CT is a commonly examination method in pediatric clinical practice.Formulating and popularizing low-dose pediatric CT scanning protocols and constructing a standard image quality evaluation system are the key directions of low-dose pediatric CT imaging.In recent years,domestic CT equipment achieved technological breakthroughs in hardware performance and image reconstruction algorithms,which could provide new paths for pediatric low-dose CT imaging in children combining with artificial intelligence technology.The current status of scanning protocols,the establishment of imaging quality evaluation system and the clinical promotion,as well as challenges of domestic CT in pediatric low-dose CT imaging were reviewed in this article.

Objective:To investigate the status and diagnostic reference levels (DRLs) of adult CT radiation dose based on survey result from some hospitals in Beijing.Methods:From September to December 2023, the survey results for 50 hospitals were collected in Beijing, including 47 tertiary hospitals and 3 second grade general hospitals. The CT data sets in total of 20 items including head (sequential scanning), head (spiral scanning), head perfusion, sinus, neck, chest, chest (low dose scanning), abdomen, pelvis, abdomen-pelvis, chest-abdomen-pelvis, lumbar spine, CT urography, coronary CTA (retrospective), coronary CTA (prospective), head CTA, neck CTA, aorta CTA, leg CTA and knee were collected on clinical commonly used CT scanners with annual qualified state inspection. For each item, radiation dose data was collected continuously and randomly for up to 50 cases for every CT scanner. Using the volume CT dose index (CTDI vol) and dose length product (DLP) as dose parameters, the median value of each item in each hospital was obtained. The median CTDI vol and DLP values of all hospitals were arranged, and the local DRL of each item was set as the 75th percentile of the median values. The obtained DRLs were compared with the DRLs issued by domestic and international radiological protection organizations. Results:A total of 26 031 dose values of adult patients were collected and 25 996 dose values were left while 35 invalid values removed.For different CT users, CTDl vol, DLP and scanning phases were different for the same item. The five items with the highest CTDI were head perfusion, head sequential scanning, head spiral scanning, coronary CTA (retrospective mode), and sinus. The five items with the highest DLP were CTU, head perfusion, leg CTA, chest-abdomen-pelvis and aortic CTA. The CTDI vol of CTU was only 16.9 mGy (75th percentile), while the DLP was as high as 2 394.9 mGy·cm (75th percentile). The survey showed that the DRLs of most items in Beijing was lower than the national DRLs of domestic and foreign standards, and the DRLs of a small number of items were slightly higher. Conclusion:The current CT dose level in Beijing is not consistent with national DRLs released at home and abroad, so it is necessary to establish local DRLs according to the clinical status in Beijing.

Objective:To investigate the radiation dose levels of digital radiography (DR) in adult patients and explore the diagnostic reference level (DRL) of radiation dose in Beijing.Methods:Radiation dose data were collected from 39 medical institutions in Beijing on 18 930 DR examinations of chest anterior and lateral view, abdomen anterior and posterior view, abdomen standing view, cervical spine anterior and lateral view, lumbar spine anterior and lateral view, knee joint anterior and lateral view as well as 5 266 digital mammography (CC view and MLO view). For ordinary DR examinations, the incident air kinetic energy ( Ka, i), incident air specific kinetic energy area product ( PKA) and effective dose ( E) to the examined individuals were used for the investigation and estimation of radiation dose. For digital mammography, the average glandular dose (AGD) was calculated. DRLs should be set at the 75 th percentile of median values obtained in each medical institution. Results:The Ka, i, PKA and E of DRL for Chest (PA), Chest (lateral), abdominal(PA), abdominal (AP), Pelvic(AP), Cervical (AP), Cervical (lateral), Lumbar (AP), Lumbar (lateral), Knee joint (AP) and Knee joint (lateral) of conventional DR were 0.14, 0.31, 1.25, 2.18, 1.86, 0.51, 0.14, 2.97, 8.39, 0.37, 0.37 mGy, 159, 259, 1 917, 2 336, 2 867, 312, 301, 3 500, 3 359, 269, 255 mGy·cm 2, 0.03, 0.05, 0.20, 0.43, 0.23, 0.03, 0.02, 0.47, 0.35, <0.001, <0.001 mSv. The DRLs for digital mammography were calculated to be 1.87 mGy (CC view), 1.94 mGy (MLO view) and 3.99 mGy (accumulated for one examination). Conclusions:The radiation dose from DR examinations is relatively low. In clinical practice, the selection of imaging parameters should be further standardized on the basis of the local DRL.

