Dosimetric analysis of the optimization algorithm for intracavitary/interstitial brachytherapy of cervical cancer / 中华放射医学与防护杂志

Objective:To provide a basis for selecting the optimization method for intracavitary/interstitial brachytherapy (IC/ISBT) of cervical cancer by comparing graphical optimization (GO), inverse planning simulated annealing (IPSA), and hybrid inverse planning optimization (HIPO) using dosimetric and radiobiological models.Methods:This study selected 65 patients with cervical cancer who were treated with image-guided IC/ISBT. The afterloading therapy plans for these patients were optimized using GO, IPSA, and HIPO individually, with a prescription dose high-risk clinical target volume (HRCTV) D90 of 6 Gy. The non-parametric Friedman test and the non-parametric Wilcoxon rank test were employed to analyze the differences in duration, dose-volume parameters, and radiobiology between the three types of optimized plans. Results:Inverse planning optimization (IPSA: 46.53 s; HIPO: 98.36 s) took less time than GO (135.03 s). In terms of gross target volume (GTV) dose, the high-dose irradiation V150% (53.66%) was slightly higher in the HIPO-optimized plans, while the V200% (30.29%) was higher in the GO-optimized plans. The GO-optimized plans had a higher conformity index (CI; 0.91) than other plans, showing statistically significant differences. Compared with other plans, the HIPO-optimized plans showed the lowest doses of D1 cm 3 and D2 cm 3 at bladders and rectums and non-statistically significant doses at small intestines ( P > 0.05). In terms of the equivalent uniform biologically effective dose (EUBED) for HRCTV, the HIPO-optimized plans showed a higher value (12.35 Gy) than the GO-optimized plans (12.23 Gy) and the IPSA-optimized plans (12.13 Gy). Moreover, the EUBED at bladders was the lowest (2.38 Gy) in the GO-optimized plans, the EUBED at rectums was the lowest (3.74 Gy) in the HIPO-optimized plans, and the EUBED at small intestines was non-significantly different among the three types of optimized plans ( P = 0.055). There was no significant difference in the tumor control probability (TCP) predicted using the three types of optimized plans ( P > 0.05). The normal tissue complication probabilities (NTCPs) of bladders and rectums predicted using the HIPO-optimized plans were lower than those predicted using the GO- and IPSA-optimized plans( χ2 = 12.95-38.43, P < 0.01), and the NTCP of small intestines did not show significant differences ( P > 0.05). Conclusions:Among the three types of optimization algorithms, inverse optimization takes less time than GO. GO-optimized plans are more conformal than IPSA- and HIPO-optimized plans. HIPO-optimized plans can increase the biological coverage dose of the target volume and reduce the maximum physical/biological exposure and NTCP at bladders and rectums. Therefore, HIPO is recommended preferentially as an optimization algorithm for IC/ISBT for cervical cancer.

Analysis of individual dose monitoring results for radiation workers in Shandong province from 2016 to 2020 / 中华放射医学与防护杂志

Objective:To summarize the levels of individual dose to radiation workers in Shandong province from 2016 to 2020, and to analyze the trends in their change in order to provide scientific basis for radiation workers′ health management.Methods:The experimental detection and quality control were carried out in compliance with the national standards Specifications for individual monitoring of occupational external exposure (GBZ 128-2019) and the Testing criteria of personnel dosimetry performance for external exposure (GBZ 207-2016). The result of the personal dose monitoring of occupational external exposure of all radiation workers monitored by the Centers for Disease Control and Prevention in 16 cities of Shandong province were retrospectively analyzed by using SPSS 23.0 software.Results:The total number of monitored workers were 25 523 with an average annual individual effective dose of 0.28 mSv. There were statistically significant differences among radiation workers in different years ( H= 2 815.91, P<0. 001). The average annual individual effective dose showed an upward trend followed by a downward trend. The average annual effective dose of 0.55 mSv for nuclear medicine radiation workers in medical applications was the highest, with statistically significant differences among different occupational radiation workers ( H=310.37, P<0.001). The average annual effective dose of 0.37 mSv for radioactivity logging workers in industrial applications was the highest, with statistically significant differences among different occupational radiation workers ( H=448.07, P<0. 001). The average annual effective dose to radiation workers in medical applications was higher than in industrial applications ( Z = -14.93, P<0.001). Conclusions:The average annual effective dose to nuclear medicine radiation workers in medical applications and logging radiation workers in industrial applications are relatively high. There would be a push to furthe improve workplace protection measures and strengthen the management and supervision of radiological workers.

