Optimisation Of Radiological Protection Research Articles

High-radiation-exposure tasks in Korean pressurized heavy-water reactors.

This study analysed the occupational dose in Korean pressurized heavy-water reactors (PHWRs) and identified tasks involving high radiation exposure. The average individual dose was sufficiently low to be below the annual effective dose limit for radiation workers and is even lower than the dose limit for the general public. However, some workers received relatively higher doses than others. Furthermore, most PHWR workers are exposed to radiation during planned maintenance periods. In this study, the radiation dose was normalized (radiation dose per unit time) to determine the high-radiation-exposure tasks in Korean PHWRs. Consequently, end-fitting lapping, delayed neutron tube work and fuel channel fixed-end change tasks were identified as high-radiation-exposure tasks in Korean PHWRs. If appropriate radiation protection measures are prioritized for the identified high-dose exposure tasks, optimization of radiological protection will be effectively achieved by reducing the dose that is relatively higher than the average.

Оценка радиационных рисков злокачественных новообразований среди российских участников ликвидации последствий аварии на Чернобыльской АЭС

The paper considers radiation risks of solid cancer incidence and mortality, as well as risk of leu-kemia incidence (other than chronic lymphocytic leukemia) among Russian Chernobyl cleanup workers (liquidators). The study of the cohort of liquidators carried out at the National Radiation Epidemiological Registry (NRER) was based on the follow-up data collected from 1992 over 2019. The size of the Chernobyl cleanup workers cohort exceeded 65 thousand people, their av-erage age at the time of entering the exclusion zone was 34 years, the average external gamma radiation dose received by liquidators during their cleanup work was about 0.133 Gy. Radiation-induced risks of solid cancer incidence and mortality in the study cohort were statistically signifi-cant, the risk magnitude rose with increasing the follow-up length. For the maximum follow-up period, from 1992 over 2019, the excess relative risk coefficient for solid cancer incidence was ERR/Gy=0.62, 95% CI (0.29; 0.98), and excess relative risk coefficient for solid cancer mortality was ERR/Gy=0.74, 95% CI (0.32; 1.22), the estimated coefficients were in good agreement with similar coefficients calcu-lated for the Russian liquidators with the use of ICRP radiation risk models. Non-parametric esti-mates of relative radiation risk within the same dose intervals for solid cancers and for leukemias in the cohort of liquidators were statistically significant for radiation doses above 0.150 Gy. For radiation doses below 0,150 Гр the linear non-threshold model is conservative, i.e. there was ev-idence for statistically significant radiation risk of leukemia incidence among liquidators during the first 11 years after the accident, from 1986 over 1997, ERR/Gy=4.41, 95% CI (0.24; 14.23). In later years, until 2018 there was no evidence of radiation-related risk of leukemia incidence. Out-comes of future studies will impact on optimization of radiological protection, development of reference levels for Russian general public exposure and improvement of the system for delivery of targeted medical care to people exposed to radiation.

Моделювання та візуалізація радіаційного стану на майданчику зберігання контейнерів ЦСВЯП за допомогою програмного комплексу ChNPP VRDose Planner

The results of three-dimensional modeling of working conditions of personnel in radiation-hazardous conditions of the Centralized Spent Nuclear Fuel Storage Facility (CSNFSF) of WWER type reactors of domestic NPPs, are presented using the software complex ChNPP VRDose Planner. Today, the software package ChNPP VRDose Planner, developed by the Institute of Energy Technology (Norway), is an effective tool for estimating the does load on personnel. It allows interpreting radiological information based on three-dimensional models of radiationhazardous objects where human activities are planned. The VRDose software complex allows creating virtual models of each worker and reproducing detailed technological process of performance of works with participation of the person. This creates a visual representation of the behavior of staff at all stages of work. The software complex is created for planning and implementation of works in difficult radiation conditions, allows carring out optimization of radiological protection and choosing the safest scenarios of performance of operations. Using this software package: 1) the predicted values of the dose rate on the surface of the container model and the model of the storage site were obtained; 2) the dose for the dosimeter was simulated and evaluated during the operation no. 32 “Control of gamma dose rate and neutron radiation of the loaded storage container HI-STORM at the storage site” for the time of operation on arrival and departure with the arrival and departure from the venue; 3) the contribution of the main emitting nuclides to the dose rate when measured on each side of the container is determined; 4) the possibility of its use to control the radiation impact on the environment and its minimization on the person during the construction and commissioning of the CSNFSF was assessed. By verifying the results obtained during the work on scientific and technical support of construction and commissioning of CSNFSF with the data obtained using the software package ChNPP VRDose Planner, it can be argued that they are sufficiently correlated. Given the above, the software package ChNPP VRDose Planner can be recommended for use during the work on scientific and technical support of the operation of CSNFSF and control of radiation exposure to the environment and its minimization for personnel for other design work to be performed, as part of work on the transformation of the Shelter object into an ecologically safe system, as well as in other projects of construction, operation and decommissioning of facilities using radiation and nuclear technologies.

