Objective To ascertain the frequency distribution of CT examinations in children.Method A wide range of information was collected through the radiology information system (RIS),including ID,sex,birth date,examination time,the examined part of body and other relevant ones related to children who underwent CT examinations between Jan 1,2012 and Dec 31,2012.The SAS software was used for data processing and statistical analysis.Results A total of 1 542 children underwent 1 670 examinations,of which 67％ were male.Head CT examination was the most frequent,accounting for 71.9％ of all CT examinations,and followed by the abdomen/pelvis examinations.The number of examinations of children undergoing the repetitive examination accounted for 6.4％; 51.7％ of the examinations was for trauma.The positive rate of CT examination was 51％,dependent upon the age and examined body parts to some extent.The younger patients had lower positive rate,and the positive rate of head CT examination was lower than those in other parts.Conclusions To reduce the possible cancer risk to be induced by the ionizing radiation from CT,justification of CT examination should be considered for children.

Objective To estimate the radiation dose and cancer risk of thyroid for children who underwent head CT or chest CT scans.Methods The parameters used in the CT scans were accessed from the DICOM files through PACS used DCMTK software, then the thyroid radiation dose was estimated with the CT-Expo(C) software and the cancer risk induced by CT scan was projected based on BEIR Ⅱ model combined with the Chinese cancer incidence and lifetime table in 2008.Results CT parameters used for different ages were roughly the same, the thyroid equivalent dose for head CT ranged from 1.2-2.0 mGy, the highest thyroid cancer risk occurs for newborn girls, about 9.6/100 thousand population;while for chest CT the thyroid equivalent dose ranged from 8.1 to 38.0 mGy, the highest thyroid cancer risk was also for newborn girls, about 244.7/100 thousand population.The radiation dose and cancer risk for thyroid decreased with the increased age.Conclusions The radiation dose for thyroid from chest CT was relatively higher than head CT, especially for newborn babies;therefore more protection should be given to the thyroid and other radio-sensitive organs during CT scanning.

Objective:To investigate the levels of dose to eye lens of interventional radiology workers in China from 2017 to 2019.Methods:The monitoring data on eye lens doses to the interventional radiology workers in 28 provinces across the country were collected from National Individual Dose Registry. Monitoring was carried out using TLDs on their left eyes and evaluated in terms of the personal dose equivalent Hp(3). By using Mann-Whitney U test and Kruskal-Wallis H test, statistical analyses were made of the average annual lens doses to interventional radiology workers in the hospitals of different types at different levels for different years. Results:From 2017 to 2019, the data on eye lens doses to 2 981 interventional radiology workers were collected, with doses ranging from below the minimum detectable level (MDL) to 64.48 mSv, the average annual eye dose of 1.38 mSv, and the annual doses incurred by 0.97% monitored workers exceeding the recently recommended dose limits, 20 mSv per year. The average annual lens dose monitored in general hospitals and in cancer hospitals were 1.33 and 1.77 mSv, respectively, without statistically significant difference ( P>0.05). The average annual lens dose in tertiary hospitals was 1.39 mSv, significantly higher than that in secondary hospitals where the value was 1.16 mSv ( Z=2.894, P<0.05). Conclusions:The estimated annual eye lens doses to the interventional radiology workers during 2017-2019 were in accordance with the current national standard GB 18871-2002, but with a few exceptions exceeding the current international standards. This means that there exists, to a certain degree, a potential risk for the eye lens in this work category to exceed the international limits. It is suggested to continue in effort to enhance the monitoring of eye lens dose for these workers and to increase risk awareness, and take effective protective measures so as to lower the level of eye lens doses.

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 understand effects of the interventional operation on thyroid,peripheral blood indexes and chromosomal aberrations (CA) of peripheral lymphocyte of children with congenital heart disease (CHD).Methods Follow-up studies were conducted in 70 child patients undergoing cardiac catheterization and 23 with open heart surgery as control from 2010 to 2013.Postoperative follow-up examinations included thyroid ultrasound,blood routine indexes and analyses of CAs.Results Difference in thyroid ultrasound abnormality rate was not statistically significant between children with cardiac catheterization and control group (40.0％ vs.43.5％,P ＞ 0.05).There was no significant difference in white blood cell (WBC) count between interventional group and control group (P ＞ 0.05).The effects of disease type and operation time on thyroid ultrasound and WBC count were not observed (P ＞ 0.05).The frequency of chromosome aberrations,including acentric fragment,dicentrics and translocation in interventional group [(0.76 ± 0.07) ％],was higher than in control group [(0.25 ± 0.07) ％,(Z =-3.631,P ＜ 0.05],and the rates of acentric fragment and translocation were also higher in interventional group (Z =-2.531,-2.397,P ＜ 0.05).Conclusions Effect of intervention therapy on thyroid structure and WBC count in children with CHD was not observed,but the genotoxic effects remain in children with cardiac catheterization.

