Establishment and Application of a Radiation Dose Rate Model for Nuclear Medicine Examinees.

Introduction: Traditional methods for determining radiation dose in nuclear medicine include the Monte Carlo method, the discrete ordinate method, and the point kernel integration method. This study presents a new mathematical model for predicting the radiation dose rate in the vicinity of nuclear medicine patients. Methods: A new algorithm was created by combining the physical model of "cylinder superposition" of the human body with integral analysis to assess the radiation dose rate in the vicinity of nuclear medicine patients. Results: The model accurately predicted radiation dose rates within distances of 0.1-3.0 m, with a deviation of less than 11% compared to observed rates. The model demonstrated greater accuracy at shorter distances from the radiation source, with a deviation of only 1.55% from observed values at 0.1 m. Discussion: The model proposed in this study effectively represents the spatial and temporal distribution of the radiation field around nuclear medicine patients and demonstrates good agreement with actual measurements. This model has the potential to serve as a radiation dose rate alert system in hospital environments.

Characterization relationship between multinuclide nonequilibrium gamma radiation dose rate and 226Ra activity concentration in contaminated soil around uranium mines.

According to the characteristics of contaminated soil around uranium mines, combined with the pollution path of soil, the response relationship between the gamma radiation dose rate and radium activity concentration in contaminated soil was proposed by using a numerical model and subequilibrium theory. The results showed that the topsoil (depth 20 cm) made the mainly contribution of gamma dose rate (above 88%), and the main nuclide of concern was radium. Additionally, the uranium-radium equilibrium coefficient between 0 and 0.3 had a great influence on the gamma dose rate. The method proposed in this study could quickly identify the radium activity concentration in topsoil by using on-site gamma dose rate monitoring data. Compared with the actual monitoring results within ±10% error control, which had strong operability. This method could quickly identify the location and scope of contaminated soil and guide the on-site monitoring points around uranium mines.

[Investigation of the Leakage Radiation Dose Rate from an Auto Infusion Device in 18F-FDG PET].

PURPOSE: The aim of this study was to investigate the leakage radiation dose rate on the surface of an auto infusion device in 18F-fludeoxyglucose (FDG) positron emission tomography. METHOD: We preliminary measured the radioactivity of delivery-supplied FDG drugs. Leakage radiation doses on the six (front, rear, right, left, top, and bottom) surface points of the auto infusion device were measured ninety minutes before the assay time using an energy-compensated gamma scintillation survey meter and an ionization chamber-type survey meter. RESULT: Leakage radiation doses on the front, rear, right, left, and top surfaces were less than 7 µSv/h and satisfied specification of the auto infusion device. However, a leakage dose exceeding 40 µSv/h was detected on the bottom surface.

Diagnostic Reference Levels for Fluoroscopy-guided Gastrointestinal Procedures in Japan from the REX-GI Study: A Nationwide Multicentre Prospective Observational Study.

BACKGROUND: Diagnostic reference levels (DRLs) are required to optimize medical exposure. However, data on DRLs for interventional fluoroscopic procedures are lacking, especially in gastroenterology. This study aimed to prospectively collect currently used radiation doses and help establish national DRLs for fluoroscopy-guided gastrointestinal procedures in Japan. METHODS: This multicentre, prospective, observational study collected actual radiation dose data from endoscopic retrograde cholangiopancreatography (ERCP), interventional endoscopic ultrasound (EUS), balloon-assisted enteroscopy (BAE), enteral metallic stent placement, and enteral tube placement from May 2019 to December 2020. The study outcomes were fluoroscopy time (FT: min), air kerma at the patient entrance reference point (Ka,r: mGy), air kerma area product (PKA: Gycm2), and radiation dose rate (RDR: mGy/min). Additionally, the basic settings of fluoroscopy equipment and the factors related to each procedure were investigated. This study was registered in the UMIN Clinical Trial Registry (UMIN 000036525). FINDINGS: Overall, 12959 fluoroscopy-guided gastrointestinal procedures were included from 23 hospitals in Japan. For 11162 ERCPs, the median/third quartile values of Ka,r (mGy), PKA (Gycm2), and FT (min) were 69/145 mGy, 16/32 Gycm2, and 11/20 min, respectively. Similarly, these values were 106/219 mGy, 23/41 Gycm2 and 17/27 min for 374 interventional EUSs; 53/104 mGy, 16/32 Gycm2 and 10/15 min for 523 metallic stents; 56/104 mGy, 28/47 Gycm2, and 12/18 min for 599 tube placements; and 35/81 mGy, 16/43 Gycm2 and 7/15 min for 301 BAEs, respectively. For the overall radiation dose rate, the median/third quartile values of RDR were 5.9/9.4 (mGy/min). The RDR values at each institution varied widely. INTERPRETATION: This study reports the current radiation doses of fluoroscopy-guided gastrointestinal procedures expressed as DRL quantities. This will serve as a valuable reference for national DRL values. FUNDING: This work was supported by a clinical research grant from the Japanese Society of Gastroenterology.

