Objective To investigate the radioactivity levels of gross α and gross β in foods around Zhangzhou nuclear power plant, China before operation. Methods Forty-nine samples from 33 kinds of foods in 5 categories of daily food around Zhangzhou nuclear power plant were collected, pretreated, dried, and ashed. The radioactivity levels of gross α and gross β were measured by the low-background α and β measuring instrument. The atomic absorption technique was employed to measure the level of potassium (K), and the radioactivity level of gross β (subtracting ⁴⁰K) was calculated with K concentrations in different foods consulted from the nutritional dietary system. Results The radioactivity levels of gross α in vegetables and fruits, grain, poultry and livestock, aquatic products, and tea around Zhangzhou nuclear power plant were < minimum detectable level (MDL)-7.97, < MDL-6.82, < MDL, < MDL-20.76, and 11.90-23.08 Bq/kg, respectively; the radioactivity levels of gross β were 34.56-122.81, 13.05-188.96, 56.00-108.34, 17.86-169.01, and 123.74-171.63 Bq/kg, respectively; the radioactivity levels of gross β (subtracting ⁴⁰K) were not detected (ND)-14.27, ND-27.86, ND-48.72, ND-45.85, and 6.69-13.79 Bq/kg, respectively. Conclusion The radioactivity of gross α and gross β in foods around Zhangzhou nuclear power plant before operation is basically at the same level as that in other areas of China.

Objective:To study the applicability of conventional detection method, gamma spectrometry and radiochemical analysis, for the determination of 137Cs activity concentratons in food samples and to compare the difference of such two methods for this purpose. Methods:By using both γ spectrometry and radiochemical analysis, the activity concentrations of 137Cs in different types of food were determined, to compare the required sample amounts, the sample pretreatment and preparation processes and the lower detection limits.With meat samples as a case study, the two method were compared for assessing the activity concentrations of 137Cs in meat samples and evaluating the uncertainties. Results:The deviation of measurement result obtained in meat by using gamma spectrometry and ammonium phosphomolybdate-β counting method is consistent, with relative extended uncertainties of 18.0% and 8.0%, respectively. The pretreatment process for γ spectrometry is characterized by its simplicity, but large sample amount required and time-comsuming process, while the ammonium phosphomolybdate method requires a small amount of sample but in need of separation and purification process.The detection limits of the two methods are 10.6 mBq/kg (sample mass 11.7 kg) and 5.1 mBq/kg (sample sample 2.1 kg ), respectively.Conclusions:The results of two methods for determinationf of the low activity concentrations of 137Cs in food samples are consistent. Therefore, when monitoring low activity concentrations of 137Cs in food samples, the appropriate detection method can be selected based on the specific objective and requirements of the monitoring study.

Objective:To investigate the differences in applicability of both the portable high-purity germanium (HPGe) γ spectrometer and the portable lanthanum bromide (LaBr) γ spectrometer for measuring thyroid 131I activity and internal exposure monitoring for radiation workers. Method:Both DETECTIVE-DX100-KT portable HPGe γ spectrometer and InSpector 1000 portable LaBr γ spectrometer were used to measure the 131I content in thyroid of radiation workers for comparison of the measuring result, minimum detectable activity (MDA) and corresponding annual committed effective doses between two types of spectrometers. Results:The detection rate of 131I in thyroid of radiation workers was 67.7% for HPGe γ spectrometer and 26.2% for LaBr γ spectrometer, respectively. The MDA was 12.26-14.74 Bq (measuring time: 3-5 min) for HPGe γ spectrometer and 56.56-80.37 Bq for LaBr γ spectrometer (measuring time: 2-4 min). The annual committed effective dose corresponding to MDA was 0.07-0.08 mSv (3-5 min) for HPGe and 0.31-0.45 mSv (2-4 min) for LaBr, respectively, in the case of using chronic continuous intake mode and 7 d monitoring period. Conclusions:The minimum detectable activity (MDA) of the two types of portable spectrometers could meet the requirements specified in GBZ 129-2016 Specifications for individual monitoring of occupational internal exposure for thyroid monitoring equipment. The two types of spectrometers could be used for routine monitoring of internal contamination. The difference between the monitoring result of LaBr γ and HPGe γ spectrometers might be due to such factors as large uncertainty in short measuring time and low activity concentrations, incomplete identical of distance between probe and neck, probe angle setting, different response of equipment to the environment, background deduction method.

Objective To investigation the radioactivity level of ⁹⁰Sr in tea leaves within and outside 30 km range of Ningde nuclear power plant. Methods The tea leaves within and outside the 30 km range of Ningde Nuclear Power Plant were collected from 2013 to 2018. According to“Radiochemical analysis of strontium-90 in water and ash of biological samples” (HJ 815—2016), the separation and analysis of ⁹⁰Sr-⁹⁰Y were carried outusing the method of di (2-ethylhexyl) phosphate (HDEHP) chromatography. Results During the period of 2013-2018, the radioactivity concentrations of ⁹⁰Sr in the tea leaves within the range of 30 km around the Ningde nuclear power plant were 0.486～13.29 Bq/kg and that of ⁹⁰Sr in the tea leaves outside the range of 30 km around the nuclear power station were 1.021～17.19 Bq/kg. Conclusion During the six years of operation in Ningde Nuclear Power Plant, there was no increase in the radioactivity level of ⁹⁰Sr in the tea leaves around the nuclear power plant.

