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  • Original Articles
    Feasibility analysis of home-made AQA phantom applied for Cyberknife quality control
    YANG Yuze, LI Mingsheng, LIU Hui, MA Xiangjie, WEI Xiao, CHENG Jinsheng
    2022, 31(6): 645-650. https://doi.org/10.13491/j.issn.1004-714X.2022.06.001
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    Objective To discuss the feasibility of applying home-made auto quality assurance (AQA) phantom in Cyberknife AQA test. Methods The same treatment plan for AQA test was designed in the Cyberknife treatment planning system. The AQA tests were performed under the same conditions using the home-made AQA phantom and the AQA phantom in the fourth-generation (G4) Cyberknife mode and the fifth-generation (VSI) Cyberknife mode, respectively, and each measurement was repeated five times to analyze and compare the differences in test results between the two phantoms. Results The total deviations of the home-made AQA phantom and the AQA phantom in the AQA test under the G4 Cyberknife mode were (0.28 ± 0.12) mm and (0.28 ± 0.15) mm, respectively (P > 0.05); the test results under the VSI Cyberknife mode were (0.46 ± 0.19) mm and (0.50 ± 0.07) mm, respectively (P > 0.05); the total deviations of all test results were smaller than 1.0 mm, which met the requirements of WS 667—2019 Specification for Testing of Quality Control in Robotic Arm Radiotherapy Device. Conclusion The test results of the home-made AQA phantom and the AQA phantom are consistent in the AQA test, and the home-made AQA phantom can be used for Cyberknife quality control.
  • Original Articles
    Results and analysis of national personal dose monitoring intercomparison in 2021
    GAO Pin, DING Yanqiu, WANG Kaiyi, HU Aiying, GUO Wen
    2022, 31(6): 651-656. https://doi.org/10.13491/j.issn.1004-714X.2022.06.002
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    Objective To improve radiation testing institutions’ ability and levels of personal dose monitoring for external exposure and standardize monitoring work. Methods According to Testing Criteria of Personnel Dosimetry Performance for External Exposure (GBZ 207—2016), the intercomparison programme was made, the 2021 class-based personal dose monitoring intercomparison were organized by the National Institute for Radiological Protection, Chinese Center for Disease Control and Prevention and provincial monitoring institutions.Results A total of 150 institutions participated in the 2021 national intercomparison of personal dose monitoring capability. Of them, 143 (95.3%) passed the assessment, including 51 excellent institutions (excellent rate, 34.0%), and 7 (4.7%) failed to pass the assessments. Conclusion The 2021 national personal dosimetry performance intercomparison showed great improvements in the pass rate and excellent rate compared with previous national assessments. However, still seven institutions failed to pass this assessment, including four institutions with class A qualifications. The testing institutions need to find out the reasons to increase their testing ability. This class-based intercomparison improved the point-to-plane relationship between the organizing and testing institutions, helping the organizing institution focus on improving the testing ability of provincial testing institutions and class A radiation health service institutions.
  • Original Articles
    Antigen presentation and T cell activation by dendritic cells in radiation damage
    LI Qian, GENG Shuang, YAN Chengming, GUO Haoxin, WANG Zhixin, WANG Meiyu, LIU Benbo, WANG Xu, WANG Yilong, YANG Zhihua, ZHU Maoxiang
    2022, 31(6): 657-662,668. https://doi.org/10.13491/j.issn.1004-714X.2022.06.003
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    Objective To explore dendritic cells (DCs)-mediated antigen presentation for radiation-injured cells by using the in vitro cell co-culture technology to simulate the in vivo microenvironment of the lung tissue. Methods 60Co γ-irradiated mouse lung epithelial cells (MLE-12) were cultured with bone marrow-derived DCs and/or splenic T lymphocytes for 48 hours. Flow cytometry was used to measure the expression levels of costimulatory molecules (CD80/86) and antigenic peptide recognition complexes (the major histocompatibility complex [MHC] class Ⅰ/Ⅱ) on DCs and T cell activation markers (CD69/28/152) as well as the numbers of CD4+ and CD8+ T cells.Results 60Co γ irradiation significantly increased the apoptosis rate of MLE-12 cells in a dose-dependent manner, and significantly stimulated the expression of CD80/86 and MHC Ⅱ on DCs, without direct activation of T cells. After γ (6 Gy)-irradiated MLE-12 cells were co-cultured with DCs and T lymphocytes for 48 h, there were significant increases in the expression of CD69 and CD28 on T cells, the numbers of CD4+ and CD8+ T cells, and the expression of CD86 and MHC I on DCs, as compared with the control groups. Conclusion Radiation-injured cells can stimulate antigen presentation by DCs and activate T cells.
