Dose conversion coefficients connect radiation field quantities with the protection quantities and operational quantities. In radiation protection practice, it plays an important role in facilitating the conversion between various measurement values, enabling compliance with individual dose limits, and optimizing radiation protection strategies. During the conversion process, conversion coefficients are affected by the types of rays, irradiation geometries, and human tissues and organs. Notably, the continuous development of anthropomorphic digital phantoms has led to the constant updating of conversion coefficients and the broadening of their application fields. However, with the development of radiation protection theory, new challenges have emerged in the establishment of conversion coefficients. This paper provides a concise overview of these aspects, aiming to give readers a basic understanding of the significance, application, and challenges associated with the conversion coefficients. Such an understanding will facilitate the effective implementation of the newly released standard WS/T 830.

Objective To evaluate the current status in the implementation of GBZ/T 201.5-2015 Radiation shielding requirements for radiotherapy rooms-Part 5: Radiotherapy room of proton accelerators, identify issues in the application of its technical indicators, and provide a basis for the in-depth implementation and further revision of the standard. Methods In accordance with the Standardization Law of the People’s Republic of China and the Guidelines for Health Standards Tracking Evaluation (WS/T 536-2017), a combination of cluster sampling and stratified sampling methods was employed to select professionals involved in proton accelerator radiotherapy devices and facilities in three provinces (or municipalities directly under the central government) as the subjects of the survey. A questionnaire was developed to collect basic information about the subjects and their understanding and application of the technical indicators in the standard. A standard evaluation indicator system with a total score of 100 points was established to score the implementation of the standard (40 points), the technical content (30 points), and the effectiveness of the implementation (30 points). Results A total of 169 professionals from 107 institutions participated in the survey, with 79.88% of the respondents having at least 5 years of experience in radiation therapy and 74.56% holding intermediate or higher professional titles. The score of standard implementation was 18.3 points. The awareness rate exceeded 80%, indicating a high level of awareness about the standard. However, the scores for the dissemination and application of the standard were relatively low, accounting for 28% and 32% of their respective full marks. The technical content of the standard and the effectiveness of its implementation scored 27.0 and 26.6 points, respectively. The overall score in the evaluation of standard implementation was 72 points, with scores of 68.6, 72.3, and 75.0 for Beijing City, Shanghai City, and Jiangsu Province, respectively. Conclusion GBZ/T 201.5-2015 Radiation shielding requirements for radiotherapy rooms-Part 5: Radiotherapy room of proton accelerators is scientific and operable, and it is well-coordinated with relevant laws and standards. However, considering the development in FLASH technology and multi-chamber radiotherapy room, it is necessary to revise and improve the standard.

Objective To analyze the abnormal individual dose monitoring results in 206 medical institutions in a selected region in 2024, and to propose improvement measures. Methods Individuals with monitoring results exceeding the investigation level were subjected to high-dose investigation, and the results were statistically analyzed. Results In 2024, the individual dose monitoring of 206 medical institutions in a selected region showed 1.04% abnormal results. The proportions of abnormal results from primary, secondary, and tertiary medical institutions were 12.22%, 3.33%, and 84.45%, respectively. In analysis of the causes of abnormal results, 52.53% of the cases were due to personal dosimeters left in the radiation workplace, and 20.20% were due to the confusion in wearing personal dosimeters inside and outside the lead apron. In analysis of the occupational distribution of the radiation workers with abnormal monitoring results, interventional radiology and diagnostic radiology accounted for 73.34% and 24.44%, respectively. Statistical analysis of the dose range showed that doses in the ranges of 1.25-2.0 mSv and 2.0-5.0 mSv accounted for 42.22% and 33.33%, respectively. In the report of abnormal monitoring results, the proportions of reporting notional dose and reporting measured results accounted for 88.89% and 11.11%, respectively. Among institutions with consecutive abnormal results, primary, secondary, and tertiary medical institutions accounted for 15.39%, 7.69%, and 76.92%, respectively. Conclusion The level of the hospital, occupational type, the perceived importance of the hospital to the management of radiation protection, and the perceived importance and compliance of the radiation workers with the individual dose monitoring are potential causes of abnormal results. It is recommended that employers should enhance radiation protection training for their radiation workers to ensure proper wearing and storage of dosimeters, and progressively improve the standardization and effectiveness of individual dose monitoring practice.

