Indoor radon concentration and its changing trend in northeastern China / 中国辐射卫生

@#<b>Objective</b> To investigate the indoor radon concentration and its changing trend in northeastern China. <b>Methods</b> We measured indoor radon levels cumulatively for over three months by solid state nuclear track detection in a total of 261 houses in multi-story or high-rise buildings in Shenyang, Changchun, Harbin, Heihe, and Yichun in northeastern China. The measurement lasted one year in Changchun for seasonal changes. <b>Results</b> The average indoor radon concentration in the five cities was 88 Bq/m³, ranging from 12 to 558 Bq/m³. The indoor radon concentrations were ≤ 100 Bq/m³ in 75.1% of the houses, and ≤ 300 Bq/m³ in 97.7% of the houses. The indoor radon concentration increased with the age of buildings. The indoor radon concentration was highest in winter, and it was higher in summer than in autumn and spring. <b>Conclusion</b> The indoor radon concentration in northeastern China increased compared with the data of 1980s and 1990s. It is highest in the winter heating season, and higher in summer than in spring and autumn. Indoor radon exposure deserves attention.

Application of laparoscopy in the management of acute mesenteric ischemia / 国际外科学杂志

Accurate determination of intestinal viability is the key step in the management of acute mesenteric ischemia. For patients with the possibility of intestinal necrosis, the application of laparoscopy for the primary exploration or second look, is significantly less invasive than laparotomy, so to avoid the unnecessary operative trauma for those with negative results. For critical patients, application of bed-side laparoscopy, with the avoidance of risks during transport process, is an effective and safer diagnostic method. And the combination with intraoperative indocyanine green fluorescence angiography may further improve the reliability of exploration so to result in more precise surgical management for these severe situation. So in the era of endovascular management for acute mesenteric ischemia, as an mimmally invasive and precise method for accurate determination of existence or not of intestinal necrosis, laparoscopy is effective in further improving the outcome of these patients.

The case and thinking for signal interference in resolver of carousel on Varian VitalBeam medical linear accelerator / 中华放射肿瘤学杂志

In this article, a case for random signal interference in resolver (or encoder) of carousel on Varian VitalBeam medical linear accelerator was illustrated. This case was considered as a rare failure of the technology platform (including TrueBeam) by Chinese, European and American technical experts in Varian. In this article, the differences of the carousel in the structure and control system between VitalBeam and traditional accelerator were comparatively analyzed to enable the peers to have a deeper understanding of resolver. The logic and methods to solve the fault were summarized, providing reference experience for analyzing the problems related to carousel. It is found that the interlocking system is imperfect, which provides a factual and technological basis for Varian to optimize the system.

Measurement and analysis of 90Y radioactivity in urine of patients treated with 90Y resin microspheres / 中华放射医学与防护杂志

Objective:To evaluate 90Y activity concentration in renal excretions during the first 48 hours after being treated with 90Y resin microspheres seleceive internal radiation therapy(SIRI) and to provide advice on the management of patient excreta after surgery. Methods:After surgery, urine excreted from 3 patients during 0-24 h and 24-48 h was collected respectively, and the 90Y activity concentration in urine was tested and analyzed. Results:90Y radioctivity in the urine excreted from 3 patients after surgery was (1 266±258)kBq/GBq during 0-24 h and (140±106) kBq/GBq during 24-48 h, respectively, and 90Y activity concentration were (640±113) kBq/L during 0-24 h and (53±12) kBq/L during 24-48 h. Conclusions:90Y radioactivity in patient′s urine excreted at 1 d was about 10 times higher than that at 2 d. After surgery, patients can accelerate the reduction of free 90Y activity by increasing excretion. Urine excreted by the patients during hospitalization should be handled in accordance with the requirements of the national standard HJ 1188-2021 Radiation protection and safety requirements for nuclear medicine.

Radiological protection detection and dose assessment of selective internal radiotherapy with 90Y resin microspheres / 中华放射医学与防护杂志

Objective:To conduct radiation detection and dose assessment in selective internal radiotherapy with 90Y resin microspheres for the purpose of providing a reference for radiological protection. Methods:The dose rates from radiotherapy with 90Y resin microspheres were detected in the process of each operation at different distances from the body surface of patients the levels of dose to the persons concerned were compared with the relevant national regulations and standards. Results:The estimated dose rates were 1.12-454 μSv/h during 90Y resin microspheres dispensing and 2.06-58.2 μSv/h during surgical procedure. The dose rates at 0.5 h after surgery were 22.7-64.1 μSv/h at 5 cm and 0.82-2.55 μSv/h at 1 m from three patient′s body surface. Assuming treating 200 patients a year, the annual individual effective dose to the radiation workers was 0.12-1.03 mSv/year. The annual individual effective dose to the public, comforters and carers of patients was 0.02-0.24 mSv/year after release of a patient. Conclusions:During the treatment, nursing and release of patients, the radiation doses to workers, carers and the public are lower than the individual dose limit given in the GB18871-2002 basic standards for protection against ionizing radiation and for the safety of radiation sources and the management target value set by of the relevant medical institutions.

