Objective To systematically analyze the medical radiation exposure levels in a district of Ningbo City and to provide a scientific basis for the reasonable and effective control of medical radiation exposure. Methods Based on the radiological diagnosis frequency and dose information system, basic medical radiation exposure data were collected, such as radiation doses received by patients in various X-ray diagnostic examinations, from all 13 public medical institutions in a district of Ningbo City from January 1 to December 31, 2020. The data were analyzed for the percentage and collective effective dose of various diagnostic examinations, the distribution of examinations by sex and age, and the number of patients undergoing two or more examinations and their cumulative doses within multiple time intervals. Results Among medical X-ray diagnostic examinations in the district, the percentages of CT examination and routine photography examination were 50.88% and 47.93%, respectively, and the collective effective dose of CT examination accounted for 97.75%. By age and sex, the frequency of examination was the highest in the age group of 45-54 years, and the frequency of examination in the male was higher than that in the female before age 55. The annual effective dose for two patients exceeded 100 mSv. Conclusion In this study, CT examination accounted for up to 50.88% of all medical X-ray diagnostic examinations, and contributed 97.75% of the collective effective dose, highlighting the need for particular attention to the justification of medical radiation exposure from CT.

Objective To investigate the impact of the artificial intelligence iterative reconstruction (AIIR) algorithm on image quality in chest computed tomography (CT) at different radiation doses, and assess its value in reducing radiation dose during chest CT examinations. Methods A simulated chest phantom was scanned with 12 groups of tube voltages and milliampere-seconds, and the radiation dose was recorded for each group. The images of each group were reconstructed using seven methods: AIIR with noise levels 1-5, KARL iterative reconstruction, and filtered back projection (FBP). The CT values and standard deviations of soft tissue, thoracic vertebrae, pulmonary nodules, and the mediastinum were measured, with standard deviation representing image noise. Subjective evaluation of image quality was performed. The Friedman test was used to compare CT values among the seven reconstruction groups, a linear mixed model was employed for statistical analysis of image noise, and the Friedman test was also used for comparing subjective evaluation scores. Results The reconstruction algorithm, tube voltage, milliampere-seconds, and their interactions all showed statistically significant effects on image noise for the four tissues (F = 2.041-391.283, P < 0.05). Among the reconstruction algorithms, noise reduction capability decreased in the following order: AIIR levels 1-5, KARL, and FBP. The interaction between the reconstruction algorithm and tube voltage or milliampere-seconds indicated that AIIR exhibited improved noise reduction efficacy under low tube voltage and low milliampere-second conditions (|t| = 1.892-8.245, P < 0.05). In terms of subjective evaluation of image quality, there was no statistically significant difference among AIIR levels 3-5 (|Z| ≤ 0.567, P > 0.05), and the score of AIIR level 3 was significantly higher than those of AIIR level 1, AIIR level 2, FBP, and KARL level 2 (|Z| = 3.449-5.906, P < 0.05). Conclusion The AIIR reconstruction algorithm significantly reduced image noise in chest CT examinations. For improving image quality while maintaining image realism, AIIR level 3 is recommended, which can reduce the radiation dose by more than 75%. Furthermore, AIIR showed superior performance in noise reduction under low tube voltage and low milliampere-second conditions, demonstrating significant potential for reducing radiation dose.

Objective To investigate the clinicopathological features,immunophenotype,diagnosis and treatment of SMARCA4(BRG1)-deficient carcinoma.Methods Clinical data of 11 patients with SMAR-CA4(BRG1)-deficient cancer were collected.The morphologic and immunohistochemical features of this tumour were summarized,and the relevant literature was reviewed.Results Among the 11 cases of SMARCA4(BRG1)-deficient carcinoma,eight were male and three were female,with median age of 60.Seven patients underwent radical resection,and four underwent traditional joint targeted chemotherapy and immunotherapy.Microscopically,the tumor cells were epithelioid,rhabdoid or spindle-shaped,with prominent eosinophilic nucleoli and frequent mitoses(>5/10 HPF).Multiple foci of necrosis were found in the tumor tissue,a large number of tumor emboli in the blood vessels and myxoid stromal degeneration.Among these cases,11 cases showed loss of SMARCA4(BRG1)expression,whereas the CK and Vim markers were expressed,SMARCB1(INI1)expression was retained,and p53 mutation was detected.The tumor cells showed high proliferation activity(Ki-67>60%),and synaptophsin was moderately positive.Three cases were mismatch repair deficient and respectively showed the loss of MLH1/PMS2,PMS2 and MSH6 expression.Conclusion The incidence of SMARCA4(BRG1)-dificient carcinoma is low.It can be easily confused with other tumors and is difficult to be diagnosed before operation,which requires confirmation by immunohistochemistry.

