Objective:To analyze the differences in pediatric CT radiation dose and scanning parameter Settings between children's specialized hospitals and general hospitals, and to provide reference for the optimization strategy of pediatric CT radiation dose.Methods:From July to August 2022, a stratified sampling method was used to select 7 comprehensive hospitals and 2 children's hospitals in Tianjin, and on-site survey was conducted to collect the dose data of children's head, chest, and abdomen and pelvic CT examinations in these hospitals. The Wilcoxon rank sum test was used to analyze the differences in CTDI vol and DLP of the same age group and examination site among different types of hospitals, and the stepwise regression analysis method was used to analyze the effects of age, examination site, and scanning parameters on radiation dose CTDI vol and DLP. Results:The CTDI vol and DLP of head (1-<5, 5-<10, 10-<15 years old group), chest (5-<10, 10-<15 years old group) and abdomen (1-<5, 5-<10, 10-<15 years old group) in children's specialized hospitals were lower than those in general hospitals (head, 1-<5, 5-<10, 10-<15 years old group, CTDI vol: Z=-9.32, -6.17, -9.86, P<0.001, DLP, Z=-4.41, -4.14, -5.76, P<0.001; chest, 5-<10, 10-<15 years old group, CTDI vol: Z=-3.84, -5.35, P<0.001, DLP, Z=-3.59, -4.63, P<0.001; abdomen, 1-<5、5-<10 and 10-<15 years old group, CTDI vol: Z=-7.88, -7.78, -8.53, P<0.001, DLP, Z=-7.24, -5.92, -3.44, P<0.001). The CT radiation dose in children was positively correlated with age, tube voltage, tube current time product and scan length, and negatively correlated with pitch and hospital type (general hospital and children's hospital) . Conclusion:There are some differences in the CT radiation dose and scanning parameters between children's hospitals and general hospitals. The results indicate that there is still much room for improvement in the optimization of radiation dose in pediatric CT examination.

Objective:To analyze the differences in pediatric CT radiation dose and scanning parameter Settings between children's specialized hospitals and general hospitals, and to provide reference for the optimization strategy of pediatric CT radiation dose.Methods:From July to August 2022, a stratified sampling method was used to select 7 comprehensive hospitals and 2 children's hospitals in Tianjin, and on-site survey was conducted to collect the dose data of children's head, chest, and abdomen and pelvic CT examinations in these hospitals. The Wilcoxon rank sum test was used to analyze the differences in CTDI vol and DLP of the same age group and examination site among different types of hospitals, and the stepwise regression analysis method was used to analyze the effects of age, examination site, and scanning parameters on radiation dose CTDI vol and DLP. Results:The CTDI vol and DLP of head (1-<5, 5-<10, 10-<15 years old group), chest (5-<10, 10-<15 years old group) and abdomen (1-<5, 5-<10, 10-<15 years old group) in children's specialized hospitals were lower than those in general hospitals (head, 1-<5, 5-<10, 10-<15 years old group, CTDI vol: Z=-9.32, -6.17, -9.86, P<0.001, DLP, Z=-4.41, -4.14, -5.76, P<0.001; chest, 5-<10, 10-<15 years old group, CTDI vol: Z=-3.84, -5.35, P<0.001, DLP, Z=-3.59, -4.63, P<0.001; abdomen, 1-<5、5-<10 and 10-<15 years old group, CTDI vol: Z=-7.88, -7.78, -8.53, P<0.001, DLP, Z=-7.24, -5.92, -3.44, P<0.001). The CT radiation dose in children was positively correlated with age, tube voltage, tube current time product and scan length, and negatively correlated with pitch and hospital type (general hospital and children's hospital) . Conclusion:There are some differences in the CT radiation dose and scanning parameters between children's hospitals and general hospitals. The results indicate that there is still much room for improvement in the optimization of radiation dose in pediatric CT examination.

Objective:To understand the level of radiation doses from digital mammography in Tianjin and the associated influencing factors.Methods:The stratified quota sampling method was used for analysis of 374 digital mammography-examined individuals by using 12 digital mammography devices in 12 selected medical institutions. The examinations were carried out in terms of exposure positions[(craniocaudal (CC) and mediolateral oblique (MLO)], compressed breast thickness, tube voltage, time product of tube current (mAs) and target/filter.Results:The median age of the examined individuals in this survey was 43 years, the median tube voltage (kV) was 29 kV, the median tube current time product was 60.3 mAs, the median compressed breast thickness was 48 mm, and the median average glandular dose (AGD) was 1.32 mGy. The mean dose to the analyzed glandular tissue in the conditions of different target/filters varies in the descent order of Mo/Mo > Mo/Rh > Rh/Rh > W/Rh > W/Al, with the difference being statistically significant difference ( χ2=885.90, P<0.05). The mean dose to the glandular tissue increased with the increase in compressed breast thickness, and the difference was statistically significant ( χ2=31.58, 8.56, 76.13, 118.47, 24.09, P<0.05). Conclusions:The median average glandular dose in Tianjin was 1.32 mGy. This level is lower than in Guangxi province and Fuzhou city, similar to that in Beijing and Guangdong province, and lower than the national survey result of average breast dose. The efforts should be dedicated to further strengthening the research on the related factors of the average glandular dose in order to protect the health and safety of the examined individuals.