Investigation on radiation doses and related influencing factors for CT adult examinations in Huai′an city / 中华放射医学与防护杂志

Objective:To investigate the level of radiation doses to adults caused by CT examination in Huai′an, and explore the local CT diagnostic reference levels (DRLs).Methods:Totally 45 CT scaners were selected to investigate the information on hospitals, equipment, scanning parameters, and radiation doses. Empirical formula were used to estimate the effective dose to adults. Nonparametric rank sum tests were used to analyze differences in radiation dose level between CT service age and hospital grade.Results:A total of 3 483 patients were collected, including 890 for head examinations, 890 for chest, 846 for abdomen, and 857 for lumbar spine. The 75% percentile values of CTDI vol to adult patients from CT scanning for head, chest, abdomen, lumbar spine examinations were 63.0, 12.4, 20.0 and 24.0 mGy, respectively. The 75% percentile values of DLP were 858.6, 416.0, 620.7 and 559.2 mGy·cm, respectively. The 75% percentile values of DLP for males was higher than those for females. There were significant statistical differences in radiation doses dependent on equipment service (head: U =10 326.00, P<0.05; chest: U=36 094.50, P<0.05; abdomen: U= 7 859.00, P<0.05; lumbar spine: U=42 408.00, P<0.05), and hospital grade (head: H=14.280, P<0.05; chest: H=17.85, P<0.05; abdomen: H=97.18, P<0.05; lumbar spine: H=138.94, P<0.05). Conclusions:The CT radiation dose levels in Huai′an city is basically consistent with standard-reommended values, which is in line with the current status of CT equipment dose levels in the country. It is necessary to strengthen the quality control and maintenance of CT equipment.

Estimation of the effective radiation dose for tunnel construction workers / 中国职业医学

Objective To analyze and set up the effective dose of different ionizing radiation for tunnel construction workers. Methods A total of five tunnels constructed using drilling and blasting methods were selected as the research subjects using the convenient sampling method. The workplace γ radiation effective dose, radon concentrations, and radioactive activity concentrations were detected, and on-site surveys were conducted to estimate the internal and external irradiation doses and total effective doses for workers in different work sites. Results Radiological hazards in tunnels constructed using drilling and blasting methods included radon and its progeny, γ radiation, radioactive dust (uranium-238, radium-226, thorium-232, and potassium-40) and others. The average total effective dose of ionizing radiation exposure for tunnel construction workers was (6.730 1±1.541 1) mSv. The average dose of radon and its progeny was (6.163 0±1.512 8) mSv, radioactive dust was (0.014 6±0.009 1) mSv, γ radiation was (0.552 6±0.138 7) mSv. The dose of radioactive dust of radon and its progeny was 0.24%. Radon and its progeny contributed more to the radioactive dose than radioactive dust and γ radiation (all P<0.05). Among all the radioactive dusts, the dose contribution ranked from highest to lowest was thorium-232, uranium-238, and radium-226. Conclusion For tunnel construction workers, the largest contribution to the effective dose of ionizing radiation exposure is from radon and its progeny for internal irradiation, followed by γ radiation for external irradiation. The contribution of radioactive dust to internal irradiation dose can be considered negligible.

Terrestrial gamma radiation level around Shidaowan nuclear power plant, China and influencing factors / 中国辐射卫生

@#<b>Objective</b> To monitor the cumulative terrestrial γ radiation dose around Shidaowan nuclear power plant, Shandong, China before operation, to analyze the dose levels and influencing factors, and to estimate the annual effective dose to local residents. <b>Methods</b> Fifty-six monitoring sites were selected within 30 km around the nuclear power plant. The environmental γ radiation dose was measured by the thermoluminescence dosimeter monitoring method. The γ radiation dose levels were investigated for 369 days in four monitoring periods (January 16 to April 14, April 15 to July 20, July 21 to October 21, 2021, and October 22, 2021 to January 20, 2022 for periods I to IV, respectively). Relations between γ radiation and monitoring time, altitude, distance from the nuclear power plant were analyzed, and the annual effective dose of terrestrial γ radiation to residents was estimated to reflect the background terrestrial γ radiation level in the area. <b>Results</b> The average values of terrestrial γ radiation dose rate in the four monitoring periods in the area were (76.196 ± 3.366), (81.773 ± 6.144), (93.554 ± 7.449), and (97.604 ± 9.396) nGy/h, respectively, and the terrestrial γ radiation dose rate in the whole year was (87.282 ± 6.589) nGy/h. The effective dose to residents was 0.428 mSv. The terrestrial γ radiation level was high from July 2021 to January 2022. There was no significant difference in the γ radiation dose rate at the monitoring sites with different distance from the nuclear power plant. No impact upon the terrestrial γ radiation dose by the altitude was observed in this study. <b>Conclusion</b> The terrestrial γ radiation level around Shidaowan nuclear power plant in 2021 was at the background level.