Effectiveness of mobile robots collecting vital signs and radiation dose rate for patients receiving Iodine-131 radiotherapy: A randomized clinical trial.

Objective: Patients receiving radionuclide 131I treatment expose radiation to others, and there was no clinical trial to verify the effectiveness and safety of mobile robots in radionuclide 131I isolation wards. The objective of this randomized clinical trial was to evaluate the effectiveness and safety of mobile robots in providing vital signs (body temperature and blood pressure) and radiation dose rate monitoring for patients receiving radionuclide therapy. Methods: An open-label, multicenter, paired, randomized clinical trial was performed at three medical centers in Shanghai and Wuhan, China, from 1 April 2018 to 1 September 2018. A total of 72 participants were assigned to the group in which vital signs and radiation doses were both measured by mobile robots and conventional instruments. Intergroup consistency, completion rate, and first success rate were the primary effectiveness measures, and vital sign measurement results, the error rate of use, and subjective satisfaction were secondary indicators. Adverse events related to the robot were used to assess safety. Results: Of the 72 randomized participants (median age, 39.5; 27 [37.5%] male participants), 72 (100.0%) completed the trial. The analysis sets of full analysis set, per-protocol set, and safety analysis set included 72 cases (32 cases in Center A, 16 cases in Center B, and 24 cases in Center C). The consistency, completion rate, and first success rate were 100% (P = 1.00), and the first success rates of vital signs and radiation dose rate were 91.7% (P = 1.000), 100.0% (P = 0.120), and 100.0% (P = 1.000). There was no significant difference in vital signs and radiation dose rate measurement results between the robot measurement group and the control group (P = 0.000, 0.044, and 0.023), and subjective satisfaction in the robot measurement group was 71/72 (98.6%), compared to 67/72 (93.1%) in the control group. For safety evaluation, there was no adverse event related to the mobile robot. Conclusion: The mobile robots have good effectiveness and safety in providing vital signs and radiation dose rate measurement services for patients treated with radionuclides.

Assessment of radiation hazard indices due to natural radioactivity in soil samples from Orlu, Imo State, Nigeria.

The use of a Radiation Alert Inspector device and a gamma-spectrometry system fitted with a Sodium Iodide (NaI) detector was used to determine the radioactivity concentration level of natural radionuclides 238U, 232Th, and 40K in soil in several locations in Orlu, Imo State, Nigeria. 19 soil samples were collected for analysis from several locations of factories, agricultural farming-lands, gullies and water eroded areas, and soil deposits very close to flowing waters from rocks, due to environmental concerns arising from human activities in this region. The activity concentration values for 238U, 232Th, and 40K were found to range from 0.14 to 9.34 Bq.kg-1, 0.03-3.75 Bq.kg-1, and 16.83-783.06 Bq.kg-1, respectively, with average mean values of 4.15, 1.64, and 134.13 Bq.kg-1. Radium equivalent activity, absorbed dose rate, and gamma index mean values for the samples were 16.822 Bq.kg-1, 8.528 nGyh-1, and 0.133 mSv respectively, the obtained values were below the safe limit values set by the United Nations Scientific Committee on the Effects of Atomic Radiation of 370.0 Bq.kg-1, 59.0nGyh-1, and 1.0 mSv. According to the findings, the regions under study are reasonably safe for human outdoor activities such as agriculture, construction, and factory operations.