  • Original Articles
    Analysis of radiation dose at the entrance of the medical linear accelerator treatment room
    XU Zhiqiang, GENG Jiwu, JIA Yuxin, ZHANG Zaoqin, WANG Meixia
    2022, 31(6): 663-668. https://doi.org/10.13491/j.issn.1004-714X.2022.06.004
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    Objective To investigate the radiation dose at the entrance of the accelerator treatment room, and to guide the radiation protection detection at the entrance of the treatment room. Methods The FLUKA program was used to build the model of accelerator head and treatment room. Under the simulation conditions of 10 MV and 600 cGy/min for the accelerator, the radiation dose rate inside the entrance of the treatment room was measured at different gantry angles, irradiation conditions, and labyrinths. Results The entrance dose rate with a water tank was significantly higher than that without a water tank under different inner labyrinth wall thicknesses and gantry angles. The entrance dose rate reached the maximum at the inner labyrinth wall thickness of 1800 mm and the gantry angle of 90°. When the inner labyrinth wall thickness was 1000 mm and the gantry angles were 0° and 180°, the entrance dose rate was significantly higher than that at other conditions. The dose rate at the entrance of the treatment room reached (82.26 ± 48.95) μSv/h to (314.09 ± 96.34) μSv/h under the following conditions: the inner labyrinth wall thickness of 1800 mm, the gantry angle of 90°, with a water tank, and the width of the inner labyrinth entrance of 1400-2200 mm. Conclusion The dose at the entrance of the accelerator treatment room mainly comes from the scattering and leakage radiation of the useful wire harness on the patient’s body surface, and the entrance dose rate increases with the increase in the width of the inner labyrinth entrance. In the entrance protection test, the gantry angle should be determined considering the inner labyrinth wall thickness, and the test should be performed at four angles in the uncertain case to ensure the comprehensiveness and accuracy of test results.
  • Original Articles
    Energy response and proton range measurement with EBT3 film simulated by Geant4
    LI Mingsheng, JIANG Qinghuan, CHENG Jinsheng
    2022, 31(6): 669-673. https://doi.org/10.13491/j.issn.1004-714X.2022.06.005
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    Objective To calculate the energy dependence of absorbed dose in EBT3 film, and to reveal the error in the measurement of proton absorbed dose by EBT3 film. Methods Beam energy was gradually increased in the clinical photon and proton energy ranges. Geant4 was used to calculate the difference in absorbed dose between EBT3 film and the same volume of water. The results were compared with the theoretical values. Results For photons and protons, the thresholds for absorbed dose with energy dependence were 100 keV and 11 MeV, respectively. The energy dependence was consistent with the theoretical values when the photon and proton energies were higher than the corresponding thresholds, and irrelevant to the theoretical values when energies were lower than the thresholds. The differences between the proton Bragg peak and 50% dose point and the actual positions were less than 1%. Conclusions For protons and photons with high energy, the energy dependence of absorbed dose in EBT3 film is negligible. For protons and photons with low energy, EBT3 film shows very different energy dependence of absorbed dose, which should be taken into consideration. The proton Bragg peak and 50% dose point measured by EBT3 film are basically the same as the actual positions.
  • Original Articles
    Current situation of treatment and disposal of NORM solid waste in China
    CHEN Chunyan, LI Jinfeng, CHEN Ling
    2022, 31(6): 674-681. https://doi.org/10.13491/j.issn.1004-714X.2022.06.006
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    China has a huge cumulative storage of NORM solid waste, which urgently needs to be treated and disposed of in a scientific and standard way. Through analyzing the current status and technologies of treatment and disposal of NORM solid waste and relevant environmental radiation protection regulations and standards, we put forward suggestions on the improvement of regulations and standards and the applicability of treatment and disposal technologies, to provide a reference for the green and sustainable development of mineral resources in China.