Objective:To explore the assessment methodology for internal dose to workers exposed to 131I radionuclide. Methods:Workers were chosen in a 131I radiopharmaceutial manufacturer and a nuclear medicine department in a hospital using 131I to treat hyperthyroidism and thyroid cancer. A portable high purity germanium (HPGe) gamma spectrometer was used to measure the content of 131I in the thyroid for 4 consecutive times in a period of 7 d. The internal dose was estimated combining with the work rotation mode for workers dealing with 131I. Results:When the monitoring month was used as a typical month to estimate the internal dose, the annual committed effective dose was 0.09-1.93 mSv for the production staff engaged in the repackaging of 131I radiopharmaceuticals in the surveyed enterprise, and 0.06-0.58 mSv for the nuclear medicine staff in the surveyed hospital. After adjusting the monitoring result of the current monitoring period based on the rotation mode, the annual committed effective dose was estimated to be 0.06-1.22 mSv for radiopharmaceutical production workers and 0.03-0.15 mSv for nuclear medicine workers, respectively. Conclusions:In the assessment of internal dose to radiation workers exposed to 131I, using a single time measurement result to estimate the annual dose would lead to a larger error. In the case of continuous monitoring, the result of subsequent monitoring periods should be corrected according to the result of previous monitoring periods. In order to accurately estimate the internal dose of workers exposed to 131I, it is necessary to take full account of the 131I exposure pattern, time and frequency and the internal contamination route. For workers who may be exposed to 131I with potential internal dose greater than 1 mSv/year, a 14 day-routine monitoring period was appropriate.

Objective:To explore the main risk factors and to assess the risk of thyroid 131I exposure among nuclear medical workers. Methods:From March to October in 2019, cluster sampling was adopted to collect the number of 131I automatic packer and patients treated for thyroid cancer, hyperthyroidism and liven cancer used 131I, the practicing categories, job rotation and 131I operation condition of nuclear medical staff were also investegated in the 21 nuclear medicine hospitals in Fujian Province that carried out 131I nuclide diagnosis and treatment in 2018. 131I aerosol and personnel thyroid 131I were measured in 20 hospitals using 131I for thyroid cancer or hyperthyroidism. The main risk factors leading to thyroid 131I exposure of nuclear medical staff were found and aninternal exposure risk assessment model was established. Results:The detection rate of 131I aerosol and personnel thyroid 131I were 80.0% (16/20) and 25.5% (62/243) in 20 hospitals. The situation of packaging and administration about 131I in the nearly 10 effective half-life, the concentration of 131I aerosol in the nuclear medicine workplace, the number of patients treated with 131I for thyroid cancer or hyperthyroidism were the main risk factors leading to thyroid 131I internal exposure ( OR=5.857, 6.808, 1.983, 1.150, P<0.05) . Conclusion:131I exposure is common among nuclear medical workers, attention should be paid to the protection of internal radiation, strengthen the control of main risk factors, so as to reduce the risk of internal radiation.

Objective:To explore the main risk factors and to assess the risk of thyroid 131I exposure among nuclear medical workers. Methods:From March to October in 2019, cluster sampling was adopted to collect the number of 131I automatic packer and patients treated for thyroid cancer, hyperthyroidism and liven cancer used 131I, the practicing categories, job rotation and 131I operation condition of nuclear medical staff were also investegated in the 21 nuclear medicine hospitals in Fujian Province that carried out 131I nuclide diagnosis and treatment in 2018. 131I aerosol and personnel thyroid 131I were measured in 20 hospitals using 131I for thyroid cancer or hyperthyroidism. The main risk factors leading to thyroid 131I exposure of nuclear medical staff were found and aninternal exposure risk assessment model was established. Results:The detection rate of 131I aerosol and personnel thyroid 131I were 80.0% (16/20) and 25.5% (62/243) in 20 hospitals. The situation of packaging and administration about 131I in the nearly 10 effective half-life, the concentration of 131I aerosol in the nuclear medicine workplace, the number of patients treated with 131I for thyroid cancer or hyperthyroidism were the main risk factors leading to thyroid 131I internal exposure ( OR=5.857, 6.808, 1.983, 1.150, P<0.05) . Conclusion:131I exposure is common among nuclear medical workers, attention should be paid to the protection of internal radiation, strengthen the control of main risk factors, so as to reduce the risk of internal radiation.