The radioactivity levels of food and the dose in residents due to food intake around Shidaowan Nuclear Power Plant / 中国辐射卫生

Objective To analyze the radionuclide levels in food and the committed effective dose due to food intake in residents around the Shidaowan Nuclear Power Plant (SNPP). Methods Daily food samples were collected within 30 km radius around the nuclear power plant in 2019—2022. The radioactivity levels before and after the operation of SNPP were determined. The data were combined with the dietary consumption of residents in Shandong province, China to estimate the committed effective dose. Results The radionuclides 238U, 232Th, 226Ra, and 40K in food were at normal background levels, and the average radioactivity was (0.062 ± 0.004), (0.121 ± 0.007), (0.162 ± 0.010), and (92.4 ± 5.5) Bq/kg fresh weight. Trace 137Cs and 90Sr were detected in some food samples and the average radioactivity was (0.047 ± 0.003) and (0.193 ± 0.200) Bq/kg fresh weight. The levels of radionuclides did not increase after the operation of SNPP compared with that before operation. The estimated committed effective dose in residents due to food intake was 0.205 mSv. Conclusion The radioactivity of food in the area around SNPP shows no difference before and after operation, and the dose burden is low in local residents.

Application of phantom for dose measurement in interventional therapy for pediatric vascular anomalies / 中国辐射卫生

@#<b>Objective</b> To apply a phantom for dose measurement in interventional therapy for pediatric vascular diseases, and calculate the effective dose (<i>E</i>) and conversion coefficient of dose area product (DAP) to <i>E</i>, and to provide a dose reference for studying radiation dose and radiation protection in children. <b>Methods</b> Thermoluminescent dosimeters were placed in the organs of the phantom. Low-, medium-, and high-dose groups were set for three types of vascular anomalies based on the duration of fluoroscopy. Digital subtraction angiography was used to simulate exposure conditions at different dose levels. The organ dose was measured, and the effective dose was calculated. <b>Results</b> For the three groups of vascular anomalies in the head and face, the red bone marrow doses were 8.15, 30.34, and 43.53 mGy, respectively, the effective doses were 12.88, 47.84, and 73.12 mSv, respectively; and the average conversion coefficient of DAP to <i>E</i> was 2.16. For the three groups of vascular anomalies in the trunk, the red bone marrow doses were 2.11, 15.62, and 31.21 mGy, respectively; the effective doses were 12.39, 70.56, and 134.60 mSv, respectively, and the average conversion coefficient of DAP to <i>E</i> was 3.03. For the three groups of vascular anomalies in the lower extremities, the red bone marrow doses were 3.58, 6.50, and 12.28 mGy, respectively, the effective doses were 3.64, 7.04, and 14.85 mSv, respectively, and the average conversion coefficient of DAP to <i>E</i> was 0.73. <b>Conclusion</b> Patient dose and DAP-to-<i>E</i> conversion coefficient are in the following order: vascular anomalies in the trunk > vascular anomalies in the head and face > vascular anomalies in the lower extremities. The dose data obtained can be used to estimate children’s radiation exposure.

Internal exposure levels of thyroid 131I in nuclear medical staff / 环境与职业医学

Background Based on numerous epidemiological studies, radionuclide 131I can result in thyroid disease. Objective To study the contamination level of thyroid 131I in 131I treatment associated radiation workers in nuclear medicine departments in Shanghai. Methods Based on a general survey on basic situation of nuclear medicine in Shanghai, the level of internal exposure of radiation workers involved in 131I treatment was assessed with questionnaires and on-site monitoring. A portable γ spectrometer was used for on-site detection, the intake and annual effective dose were estimated according to the measurement results. Physical examination reports were collected for radionuclide positive workers, and chromosome testing was performed. Results There were 579 nuclear medicine workers and 175 were engaged in 131I treatment in Shanghai. 131I was detected in thyroid of 18 workers, with a detection rate of 10.3%. Among them, the detection rates of thyroid 131I in nurses and cleaners were 23% and 25% respectively. The mean measured activity of thyroid 131I was 306.1 Bq and the maximum measured activity was 3716.9 Bq (nurse). The maximum intake was estimated at 37544 Bq and the median was 786.4 Bq. The average annual committed effective dose was 1.22 mSv and the maximum value was 14.87mSv. The chromosomal aberration rates of all detected workers were negative, and all blood indicators were normal except one with low hemoglobin. Conclusion The annual dose of nuclear medical staff engaged in 131I treatment does not exceed the national standard limit, but the internal exposure of nurses and cleaners should not be ignored. On the basis of strengthening protection and decontamination, routine internal exposure monitoring should be carried out.

