The rapid development of medical application of ionizing radiation has seen a range of safety and protection problems that might be of importance. This paper aims to introduce the current situation and existing problems in the public medical exposure, and to propose the relevant suggestions, based on a combination of judgment of medical radiation exposure justification, quality assurance and control of equipment in radiodiagnosis and radiotherapy, occupational protection of radiation workers, and health effects on patients undergoing radiodiagnosis and radiotherapy.

Objective:To estimate the attribution share of residents′lung cancer caused by indoor Radon.Methods:Based on the 2015 lung cancer mortality, all-cause mortality from China together with nationally representative smoking rate and the average indoor radon concentration of 30 Bq/m 3, the relatively authoritative and applicable EPA/BEIR-VI risk model was used to predict the lung cancer mortality caused by indoor radon exposure. Results:The excess relative risk (ERR) of indoor radon-related lung cancer mortality among the male non-smokers is higher than that of smokers. For the age-group above 50, the male smokers and male non-smokers have the highest ERR values, which were 0.511 and 0.230, respectively. Assuming the exposure incurred starting at age 0 with the same radon concentration, the lifetime risk of men and women non-smokers is higher than that of the smokers of the same gender. The higher the radon concentration, the higher the lifetime risk of lung cancer. Assuming that the radon concentration level in China is 30 Bq/m 3, the number of deaths from indoor radon-related lung cancer in 2015 is about 55 512. According to this, about 6.62% of lung cancers are caused by indoor radon exposure. If we assume that radon concentration levels are 40 Bq/m 3and 70 Bq/m 3 in China, approximately 8.82% and 15.38% of lung cancer deaths can be attributed to indoor radon exposure. Conclusions:Indoor radon exposure is an important environmental factor that causes Chinese residential lung cancer. Effective measures should be taken to prevent and control the increasing indoor radon levels. In order to accurately assess risk of lung cancer morality caused by indoor radon, more detailed data such as the indoor radon level in China are needed.

Objective Collect and analyze data of radiation level of ²¹⁰Po/²¹⁰Pb in cigarettes in China, evaluate the internal radiation dose caused by smoking to Chinese smokers and compare it with other countries. Methods The radiation levels of ²¹⁰Po/²¹⁰Pb in cigarettes in domestic and foreign countries were summarized and analyzed, and the fractions of ²¹⁰Po/²¹⁰Pb in mainstream smoke were recommended, and the internal radiation doses to smokers in China were estimated. Results In 2015, there were 320 million smokers among aged 15 and above in China with an average smoking amount of 15.2 cigarettes per day. The average activities of ²¹⁰Po/²¹⁰Pb weighted by the number of cigarette brands were 28.2 mBq per cigarette and 39.3 mBq per cigarette respectively. The mainstream smoke fraction of 20% of ²¹⁰Po was used to make the does estimation which was the mean value of the experimental results of simulator and volunteers, and that of ²¹⁰Pb was 10% measured by simulators. Based on the average smoking amount per day and the number of smokers in China, the annual effective dose of current smokers in China is 126 μSv·a⁻¹, and the collective effective dose is 40746 man·Sv. Conclusion The content of ²¹⁰Po/²¹⁰Pb in Chinese cigarettes is about 2～3 times that of other country's cigarettes. However, the fraction of mainstream smoke and dose conversion coefficient of ²¹⁰Po/²¹⁰Pb adopted in this paper are different from those in other literatures. Therefore, the estimated dose of 20 cigarettes for Chinese smokers is lower than that for smokers in some countries.