Objective:To ascertain the basic situation of radiotherapy in Fujian in 2016.Methods:Based on the unified questionnaire, the types and quantity of radiotherapy and its corollary equipment, the number of radiotherapy staff and the work for quality control were surveyed in the radiotherapy units in the whole province, and the data on patients undergoing radiotherapy and other types of patients were collected from 26 hospitals. The total number of radiotherapy patients in the whole province was estimated by the correlation analysis and multiple linear regression analysis.Results:Radiotherapy was performed in a total of 32 hospitals in Fujian province in 2016. Among them, there were 62 sets of radiotherapy equipment, 33 sets of the simulators, 57 sets of treatment planning systems and 762 workers. The total number of 15 156 radiotherapy patients in 26 hospital were available for the survey. Multiple linear regression models showed that the frequency of application of medical electron accelerator was positively correlated with number of outpatients, emergency patients and inpatients, number of radiotherapy staff, number of electron accelerators ( r=0.311, 0.893, 0.956, P<0.05). Meanwhile, the frequency of aterloading brachytherapy was positively correlated with number of outpatients, emergency patients and inpatients, number of radiotherapy staff, number of aterloading brachytherapy units ( r=0.307, 0.966, 0.988, P<0.05). The frequency of radiotherapy was 0.54 patients per 1 000 population in Fujian in 2016. The delivered dose calibration of accelerators was performed in all hospitals involved in line with the relevant regulations, but the number of quality control equipment for radiotherapy was insufficient, such as the QA beam checker or well-type ionization chamber. Conclusions:In recent years, the rapid development of radiotherapy has been seen in Fujian province. The radiotherapy management should focus on standardenized and improved quality control and regulation in future.

Objectives:This study aimed to evaluate the effect of the strategies on COVID-19 outbreak control in Shenzhen, and to clarify the feasibility of these strategies in metropolitans that have high population density and strong mobility.Methods:The epidemic feature of COVID-19 was described by different phases and was used to observe the effectiveness of intervention. Hierarchical spot map was drawn to clarify the distribution and transmission risk of infection sources at different time points. The Susceptible-Exposed-Infectious-Asymptomatic-Recovered model was established to estimate case numbers without intervention and compare with the actual number of cases to determine the effect of intervention. The positive rate of the nucleic acid test was used to reflect the risk of human exposure. A survey on COVID-19 related knowledge, attitude and behaviors were used to estimate the abilities of personal protection and emergency response.Results:The epidemic of COVID-19 in Shenzhen experienced the rising, plateau and decline stage. The case number increased rapidly at the beginning, with short duration of peak period. Although the epidemic curve showed human-to-human transmission, the "trailing" was not obvious. From the spot map, during the intervention period, the source of infection was widely distributed. More cases and higher transmission risk were observed in areas with higher population density. After the effective intervention measures, both infection sources and the risk of transmission decreased. After compared with the estimated case numbers without intervention, actual number proved the COVID-19 control strategies were effective. The positive rate of nucleic acid test for high risk populations decreased and no new cases reported since February 16. Shenzhen citizens had high knowledge, attitude and behavior level, and high protection ability and emergency response.Conclusions:Although the response initiated by the health administration department played a key role at the early stage of the epidemic, it was not enough to contain the outbreak of COVID-19. The first-level emergency response initiated by provincial and municipal government was effective and ensured the start of work resumption after the Spring Festival. Metropolitans like Shenzhen can also achieve the goals of strategies and measures for containment and mitigation of COVID-19.

Objective:To explore the association between long-term low-dose radiation exposure and other influencing factors with the risk of lens opacity on medical radiation workers.Methods:In July 2019, a retrospective cohort study was conducted by collecting the basic demographic information, dose data and health inspection result of 2708 radiologists in 22 hospitals of Guangzhou from the Occupational Health Inspection Information System and the Personal Dose Monitoring System of the Guangdong Prevention and Treatment Center for Occupational Disease between 2010 to 2018. The association between the average annual effective dose and lens opacity risk was calculated by using Time-Dependent Cox Regression Model.Results:From 2010 to 2018, the incidence density of lens opacity was 185.90/10000 person years. Compared with the radiation workers in the age <30 years group (93.74%) , the 5-year normal rate of lens in the age ≥50 years group (72.51%) was lower ( P<0.01) ; Compared with the radiation workers in the exposure age <10 years group (92.69%) , the 5-year normal rate of lens in more than 20 years exposed group (83.05%) was lower ( P<0.01) . Multifactor analysis showed that age was an independent influencing factor for lens opacity in medical radiation workers ( HR=14.485, P<0.01) . The risk of lens opacification increased by 4.9%, 10.1% and 15.5% in 30-, 40- and 50-years group, respectively. Gender, cigarette, alchol, type of work, length of service and annual effective dose had no significant effect on lens opacity ( P>0.05) . Conclusion:Age is the main influencing factor of lens opacification in medical radiation workers, their radiation working time and intensity should be strictly controlled and radiation protection should be done.