We conducted in-depth analysis on the use of a popular Chinese social networking and microblogging site, Sina Weibo, to monitor an avian influenza A(H7N9) outbreak in China and to assess the value of social networking sites in the surveillance of disease outbreaks that occur overseas. Two data sets were employed for our analysis: a line listing of confirmed cases obtained from conventional public health information channels and case information from Weibo posts. Our findings showed that the level of activity on Weibo corresponded with the number of new cases reported. In addition, the reporting of new cases on Weibo was significantly faster than those of conventional reporting sites and non-local news media. A qualitative review of the functions of Weibo also revealed that Weibo enabled timely monitoring of other outbreak-relevant information, provided access to additional crowd-sourced epidemiological information and was leveraged by the local government as an interactive platform for risk communication and monitoring public sentiment on the policy response. Our analysis demonstrated the potential for social networking sites to be used by public health agencies to enhance traditional communicable disease surveillance systems for the global surveillance of overseas public health threats. Social networking sites also can be used by governments for calibration of response policies and measures and for risk communication.

Objective To analyze the changes in distribution of occupational radiation cases reported from 2013 to 2017 in China and learn about the occupational health risks of radiation workers.Methods Descriptive analyses were made of regional distribution,disease category distribution,occupation category distribution and exposure mode distribution of these cases,according to the reports (2013-2017) of occupational radiation sickness from " Occupational Health of Radiation Workers Management System".Results There were 54 diagnostic radiology agencies for occupational radiation sickness in China that covered all provinces,autonomous regions and municipalities except Tibet and Production and Construction Corps of Xinjiang.A total of 106 new cases were reported from 2013 to 2017.Most of the cases were radiogenic neoplasm (43.40％),and chronic radiation sickness were from external exposure (16.98％) and radiation cataract (16.04％).Most of the cases (70.75％) were engaged in medical application and a small part of the cases (13.21％) engaged in industry application.Chronic exposure (80.19％) was the most frequent form of exposure mode,but acute exposure (5.66％) was very few.A part of cases (14.15％) were reported without exposure mode.Conclusions The morbidity of occupational radiation sickness declined generally in China and occupational health management of key workers should be strengthened continuously.

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 explore the probability of causation method ology of male breast cancer and to provide theoretical basis for the diagnosis of occupational radiogenic male breast cancer in China.Methods:Using the male excess relative risk model (EAR) fitted from the Japanese atomic bomb survivors and the female excess absolute risk model (ERR) provided by the Biological Effect of Ionizing Radiation Committee VII (BEIRVII), the breast dose and the probability of causation of the previous case of male breast cancer were calculated.Results:The average probability of causation ( PC) calculated by male ERR model was 94.6%, and the upper limit of 95% PC was 98.3%. Using female EAR model and female breast cancer incidence, the average PC was 70.3%, and the upper limit of 95% PC was 153.3%. when male breast cancer incidence was used, the average PC was 99.2%.By both methods, the male breast cancer patient could be determined to be caused by occupational radiation exposure. Conclusions:The upper limit of 95% PC calculated by female EAR model and female breast cancer incidence was higher than that by male ERR model.The uncertainty of probability of causation for female EAR model still need further research. Occupational radiogenic male breast was proposed to listed in occupational radiogenic neoplasms, which will make the list more perfect and scientific and reasonable to meet potential claims.

In March 2011, a nuclear accident happened and released a large amount of radionuclides into the environment in Fukushima, Japan. This review introduced the latest findings on the relationship between childhood thyroid cancer and radiation exposure after the accident in Fukushima. Many reports suggested that there was no accurate correlation between the incidence of childhood thyroid cancer and the local external dose due to the accident at the Fukushima Daiichi nuclear power, while the relationship between the two varied with method of dose calculation and statistics. Also there was no clear evidence that radiation exposure had a negative impact on children′s thyroid, and the increased incidence of thyroid cancer may be due to over-screening.