177Lu-prostate specific membrane antigen(PSMA)radio-ligand therapy has been approved abroad for advanced prostate cancer and has been in several clinical trials in China.Based on domestic clinical practice and experimental data and referred to international experience and viewpoints,the expert group forms a consensus on the clinical application of 177Lu-PSMA radio-ligand therapy in prostate cancer to guide clinical practice.

In recent years, the diagnostic radiology, especially CT scanning, has a rapidly increased frequency in our country, becoming the largest artificial radiation source to the average individual doses to the population. In clinical diagnosis and treatment activities, the examined patients and individuals may undergo multiple procedures and multiple frequencies of medical imaging in a short period of time and receive high cumulative radiation doses even exceeding 50 or 100 mSv in a single day, posing a potential risk to their health. Therefore, it is necessary to carry out statistical analysis and management of diagnostic radiation dose information to minimize the probability of excessive dose and associated radiation risk. In this paper, the international cognition of radiation risks in diagnostic radiology, diagnostic equipment and medical imaging frequency, radiation dose and its management status are described. Four countermeasures for radiation dose management are put forward to provide reference for further improving radiation protection in clinical practice.

Objective:To study the healthcare level (HCL) in China and its influencing factors.Methods:By using the data reported in the China statistical yearbook published by the National Bureau of Statistics and in other public literature, HCL was calculated in terms of the number of population and physicians in the whole country and various provinces. Multiple regression was used to analyze the relationship between HCL and regional population, area, number of administrative divisions and gross domestic product (GDP). Pearson correlation analysis was applied to analyze the relationship between healthcare level and medical radiation frequency. Results:Since 2015, Chinese HCL value was lower than 1 000, but there were two provinces with HCL value greater than 1 000 in 2019. Population and GDP were the influencing factors for the HCL, with correlation coefficients of 0.416 and -0.583, respectively. There was a correlation between HCL and medical exposure frequency of Chinese population( r= -0.620, P=0.028). Conclusions:Chinese HCL value was 542 in 2020, but there has been great differences between various provinces. HCL as an indicator of medical exposure assessment needs further research in China.

Objective:To develop a software for rapid estimation of external dose to the public due to environmental radioactive contamination.Methods:Based on the data provided by the International Commission on Radiological Protection (ICRP), a database of the conversion coefficients of external dose rates for the public (adult and children of different age groups) under different environmental exposure scenarios was created. The programs of data search and calculation were written using Python language, and the software interface was designed using PyQt toolkit. To test the calculation results, the differences in external doses to different age groups of the public caused by most likely produced radionuclides under three environmental exposure scenarios were calculated, and their rationalities were analyzed.Results:The software can immediately complete the estimation of the organ equivalent doses and the effective dose due to the external exposure form environmental contamination by using a personal computer with a Windows system, and its results are reasonable. The test results showed that the younger the public members, the larger the organ dose and effective dose. For soil surface and water contaminated with 90Sr with the same activity concentration reaching radioactive equilibrium, the effective dose to infants was about 6.08 times and 2.51 times those to adults, respectively. Conclusions:The software developed in this study has the advantages of simple operation and fast calculation, and is suitable for rapid estimation of external dose to the public members of different age groups in emergency situations such as nuclear accidents.

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:To construct a system for evaluating the professional capability of provincial radiological health institutions.Methods:Based on the Donabedian model and the main professional responsibilities of provincial radiological health institutions, the logical framework and indicator database of the capability evaluation system were initially constructed, the Delphi expert consultation method and analytic hierarchy process were further used to determine each indicator and its weight. The self-assessment test was carried out throughout the provincial radiological health institutions by using the system established in this study.Results:The evaluation system included 3 primary-class indicators, 11 second-class indicators, 30 third-class indicators and 76 fourth-class indicators. Taking 100 points as the full score, the self-assessment scores of the 29 provincial institutions ranged from 28.7 to 97.7 with an average of 78.7, and the scores conform to the normal distribution.Conclusions:The system established in this study are scientific, comprehensive and operable, which can be used as an effective tool to evaluate the professional capability of provincial radiological health institutions.

