Background The air quality index (AQI), which is based on the concentration of a dominant pollutant, and the air quality health index (AQHI), which is constructed using excess risk estimates for individual pollutants, may not fully capture the health risks associated with combined exposure to air pollutants. These approaches also provide limited information on the relative contributions of different pollutants. Given the geographical heterogeneity in the composition and health effects of air pollutant mixtures, it is necessary to develop region- and disease-specific AQHIs for different population groups. Objective To develop and evaluate a health risk-based AQHI for respiratory disease mortality associated with air pollutant mixtures using the weighted quantile sum (WQS) regression model and to quantify the relative weight contributions of selected pollutants. Methods Daily data on six air pollutants, the AQI, meteorological factors, and deaths from respiratory diseases in the central urban districts of Tianjin from 2014 to 2019 were collected and integrated into a time-series database. First, generalized additive models (GAMs) were applied to identify indicator pollutants associated with respiratory disease mortality. Second, the WQS regression model was then applied to estimate the relative weight contributions of selected pollutants and to establish the exposure-response relationship between air pollutant mixtures and respiratory disease mortality for AQHI development. Finally, the exposure-response relationships of the AQHI and AQI with respiratory disease mortality were evaluated and compared across population subgroups and seasons. Results Fine particulate matter (PM_2.5), inhalable particulate matter (PM₁₀), sulfur dioxide (SO₂), and ozone (O₃) were identified as indicator pollutants for combined air pollution exposure. Particulate matter, including PM_2.5 and PM₁₀, and O₃ contributed the most to the mixture index, followed by SO₂. Each interquartile range (IQR) increase in the WQS-based AQHI was significantly associated with respiratory disease mortality in the total population, males, elderly individuals, non-elderly individuals, and during the warm season. The corresponding excess risks (ER) were 3.79% (95%CI: 1.24%, 6.27%), 4.37% (95%CI: 0.96%, 7.67%), 3.16% (95%CI: 0.47%, 5.77%), 9.36% (95%CI: 2.01%, 16.15%), and 7.13% (95%CI: 1.31%, 13.30%), respectively. Compared with the AQI, the AQHI showed stronger associations with respiratory disease mortality across different population subgroups and seasons. Conclusion PM_2.5, PM₁₀, and O₃ contribute substantially to the association between air pollutant mixtures and respiratory disease mortality in Tianjin. Compared with the AQI, the WQS-based AQHI better characterizes the association between air quality and respiratory disease mortality across population subgroups.

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 investigate the basic conditions of non-medical radiation institutions and their current status of occupational health management of radiation workers and radiation protection in workplaces in Tianjin City, China, and to clarify the key points of occupational health management and radiation protection efforts. Methods A comprehensive survey was conducted to assess the basic conditions of non-medical radiation institutions and their status of occupational health management for radiation workers across 16 districts in Tianjin in 2023. Then, some non-medical radiation institutions were chosen according to their industrial sections as sentinel institutions to investigate radiation protection in workplaces. Results In 2023, there were a total of 431 non-medical radiation institutions in 16 districts of Tianjin, primarily in the industries of nuclear instrument, industrial radiography, and others. In these institutions, there were a total of 5264 radiation workers, with 93.8%, 93.0%, and 93.7% participating in the training of radiation protection, the occupational health examination, and the personal dose monitoring, respectively. Eighty-six non-medical radiation institutions were chosen as the sentinel institutions for investigation of radiation protection conditions in workplaces. The resulting data met the stipulated limits according to relevant standards. Conclusion The current status of occupational health management and radiation protection in non-medical radiation institutions in Tianjin is satisfactory. However, there is a need for further management enhancements, particularly in key industries such as nuclear instrumentation and industrial radiography.

Objective To investigate the basic conditions of non-medical radiation institutions and their current status of occupational health management of radiation workers and radiation protection in workplaces in Tianjin City, China, and to clarify the key points of occupational health management and radiation protection efforts. Methods A comprehensive survey was conducted to assess the basic conditions of non-medical radiation institutions and their status of occupational health management for radiation workers across 16 districts in Tianjin in 2023. Then, some non-medical radiation institutions were chosen according to their industrial sections as sentinel institutions to investigate radiation protection in workplaces. Results In 2023, there were a total of 431 non-medical radiation institutions in 16 districts of Tianjin, primarily in the industries of nuclear instrument, industrial radiography, and others. In these institutions, there were a total of 5264 radiation workers, with 93.8%, 93.0%, and 93.7% participating in the training of radiation protection, the occupational health examination, and the personal dose monitoring, respectively. Eighty-six non-medical radiation institutions were chosen as the sentinel institutions for investigation of radiation protection conditions in workplaces. The resulting data met the stipulated limits according to relevant standards. Conclusion The current status of occupational health management and radiation protection in non-medical radiation institutions in Tianjin is satisfactory. However, there is a need for further management enhancements, particularly in key industries such as nuclear instrumentation and industrial radiography.

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.