  • Original Articles
    Investigation and analysis of concentrations of radium-226 and uranium in agricultural products around uranium tailings pond
    LIU Chang, LIAN Bing, WANG Yan, CHEN Hailong, SHI Linfeng
    2022, 31(6): 682-686,693. https://doi.org/10.13491/j.issn.1004-714X.2022.06.007
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    Objective To investigate the radionuclide radium-226 and natural uranium content in the main agricultural products around a decommissioned uranium tailings pondand to determine the radioactivity level in the food around the tailings pond.Methods From 2017 to 2021, several samples of rice and beans were collected in the surrounding area of the tailings pond for five consecutive years, and the concentrations of radium-226 and natural uranium were measured by a high-purity germanium gamma spectrometer. The annual accumulated effective dose of internal exposure caused by radium-226 ingested through local standard human diet was estimated by the indirect method.Results The detection rate of natural uranium in rice was 96.0%, and the detection rate of radium-226 was 74.0%; the detection rate of natural uranium in beans was 96.7%, and the detection rate of radium-226 was 73.3%. The annual accumulated effective dose caused by radium-226 ingested through diet was about 170.22 μSv/a in surrounding residents.Conclusion The concentrations of radium-226 and natural uranium in the main agricultural products around the tailings pond are within the limit of the national standard. By comparing with the research results in related fields in China, the radiation effects caused by radium-226 ingested through dieton the residents around the tailings pond are acceptable.
  • Original Articles
    Analysis of radionuclide content in the surface soil of Panjin, China
    LI Zhengru, HUANG Yanru, ZHANG Suyalatu, WANG Dexin, LI Xue, MENG Gufu
    2022, 31(6): 687-693. https://doi.org/10.13491/j.issn.1004-714X.2022.06.008
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    Objective To measure the specificactivity of natural and synthetic radionuclides in the environmental soil of Panjin, China and determine the content of radionuclides in the surface soil, and to conduct a scientific assessment of the radiation health risks of residents in this area.Methods Thirty-one surface soil samples were collected within the jurisdiction of Panjin, and a high-purity germanium detector was used for γ spectrum analysis to obtain the content of radionuclides and the current environmental radioactivity level. The two independent samples mean t-test was used to compare the specific activity data of radionuclides in soil samples between Panjin and Liaoning Province or China.Results The meanspecific activities of natural radionuclides 238U, 226Ra, 232Th, 40K, and synthetic radionuclide 137Cs in the surface soil samples of Panjin were 18.7 Bq/kg, 19.6 Bq/kg, 23.5 Bq/kg, 604.6 Bq/kg, and 0.9 Bq/kg, respectively. Conclusion The specific activities of natural and synthetic radionuclides in the surface soil samples of Panjin Area at the background level, causing a very low health risk to the people in this area.
  • Original Articles
    A linear model-based dental panoramic tomography localization method
    HE Yuxin, TANG Zhirui, TANG Yaolei, SHU Mingming
    2022, 31(6): 694-697. https://doi.org/10.13491/j.issn.1004-714X.2022.06.009
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    Objective To solve the problem of fast locating primary radiation in dental panoramic tomography apparatus by designing a linear model-based positioning die body.Methods By applying the mathematical principle of solving the linear equation,the two-dimensional plane coordinates were mapped to the detector plane of dental panoramic tomography apparatus, and the horizontal coordinate position was determined by determining the vertical coordinate value through X-ray imaging in the detector plane. Finally, the position of primary radiation in the detector plane was determined. Results The longitudinal characteristics of the image were determined by analyzing the images taken after the application of the model, and the final position of the primary radiation in the detector plane was accurate. By comparing the detection results of die body method and film method, the localization results by the die body method fell within 90% of the image center by the film method. There was no significant difference in the localization results between the two methods by Shapiro-Wilk normality test and paired-samples t test (P > 0.05).Conclusion For narrow-beam devices, the positioning die body designed based on the linear model method can locate the position of the primary radiation in the detector plane quickly and effectively and replace the film method.