Radiation dose rate to Japanese cedar and plants collected from Okuma, Fukushima Prefecture.

After the 2011 Fukushima Dai-ichi Nuclear Power Station (FDNPS) accident, wild populations of animals and plants living in the evacuation zone received additional ionizing radiation of both internal and external radiation doses. Morphological abnormalities of pine and fir trees near the FDNPS were reported. In order to evaluate dose-effect relationships, it is necessary to quantify the radiation doses to trees and plants. In this study, the internal and external dose rates to Japanese cedar and plants collected at three sites in Okuma, approximately 4 km southwest of FDNPS were estimated applying the ERICA Assessment Tool. The activity concentrations of 134Cs and 137Cs in soils, cedar trunks, and plants were determined. The total dose rates to cedar ranged from 2.2 ± 1.2 to 6.1 ± 2.2 µGy h-1. These rates were within the derived consideration reference levels (DCRLs) reported by ICRP 108 as 4-40 µGy h-1 for pine trees. The highest estimate for plants was 7.1 ± 2.7 µGy h-1, much smaller than the DCRLs reported for grasses and herbs (40-400 µGy h-1). On average, the internal radiation dose rates to cedars at the two sites accounted for 5% and 29% of the external dose rates, respectively, while the value in another site was only 0.4% for cedar. This was attributed to differences in the crown area between the three sites. The trunk diameter of cedars shows a positive correlation with the ratio of internal to external radiation dose rates. It indicates that the total dose rate to cedars is easily estimated with the soil radiocaesium inventory and trunk diameter. The internal radiation dose rate to the plant varied depending on the plant species. This variation was considerably large in plants due to the presence of two species, including Solidago altissima and Artemisia indica var. maximowiczii.

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.

Evaluating the effect of low dose rate of gamma rays in germ cells of Drosophila melanogaster.

Purpose: Evaluation of genetic risk in germ cells is still matter of research, mainly due to their role in the transmission of genetic information from one generation to another. Although numerous experiments have been carried out in Drosophila in order to study the effect of radiation on germ cells, the role of dose rate (DR) has not been fully explored. The purpose of this study was to evaluate the action of DR on the radioprotection induction on male germ cell of D. melanogaster.Material and method: The productivity and the sex-linked recessive lethal (SLRL) tests were used to evaluate the radio-sensitivity of different states of the germ line of males. Two-day-old males of Canton-S wild type strain were pretreated with 0.2 Gy at 5.4 or 34.3 Gy/h of gamma rays from a 60Co source, three hours later, they were irradiated with 20 Gy at 907.7 Gy/h. Thereafter, each single male was crossed with 3 five-day old Basc virgin females, that were replaced every other day by new females. This procedure was conducted three times, to test the whole germ cell stages.Results: Females crossed with males irradiated with 0.2 Gy at both DR tested, laid a higher number of eggs than control, but egg-viability was reduced. On the other hand, in the group of 0.2 Gy + 20 Gy -combined treatments- the total number of eggs laid decreased only when 0.2 Gy were delivered at 34.3 Gy/h however, the egg-viability increased. The dose of 0.2 Gy at both DR did not modify the baseline frequency of SLRL. A tendency to decrease in the frequency of lethals in brood III was found in combined treatments at both DR.Conclusion: The fact that 0.2 Gy at 5.4 or 34.3 Gy/h induced an increase in the egg-viability and a tendency to decrease the genetic damage in pre-meiotic cells provoked by 20 Gy, might indicate the induction of any mechanism that could be interpreted as radioprotection in male germ cells of D. melanogaster. Results emphasize the need to carry out more studies on the effect of the DR on the induction of genetic damage in germ cells.

Relationship between viability and genotoxic effect of gamma rays delivered at different dose rates in somatic cells of Drosophila melanogaster.