OBJECTIVES: To evaluate the regulatory effects of lncRNA LINC00261 on proliferation, invasion, and metastasis of esophageal squamous cell carcinoma (ESCC) cells. METHODS: The differentially expressed RNAs in ESCC were identified using the GSE149612 dataset from the GEO database. PCR was used to detect LINC00261 expression levels in clinical ESCC and normal esophageal tissue samples and in multiple ESCC cell lines and normal esophageal epithelial cells (HEEC). In ESCC cells, the effects of overexpression of LINC00261 on cell proliferation, invasion, metastasis and apoptosis were analyzed using CCK-8 assay, clone formation assay, Transwell assay and flow cytometry. The potential targets of LINC00261 were predicted using bioinformatics tools including ENCORI and verified using dual-luciferase reporter assay and Western blotting. The effects of LINC00261 overexpression on ESCC were confirmed in a nude mouse model bearing ESCC xenograft. RESULTS: Analysis of the GSE149612 dataset revealed significantly lower LINC00261 expression in ESCC tissues and cell lines. In cultured ESCC cells, LINC00261 overexpression markedly suppressed cell proliferation, invasion, and metastasis and promoted cell apoptosis. Dual-luciferase reporter assays confirmed that LINC00261 targets the miR-23a-3p/ZNF292 axis. In the tumor-bearing mouse model, LINC00261 overexpression significantly inhibited ESCC xenograft proliferation and metastasis. CONCLUSIONS LINC00261 suppresses ESCC progression by targeting the miR-23a-3p/ZNF292 axis, suggesting a potential therapeutic strategy for ESCC treatment.
Humans ; MicroRNAs/genetics* ; Cell Proliferation ; Esophageal Neoplasms/genetics* ; Animals ; Esophageal Squamous Cell Carcinoma ; Mice, Nude ; RNA, Long Noncoding/genetics* ; Cell Line, Tumor ; Neoplasm Invasiveness ; Mice ; Carcinoma, Squamous Cell/genetics* ; Apoptosis ; Gene Expression Regulation, Neoplastic ; Neoplasm Metastasis

Objective To compare H_p(3) calibration with a homemade (A) thermoluminescent dosimeter (TLD) and an imported (B) TLD in a standard X-ray RQR radiation field, to explore the different responses of A and B, and to provide foundation for the calibration of H_p(3). Methods A column mode was selected. H_p(3) calibration was performed using A and B in a standard X-ray RQR radiation field in the Secondary Standard Dosimetry Laboratory, National Institute for Radiological Protection, China Center for Disease Control and Prevention. Angle response, energy response, and linear response were calibrated with RQR4 (60 kV), RQR7 (90 kV), and RQR9 (120 kV), respectively. Results In terms of angle response, the calibration results of A were relatively high, while the calibration results of B were relatively low. In terms of energy response, the calibration results showed a similar pattern to angle response. In terms of linear response, the calibration results of both A and B were satisfactory. Conclusion Both A and B can be used for normal calibration of H_p(3) in a standard X-ray RQR radiation field. However, in actual monitoring, attention should be paid to the energy and angle response values of TLDs.

With the utilization of more types of radiation with a wider energy range, the application scope of the currently valid operational quantities is limited due to some conceptual defects, so a new group of operational quantities was proposed recently by the International Commission on Radiation Units and Measurements. The unification of protection quantities and operational ones is achieved in conceptual and physical sense. However, to achieve the comprehensive application of these new operational quantities in China, such preliminary work should be done as computational model construction and built-in of a calibration system in monitoring equipment, which depends on the collaborative development of multi-parties.