Application and analysis of radon-reduction methods in indoor radon pollution control / 中国辐射卫生

@#<b>Objective</b> To investigate the suitable methods for reducing the concentration levels of residential radon and its daughters. <b>Methods</b> Three rooms were selected and treated by natural ventilation, air purifier, and sealing/shielding, respectively. The EQF3120 device was used to measure the concentrations of radon and its daughters, and the alpha nuclear trail detector was used to measure indoor radon concentration. The three methods were compared in terms of radon reduction effect. <b>Results</b> After natural ventilation for 2-10 hours, the average reduction rates of the concentrations of radon and attached and unattached radon daughters in the room were 87.7%, 89.8%, and 93.7%, respectively; in the room with air purifier, the concentrations of radon and attached and unattached radon daughters were reduced by 46.3%, 94.5%, and 45.3%, respectively; after sealing and shielding, the concentration of radon was reduced by 74.9% after 1 month and 59.2% after 1 year. <b>Conclusion</b> All three methods have a marked effectin reducing the concentrations of indoor radon and its daughters, and natural ventilation is the most economical and effective method for reducing radon.

Preliminary investigation of radon concentration in drinking water in 31 cities of China / 中华放射医学与防护杂志

Objective:To obtain the distribution characteristics of radon levels in drinking water in cities of China and analysis their influencing factors.Methods:A total of 31 cities were selected and 406 tap water samples were collected in accordance with the sampling plan based on administrative division. Radon concentrations in the water samples were determined by using RAD7 H 2O measuring devices, and the closed loop liquid-gas balance method and grab method . The radon concentrations in the gas loop were measured by using semiconductor detector. After four measurement periods, radon concentrations in water were calculated. Results:The arithmetic mean of radon concentrations in drinking water from 31 cities was (4.92±9.44) Bq/L and the geometric mean (0.71±7.77) Bq/L, ranging from less than the lower detection limit (LLD) to 43.15 Bq/L. For 84.2% of drinking water samples, radon concentrations were less than US EPA recommended 11.1 Bq/L, all lower than the EU-recommended value of 100 Bq/L.Conclusions:The radon concentrations in drinking water are higher in northeastern, northwestern, southwestern, northern China than those in southern, central China and eastern China. The factors influencing radon concentrations in drinking water are closely related to geological structure and water source type. Compared with the global values, the radon concentrations in drinking water in our cities are low and safe in general in China.

Analysis of external exposure dose during 131I treatment for thyroid cancer patient / 中华放射医学与防护杂志

Objective:To explore the existing issues in radiation protection during the treatment of 131I by means of measuring the ambient dose equivalent rate to patients with thyroid cancer and the dose equivalent to the surface of chest of patients during hospitalization. Methods:The ambient dose equivalent rate (peer) was measured by using gamma ray detector for selected 78 patients who received 131I treatment in a hospital 10 min, 1 d, 2 d, 3 d and 5 d after administration with 131I. The measurements were made at distances of 5 cm, 0.5 m and 1 m from the body surface in front, rear, left and right directions. The photoluminescence dosimeter on the chest of the patients was used to measure the effective dose during hospitalization period (6 d). Results:The ambient dose equivalent rate on the surface of chest of patients was up to 4.81 mSv/h 10 min after administration of medicine. The dose equivalent on the surface of chest of patients before discharge ranged 2.6-64.1 μSv/h. The cumulative dose on chest surface during hospitalization was 15.9-58.8 mGy. There was a significant difference in the dose rate at 5 cm from the body surface between 3.7 GBq group and 5.55 GBq group 10 min after medication ( t=-6.11, P<0.05). There was a significant difference in the dose rate at 5 cm from the body surface between male and female groups 10 min after medication ( t=4.52, P < 0.05). There was no significant difference in other groups ( P > 0.05). Conclusions:During the 131I treatment, patients had high level of radiation around them, so it is necessary to strengthen the protection and management of patients and reduce unnecessary exposure to the public.