An investigation of indoor radon concentrations and estimation of public exposure doses in Yinchuan, China / 中国辐射卫生

Objective To primarily investigate the indoor radon concentrations in the urban and rural dwellings in Yinchuan, China, and to estimate the effective dose. Methods A total of 67 dwellings, which included 49 urban households and 18 rural households in Yinchuan, were selected to cumulatively measure the indoor radon concentrations for more than 3 months using solid state nuclear track detection. Results The arithmetic mean, geometric mean, median, and range of indoor radon concentrations in urban and rural areas in Yinchuan were 64 Bq/m3, 59 Bq/m3, 57 Bq/m3, and 25-172 Bq/m3, respectively. Surveillance sites with an indoor radon concentration higher than 100 Bq/m3 accounted for 7.5%. Indoor radon concentrations in rural areas were higher than those in urban areas. Indoor radon concentrations were highest in winter and lowest in summer. The effective dose of indoor radon exposure among residents in Yinchuan was 1.86 mSv/a. Conclusion The results of indoor radon concentrations measured in this investigation in Yinchuan are significantly higher than those measured in the 1990s. The annual effective dose is higher than the mean levels in the world and China.

Dosis efectivas asociadas a estudios híbridos SPECT-CT en pacientes adultos / Effective dose associated to hybrid SPECT-CT imaging in adult patients / Doses eficazes associadas a estudos de SPECT-CT híbridos em pacientes adultos

Introducción: la técnica de imagen híbrida de SPECT-CT combina la imagen de la tomografía por emisión de fotón único (SPECT) con el estudio de tomografía computada (TC), obteniendo información funcional y anatómica en un mismo estudio. La dosis efectiva total de radiación ionizante recibida en los estudios SPECT-CT puede ser estimada a partir de la dosis efectiva atribuible a la actividad administrada del radiofármaco y la dosis efectiva del componente de tomografía computada (TC). Objetivos: estimar la dosis efectiva total en los protocolos SPECT-CT utilizados en población adulta y determinar el aporte adicional del estudio TC sobre la dosis efectiva total. Método: se evaluaron 258 estudios SPECT-CT para estimar la dosis efectiva total aportada por la administración de los radiofármacos y los estudios de TC de baja dosis. Para estimar el aporte de ambos componentes se utilizaron factores de conversión específicos de cada radiofármaco y región explorada mediante TC. Resultados: la dosis efectiva total (media ± DS) en los estudios SPECT-CT fueron: 12,4 ± 1,44 mSv en el estudio de perfusión miocárdica, 1,14 ± 0,25 mSv en ganglio centinela de mama, 8,6 ± 0,6 mSv paratiroides, 1,48 ± 1,02 mSv tiroides y los estudios óseos de las regiones de cuello 4,5 ± 0,3, tórax 6,07 ± 0,3 mSv, abdomen y pelvis 6,1 ± 0,3 mSv. La dosis de radiación aportada por el estudio TC se encuentra entre 0,46 mSv para la región del tórax en el estudio de ganglio centinela de mama y 2,3 mSv para el SPECT-CT óseo en la región de abdomen y pelvis. Conclusión: se logró estimar la dosis efectiva en los protocolos SPECT-CT de uso clínico más frecuente en población adulta y el aporte de los estudios TC a la dosis efectiva total siendo relativamente baja comparado con la dosis aportada por los radiofármacos administrados con la excepción del estudio de ganglio centinela donde la contribución del componente TC es aproximadamente la mitad de la dosis efectiva total.

Introduction: SPECT-CT Hybrid image technique combines the SPECT (single-photon emission computed tomography) image with the CT (computerized tomography) image to obtain both functional and anatomical images in the same study. The total effective ionizing radiation dose received in SPECT-CT studies may be estimated based on the effective dose from the radiopharmaceutical administered and the effective dose from the CT (computerized tomography) component. Objectives: the study aims to estimate the total effective dose in SPECT-CT protocols applied for the adult population, and to determine the additional contribution from the CT component to the total effective dose. Method: 258 SPECT-CT studies were evaluated to estimate the total effective dose from the administration of radiopharmaceuticals and low dose CT studies. Specific conversion factors for each radiopharmaceutical and area of the body explored with the CT were used to estimate radiation doses from both components. Results: total effective dose (average ± SD) in the SPECT-CT studies was: 12.4 ± 1.44 mSv in the myocardial perfusion study, 1.14 ± 0.25 mSv in the breast sentinel lymph node study, 8.6 ± 0.6 mSv in the parathyroid study, 1.48 ± 1.02 mSv in the thyroid study. As to bone studies, doses found were: 4.5 ± 0.3, in neck studies, 6.07 ± 0.3 mSv in thoracic studies and 6.1 ± 0.3 mSv in abdominal and pelvic studies. The radiation dose from the CT study ranges from 0.46 mSv for the thoracic region on the breast sentinel lymph node study to 2.3 mSv for the bone SPECT-CT study of the abdominal and pelvic region. Conclusions: we managed to estimate the effective dose in the the most frequently used SPECT-CT protocols for the adult population and the contribution of CT studies to the total effective dose. It was found to be relatively low when compared to the dose contributed by the radiopharmaceuticals administered, with the exception of the sentinel lymph node study for which the contribution from the CT study is approximately half the total effective dose.