Radon is the second largest environmental factor inducing lung cancer after smoking. In recent years, with the deeper epidemiological investigation on radon and lung cancer and the further improvement of its methodology, new progress has been made in the research on risk assessment models. This paper reviews the relative risk models of radon-induced lung cancer developed by several international academic organizations or research teams, and briefly introduces the background information on the models and the main factors considered. Based on the indoor radon concentrations in different decades in China, the relative risks of radon-induced lung cancer were estimated and analyzed, together with some suggestions given for more accurate evaluation of lung cancer induced by indoor radon in the future.

Objective:To simulate the effects of different thyroid-neck phantoms and monitoring positions on the detection efficiency of portable γ spectrometer, and to provide guidance for more accurate on-site measurement of 131I activity in the human thyroid. Methods:Based on the models of 4 typical thyroid-neck phantoms and a 3-inch NaI (TI) γ spectrometer used for the measurement of 131I in the thyroid and combined with the possible field monitoring scenarios, the Monte Carlo method was used to simulate and calculate the detection efficiency of the spectrometer under different conditions of monitoring distance, thyroid depth and thyroid volume. Results:The detection efficiency decreased significantly with the increase in the distance between the detector and the neck surface. The efficiency close to the neck surface was about 15 times that at 15 cm away from the neck surface. The detection efficiency decreased significantly with the increase in thyroid depth. When it was measured at the surface of the neck, the detection efficiency of thyroid at depth of 2 mm was about 3.6 times that of 30 mm. The detection efficiency decreases with the increase in thyroid volume. When it was measured at the neck surface, the detection efficiency of thyroid with 1 ml volume was 1.71 times that with 30 ml. The detection efficiency decreased with the center-point offset of the detector, especially at the neck surface, an offset of 2 cm would reduce the detection efficiency by about 15%.Conclusions:Not only the measurement distance used in calibration, but also the information of the depth and volume of thyroid in the neck-thyroid phantom, is important to know in advance for an accurate measurement of 131I activity in thyroid by using a portable gamma spectrometer.

The radiation risk caused by CT examination is of great concern. Organ dose is considered to be the most significant technical parameter for quantifying the patient radiation dose and assessing the corresponding risk. At present, the methods to obtain patient organ dose caused by CT examination mainly include physical phantom measurement, direct human body measurement, dose conversion coefficient, Monte Carlo simulation, and dose calculation software. Although different methods have their own characteristics and application, the individualization of organ dose is always the goal of radiation protection and dosimetry research. Patient-specific phantom developed with artificial intelligence and GPU-accelerated Monte Carlo simulation make it possible to calculate the patient-specific organ dose, and the patient-specific organ dose extrapolated by the CT detector signal provides a new solution.

Objective To compare the precision and efficiency of computing the specific absorbed fraction (SAF) of a reference human with two grid methods in MCNP6.0. Methods Based on the adult female reference voxel phantom provided by the International Commission on Radiological Protection, assuming the liver as the source organ emitting single-energy photons (0.5 MeV), the SAF of each target organ/tissue was calculated by using the mesh method and repeated structure lattice method with the F4, F6, and *F8 tally cards in MCNP6.0. We compared the methods by assessing the relative deviation of SAF and computing time for 27 organs/tissues. Results Compared with reported data, the absolute values of relative deviations of SAF values for all the organs/tissues were less than 5%, except for the eye lens and skin. By using the repeated structure lattice-based *F8 tally, the relative deviations of SAF values of the organs/tissues were all smallest, but with the longest computing time. The computing time of the mesh-based F4 tally was slightly longer than that of the repeated structure lattice-based F6 tally, which was shortest. Conclusion The *F8 tally simultaneously simulating primary and secondary particle transport showed the highest precision. The mesh tally requireda longer computing time than the lattice tally when using the same tally card.