The role of dose rate (DR) on biological effects of ionizing radiation is an area of significant research focus and relevant to environmental exposures. The present investigation was aimed to examine the direct relationship between viability and genotoxicity in Drosophila melanogaster, induced by gamma rays in a range of doses from 2 to 35 Gy administered at three different DR. Results indicated that larval-adult viability was reduced in relation to dose but not DR. No marked differences were found in the LD50 produced by differing DR tested. Frequencies of somatic mutation and recombination increased in direct correlation with dose and DR. Data demonstrate the importance of determination of the relationship between viability and genotoxicity induced by DR in in vivo systems for toxicological and radioprotection studies.

Different radiation dose rate as radioprotection and the cross effect with chromium using in vivo somatic cells of Drosophila.

Ionizing radiation plays a key role in the adaptation of an individual organism to environmental pollution, at the same time, it has biological effects that depend on radiation intensity or dose rate (DR). Although the effect of DR has been studied in vitro, the phenomenon known as the inverse effect of DR, which indicates as it decreases that the induction of damage is greater, has not been widely studied in vivo. The present study is aimed to test 0.5 and 1 Gy in somatic cells of the wing of D. melanogaster, administered at 5.4 or 34.3 Gy/h and from 0.037 to 0.3 mM of CrO3 as conditioning treatment. No changes were found in larva-to-adult viability. A protective as well as a cross effect of pre-exposure to different DR and CrO3 concentrations against genetic damage induced by 20 Gy or 1 mM CrO3 was evident.

Evidence that the radioprotector effect of ascorbic acid depends on the radiation dose rate.

Many studies have revealed that ascorbic acid (Aa) acts as a powerful inhibitor of genetic damage. The objetive of the present study was to evaluate the radioprotector effect of Aa at two diferent radiation dose rates. The somatic mutation and recombination test in Drosophila melanogaster was used. 48 h larvae were treated for 24 h with 25, 50 and 100 mM of Aa. After pretreatment, larvae were irradiated with 20 Gy of gamma rays administered at 36 or 960 Gy/h. Toxicity, development rate and frequency of mutant spots were recorded. Results provide evidence of a radioprotective effect for all tested concentrations of Aa only when 20 Gy were delivered at 36 Gy/h and only with 25 mM using the 960 Gy/h. To consider the use of Aa as radioprotector or therapeutic agent, it is necessary to know its potential under different situations to avoid unwanted injuries.

Dataset on ground radiometric survey in part of the Eastern Dahomey Basin, SW Nigeria.

The dataset for this article contains the measured activity concentration of radionuclides and gamma-radiation dose rate obtained from the radiometric survey in Ota, Ado-Odo Local Government Area, Ogun State, Nigeria. The data were manually collected in fifty (50) locations using the Super SPEC RS-125 spectrometer for about three (3) weeks in January, 2017. The descriptive statistical analysis of the data were equally explored for possible statistical relationships. The field dataset is made available publicly for further extended analyses that can provide insights into the safety status of the study area from radiological health concerns. The dataset could also serve as a significant baseline radiometric data for future epidemiology researches and monitoring initiative in Ota and its environs.

Effect of different dose rate of X-rays on cell migration of human non-small cell lung cancer cell line A549 / 肿瘤研究与临床

Objective To explore the effect of dose rate of X-rays on migration of non-small cell lung cancer (NSCLC) cells and provide the experimental basis for developing radiotherapy scheme. Methods Human NSCLC cell line A549 was cultured and irradiated with X-rays at dose of 6 Gy from a linear accelerator. The dose rates of 1, 2, 4 and 6 Gy/min were selected. Monolayer adherent cells were scratched and photographed at 0 hour and 24 hours under a microscope to measure the scratch width. Results After 24 hours, the scratch width of nonirradiated control cells was (640.7±8.1)μm. The scratch widths of cells were different when cells were irradiated with X-rays of various dose rates. Scratch widths were the largest in cells irradiated at dose rates of 1 Gy/min [(691.4±7.6)μm] and 6 Gy/min [(691.8±12.1)μm]. The scratch width was (666.2±1.3) μm of X-rays at 4 Gy/min, and there were significant differences compared with nonirradiated group (all P< 0.01), which suggested that inhibitory effect of X-rays at dose rates on A549 cell migration was obvious. However, the scratch width of cells irradiated at 2 Gy/min [(643.5 ±6.8) μm] had no difference compared with the control cells (t=-0.336, P=0.742). Conclusions The effect of X-rays irradiation on cell migration of human NSCLC cell line A549 is related with irradiated dose rate. The effect of different dose rates on cell migration is significantly different. Selecting appropriate dose rates for irradiation may help to improve the efficacy of radiotherapy.