Introdução: a técnica de imagem híbrida SPECT-CT combina a imagem de tomografia por emissão de fóton único (SPECT) com o estudo de tomografia computadorizada (TC), obtendo informações funcionais e anatômicas no mesmo estudo. A dose efetiva total de radiação ionizante recebida em estudos SPECT-CT pode ser estimada a partir da dose efetiva atribuível à atividade administrada do radiofármaco e da dose efetiva do componente de tomografia computadorizada (TC). Objetivos: estimar a dose efetiva total nos protocolos SPECT-CT utilizados na população adulta e determinar a contribuição adicional do estudo de TC na dose efetiva total. Método : 258 estudos SPECT-CT foram avaliados para estimar a dose efetiva total fornecida pela administração de radiofármacos e estudos de TC de baixa dose. Para estimar a contribuição de ambos os componentes, foram utilizados fatores de conversão específicos para cada radiofármaco e região explorada pela TC. ⁠ Resultados: a dose efetiva total (média ± DP) nos estudos SPECT-CT foi: 12,4 ± 1,44 mSv no estudo de perfusão miocárdica, 1,14 ± 0,25 mSv no linfonodo sentinela mamário, 8,6 ± 0,6 mSv paratireoide, 1,48 ± 1,02 mSv estudos de tireoide e ossos das regiões do pescoço 4,5 ± 0,3, tórax 6,07 ± 0,3 mSv, abdômen e pelve 6,1 ±0,3mSv. A dose de radiação fornecida pelo estudo de TC está entre 0,46 mSv para a região do tórax no estudo do linfonodo sentinela da mama e 2,3 mSv para o SPECT-CT ósseo na região do abdome e pelve. Conclusão: foi possível estimar a dose efetiva nos protocolos de SPECT-CT mais utilizados clinicamente na população adulta e a contribuição dos estudos de TC para a dose efetiva total, sendo relativamente baixa em relação à dose fornecida pelos radiofármacos administrados com a exceção do estudo do linfonodo sentinela onde a contribuição do componente TC é aproximadamente metade da dose efetiva total.

Investigation and analysis of concentrations of radium-226 and uranium in agricultural products around uranium tailings pond / 中国辐射卫生

@#<b>Objective</b> 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. <b>Methods</b> 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. <b>Results</b> 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. <b>Conclusion</b> 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.

Radiation dose estimation and protective measure discussion of 241Am-Be neutron source logging / 中国辐射卫生

Objective To investigate the radiation dose to operators in the process of 241Am-Be neutron source logging, and discuss neutron source management and protective measures for operators in well logging. Methods Through on-site observation and measurement of 241Am-Be neutron source logging in a company, we obtained the surface γ dose rate and neutron dose rate of the neutron source, as well as the operating time and distance of various processes including source taking, transfer, and loading, calculated the radiation dose to operators in various processes, and analyzed the source and proportion of the personal effective dose to operators. Results The effective doses of neutron irradiation and γ irradiation were 94.17 μSv and 2.72 μSv, respectively, for the combined processes of source tank inspection, transfer, and detection; 36.66 μSv and 24.08 μSv, respectively, for source loading and unloading; and 130.83 μSv and 26.80 μSv, respectively, for the whole neutron source logging process. The total annual effective dose of neutron source logging was 15.78 mSv, as estimated by logging 100 times per year. Conclusion In the process of 241Am-Be neutron source logging in the company, the effective dose to operators mainly arises from neutron irradiation. Therefore, it is necessary to strengthen neutron source management and take effective protective measures against neutron radiation.

Monitoring on individual dose among radiation workers in medical institutions in Shanghai from 2015 to 2019 / 上海预防医学