Objective:To investigate devices for radiodiagnosis used in medical institutions in Beijing, China, as well as radiation workers and the devices′ application frequencies, in order to provide data support for determining radiation protection measures and allocating resources for clinical radiodiagnosis.Methods:In October 2023, questionnaires were distributed to the members of the Radiation Technology Branch of the Beijing Medical Association who work in medical institutions at different levels across varying districts of Beijing. The collected data included information about devices for radiodiagnosis and radiation workers, as well as the application frequencies of various medical X-ray imaging devices during 2018-2022, in 38 medical institutions of Level 3 Grade A, Level 3, and Level 2 in 14 municipal districts of Beijing. Then, the collected data were organized using the Microsoft Power BI software to form report models, followed by the statistical analysis of data on the devices, radiation workers, and application frequencies were using the RStudio software.Results:The 38 medical institutions in Beijing possess 591 devices for radiodiagnosis and 2 018 staff in the departments of radiology, including 1 037 radiologic technologists and 738 physicians, with 1.77 technologists and 1.26 physicians arranged for a single device on average. From 2018 to 2022, among all examinations of radiodiagnosis, computed tomography (CT) scans showed the highest frequencies, with total and average annual growth rates of 138.06% and 108.40%, respectively. Specifically, chest CT scans exhibited total and average annual growth rates of 225.20% and 122.50%, respectively. X-ray imaging ranked second in application frequency, with total average annual growth rates of 70.20% and 91.53%, respectively. Notably, chest X-ray imaging showed total and average annual growth rates of 63.89% and 89.41%, respectively.Conclusions:From 2018 to 2022, X-ray imaging examinations displayed significantly fluctuating frequencies with an overall decline trend in the 38 medical institutions. In contrast, the CT scans showed increased frequencies, with chest CT scans displaying an increased frequency and proportion. This necessitates ensuring the justification of CT scans.

As the number of CT scans continues to rise, the contribution rate of CT to the cumulative radiation dose to the public has exceeded 60%. During CT scanning, a shorter distance to the surface of the human body result in a higher radiation dose. Both the development of new CT imaging techniques and the selection of scanning parameters influence the dosage to superficial radiosensitive organs (e.g., eye lens, thyroid, and mammary glands). Effectively reducing the radiation dose to superficial radiosensitive organs has emerged as a hot research topic. This review aims to summarize the factors influencing the radiation dose to superficial radiosensitive organs and the dose reduction strategies, thus providing a reference for clinical practice and research on dose optimization.

There exist risks of ionizing radiation in radiodiagnosis examinations. Implementing shielding protection following the optimization and as low as reasonably achievable (ALARA) principles represents a measure to reduce radiation doses to patients. The implementation of shielding protection in clinical practices should meet high requirements due to variations in the modalities and items in radiodiagnosis examinations, the characteristics and irradiation method of X-ray beams, the method of automatic selection of image quality and radiation dose-related parameters by imaging equipment, the radiation sensitivity of human tissues and organs. This review introduced the shielding products, methods and effects in various radiodiagnosis examinations, as well as the current status and challenges in their applications, aiming to provide a reference for future related research and clinical practices.