Objective To discuss the shielding calculation method for proton therapy room, and to provide a scientific basis for shielding design of proton therapy room and improvement of existing national standards. Methods Using the calculation formula and key characteristic parameters from national standards and Chinese and foreign literature, combining with the FLUKA Monte Carlo method, empirical formula calculation and Monte Carlo simulation were conducted for the neutron ambient dose equivalent rates of the focuses outside the shielding of proton therapy room. The estimation results of the two methods were analyzed. Results Relative to the calculation results of the single exponential formula in the two directions of 0° and 50° in the beam loss point of divergence slit (0.13 and 12.4), the calculation results of the double exponential formula (0.40 and 17.9) were more consistent with the Monte Carlo simulation results (0.32 ± 0.19 and 18.2 ± 4.98). The Monte Carlo simulation results of copper target and nickel target were similar, suggesting that the key characteristic parameters of concrete shielding for copper target could be well applied to the calculation of nickel target, but the neutron ambient dose equivalent rates were underestimated when applied to tantalum target, with a difference of 5.7 times and 1.3 times in the two directions of 0° and 40°, respectively. Conclusion The dose rate estimates based on the calculation formula and key characteristic parameters from Chinese and foreign literature are consistent with FLUKA simulation results, and this method can be used in the shielding design of proton therapy room as a supplement and improvement to the existing national standards.

Objective To analyze the room layout and shielding of three types of self-shielded accelerators, and to provide a basis for optimizing the shielding design of rooms for self-shielded accelerators. Methods We compared the radiation shielding levels (transmitted radiation dose rate outside the primary barrier and scattered radiation dose rate outside the secondary barrier) of three self-shielded accelerator rooms by Monte Carlo simulation and empirical formula calculation. Results According to Monte Carlo simulation and empirical formula calculation, for the Unity MR Linac accelerator, the scatter radiation dose rate outside the secondary barrier was significantly higher (up to five times) than the transmitted primary radiation dose rate outside the primary barrier. The scatter radiation dose rate of the cross section was significantly higher than that of the sagittal section for both Unity MR Linac and TOMO accelerators. Conclusion The differences in the shape, material, and thickness of self-shielding structures complicate the shielding calculation and design for accelerator rooms. The shielding calculation method should be improved to optimize the radiation shielding of novel accelerator rooms.

Objective To investigate the dose level of pediatric CT scan in one hospital, and to provide recommendations for optimized scanning. Methods The CT scan data of children were collected from this hospital to analyze the differences in typical dose values and typical scanning parameters between different age groups and different scanning parts. Results The sample size was >10 for routine cranial scan, routine maxillary sinus scan, and routine chest scan in each age group, and the 1-year-old group and the 5-year-old group had the same kV, mA, and CTDIvol values of routine cranial scan and maxillary sinus scan, but with relatively great differences in the parameters of chest scan. Conclusion Scanning parameters in this hospital can be further optimized, and optimization measures should be adopted continuously.

Objective To evaluate effect of dexmedetomidine on mitochondrion-dependent apoptosis during hypoxia-reoxygenation (H/R) injury to hippocampal neurons of rats.Methods The primarily cultured hippocampal neurons of Sprague-Dawley rats were divided into 4 groups (n =40 each) using a random number table method:control group (C group),vehicle group (V group),H/R group and dexmedetomidine group (D group).Hippocampal neurons were subjected to oxygen-glucose deprivation followed by restoration of oxygen supply to establish the model of H/R injury.Dexmedetomidine 1 μmol/L was added at 6 h of reoxygenation in D group.The viability of neurons was measured by methyl thiazolyl tetrazolium assay at 20 h of reoxygenation.The ultrastructure of mitochondria was observed by transmission electron microscopy.The expression of cytochrome c (Cyt c),caspase-3,Fis1 and Drp1 was detected by Western blot.The neuronal apoptosis was detected by flow cytometry,and apoptosis rate was calculated.Results Compared with C group,no significant change was found in the viability of neurons in group V (P＞0.05),and the viability of neurons was significantly decreased,the apoptosis rate was increased,the expression of Cyt c,caspase-3,Fis1 and Drp1 was up-regulated (P＜0.05),and the damage to mitochondrial ultrastructure was accentuated in H/R and D groups.Compared with H/R group,the viability of neurons was significantly increased,the apoptosis rate was decreased,the expression of Cyt c,caspase-3,Fis1 and Drp1 was down-regulated (P＜0.05),and the damage to mitochondrial ultrastructure was significantly attenuated in D group.Conclusion The nechanism by which dexmedetomidine reduces the H/R injury to hippocampal neurons is related to inhibiting mitochondrion-dependent apoptosis in rats.