  • Original Articles
    Analysis of external exposure dose monitoring results of interventional radiology staff in a hospital from 2018 to 2020
    YANG Yanyan, ZHU Chendi, ZHOU Chunlian, CHEN Huiqing
    2022, 31(6): 698-703. https://doi.org/10.13491/j.issn.1004-714X.2022.06.010
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    Objective To analyze the monitoring results of external exposure dose of interventional radiology staff in a tertiary general hospital in Beijing, China, 2018—2020, and to provide a basis for safe guarding staff health and hospital radiation protection management. Methods A total of 321 interventional radiology staff in a hospital in Beijing were selected to collect information on the types of interventional work, positions, and personal dose monitoring results in 2018—2020. The dose monitoring results were analyzed using SPSS 22.0. Results The effective monitoring rate for the three years was 78.82%, 81.65%, and 96.85%, respectively, showing an increasing trend (χ2 trend = 16.134, P < 0.001). The annual dose equivalent per capita was 0.142, 0.142, and 0.265 mSv, respectively. The annual dose equivalent per capita in 2020 was significantly higher than those in 2018 (H = 24.562, P < 0.001) and 2019 (H = 39.378, P < 0.001). The annual dose equivalent per capita in 2020 was in the order of interventional clinician > interventional nurse > technician (H = 10.699, 6.562, P < 0.01). The annual dose equivalent per capitain 2020 was higher in the cardiology interventional department than in the comprehensive interventional, neuro interventional, and vascular surgery departments (H = 35.530, 37.614, 35.496, P < 0.001). Conclusion The number of interventional radiology staff monitored from 2018 to 2020 increased year by year, so did the effective monitoring rate.The external exposure dose was at low levels, which generally meets the requirements of national occupational exposure limits. Training on radiation protection for interventional radiology staff should be further strengthened to raise awareness of radiation protection.
  • Original Articles
    Current situation and discussion on common problems of radiation protection for dental X-ray diagnostic project in 44 dental clinics in Guangdong Province, China
    ZHANG Zaoqin, GENG Jiwu, XU Zhiqiang, LI Lichun
    2022, 31(6): 704-707,712. https://doi.org/10.13491/j.issn.1004-714X.2022.06.011
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    Objective To analyze the relevant measures of radiation protection for dental X-ray diagnostic projects in 44 dental clinics in Guangdong Province, China, and discuss common problems. Methods Based on the three principles of radiation protection, relevant laws, regulations and standards of the state, combined with field investigations and test results of radiation protection, the situation of radiation protection and management was analyzed. Results The layout of 56 dental diagnostic rooms in 44 clinics was (basically) reasonable. The protective performances and quality control tests of 56 dental X-ray diagnostic machines met the standard requirements, and the dose equivalent rate around 56 dental diagnostic rooms was from the background to 1.47 μSv/h, which met the national standard. The coincidence rates of ionizing radiation warning signs, working status indicator lights and door light interlocks, automatic door closing devices, power ventilation devices, and personal protective equipment were from 85.70% to 98.20%. The compliance rates of dental radiologists and full-time (part-time) administrative staffs, occupational health monitoring, management system related to radiation protection, and radiation health files were from 79.5% to 100.0%. Conclusion The current situation of radiation protection and management in the dental X-ray diagnostic room is good, and relevant national regulations and standards should be promulgated or improved to standardize the cone-beam CT quality control testing, dental clinic location requirements, and radiation staff configuration.
  • Original Articles
    Analysis of occupational health examination of workers in a nuclear power plant in Guangdong, China
    SHI Yiming, HUANG Fuyong, CHEN Biyin, ZHAO Chaoting, LIU Jingwen
    2022, 31(6): 708-712. https://doi.org/10.13491/j.issn.1004-714X.2022.06.012
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    Objective To analyze the abnormality of radiation damage sensitive indices in radiation workers after operation of a third-generation nuclear power plant in Guangdong Province, China, and to provide a basis for promoting the occupational health management of radiation workers. Methods A two-way cohort study (2019—2021) was conducted to compare the radiation sensitive indices of occupational health examination in the exposed group (453 subjects) and the control group (160 subjects). Results In 2021, the free triiodothyronine (FT3) level of the exposed group was significantly higher than that of the control group [(5.57 ± 0.56) pmol/L vs (5.42 ± 0.60) pmol/L, t = 0.59, P < 0.05]. From 2019 to 2021, the exposed group showed significant changes in the average levels of platelet, hemoglobin, FT3, free thyroxine (FT4), and thyroid-stimulating hormone (P < 0.05); FT3 and FT4 first increased and then decreased, while TSH decreased continuously. Conclusion Long-term exposure to low-dose ionizing radiation from nuclear power plants can affect the platelet, hemoglobin, FT3, FT4, and thyroid-stimulating hormone of radiation workers, and the effect is relatively prominent on thyroid function by causing a tendency to hypothyroidism.