Analysis of the current status of radiation protection in non-medical sectors in China / 中华放射医学与防护杂志

Objective:To analyzes the current status of radiation protection in non-medical sectors, together with the vulnerable spots in the prevention and control of occupational radiation sickness in China in order to provides both technical basis for occupational health management in non-medical radiation sectors and the better protection of occupational health benefits for radiation workers.Methods:The monitoring plan for this survey was worked out on the part of the National Institute for Radiological Protection, China CDC. Survey and monitoring of the current status of radiation protection and occupational health management were, under the monitoring the plan, completed by the relevant agencies of all provincial-level regions for the key industries of non-medical sectors countrywide, involving occupational health monitoring, personal dose monitoring, radiation protection monitoring instruments equipped, and radiation protection monitoring in workplace. Based on the survey result , the deficiencies in radiation protection and occupational health monitoring in non-medical sectors were analyzed.Results:The survey of non-medical sectors was divided into general investigation and detailed monitoring, with the general investigations covering 9 075 non-medical institutions in 31 provincial-level regions across the country. Of them, a total of 4 911 institutions within 329 district-level regions received detailed investigation and radiation protection monitoring. As survey result , the X, γ ambient dose equivalent rates for the institutions using ray-generator are greater than 2.5 μSv/h, about 2.35% of the total, with a maximum of 817 μSv/h. The values for those using radioactive sources were greater than 2.5 μSv/h, about 9.57%, with a maximum of 1 700 μSv/h. The frequencies of personal dose monitoring and occupational health examination were 72.9% and 82.1%, respectively.Conclusions:There is still a gap in radiation protection between the current status and the national regulations and standards in non-medical sectors, so both regulation and management of radiation protection should be further strengthened.

Principle and troubleshooting for the irregular case of UDRS interlock for Varian CLINAC-IX linear accelerator / 中华放射肿瘤学杂志

The UDRS interlocking fault is a common dose interlocking of Varian high-energy linear accelerator. Due to the complexity of the system, this fault has brought challenges to the engineers for a long time. Hence, an effective solution is urgently required. In this article, the circuit and principle for UFRS interlocking fault for Varian CLINAC-IX linear accelerator were explicitly analyzed and the maintenance methods were summarized. The management methods of such rare fault were shared, aiming to provide reference for subsequent management of similar interlocking faults.

Building management and effect evaluation of high radon in geothermal field / 中国辐射卫生

Objective To explore the source and control of radon in high radon houses in geothermal fields; Methods Radon concentration in indoor and soil was measured by ATD detector in winter and summer; radionuclides in building materials were measured by gamma-ray spectrometry; radionuclides dose rates of building materials were measured by 6150 A D/ 6H X-γ ray detector; and radon reduction technology was applied to one of the houses;Results The average radon concentrations in 32 rooms were （106.4 ± 63.7） Bq/m3 (summer) and （421.3 ± 138.2） Bq/m3 (winter), and the concentrations in 12.5% (summer) and 96.9% (winter) of the rooms exceed 150 Bq/m3. The average radon concentration in soil around buildings was 12890 Bq/m3 (n = 24), which is 1.7 times of the typical soil radon concentration in Beijing (7600 Bq/m3). After soil decompression, the radon concentration in the house could be reduced to less than 100 Bq/m3. The radon reduction rates of active decompression and passive decompression were 94.6% and 71.4%, respectively. Conclusion The effect of soil decompression on reducing radon concentration in the bottom rooms is obvious. Attention should be paid to the radon in residential environment of geothermal field.

Implementation of survey on diagnostic medical X-ray frequency in 2016 in China / 中华放射医学与防护杂志

To ascertain the background and frequency of diagnostic medical X-ray procedures in China and provide the basis for regulatory oversight of such applications,a total of 557 medical institutions in 25 provinces or municipalities were surveyed by means of the optimally designed questionnaires and through stratified quota sampling.The numbers of procedures were calculated in terms of the type of procedures and the sex and age of examined patients.As a result,the frequencies of diagnostic X-ray procedures for 2016 in the country were derived using multiple linear regression analysis.The frequency of X-ray diagnosis in 10 provinces of China in 2016 was estimated to be 379-1 228 examinations per 1 000 population.Diagnostic X-ray applications have shown a rapid expansion in 2016 as compared with the period of "9th Five-Year Plan".It is very important to strengthen the regulation of medical diagnostic X-ray applications.