Objective To propose a method for correcting the attenuation of positron emission tomography (PET) data in PET/magnetic resonance (MR) based on transmission scan, and to improve image quality, diagnostic accuracy, and lesion location accuracy. Methods In this study, the head phantom in the national standard GB/T 18988.1—2013 was used as the experimental model. The head phantom contained three 50 mm diameter cylindrical inserts filled with air, water, and solid teflon. The attenuation correction coefficients were calculated and analyzed based on transmission scan. Results With slice = 33 and theta = 0, the attenuation correction coefficient was the largest (about 7.5) when the coincidence line passed through the axis of the phantom. The spatial distribution of the attenuation correction coefficients clearly showed the positions of air insert and teflon insert, indicating that the attenuation correction coefficients calculated from transmission scan data were accurate. In the clinical verification experiment, the attenuation correction method based on transmission scan significantly improved the image quality and showed efficient attenuation correction. Conclusion This paper studied the attenuation correction method for PET data in PET/MR based on transmission scan. This method can improve the image quality. In the future work, the attenuation correction method of PET/MR will be further studied and optimized to facilitate clinical applications.

Objective With the increase in pet-owning households in China, veterinary clinics have increased at an annual rate of 19.86%. However, the management blind area that may exist in multi-department supervision has led to a significantly worse working environment of radiation workers in veterinary clinics than that of medical institutions. The purpose of this study was to understand the levels of occupational external exposure of radiation workers in veterinary clinics in China, analyze the occupational risks faced by radiation workers in veterinary clinics, contribute to the protection of the occupational health of radiation workers, and provide data and scientific basis for the formulation of national relevant regulations and standards. Methods The individual dose monitoring data of radiation workers in selected veterinary clinics in 2022 were obtained from the National Individual Dose Registration System. Results This study involved 1868 radiation workers from 1216 veterinary clinics in 28 provinces and municipalities in China. The maximum annual effective dose was 8.93 mSv, the annual collective dose was 536.77 man·mSv, the average annual effective dose was 0.29 mSv, and the median was 0.15 mSv. The largest proportion of individuals (94.5%) received a dose of less than 1.0 mSv, while 5.4% had doses ranging from 1.0 mSv to less than 5.0 mSv. For radiation workers with an annual effective dose of 1.0 mSv and above, the individual distribution ratio of radiation workers in veterinary clinics was significantly higher compared with those in medical institutions and industrial applications (P < 0.05). Conclusion The levels of occupational external exposure of radiation workers in veterinary clinics meet the requirements of national standards. However, attention should still be paid to the radiation protection of radiation workers in veterinary clinics. This includes enhancing the responsibility awareness of veterinary clinic owners, strengthening protection training for radiation workers, protecting the occupational health of practitioners, and preventing the occurrence of occupational radiation diseases.

Objective To propose a method for correcting the attenuation of positron emission tomography (PET) data in PET/magnetic resonance (MR) based on transmission scan, and to improve image quality, diagnostic accuracy, and lesion location accuracy. Methods In this study, the head phantom in the national standard GB/T 18988.1—2013 was used as the experimental model. The head phantom contained three 50 mm diameter cylindrical inserts filled with air, water, and solid teflon. The attenuation correction coefficients were calculated and analyzed based on transmission scan. Results With slice = 33 and theta = 0, the attenuation correction coefficient was the largest (about 7.5) when the coincidence line passed through the axis of the phantom. The spatial distribution of the attenuation correction coefficients clearly showed the positions of air insert and teflon insert, indicating that the attenuation correction coefficients calculated from transmission scan data were accurate. In the clinical verification experiment, the attenuation correction method based on transmission scan significantly improved the image quality and showed efficient attenuation correction. Conclusion This paper studied the attenuation correction method for PET data in PET/MR based on transmission scan. This method can improve the image quality. In the future work, the attenuation correction method of PET/MR will be further studied and optimized to facilitate clinical applications.

Ceramide (Cer) is a second messenger produced by the degradation of plasma membrane phospholipids in cells. It is an essential lipid mediator for normal cellular function, composed of sphingosine and different chains of fatty acids. Its receptors are widely present in red blood cells, endothelial cells, glial cells, immune cells, and nerve cells, and participate in various pathophysiological processes such as oxidative stress, inflammatory response, signal pathway transduction, and immune regulation. Many studies have confirmed that the increase of Cer level is related to cardiovascular disease, type 2 diabetes and lipid metabolism. Ceramide score can be used as a tool to evaluate the severity and prognosis of cardiovascular events. However, there is limited research on the impact of Cer on acute ischemic stroke (AIS). This article aims to elucidate the role of Cer and its impact on the occurrence, development, and prognosis of AIS.

