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 simulate and analyze the CT examination doses to typical patients based on Chinese reference human phantom, and to develop an online software for assessing the organ absorbed dose and effective dose to the examinees undergoing CT examination in order to provide a tool for rapid assessment of radiation dose from CT examination. Methods Based on the Monte Carlo simulation, a GE LightSpeed 16 CT scanner was modeled. The organ doses to Chinese adult male, female and 1 year-old child male from single axial scan were calculated based on the Chinese reference phantoms and an organ dose database was established. A web-based CT dose assessment software was developed to read the data from the organ dose database according to the CT scanning parameters entered by the user and to calculate the organ absorbed dose and effective dose rapidly. Results A new CT dose assessment software was developed, which can be used to assess organ doses to Chinese adult male, female and 1-year-old male for different CT scanner, voltage, current, collimator width and other CT parameters. The organ doses calculated in this work were compared with simulation data in two relevant studies. Dose differences for the organs completely included in the scan range were small, with relative differences less than 15％ and 25％, respectively. Conclusions The CT dose assessment software provides a powerful tool for the simple and rapid assessment of radiation dose to the examinees undergoing CT examinations.

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 study the estimation method of medical exposure frequency in China through the survey of diagnostic radiology and radiotherapy institutions in selected provinces.Methods A survey of medical exposure frequency was carried out involving 557 diagnostic radiology and radiotherapy institutions in 25 provinces.The correlation analysis and multiple linear regression analysis were conducted,with the fitting effects of the models with different variables being compared.Results The total medical exposure frequencies highly correlated with number of outpatient,number of equipment and number of radiation workers (| r| ＞0.5).Representative samples of the daily medical exposure workload were obtained by stratified random sampling from the survey data.Mathematical models were built using the multiple linear regression between total medical exposure frequency and hospital levels,number of outpatients,number of inpatients,number of equipment,and number of radiation workers.The total medical exposure frequency in 2016 was estimated to be 589 million examinations based on the models.In addition,the frequencies of medical procedures were derived using the robust regression and the median regression.Conclusions There are several methods for estimating the total medical exposure frequency.It is desirable to use the stratified random sampling combined with the published statistical and monitoring data.The representativeness of sample is critical.The specification and optimization of models also require further study.

Objective:To investigate the allocation of radiation protection equipment and status of radiological protection management for radiation workers in hospitals nationwide.Methods:A descriptive analysis was conducted of the data reported from the investigated hospitals based the data for 2019 available from the National Radiological Health Information Platform.Results:A total of 3 806 hospitals were investigated in 2019, including 609 tertiary hospitals, 1 421 secondary hospitals, 1 776 primary and ungraded hospitals. Large differences had been shown in the number of radiation workers in different grade hospitals. The average number of radiation workers were found to be, respectively, 99 in tertiary hospitals, 19 in secondary hospitals, 2 in primary and/or ungraded hospitals. Interventional radiology and nuclear medicine workers were equipped seperately with 0.40 and 0.43 pieces of lead apron, 0.27 and 0.31 lead caps, 0.38 and 0.45 lead rubber neck sleeves, 0.18 and 0.08 pairs of lead rubber gloves and 0.31 and 0.22 pairs of lead glasses. No personal alarming dosimeter was available in 15.25% hospitals where radiotherapy was performed, nor radiation surveillance meter in 27.90% such hospitals. In the hospitals considered, 88.13% workers were granted the Radiation Worker Cetificate and 83.69% received the on-the-job radiation protection training. The number of monitored workers accounted for 99.20%, of which 0.40% received the personal annual dose Hp(10)≥20 mSv. The occupational health surveillance files that had been completed reached 98.05% of the total and the on-the-job radiation workers who had passed the occupational health examination made up to 96.00%. It was advised that, of 76 627 radiation workers who received the 2019 health examination, 0.88% should get out of radiation work for the being time and 0.11% should not continue for this work. Conclusions:The considerably large proportion of radiation workers in China have received individual dose monitoring and occupational health examination. Radiological diagnosis and therapy departments should enlarge the allocation of radiation monitoring and personal protection equipment for radiaton workers in their hospitals.