ObjectiveTo determine the individual dose level and changing trend in the occupational external exposure of radiation workers in Shanghai， and provide scientific evidence for health risk assessment for radiation workers. MethodsIn the Occupational Health Management System for Radiation Workers of the National Health Commission-External Exposure Personal Monitoring and Management Subsystem， we retrieved the monitoring data of 38 077 external exposure individual dose of all medical radiation workers in Shanghai from 2015 to 2019. Using clustered sampling method， a total of 11 370 radiation workers in medical institutions （including tertiary， secondary， and primary hospitals） were selected in the study. Statistical analyses were conducted using SPSS 22.0. ResultsThe collective annual effective dose of 11 370 radiation workers was determined to be 4.340 person Sv， including 2.270 man·mSv in diagnostic radiology， 1.112 man·mSv in interventional radiology， and <0.5 man·mSv in other categories. The average annual effective dose was 0.382 mSv， which was 0.482 mSv in nuclear medicine， 0.431 mSv in radiotherapy， and <0.5 mSv in other categories. Moreover， the average annual effective dose of 6 workers （0.05%） was higher than 5 mSv， whereas that of 10 453 workers （92%） were less than 1 mSv； in addition， the annual dose of 911 workers （8.0%） was between 1‒5 mSv. All workers had average annual effctive dose lower than 20 mSv. The annual effective dose differed significantly by years （F=161.1， P<0.01）， by occupational groups （F=13.5， P<0.01）， and by hospital levels （F=264.5， P<0.01）. ConclusionThe average annual effective dose of radiation workers in medical institutions in Shanghai is lower than the national standard limit， suggesting proper and adequate radiation protection system and measures in medical institutions.

Clinical study on individual protection after 125I seed implantation for abdominal and pelvic tumors / 中华放射医学与防护杂志

Objective:To study the radiation dose rate and effective dose in ambient environment due to 125I seed implantation in the treatment of the patients suffering abdominal and pelvic tumors, so as to provide reference for occupational protection of different groups. Methods:Within 24 hours after operation, the radiation dose rate to 42 patients with abdominal and pelvic tumor with 125I seed implantation was monitored by using pocket dosimeter. The relationships between the total activity in the implanted particles and the measured dose rate, as well as between the implanted depth and the dose rate under the standard activity, were obtained by curve fitting. According to the formula, the relationship between the dose rate and the warning time was calculated. Results:The dose rates at 30 cm, 50 cm and 100 cm of vertical particle implantation site were (6.92±2.87), (4.10±1.62) and (1.30±0.48) μSv/h, respectively ( χ2=73.71, P<0.05). The dose rates on the left and right sides were (0.378±0.156) and (0.384±0.153) μSv/h at 30 cm, (0.170±0.089) and (0.17±0.086) μSv/h at 50 cm, (0.039 ±0.014) and (0.043±0.017) μSv/h at 100 cm, respectively ( χ2=76.19, 76.33, P<0.05). There was a linear relationship between the dose rate at the vertical particle implantation site and the total activity in the implanted particles, and between the dose rate and the implantation depth under the standard activity. The relationship between the warning time and the dose rate to adults in the same bed, co-workers, minors in the same bed and pregnant women were as follows: t ( d)=-106.616+ 83.779ln D( t), t ( d)=26.556+ 85.933ln D ( t), t( d)=3.088+ 85.017ln D( t). Conclusions:After 125I seed implantation, the radiation dose in the ambient environment is low, ensuring the radiation safety; and the measured dose rate decreases with the decrease in the total activity in the implanted particle and the increase in the implantation depth; at the same time, the warning time for different groups is calculated according to the measured dose rate or the total activity in the implanted particle and the depth of the implanted particle, so as to carry out individualized protection.

Estimating organ dose and specific effective dose in coronary artery CT angiography based on size-specific dose estimation / 中华放射医学与防护杂志

Objective:To study the feasibility that using size-specific dose estimation (SSDE) to estimate organ dose and effective dose in coronary CT angiography (CTA).Methods:Totally 421 consecutive patients with coronary artery CTA were included and retrospectively analized. All patients were scanned using the 3rd generation dual-source Force CT with prospectively ECG gated axis scan mode. The size specific dose estimation(SSDE) for each patient was conducted by calculate water equivalent diameters with Radimetrics. The organ doses of heart, lung, liver and breast, were estimated with Monte Carlo method. Patient-specific effective dose was calculated as a weighted sum of simulated organ doses with the coefficients from ICRP 103. Linear correlation analysis was used to validate the relationship between SSDE and organ doses as well as effective dose, and to derive coefficients for patient specific dose estimation. The mean error rate was used to evaluate estimation accuracy.Results:The CTDI vol, SSDE and effective dose were (16.8±8.7)mGy, (20.8±8.8)mGy and (4.4±2.9)mSv, respectively. The linear fitting formula for estimating organ dose based on SSDE were: Y=1.2 X-6.4 ( R2=0.91, P<0.05, mean error 0.1%) for heart, Y=1.4 X-7.4 ( R2=0.91, P<0.05, mean error 7.9%) for breast, Y=0.89 X-4.6 ( R2=0.86, P<0.05, mean error 8.3%) for lung, and Y=0.36 X-1.8 ( R2=0.64, P<0.05, mean error -17.9%) for liver. The linear fitting formula for estimating the individual effective dose based on SSDE were: Y=0.21 X-1.2 ( R2=0.92, P<0.05, mean error 0.2%) for men, Y=0.39 X-2.2 ( R2=0.93, P<0.05, mean error 1.7%) for women. Conclusions:In coronary artery CTA, the absorbed dose of the organs and patient specific effective dose could be estimated with SSDE and the corresponding conversion coefficients, which will help to achieve personalized assessment and precise management of patient radiation dose and risk in clinical practice.