Objective:To estimate and analyze the levels of occupational exposure of aircrews in China, and to provide scientific basis for strengthening occupational health management.Methods:Through the FlightAware website, the flight data were collected of a total of 104 routes flying between airports with large passenger volume in China. Four kinds of cosmic radiation dose estimation programs CARI, SIEVERT, PCAIRE, and JISCARD-EX were compared and analyzed from the aspects of covering the number of airports in China, program user experience and example calculation of airline effective dose. Based on route logs, CARI-7A was applied to estimate the levels of occupational exposure of Chinese aircrews to cosmic radiation.Results:The difference in the effective doses calculated by use of these four cosmic radiation dose estimation programs for the routes with different solar activity levels was statistically significant ( M=7.52-180.98, P<0.05). The annual effective dose estimated by PCAIRE for 68 routes from 2014 to 2021 was significantly higher than that estimated by CARI-7A ( Z=2.52, P<0.05). Based on CARI-7A, the annual effective doses from cosmic radiation to aircrews in China from 2014 to 2021 were estimated, being 1.26 (0.57-2.35) mSv for flight attendants and 1.03 (0.47-1.92) mSv for pilots. The effective dose from cosmic radiation to aircrews on a single flight on some high-frequency routes in China ranged from 0.57 to 6.88 μSv. Conclusions:The level of occupational exposure of Chinese aircrews to cosmic radiation meets the requirements of national standards, but is higher than that of occupational exposure from medical and industrial applications of radiation, so it is still necessary to further strengthen the mamagememt of occupational exposure and occupational health of aircrews.

Objective To analyze the factors influencing the levels of occupational exposure in medical radiation workers in China, and to provide a scientific basis for determining the key points of radiation protection in the medical sector. Methods The individual monitoring data on occupational external exposure in medical radiation workers in 2021 were collected from the “National Individual Dose Registry”. The Chi-squared test and logistic regression were used to analyze the factors influencing the levels of occupational exposure in medical radiation workers. Results The Chi-squared test showed that gender, occupational category, medical institution category, region, number of radiation workers per thousand population, and regional per capita GDP were significantly associated with occupational exposure in medical radiation workers exceeding the annual effective dose of 5 mSv and an annual effective dose limit of 20 mSv (χ² = 21.456−262.329, 7.601−78.650, P < 0.05). The logistic regression analysis further showed that gender, occupational category, region, and number of radiation workers per thousand population were factors influencing the occupational exposure in medical radiation workers exceeding the annual effective dose of 5 mSv (χ² = 14.621−170.857, P < 0.05); gender, occupational category, region, and regional per capita GDP were factors influencing the occupational exposure in medical radiation workers exceeding the annual effective dose of 20 mSv (χ² = 5.401−48.709, P < 0.05). Conclusion Male radiation workers in interventional radiology and in central China have high risks of exceeding annual effective doses of 5 and 20 mSv. Moreover, high number of radiation workers per thousand population and regional per capita GDP are associated with low risks. Medical institutions should maintain a sufficient number of radiation workers and strengthen training on radiation protection knowledge for male and interventional radiology workers to enhance their radiation protection awareness. Investigation of the factors contributing to the high occupational exposure in central China should be intensified, and targeted effective measures should be conducted to reduce the occupational exposure in medical radiation workers.

Objective To establish a model for estimating the eye lens dose of the first operator in interventional therapy based on the Monte Carlo simulation, and to provide a scientific basis for the rapid and accurate evaluation of the eye lens dose for radiation workers in interventional therapy. Methods Based on the MIRD phantom and eye model for adult Chinese males, the MCNPX program was used to establish the physical model to calculate the spatial distribution of radiation field and eye lens dose for the first operator. A GR200 Type A LiF (Mg, Cu, P) thermoluminescence dosimeter was used for experimental measurement to verify the simulation results. Results Monte Carlo simulation and experimental measurements showed that the spatial distribution of radiation field was symmetrical. Compared with the measured doses, the errors of the simulated eye lens dose of the first operator were between −8.3% and 7.3%. The dose of the left eye lens was higher than that of the right eye. Conclusion The Monte Carlo model constructed in this study initially realizes the simulation of eye lens dose of the first operator in interventional therapy. In the future, the model will be further optimized based on irradiation parameters such as exposure time, tube voltage, tube current, and projection direction used in clinic practice, so as to more accurately evaluate the eye lens dose of interventional therapy staff.