Objective:To study the level of CT dose to paediatric patients in Tianjin, and to provide basic data for establishing the diagnostic reference levels for paediatric patients from CT examinations in Tianjin.Methods:In 2022, a general survey was carried out of the CT doses to the head, chest, abdomen and pelvis of the scanned paediatric patients in two tertiary pediatric hospitals and seven tertiary general hospitals in Tianjin. The scanned pediatric patients were divided into four age groups in terms of the age of -1, -5, -10 and -15 years, and 20 patients were investigated in each age group in each hospital. The basic information were collected on the scanned patients, CT scanning parameters, volume CT dose index (CTDI vol), dose length product (DLP), and the differences in CTDI vol and DLP on the same site among different age groups and different types of hospitals were analyzed. Results:There were significant differences in CTDI vol and DLP between different age groups at the same site (head, chest, abdominal and pelvic, CTDI vol:χ2=296.51, 193.82, 291.72, P<0.001; DLP: χ2=291.22, 263.63, 344.97, P<0.001). There were significant differences in CTDI vol and DLP among different types of hospitals on the same site (head, chest, abdominal and pelvic, CTDI vol:Z=-13.13, -7.57, -15.27, P<0.001; DLP: Z=-9.07, -6.15, -11.57, P < 0.001). Conclusions:The 75 th percentile values of CTDI vol and DLP for pediatric head, chest, abdomen and pelvis CT scanning in tertiary hospitals in Tianjin are at a good level, and the dose on some examination sites are relatively high. Further optimization of pediatric CT scanning procedures is necessary.

Objective To assess the frequency of medical exposure from X-ray diagnostic equipment in Tianjin,and provide recommendations for regulating medical radiation management and rational allocation and use of medical and health resources.Methods Using the census method,questionnaries were issued in the form of an administrative document to investigate the basic information on X-ray diagnostic equipment and medical procedure frequency in 687 hospitals (excluding military and armed police hospitals) in 2018.Mean values of frequencies were derived by dividing the number of procedures for each type of X-ray equipment by the total number of permanent residents.Results There were 1 562 pieces of X-ray diagnostic equipment (including interventional radiology),with an average of 1.00 unit per 10 000 population.There were 4 782 radiation workers engaged with X-ray diagnostic work (including interventional radiology),averaged on 3.06 workers per unit,with the highest of 5.25 workers per unit in tertiary hospitals and the lowest of 1.18 in ungraded hospitals.The city's X-ray diagnostic medical exposure came from 8 905 970 medical procedures,including 54.81％ for tertiary hospitals,18.00％ for secondary hospitals,16.21％ for primary hospital,and 10.98％ for ungraded hospitals.X-ray photography contributed 71.30％ with annual frequency of 407.84 examinations per 1 000 population,CT scans 21.81％ with annual frequency of 124.74 examinations per 1 000 population,interventional radiology 1.04％,with annual frequency of 5.98 examinations per 1 000 population,and other types of X-ray examinations 5.85％ with annual frequency of 33.47 examinations per 1 000 population.Conclusions The configuration of X-ray diagnostic equipment in Tianjin is basically reasonable.The frequency of X-ray diagnostic medical exposure is increasing year by year.The rationality of the distribution of X-ray diagnostic examinations needs to be further improved.To reduce dose to population,for the public health and safety is important issues in the future of radiation protection.

Objective: To investigate the usage frequency of radiological diagnosis devices in ten hospitals in Tianjin, China, and to provide a basis for the survey of medical radiation frequency in Tianjin. Methods: Ten hospitals from the ten districts in Tianjin were enrolled as subjects by a convenient sampling method. A survey was conducted to assess the general information and radiological diagnosis device information and usage frequency in those hospitals in 2016. The radiological examination frequency in Tianjin was estimated. Results: A total of 610 458 patients received radiological examinations in the sampled hospitals in 2016. In those patients, 371 882 received X-ray examinations for imaging and 238 576 for computed tomography (CT) ; there were slightly more female patients than male patients, suggesting a relatively equal gender distribution; patients older than 40 years accounted for 65.53%, which was the highest among all the age groups. Different types of radiological diagnosis devices were mostly used in tertiary and secondary hospitals. In Tianjin, the estimated frequency of X-ray examination for imaging and CT scanning was 451 and 188 per thousand people, respectively, in 2016. Conclusion The frequency of radiological diagnosis is relatively high in the ten hospitals in Tianjin. The investigation of medical radiation in Tianjin needs to be improved.