  • Original Articles
    Current status of application of resources on medical exposure in Dongying, China
    WANG Haiqing, ZHANG Wenjing, CHEN Shengyun, YANG Ke
    2022, 31(6): 713-718,723. https://doi.org/10.13491/j.issn.1004-714X.2022.06.013
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    Objective To investigate the current status of application of resources on medical exposure in Dongying, China, and to provide fundamental data for setting up the health information management system of occupational radiation diseases and implementing health supervision and management strategies. Methods According to the requirements of monitoring program on radiation health of Dongying in 2021, a general survey was carried out in all medical institutions (other than dental clinics) providing radiodiagnosis and radiotherapy services by the field investigation method using the unified questionnaires and survey content, and a descriptive analysis was conducted on the results. Results There were 92 institutions of radiodiagnosis and radiotherapy in Dongying, 1112 radiation workers who accounted for 5.9% of all workers on duty, including 679 (61.1%) males and 433 (38.9%) females, and 364 pieces of radiation equipment, including 339 for X-ray diagnosis, 8 for radiotherapy, 2 for nuclear medicine, and 15 for interventional radiology. The allocation of personal protective equipment for interventional radiology staff in tertiary hospitals was higher than that in secondary hospitals, in which there were 0.36 and 0.23 pieces of lead-rubber aprons, 0.43 and 0.30 pieces of lead-rubber hats, 0.50 and 0.35 pieces of lead-rubber collars, 0.05 and 0 pairs of lead-rubber gloves, and 0.31 and 0.17 pairs of lead protection glasses per capita, respectively. The allocation rates of lead-rubber collars and lead protection glasses in the nuclear medicine staff were higher than those in the interventional radiology staff, with 0.63 collars and 0.88 pairs per capita, respectively. The annual frequency of medical exposure was calculated to be 864.3 person-times per 1000 population for radiodiagnosis and 5.2 patients per 1000 population for radiotherapy. Conclusion The allocation and application of resources on medical exposure in Dongying is unbalanced, so it is demanded to set up a health information management system of occupational radiation diseases for continuously mastering the application of medical exposure and adopting differentiated regulatory measures such as rating classification in Dongying.
  • Original Articles
    Discussion on problems and countermeasures of military medical radiation license management
    LI Xiuqin, LIU Yi, XIE Peng
    2022, 31(6): 719-723. https://doi.org/10.13491/j.issn.1004-714X.2022.06.014
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    Practice in military medical radiation license management in the new era of military reform have surfaced problems in military radiation protection, involving radiation protection management regulation, occupational health monitoring for radiation workers, inspection of radiation equipment and site protection, implementation of the “Three Synchronizations System” for construction, renovation, and extension projects of radiation facilities, as well as quality control for radiation protection and diagnosis and treatment. Efforts should be focused on radiation protection training, self-management of medical radiation institutions, supervision and regulation from medical radiation license management institutions, and joint coordination of relevant departments. Under new regulations and standards, creatively conducting medical radiation license management and running the army in accordance with the law in the new era of military reform are of great significance for standardizing military radiation protection and ensuring the healthy development of military medical radiation services.