Background Cumulative risk index (CRI), as a commonly used approach to estimate the joint effects of multiple air pollutants on health, has been used by few studies to construct an air quality health index (AQHI). Objective To construct an AQHI based on the CRI of air pollution in Tianjin and evaluate the validity of the AQHI. Methods Daily data on air pollutants, meteorological factors, and non-accidental deaths during 2015–2019 in Tianjin were collected to create a time-series object. Descriptive statistical analyses were used to describe the characteristics of the data. To determine the best lag day and indicative pollutant, single-pollutant and two-pollutant generalized additive models were fitted to construct the exposure-response relationships between air pollutants and non-accidental deaths. After that we evaluated a CRI of air pollution using multi-pollutant models and constructed an AQHI and its classifications based on the CRI. Finally, we compared the exposure-response associations and coefficients of the AQHI and the conventional air quality index (AQI) with non-accidental deaths, and evaluated the health risk communication validity of the AQHI using generalized cross validation (GCV) values and R² values. Results We selected lag1 as the best lag day and PM_2.5, SO₂, NO₂ and O₃ as the appropriate pollutants according to the unqualified rates of pollutants and significant statistical results. One μg·m⁻³ increase of PM_2.5, SO₂, NO₂, and O₃ was associated with −0.00002, 0.00079, 0.00015, and 0.00042 increase in effect size b of the non-accidental mortality, respectively. Based on these coefficients, we calculated the CRI and AQHI. According to a pre-determined classification scheme of the AQHI, the air quality of 63% study days was low risks and that of 34% study days was median risks. The associations of AQHI and AQI with non-accidental deaths in different populations were evaluated. The results showed that the excess risks of non-accidental deaths in total, female, and male populations for per interquartile range (IQR) increase in AQHI were higher than the corresponding values of AQI. The GCV values of the AQHI model (2.694, 1.819, and 1.938, respectively) were lower than those of the AQI model (2.747, 1.850, and 1.961, respectively), and the R² values of the AQHI model (0.849, 0.780, and 0.820, respectively) were higher than those of the AQI model (0.846, 0.776, and 0.817, respectively). Conclusion Compared with AQI, the CRI-based AQHI may communicate the air pollution-related health risk to the public more effectively in Tianjin.

Objective:To verify radiation shielding effect of the maze of the CyberKnife room, so as to identify and correct the deficiencies in the shielding designs in certain circumstances.Methods:In line with the radiation protection shielding design scheme of the CyberKnife room provided by the producer, the consideradtions are focused on the useful beam that could mainly pass through the image center, but not the outer wall of the maze. However, during the inspection and acceptance of radiological protection in the built room, it was found that in a certain situations useful wire did not pass through the imaging center. Therefore, the additional shielding and protection facilities were built and verified.Results:After verification and acceptance on the scene, in the case where the useful beam was passing through the image center, the highest ambient dose equivalent rate at the concerned points 30 cm away from the outer wall of the maze was 0.31 μSv/h, less than the control level 10 μSv/h. In the opposite case, the highest ambient dose equivalent rate at the same points as above was 301.67 μSv/h, ablut 30 times as much as the control level. After the thickness in maze outer wall was enhanced, the highest ambient dose equivalent rate at the same as above was 2.14 μSv/h. This testing result met the concerned national standard.Conclusions:It is desirable that in designing the outer wall shielding in the maze in a CyberKnife room, attention should be paid to whether or not the useful beam could pass through the image center, or otherwise directly irradiate on the maze on the basis of the movement range of the accelerator. Shielding wall thickness should be calculated on the basis of the irradiation ragne and the distance between source location and the concerned points to ensure being in compliance with the requirements of the concerned national standard. Meanwhile, it should protect the workers occupying at the concerned locations from receiving higher radiation doses.

Objective To investigate the actual situation and problems faced by radiological professionals in implementing The Specification of Radiological Protection Assessment for Occupational Hazard in Construction Project Part 2: Radiotherapy Facility (GBZ/T 220.2—2009). Methods A questionnaire survey was performed on radiological professionals who were selected, using the multi-stage stratified sampling method, from those who had participated in the assessment for occupational hazard in the construction project of radiotherapy facility from seven provinces and cities in China. A descriptive statistical analysis was used to analyze the general information and the awareness, promotion, and implementation of the standard of the participants. The chi-squared test was used to compare the data of different regions. Results A total of 173 radiological professionals from seven provinces and cities were investigated. They had a relatively high awareness rate (98.8%) of the standard, but a relatively low training and promotion rate (65.3%) of the standard. There were no significant differences in the awareness rate and the training and promotion rate between different regions (χ² = 2.743, P = 0.602; χ² = 5.584, P = 0.061). The use frequency of the standard was relatively low among the radiological professionals, and 64.9% of them thought that it was necessary to revise the standard, especially to further refine the scope of application, key technical indicators such as assessment methods, and radiological protection management regulations. Conclusion The training and promotion of the standard should be strengthened among radiological professionals. Some key technical indicators in the standard should be clarified and refined.