Objective:To investigate the relevant data on radiation dose in interventional radiodiagnosis and radiology of adults in Beijing and to provide a basis for establishing relevant diagnostic reference levels (DRLs) in this region.Methods:A total of 30 medical institutions in Beijing were surveyed, covering interventional radiodiagnosis and radiology surgeries for coronary artery, structural heart diseases, permanent cardiac pacemaker implantation, electrophysiological study and radiofrequency ablation, nervous systems, abdominal systems, and the blood vessels of the lower limbs. The primary parameters investigated included the air kerma area product ( PKA) and incident air kerma ( Ka, r). The 75 th percentiles of radiation dose were considered DRLs, which were analyzed at both the overall and individual medical institution levels. Results:A total of 3 331 cases of the abovementioned radiodiagnosis and radiology surgeries were collected. The DRLs (i.e., PKA and Ka, r) of various diagnostic examinations were 37.87 Gy·cm 2 and 509.00 mGy for coronary artery, 9.34 Gy·cm 2 and 48.00 mGy for electrophysiological study and radiofrequency ablation, 218.50 Gy·cm 2 and 901.70 mGy for nervous systems, 81.00 Gy·cm 2 and 302.20 mGy for the abdominal system, and 83.37 Gy·cm 2 and 214.69 mGy for the blood vessels of the lower limbs. In contrast, the DRLs (i.e., PKA and Ka, r) for interventional radiodiagnosis and radiology were determined at 135.00 Gy·cm 2 and 1 897.58 mGy for coronary artery, 26.91 Gy·cm 2 and 172.30 mGy for structural heart diseases, 27.77 Gy·cm 2 and 87.75 mGy for permanent cardiac pacemaker implantation, 34.46 Gy·cm 2 and 247.00 mGy for electrophysiological study and radiofrequency ablation, 214.36 Gy·cm 2 and 1 282.80 mGy for the nervous system, 196.64 Gy·cm 2 and 875.71 mGy for abdominal system, and 108.25 Gy·cm 2 and 523.25 mGy for the blood vessels of the lower limbs. Conclusions:The DRLs of radiation dose in interventional radiodiagnosis and radiology in Beijing were determined through a survey and statistic analysis. These findings suggest that for certain interventional procedures, the optimized radiation protection should be enhanced.

Objective:To explore age-related variations in the angle of the cochlear basal turn using temporal bone CT, providing a reference for selecting the optimal Stenvers position radiographic projection angle in children and adults.Methods:The retrospective study included children and adults who underwent temporal bone CT scans at Beijing Tongren Hospital from November 2014 to April 2023. A total of 620 participants were included, including 368 males and 252 females. Patients were divided into 20 age-ralated groups: infants under one year old (3 to 11 months) were divided into monthly subgroups (9 groups); children and adolescents aged 1 to 18 years were grouped biennially (9 groups); adults were divided into two groups: 19 to 29 years and 30 to 40 years. Using multiplanar reconstruction (MPR) techniques, the CT images of the temporal bone were reformatted into oblique transverse sections to maximize the visibility of the cochlear basal turn.The cochlear basal turn angle was defined as the angle between the vertical axis of the cochlear basal turn and the mid-sagittal plane of the skull. Statistical analysis was performed to compare age-related differences in cochlear basal turn angles. Two additional patients were included to compare Stenvers position X-ray images with corresponding temporal bone CT scans, assessing the visibility of cochlear implant electrodes post-implantation.Results:Among infants aged 3 to 11 months, the cochlear basal turn angle was 29.4°±4.5°, with no significant differences observed between subgroups ( P>0.05). However, significant differences were found between infants (<1 year old) and the 1-2-year-old group compared to each age group from 3 to 40 years ( P<0.05). Additionally, the angles differed significantly between the 3-14-year-old groups and the 19-40-year-old groups ( P<0.05), whereas no significant differences were found among the remaining groups ( P>0.05). The visibility of the cochlear implant electrodes, appearing round in shape on standard Stenvers position X-ray images, closely resembled that observed in temporal bone CT scans. Conclusion:Age-related variations in the cochlear basal turn angle provide a valuable reference for optimizing Stenvers position radiography angles after cochlear implantation, improving the accuracy and quality of post-implantation imaging.