  • Original Articles
    Dosimetric effect of CT truncated regionson radiotherapy for thoracic esophageal cancer
    XIE Kai, ZHANG Heng, XI Qianyi, ZHANG Fan, ZHANG Sai, GAO Liugang, SUN Jiawei, LIN Tao, SUI Jianfeng, NI Xinye
    2022, 31(6): 724-730. https://doi.org/10.13491/j.issn.1004-714X.2022.06.015
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    Objective To investigate the dosimetric effect of truncated regions in computed tomography (CT) images on the targets and organs at risk in volumetric modulated arc therapy (VMAT) for middle thoracic esophageal cancer. Methods CT images of 15 patients with middle thoracic esophageal cancer were selected. Circle masks were used to make the volume of the truncated region account for 10%, 20%, 30%, and 40% of the arm volume, and the corresponding truncated CT images were obtained. The real CT was denoted as CT0. Two radiotherapy plans were made on CT0. One plan was VMAT_1F with full arcs, and the other one was VMAT_3F with arm avoidance. The plans were transplanted to four truncated CT, respectively, and the dosimetric differences between different plans were compared using Wilcoxon signed-rank test. Results Compared with VMAT_1F in CT0, Dmean and V5 of the lung decreased in VMAT_3F, but Dmax of the spinal cord, Dmean of the heart, and V20 of the lung increased. In VMAT_3F, there was no statistically significant difference between the dosimetric parameters in the four truncated CT and those in CT0 (all P > 0.05). In VMAT_1F, except for homogeneity index and Dmax of the spinal cord, the dosimetric parameters in four truncated CT were significantly different from those in CT0 (P < 0.05). The dosimetric difference increased with the increase in truncated region-to-volume ratio.Conclusion Complete CT data should be collected in clinical practice, and the radiation field avoiding the truncated regionshould be set if necessary to reduce the influence of the truncated region on dosimetry.
  • Original Articles
    Clinical significance of transvaginal color Doppler ultrasound for the differential diagnosis of benign and malignant ovarian cysts
    CHEN Li, ZHANG Xiaojuan, HUANG Lifen
    2022, 31(6): 731-734. https://doi.org/10.13491/j.issn.1004-714X.2022.06.016
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    Objective To evaluate the clinical significance of transvaginal color Doppler ultrasound for the differential diagnosis of benign and malignant ovarian cysts. Methods Patients who were diagnosed with clinically suspected or palpable adnexal masses and underwent gray-scale ultrasonography, transvaginal color Doppler ultrasonography, and ultrasound-guided fine-needle aspiration cytology (FNAC) during the period from 2018 to 2021 were enrolled in this study. The pulsatility index (PI) and resistance index (RI) were estimated, and an ovarian cyst with the lowest PI value of < 1.0 or the lowest RI value of < 0.4 was considered as malignant. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of gray-scale ultrasound and transvaginal color Doppler ultrasound for the differential diagnosis of benign and malignant ovarian cysts were estimated with FNAC as the gold standard. Results A total of 180 patients with ovarian cysts were recruited, and FNAC revealed that 81 of them had malignant lesions and 99 of them had benign lesions. The transvaginal color Doppler ultrasonograms showed that 75 patients (92.59%) with malignant lesions had blood-flow signals in their cysts and 42 patients (42.24%) with benign lesions had blood-flow signals in their cysts, with a significant difference in the proportion between the two groups (χ2 = 49.29, P < 0.01). Among the 75 patients with blood-flow signals in malignant ovarian cysts, 75 had PI < 1.0 and 24 had RI < 0.4; among the 42 patients with blood-flow signals in benign ovarian cysts, 15 had PI < 1.0 and no one had RI < 0.4; there were significant differences in the proportions of PI < 1.0 and RI < 0.4 between the two groups (χ2 = 62.68, P < 0.01; χ2 = 16.91, P < 0.01). In addition, compared with the combination of gray-scale ultrasound and transvaginal color Doppler ultrasound, gray-scale ultrasound alone had significantly lower sensitivity (51.85% vs 81.48%; χ2 = 16.00, P < 0.01), specificity (75.76% vs 93.94%; χ2 = 12.73, P < 0.01), PPV (63.64% vs 91.67%; χ2 = 15.90, P < 0.01), and NPV (65.79% vs 86.11%; χ2 = 12.44, P < 0.01) for the differential diagnosis of benign and malignant ovarian cysts. Conclusion Gray-scale ultrasound is effective for diagnosing ovarian cysts; however, gray-scale ultrasound combined with transvaginal color Doppler ultrasound can improve the differential diagnosis of benign and malignant ovarian cysts.