Radioactivity levels in foods during 2013 to 2020 around Hongyanhe Nuclear Power Plant and study on internal doses to the public / 中华放射医学与防护杂志

Objective:To evaluate the impacts of radioactivity in foods since begining of the operation of the Hongyanhe Nuclear Power Plant (HNPP).Methods:The levels of radioactivity in foods collected within 30 km of HNPP from 2013 to 2020 were analyzed by comparison of the control samples and those collected before the operation. The impacts on the operation of the HNPP on foods were evaluated.Results:The man-made radionuclides such as 131I, 134Cs, 60Co, 58Co, 110Ag m were not found in food samples. The nautral radionuclides such as 238U, 226Ra, 232Th, 40K were at the normal levels, with the average levels of (0.088±0.053), (0.155±0.178), (0.314±0.388)and(81.3±18.1)Bq/kg(fresh weight)in foods, respectively. The average levels of man-made nuclide 137Cs in foods were (0.013±0.010) Bq/kg (fresh weight). There was no increase in radionuclide levels compared with the control samples and the samples before the operation. Conclusions:The impacts on foods due to the operation of HNPP was not found.

Study on image quality optimization of abdominal digital radiography with different additional filters / 中华放射医学与防护杂志

Objective:To investigate the effect of different additional filters on the image quality and radiation dose in abdominaldigital radiography (DR).Methods:Retrospective analysis was performed on 10 cases of abdominal DR from December 2020 to January 2021 in Fuxing Hospital, and the average mAs was calculated. Using automatic exposure control (AEC) technology, a polymethyl methacrylate (PMMA) slab of the corresponding thickness (18 cm) at the same output of above mAs was confirmed and used as the attenuator to simulate the abdomen. The phantom of CDRAD 2.0 and 17 slices of 10 mm thick PMMA plates (total thickness 18 cm) were placed on the bed. The additional filters were selected as no additional filter, 2 mmAl, 0.1 mmCu+ 1 mmAl, 0.1 mmCu+ 2 mmAl respectively. The AEC levels were selected at -2, -1, 0, 1, and 2 respectively. The images were collected and analyzed by using CDRAD 2.0 software to obtain the image quality factor (IQF inv). The incident air kinetic energy on the surface of the PPMA was measured for each exposure, and PCXMC software was used to estimate the organ dose and effective dose, and a comparative analysis was made. Results:The skin incident doses at no additional filter, 2 mmAl, 0.1 mmCu+ 1 mmAl, 0.1 mmCu+ 2 mm Al were (0.546 1±0.200 8), (0.376 2±0.133 8 ), (0.285 3±0.100 1) and (0.289 9±0.099 2) mGy, respectively. The estimated effective doses were (79.63±29.24)×10 -3, (71.05±25.56)×10 -3, (63.58±22.18)×10 -3 and (67.64±23.11)×10 -3 mSv, respectively. The gonadal doses were (0.058 1±0.020 8), (0.050 0±0.018 0), (0.044 8±0.015 6) and (0.047 7±0.016 3) mGy.The IQF inv values were 4.70±0.61, 4.80±0.84, 4.60±0.55, 4.60±0.60, respectively. There were linear correlations between the effective dose and the skin incident dose under different additional filtration, and the effective doses increased with the increase of the incident doses. The dose was lowest at the addition filtration of 0.1 mmCu+ 1 mmAl. There was no significant difference in the IQF inv between groups( P>0.05). Conclusions:The optimal additional filtration for abdominal DR was 0.1 mmCu+ 1 mmAl with the image quality meeting the requirements of clinical diagnosis, the radiation dose reduced reasonably, and the objective of the optimization of radiographic parameters achieved.

Study on the activity concentration of total α and natural radionuclides in drinking water in Inner Mongolia region / 中华放射医学与防护杂志

Objective:To ascertain the level of radioactivity in drinking water in Inner Mongolia region, and analyze the reasons why the total alpha radioactivity index is high in drinking water in some areas thereof.Methods:Water samples with high total alpha radioactivity index were collected in some towns in the region on the basis of surveyed result , with the causes of abnormal radioactivity index being analyzed, using low background α radioactivity measuring instrument, microuranium analyzer, and inductively coupled plasma mass spectrometer, to estimate the accumulative effective dose caused by ingestion of radioactivity in drinking water.Results:The total alpha activity was 0.508-1.008 Bq/L in tap water samples and 0.507-1.965 Bq/L in finished water samples. Uranium concentration was 3.41-35.71 μg/L in tap water measured using laser fluorescence method and 3.62-32.61 μg/L in finished water measured using laser fluorescence method, respectively. The concentration of 238U and 232Th in tap water measured by inductively coupled plasma mass spectrometry was 5.83-34.36 μg/L, 0.002-0.359 μg/L, respectively, while that in finished water was 5.62-29.41 μg/L, 0.003-0.327 μg/L, respectively. Conclusions:Based on the repeated measurement analysis of drinking water samples from some areas in Inner Mongolia, the high level of total α radioactivity in water samples is caused by uranium, and the high content of uranium leads to a high total alpha value.

