposure among residents in Yinchuan was 1.86 mSv/a. Conclusion The results of indoor radon concentrations measured in this investigation in Yinchuan are significantly higher than those measured in the 1990s. The annual effective dose is higher than the mean levels in the world and China.