  • Original Articles
    SRIM-based analysis of distribution features of Bragg peak of carbon ion radiotherapy
    LIANG Yulin, ZENG Jianrong, WANG Lun, FU Qingguo
    2022, 31(6): 735-739,745. https://doi.org/10.13491/j.issn.1004-714X.2022.06.017
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    Objective To analyze the distribution features of the Bragg peak of carbon ion beams in materials using SRIM software, and to explore the use of computed tomography (CT) number to calculate the incident energy of carbon ion beams. Methods SRIM software was used to study the travel of carbon ion beams (100 to 300 MeV/u) in different equivalent materials, and analyze the effects of the incident energy of carbon ion beams and the type and thickness of equivalent materials on the depth of the Bragg peak of carbon ion beams. Origin 2017 was used to analyze the functional relationship between CT number and water-equivalent Bragg peak depth ratio (Di) through data fitting. Results The ratios of the Bragg peak depths in equivalent materials to that in water almost stayed constant with the increase in the incident energy of carbon ion beams. Through the functional relation between CT number and Di, the Bragg peak depth of a carbon ion beam of a given energy in an equivalent material could be converted to the equivalent Bragg peak depth in water. Conclusion With the water-equivalent Bragg peak depth ratio Di and CT number of different volume units of human tissues, the equivalent Bragg peak depth in water required for the Bragg peak to fall in the tumor can be accurately calculated, which can be used to reversely infer the needed incident energy of carbon ion beams.
  • Original Articles
    Dosimetric comparison of hippocampal avoidance wholebrain radiotherapy with flattening filter and flattening filter-free modes
    SHAO Wei, LIU Jing, SUN Yi, WANG Gang, GUO Xingzhao, SUN Duoping, FU Qiang
    2022, 31(6): 740-745. https://doi.org/10.13491/j.issn.1004-714X.2022.06.018
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    Objective To compare the dosimetric differences of volumetric modulated arc therapy (VMAT) with flattening filter(FF) and flattening filter-free(FFF) modes in hippocampal avoidance whole brain radiotherapy. Methods We included 15 patients with hippocampal-sparing whole brain radiotherapy, and designed two radiotherapy plans of FF-VMAT and FFF-VMAT for each patient. On the premise of meeting clinical dose requirements, the two plans’ dosimetry, total number of monitor units, and beam-on time were compared. Results There were no significant differences in the target coverage, conformity index, and dose gradient of the FF-VMAT and FFF-VMAT plans (P > 0.05). The Dmax, D100%, and Dmean to the hippocampal tissue were significantly lower with FFF-VMAT [(15.13 ± 0.38) Gy, (7.12 ± 0.34) Gy, and (9.76 ± 0.43) Gy, respectively)] than with FF-VMAT (16.46 ± 0.56) Gy, (7.72 ± 0.28) Gy, and (10.54 ± 0.48) Gy, respectively)] (P < 0.05). The Dmax to the left and right lenses and the Dmean to the left and right eyeballs with FFF-VMAT were (7.26 ± 0.43) Gy, (6.29 ± 1.13) Gy, (11.01 ± 0.94) Gy, and (9.78 ± 1.13) Gy, respectively, which were significantly lower than FF-VMAT’s corresponding doses of (8.09 ± 0.66) Gy, (7.80 ± 0.74) Gy, (11.38 ± 1.09) Gy, and (11.05 ± 0.90) Gy, respectively (P < 0.05). The doses to other organs at risk including the optic nerve and optic chiasm were all controlled within the safe dosage ranges, with no significant differences between the two plans (P > 0.05). The FFF-VMAT plan had a significantly greater number of monitor units and a significantly shorter beam-on time than the FF-VMAT plan (P < 0.05).Conclusion Both FF-VMAT and FFF-VMAT can meet the clinical requirements, with FFF-VMAT having better hippocampus and lens protection, shorter beam-on time, and higher treatment efficiency.