Measurements of CTDI and DLP from CT image data for paediatrics radiological performance evaluation and dose optimisation in Ghana

Risk of developing cancer in paediatric patients is higher compared with adults and hence need for optimization strategies in paediatric medical imaging is very critical. The higher risk is attributable to the fact that children have developing organs and tissues which are more sensitive to the effects of radiation, and also they have longer life expectancy which allows more time for any harmful effects of radiation to manifest. Optimization of radiological protection is a means of adjusting imaging parameters and instituting protective measures such that required images are obtained with lowest possible radiation dose, and net benefit is maximized to maintain sufficient image quality for diagnostic purposes. Special consideration is given to the availability of dose reduction measures for paediatric imaging equipment. A unique aspect of paediatric imaging is with regards to the wide range in patient sizes and weights, therefore requiring special attention to optimization and modification of equipment, technique, and imaging parameters. Good radiographic technique for paediatrics include attention to patient positioning, field size and adequate collimation, use of protective shielding, optimization of exposure factors etc. In CT, dose reduction is optimized by the adjustment of scan parameters such as mA, kVp, and pitch in accordance with patient weight, age, region scanned, and study indication. Paediatric radiological imaging should therefore be performed by trained and experienced health personnel in the medical imaging department. The overall aim of the research was to enhance the capability of Ghana to improve the efficiency of existing modalities for paediatric medical imaging and to implement and enhance optimization techniques and methodologies for advanced paediatric medical imaging in CT. In addition to providing appropriate clinical recommendation for clinicians for dose management during CT scan. MVL DICOM application software was used to access image data during abdominal CT scan. Effective dose estimates were estimated as developed by ICRP 103 recommendations. The data collection was based on retrospective extraction of image data, using MVL platform where detailed information of the CTDIvol and DLP were available for recording. The weighted CTDI (CTDIW) was estimated by multiplying the volumetric CTDI (CTDIVOL) by the pitch factor. The effective dose was estimated by the product of the region-specific normalizing constant and the dose length product on each image. For image quality Signal to Noise Ratio was estimated and compare with effective dose for dose optimisation. In conclusion, the mean dose parameters exceeded the recommended dose parameter and hence an urgent need for an action to minimise radiation dose to paediatric patients.

Challenges assessing radiation risk in image-guided treatments—implications on optimisation of radiological protection

The present work explores challenges when assessing organ dose and effective dose concerning image-guided treatments. During these treatments considerable x-ray imaging is employed using technically advanced angiographic x-ray equipment. Thus, the radiation dose to organs and the related radiation risk are relatively difficult to assess. This has implications on the optimisation process, in which assessing radiation dose is one important part. In this study, endovascular aortic repair treatments were investigated. Organ dose and effective dose were assessed using Monte Carlo calculations together with a detailed specification of the exposure situation and patient size. The resulting normalised organ dose and effective dose with respect to kerma-area product for patient sizes and radiation qualities representative for the patient group were evaluated. The variability and uncertainty were investigated and their possible impact on optimisation of radiation protection was discussed. Exposure parameters, source to detector distances etc varied between treatments and also varied between image acquisitions during one treatment. Thus the derived normalised organ dose and effective dose exhibited a large range of values depending greatly on used exposure parameters and patient configuration. The derived normalised values for effective dose varied approximately between 0.05 and 0.30 mSv per Gy·cm2 when taking patient sizes and exposure parameters into consideration, the values for organ doses exhibited even larger variation. The study shows a possible systematic error for derived organ doses and effective dose up to a factor of 7 if detailed exposure or patient characteristics are not known and/or not taken into consideration. The intra-treatment variability was also substantial and the normalised dose values varied up to a factor of 2 between image acquisitions during one treatment. The study shows that the use of conversion factors that are not adapted to the clinic can cause the radiation dose to be exaggerated or underestimated considerably. A conclusion from the present study is that the systematic error could be large and should be estimated together with random errors. A large uncertainty makes it difficult to detect true differences in radiation dose between methods and technology—a prerequisite for optimising radiation protection for image-guided treatments.