Investigation on 90Sr level in offshore seawater and seafood therein around Sanmen nuclear power plant site and assessment of committed effective dose from 2015 to 2019 / 中华放射医学与防护杂志

Objective:To investigate and analyze the radioactivity level of 90Sr in offshore seawater and seafood therein around Sanmen nuclear power plant (NPP) and to estimate the annual committed effective dose to local population from ingestion of 90Sr in seafood from 2015 to 2019. Methods:From 2015 to 2019, the offshore seawater and 3 kinds of marine products grown locally in Sanmen and consumed by local residents were collected for measurement of the level of 90Sr radioactivity. The committed effective doses to the local population were estimated based on monitoring result and consumption data on seafood in Zhejiang offshore. Results:The radioactivity concentrations of 90Sr ranged from 2.4 to 4.1 mBq/L in the seawater, close to the natural radioacrive background level and from 6.7×10 -2 to 1.3 Bq/kg in seafood, lower than the standard values specified in the "Limited concentrations of radioactive materials in foods" (GB 14882-94). Annual committed effective dose to the local population from 90Sr attributable to consumption of seafood in Sanmen County from 2015 to 2019 were 2.2×10 -4-4.2×10 -4mSv, respectively, far lower than the worldwide committed effective dose result ing from internal exposure. Conclusions:From 2015 to 2019, the radioactivity concentration of 90Sr in seawater and seafood are stable, with neglectable dose burden to the local population.

Studies on resistance of Schistosoma to praziquantel XVIII Sensitivity to praziquantel in filial generations of praziquantel-resistant and -sensitive Schistosoma japonicum mixed infections / 中国血吸虫病防治杂志

Objective To investigate the sensitivity of adult worms of filial generations from praziquantel-resistant and -sensitive Schistosoma japonicum mixed infections to praziquantel. Methods Mice were infected with the cercariae of an experimentally generated praziquantel-resistant S. japonicum isolate [median effective dose (ED50) = 277.4 mg/kg] and a laboratory-maintained praziquantel-sensitive S. japonicum isolate (ED50 = 99.6 mg/kg) at a mixture ratio of 1:1 and 2:1, which was maintained in the laboratory via the mouse-snail cycle for 8 generations. Then, mice were infected with the cercariae of the 8th filial-generation parasite, and grouped 35 days post-infection. Mice in the 5 treatment groups were given praziquantel treatment by gavage at a single oral dose of 37.5, 75, 150, 300 mg/kg and 600 mg/kg, while animals in the control group was administered orally with 2.5% cremophor EL. All mice were sacrificed 14 days post-treatment and adult worms were collected by perfusion of the portal vein. The worm burden reductions and praziquantel ED50 values were calculated. The praziquantel-resistant S. japonicum isolate generated from experimental induction with 12 rounds of praziquantel treatment with sub-curative doses was maintained in the laboratory via the mouse-snail cycle, and mice were infected with the cercariae of the 8th filial-generation parasite. The praziquantel ED50 value against the 8th filial-generation adults was measured. Results After mice were infected with the mixture of cercariae of PZQ-resistant and -sensitive S. japonicum isolates at a ratio of 1:1, the praziquantel ED50 was 135.2 mg/kg against the adults of the 8th filial-generation parasite. After mice were infected with the mixture of cercariae of PZQ-resistant and -sensitive S. japonicum isolates at a ratio of 2:1, the praziquantel ED50 was 129.2 mg/kg against the adults of the 8th filial-generation parasite. In addition, the praziquantel ED50 was 208.4 mg/kg against the adults of the 8th filial-generation S. japonicum without the selection pressure of praziquantel. Conclusions Compared with the experimentally induced praziquantel-resistant S. japonicum isolate, the adult worms of the filial-generation S. japonicum show a reduced sensitivity to praziquantel in the same host following infection with the mixture of cercariae of praziquantel-resistant and -sensitive S. japonicum isolates. The adult worms of the filial generation of the praziquantel-resistant S. japonicum isolate without the selection pressure of praziquantel may still maintain the resistance to praziquantel.