The feasibility study of gold nanoparticle composites (ssDNA-AuNPs) for the colorimetric detection of gamma radiation dose / 中华放射医学与防护杂志

Objective To establish a simple and convenient method and study the feasibility of using gold nanoparticle composites (ssDNA-AuNPs) for colorimetric detection of gamma radiation.Methods The composites ssDNA-AuNPs were prepared by applying the ssDNA to the surface of AuNPs,and then were irradiated with gamma ray with absorbed doses of 0,5,10,20,and 30 Gy,respectively.Subsequently the color change in the solutions were observed simultaneously with absorption spectra being measured.The linear relationship between the ratio of A625/A521 in the absorption spectrum and the absorbed dose was established.Results With the increase of radiation dose,the color of the solutions changed from wine-red to blue-violet gradually,the ratio of A625/A521 in absorption spectra had excellent liner response for absorbed dose ranging from 0 to 30 Gy,and the linear equation was A625/A521 =0.020 6 + 0.303 6 E(R2 =0.991 5).Conclusions The ssDNA-AuNPs synthesized in this experiment can be successfully used for colorimetric detection of gamma absorbed dose,and a simple and convenient method for detection of gamma radiation has been newly established.

Validation and discussion of the time response correction formula for radiation detectors / 中华放射医学与防护杂志

Objective To validate and discuss the time response correction formula for four types of dosimeters (6150AD6 + 6150AD-b,FH40G + FHZ672E-10,451P ionization chamber and AT1123).Methods The ambient dose equivalent rates shown by survey meters were recorded separately when X-ray emission time was 500,200,100 and 50 ms.The corrected values were obtained by the formula of circuit having a capacitance C and asistance R in series.Results Therewas no correlation between the value measured by AT1123 dosimeter and the time of irradiation.The values by other three kinds of dosimeters obviously varied with the time of irradiation.Conclusions It is not required to make the time response correction for the measured value of ATl123 dosemeter,whereas the values measured by the other three dosimeters could be corrected by the time response correction formula.

Analysis of intercomparison results for radon-thoron discriminative detector / 中华放射医学与防护杂志

Objective To increase the cumulative measurement level of 222 Rn and 220 Rn and ensure the accuracy and reliability of the measurement result . Methods By using improved 222 Rn-220 Rn discriminative detectors ( LD-P detectors) , the radon research group of National Institute for Radiological Protection Chinese Center for Disease Control and Prevention participated with the intercomparison organized by National Institute of Radiological Science ( NIRS) , Japan. Specifically, with the 222 Rn-220 Rn discriminative detectors being sent to Japan, the comparison was completed under different conditions in the 222 Rn chamber and 220 Rn chamber in NIRS. After exposure, the detectors were sent back to our laboratory for etching and analysis, and then measurement result were informed to NIRS. Finally, NIRS returned the exposure reference values of 222 Rn and 220 Rn to our laboratory. Results Under the conditions of high and low levels of 222 Rn, the relative percentage differences ( RPD ) between the measured values and the reference value provided by the NIRS were -12. 0％ and -11. 8％, respectively, while coefficients of variation ( COV) were 3. 0％ and 6. 2％, respectively. Under the conditions of high level and low levels of 220Rn, the relative percentage differences (RPD) between the measured value and the reference value provided by the NIRS were -0. 8％ and -8. 0％, respectively; coefficients of variation ( COV ) were 6. 7％ and 4. 5％, respectively. Conclusions This intercomparison result were categorized by NIRS ( PRD<10％) , with the satisfactory result of LD-P detectors available.

Measurement and discussion of circuit time constants for radiation detectors / 中华放射医学与防护杂志

Objective To measure the circuit time constants of 4 kinds of radiation survey meters (451P ionization chamber dosimeter,6150AD6 + 6150AD-b dose meter,FH40G + FHZ672E-10 dose meter and AT1123 dose meter) and,to discuss the formula of time response correction and its application.Methods In the condition of continuous exposure of X-ray machine,the ambient dose equivalent rates shown by survey meters were recorded.In order to get the circuits time constant,the least squares fittingmethod was used to fit the data using the time response formula of circuit having a capacitance C and a resistance R in series.Results The relative uncertainty of fitted circuit time constants was higher than 20％ except for 6150AD6 + 6150AD-b dose meter.The relative uncertainty of fitted r was 8％ for 6150AD6 + 6150AD-b dose meter.Conclusions The time required to stabilize the dosimeter readings was 8,5,3 and 2 s,respectively,for the 451P ionization chamber dosimeter,6150AD6 +6150AD-b dose meter,FH40G + FHZ672E-10 dose meter and AT1123 dose meter.The rising trend of their measured values was not fully accordance with the RC circuit time response correction formula.