Effect of dose rate of X-ray on clonogenic formation in human lung cancer cell line A549 / 肿瘤研究与临床

Objective To explore the effects of different dose rates of X-ray under the same dose on cell clonogenic formation in non-small-cell lung cancer cell line A549 in order to provide experimental basis for clinical radiotherapy plan. Methods The A549 cells were cultured at low density and irradiated with X-rays at dose of 4 Gy and selected dose rates of 1, 2, 4 and 6 Gy/min, respectively, from a linear accelerator. The 8th day after irradiation, the cells were fixed and stained with Giemsa solution, and colonies containing at least 50 cells were counted. The plating efficiency and surviving fraction were calculated. Results The clonogenic number in non-irradiated cells was 88.6±4.6. The numbers were significantly reduced in irradiated cells at dose rate 1, 2, 4 and 6 Gy/min (12.3±3.4, 9.0±0.8, 5.6±1.0, 11.5±1.7, respectively) than that in non-irradiated control cells (F=678.799, P<0.05). The plating efficiencies were decreased in irradiated cells, especially in 4 Gy/min irradiated cells, which was lower than that in any of the other three dose rate groups (P< 0.05). Conclusions Though at same radiation dose, cancer cells have different clonogenic formation efficiency when irradiation with X-ray at different dose rates. Thus, treatment with optimal dose rate may improve the radiotherapy efficacy.

Radiation dose rate received by patients with coronary heart disease during interventional management:comparison between fluoroscopy and movies / 介入放射学杂志

Objective To determine the real time radiation dose rate displayed on DSA equipment in interventional management for patients with coronary heart disease in order to provide medical staff with useful basis to reasonably control the radiation dose. Methods A total of 30 patients with coronary heart disease, who received interventional treatment at authors’ hospital in September 2014 with a GE DSA unit, were randomly selected. Intraoperative radiation dose rates when fluoroscopy was converted to movies , which were displayed on DSA at respective sequence, were determined, and the results were analyzed and compared. Results The fluoroscopy radiation dose rate ranged from 18.5 to 212.0 mGy/min, the mean value was (114.7±42.1) mGy/min;while the radiation dose rate of movies varied from 216 to 1 691 mGy/min, with a mean value of(970.1±298.4) mGy/min. The overall mean fluoroscopy-to-movies radiation dose ratio was 1 ∶8.5. The larger the digital flat panel detector area was , the bigger the mean radiation dose rate would be and the more obvious increase in the mean radiation dose rate of movies than that of the fluoroscopy would be observed; the mean radiation dose rate of fluoroscopy was lower than that of movies , and the difference was significantly. Conclusion During the performance of coronary intervention , the medical staff should make reasonable choice of the equipment and closely observe the dynamic real-time display of the radiation dose rate, promptly adjust the inspection mode and the controllable parameters when it is needed , make immediate evaluation of dose level that might cause radiation injury to the patient , and reasonably control the radiation dose to reduce the effects of ionizing radiation on human health.

Estimation of typical value and confidence interval of gamma-radiation dose rate from tank-transported copper ore by means of bootstrap resampling method / 中华放射医学与防护杂志

Objective To investigate the typical value of gamma-radiation dose rate and its confidence interval in tank-transported copper ore by using bootstrap resampling techniques. Methods Bootstrap resampling method, coupled with kernel density estimation, introduced to acquire the typical value of gamma-radiation dose rate in copper ore. Results The typical value of gamma-radiation dose rate in copper ore was expressed as the central tendency of the means of resampling, and two kinds of confidence interval, empirical percentile and bias-corrected accelerated confidence interval, were provided as standard error. Conclusion It is clearly demonstrated that this method has an advantage to give a robust description in explanation of central tendency and variation range of gamma-radiation dose rate data profiles.