Objective:To study the consistency between post-processing bone mineral density(BMD)values of multi-slice spiral computed tomography(MSCT)scan and the BMD value of quantitative computed tomography(QCT)for lumbar vertebra,so as to explore the feasibility of utilizing MSCT scan-based post-processing BMD values for lumbar vertebra in clinical practice.Methods:The MSCT equipment and QCT equipment were respectively adopted to conduct imaging scan for the L2-L4 of lumber vertebra of QRM-ESP145 European Spine Phantom(ESP),and L2-L4 of lumbar vertebra of adult sheep,and L2-L4 of lumbar vertebra of adult volunteer.The L2-L4 of ESP lumber vertebra and L2-L4 of lumbar vertebra of adult sheep were scanned respectively MSCT and QCT for three times,so as to measure BMD values.The L2-L4 of lumbar vertebrae of volunteers were scanned respectively by the two methods for one time according to the standard of clinical examination,which were reconstructed by three times so as to obtain mean of them.The BMD values of QCT scan were set as control group,and the BMD values of MSCT scan were set as experiment group.The experiment group was further divided into experiment 1 group[two dimension(2D)regional volumetric BMD values of the lumbar vertebra]and experiment 2 group[three dimension(3D)global volumetric BMD post-processing of the lumbar vertebra]according to the reliability of experiment.Then,the consistency between the MSCT 3D post-processing BMD values of three groups and QCT-measured BMD values was compared and analyzed.Results:The MSCT 3D post-processing BMD values of L2-L4 of ESP lumbar vertebra of three groups were respectively(120.83±0.97),(199.57±0.54)and(119.19±1.04)mg/cm3,and that of L2-L4 of lumbar vertebra of adult sheep of three groups were respectively(414.89±1.72),(410.50±0.77)and(420.25±2.71)mg/cm3,and that of L2-L4 of lumbar vertebra of volunteer were respectively(141.22±0.09),(137.38±0.37)and(152.03±1.03)mg/cm3.There were not statistically significant differences in BMD values between MSCT examination and QCT examination(P＞0.05).Conclusion:MSCT 3D post-processing BMD values on lumbar vertebra has high consistency with that of QCT measurements,which post-processing technique can replace QCT to conduct BMD examination,and reduce unnecessary radiation exposure and examination costs for patients.

Objective:To investigate the status and diagnostic reference levels (DRLs) of adult CT radiation dose based on survey result from some hospitals in Beijing.Methods:From September to December 2023, the survey results for 50 hospitals were collected in Beijing, including 47 tertiary hospitals and 3 second grade general hospitals. The CT data sets in total of 20 items including head (sequential scanning), head (spiral scanning), head perfusion, sinus, neck, chest, chest (low dose scanning), abdomen, pelvis, abdomen-pelvis, chest-abdomen-pelvis, lumbar spine, CT urography, coronary CTA (retrospective), coronary CTA (prospective), head CTA, neck CTA, aorta CTA, leg CTA and knee were collected on clinical commonly used CT scanners with annual qualified state inspection. For each item, radiation dose data was collected continuously and randomly for up to 50 cases for every CT scanner. Using the volume CT dose index (CTDI vol) and dose length product (DLP) as dose parameters, the median value of each item in each hospital was obtained. The median CTDI vol and DLP values of all hospitals were arranged, and the local DRL of each item was set as the 75th percentile of the median values. The obtained DRLs were compared with the DRLs issued by domestic and international radiological protection organizations. Results:A total of 26 031 dose values of adult patients were collected and 25 996 dose values were left while 35 invalid values removed.For different CT users, CTDl vol, DLP and scanning phases were different for the same item. The five items with the highest CTDI were head perfusion, head sequential scanning, head spiral scanning, coronary CTA (retrospective mode), and sinus. The five items with the highest DLP were CTU, head perfusion, leg CTA, chest-abdomen-pelvis and aortic CTA. The CTDI vol of CTU was only 16.9 mGy (75th percentile), while the DLP was as high as 2 394.9 mGy·cm (75th percentile). The survey showed that the DRLs of most items in Beijing was lower than the national DRLs of domestic and foreign standards, and the DRLs of a small number of items were slightly higher. Conclusion:The current CT dose level in Beijing is not consistent with national DRLs released at home and abroad, so it is necessary to establish local DRLs according to the clinical status in Beijing.