  • Original Articles
    Efficacy of postoperative radiotherapy with reduced target volume in patients with glioblastoma multiforme
    LI Shouguo, GUO Qunhuang, GUO Ruixiang
    2022, 31(6): 746-749,755. https://doi.org/10.13491/j.issn.1004-714X.2022.06.019
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    Objective To evaluate the therapeutic efficacy of radiotherapy with reduced target volume in glioblastoma multiforme patients following surgical treatment, and to provide a basis for the development of postoperative radiotherapy regimens for glioblastoma multiforme. Methods The medical records of 29 patients with glioblastoma multiforme receiving postoperative adjuvant radiochemotherapy with a reduced radiation target were retrospectively reviewed. The gross tumor volume (GTV) included postoperative tumor cavity and residual lesions, and the clinical target volume (CTV) was GTV plus 2.5 cm margin with adaptation according to the affected organs and anatomic structures. GTV and CTV received intensity-modulated radiotherapy with concomitant boost at 60 Gy/30 fractions and 54 Gy/30 fractions, respectively. The progression-free survival (PFS) and site of recurrence were analyzed. Results The patients were followed up until March 2022. Among the 29 patients with glioblastoma multiforme, 3 showed recurrence-free survival of 52, 20, and 19 months, respectively. Among the 26 patients with recurrent glioblastoma multiforme, there were no case with recurrence in CTV, 25 cases with recurrence in GTV (including 3 cases with intracranial dissemination), and one case with intracranial dissemination and without recurrence in GTV. The median PFS was 7 months (4 to 15 months). Among the 3 patients with recurrence in GTV and intracranial dissemination, one showed primary lesion in the right frontal parietal lobe and the metastatic lesion in the right occipital lobe, one primary lesion in the right occipital lobe and multiple metastatic lesions in the cerebellum, and one primary lesion in the left frontal lobe and the metastatic lesion in the right frontal lobe. The PFS was 4 to 5 months for seven patients receiving partial resection, and 6 to 15 months for patients receiving total and subtotal resection. The three recurrence-free survivors all underwent total resection. Conclusion Recurrence in target volume still prevails in patients with glioblastoma multiforme receiving postoperative radiotherapy with reduced target volume, and 60 Gy/30 fractions fail to control the tumor cavity and residual lesions of glioblastoma multiforme.
    • Review Articles
  • Review Articles
    Research progress in effects of ionizing radiation on the heart
    LIU Dan, XU Hanli
    2022, 31(6): 750-755. https://doi.org/10.13491/j.issn.1004-714X.2022.06.020
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    It has been recognized that long-term exposure of the heart to high-dose ionizing radiation can result in cardiac injury. Nevertheless, recent epidemiological, experimental, and clinical studies have demonstrated that exposure to low-dose ionizing radiation may also cause cardiovascular injury via various mechanisms. This article reviews the cardiac injury and potential cardiovascular risk caused by ionizing radiation, summarizes the currently available non-invasive approaches used for detecting radiation-induced cardiac injury, and proposes interventions to prevent and alleviate it, with the hope of providing a reference for early identification and interventions for radiation-induced cardiac injury.
  • Review Articles
    Research progress of patient-specific organ doses from CT
    WANG Chuyan, ZHUO Weihai, LIN Xin, LU Heqing, XIE Tianwu, LIU Haikuan
    2022, 31(6): 756-762. https://doi.org/10.13491/j.issn.1004-714X.2022.06.021
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    The radiation risk caused by CT examination is of great concern. Organ dose is considered to be the most significant technical parameter for quantifying the patient radiation dose and assessing the corresponding risk. At present, the methods to obtain patient organ dose caused by CT examination mainly include physical phantom measurement, direct human body measurement, dose conversion coefficient, Monte Carlo simulation, and dose calculation software. Although different methods have their own characteristics and application, the individualization of organ dose is always the goal of radiation protection and dosimetry research. Patient-specific phantom developed with artificial intelligence and GPU-accelerated Monte Carlo simulation make it possible to calculate the patient-specific organ dose, and the patient-specific organ dose extrapolated by the CT detector signal provides a new solution.
  • Review Articles
    Advances in the application of positron emission tomography in the diagnosis and treatment of gynecological malignancies
    LIU Xuefen, LI Yuan
    2022, 31(6): 763-766. https://doi.org/10.13491/j.issn.1004-714X.2022.06.022
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    Positron emission tomography (PET) has been used for the diagnosis of gynecological malignancies and is superior to conventional imaging tools in detecting metastatic lesions, diagnosing local recurrence, and evaluating treatment outcome. Compared with the in vitro assessment of tumor biopsy materials, PET imaging has advantages in measuring in vivo tumor behaviors, characterizing overall tumor burden, and capturing the phenotypic heterogeneity of tumors. PET imaging provides precision data on tumor staging and recurrence through integrating the anatomic and functional data of metabolic features, thereby achieving the high-quality assessment of gynecological malignancies. This article reviews the advances in the application of PET imaging in the diagnosis and treatment of cervical cancer, ovarian cancer, and endometrial carcinoma.