Monte Carlo method for proton and heavy ion treatment room shielding calculation / 中华放射医学与防护杂志

Objective To use Monte Carlo method to build a shielding calculation model for the proton and heavy ion treatment room,and to provide a reliable calculation method for shielding design.Methods A Monte Carlo-based FLUKA code was adopted to build the shielding calculation model for the proton and heavy ion treatment room,and to simulate the radiation field distribution in the proton and heavy ion treatment room.The calculation model was verified through the radiation detection around the proton and heavy ions treatment room.Results The FLUKA code-based simulation results were consistent with the radiation detection.Conclusions The shielding calculation model based on FLUKA code can simulate the radiation field from proton and heavy ions.Among the secondary particles,secondary neutrons are the dominant component and the main concern of accelerator shielding design.In shielding calculation,the emphasis should be put on both beam intensity and energy.

The investigation on radiation level and radiation protection in nuclear medicine diagnosis workplace / 中华放射医学与防护杂志

Objective To investigate the current situation of radiation protection in nuclear medicine diagnosis workplace.Methods The study was performed in 3 hospitals in northeast,north and central of China from February to December in 2013.The γ dose rate instrument was used to detect the workplace ambient dose equivalent rate of medicine preparation,leaching,packing,injection and imaging.Individual effective dose and equivalent dose were evaluated by photoluminescent dosimeter.Results The ambient dose equivalent rate was up to 1.92 mSv/h at repacking place and 1.2 mSv/h at injection place.The ambient dose equivalent rate of patients after injection was 5.36-240 μ,Sv/h.The hand equivalent dose was 0.01-0.02 mGy.Moreover,there were problems of staff route intersection,as well as the patients after injection staying in the public area.Conclusions Radiation workers should pay more attention to individual protection,and improve the operation proficiency to shorten the operation time.Furthermore,in order to protect public from unnecessary irradiation,there should be some changes in staff route and patients administration.

Calculation and analysis of effect of radon exhalation on external dose model for building materials / 中华放射医学与防护杂志

Objective To study the effect of radon exhalation on the external dose model for building material,so as to provide the scientific and precise assessment of external radiation exposure hazard.Methods The mechanism of exhalation of radon from building material was analyzed,mathematical model of correction factor for the effect of radon exhalation was derived and resolved by Matlab program and the relationship between correction factor and diffusion length,surface emanation coefficient and thickness of building material was discussed.The absorbed dose rate induced by several classical building materials was calculated and compared.Results The radon exhalation correction factor was independent of diffusion length and thickness of building material in most cases.Negative correlation was found between radon exhalation correction factor and radon surface emanation coefficient.Radon exhalation correction factor numerically equals to '1-radon surface emanation coefficient'.The relative percentage deviation between absorbed dose rate induced by several classical building materials was in the range of 2.23％-10.02％,for both corrected and uncorrected radon exhalation effects.Conclusions Radon exhalation from building material has a certain effect on external dose model for building material,which should attract attention.It is important to conduct the correction for external dose model by introducing ‘1 -radon surface emanation coefficient’ as the radon exhalation correction factor,in order for the scientific assessment and control of external radiation exposure hazards from building materials.

Analysis of international intercomparisons results organized by Japan for integrating 222Rn-220Rn detectors / 中华放射医学与防护杂志

Objective To guarantee the quality of measurenents with the radon-thoron discriminative detectors of our laboratory.Methods LD-P radon-thoron discriminative detector participated in the international intercomparison for integrating radon/thoron detectors organized by National Institute of Radiological Science (NIRS,Japan).Detectors were sent to NIRS for exposure.Radon intercomparison was conducted with radon chamber providing three levels of exposure:low,medium and high levels.Thoron intercomparison was carried out at thoron chamber,which also provided three levels of exposure:low,medium and high levels.Detectors were posted back to our laboratory for etching and analysis after exposure.Then the measured values were submitted to NIRS.Finally the reference values were informed of us.Results The relative percent difference (RPD) between the measured value and the reference value for radon was-13.8％,-14.4％ and-17.1％ at low,medium and high levels respectively,and that of thoron were-14.4％,8.9％ and-3.2％ at three levels respectively.Conclusions Both radon and thoron measurement of our detectors rank asCategory Ⅰ in the 4th international intercomparisons for integrating radon/thoron detectors with the NIRS radon/thoron chambers.