Optimization of Radiological Protection in Pediatric Patients Undergoing Common Conventional Radiological Procedures: Effectiveness of Increasing the Film to Focus Distance (FFD)

Background Increasing the x-ray film to focus distance (FFD), has been recommended as a practical dose optimization tool for patients undergoing conventional radiological procedures. In the previous study, we demonstrated a 32% reduction in absorbed dose is achievable due to increasing the FFD from 100 to 130 cm during pediatric chest radiography. The aim of this study was to examine whether increasing the FFD from 100 to 130 cm is equally effective for other common radiological procedures and performing a literature review of published studies to address the feasibility and probable limitations against implementing this optimization tool in clinical practice. Materials and Methods Radiographic examination of the pelvis (AP view), abdomen (AP view), skull (AP and lateral view), and spine (AP and lateral view), were taken of pediatric patients. The radiation dose and image quality of a radiological procedure is measured in FFD of 100 cm (reference FFD) and 130 cm (increased FFD). The thermo-luminescent dosimeters (TLD) were used for radiation dose measurements and visual grading analysis (VGA) for image quality assessments. Results: Statistically significant reduction in the ESD ranged from 21.91% for the lateral skull projection to 35.24% for the lateral spine projection was obtained, when the FFD was increased from 100 to 130 cm (P 0.05). Conclusion Increasing the FFD from 100 to 130 cm has significantly reduced radiation exposure without affecting on image quality. Our findings are commensurate with the literatures and emphasized that radiographers should learn to use of an updated reference FFD of 130 cm in clinical practice.

SCATTERED X-RAY ENERGY DATA FROM INTEGRATED MULTI-FILTER PERSONAL DOSEMETERS WORN BY INTERVENTIONAL RADIOLOGY STAFF.

The accuracy and usability of scattered X-ray energy data obtained from multi-filter dosemeters were investigated by comparing the data with results obtained via Monte Carlo simulation. The energy data, which were read from integrated personal dosemeters used by interventional radiology (IR) staff in individual monitoring, were plotted against relative frequency and statistically assessed. The effective energy obtained from the multi-filter dosemeters was inversely proportional to detector size and lower than the results of the Monte Carlo simulation. All distributions of scattered X-ray energy to which the IR staff were exposed had only one peak value, which corresponded with the effective energy measured using a water phantom. For abdominal IR, there was a significant difference in the distributions between IR staff (p < 0.01). The results suggest that rectifying systematic errors resulting from oblique incidence of X-rays against the filters would make the energy data usable for optimisation of radiological protection.

Assessment of the occupational exposure in real time during interventional cardiology procedures.

Interventional cardiology (IC) procedures can be complex, requiring the operators to work near the patient, during long exposure times. Owing to scattered radiation in the patient and the fluoroscopic equipment, the medical staff are exposed to a non-uniform radiation field and can receive high radiation doses. In this study, it is proposed to analyse staff doses obtained in real time, during IC procedures. A system for occupational dosimetry in real time was used. In order to identify some parameters that may affect the staff doses, Monte Carlo (MC) calculations, using MCNPX v.2.7.0 code and voxel phantoms, were performed. The data obtained from measurements, together with MC simulations, allowed the identification of actions and behaviours of the medical staff that could be considered a risk under routine working conditions. The implementation of this monitoring system for exposure of personnel may have a positive effect on optimisation of radiological protection in fluoroscopically guided cardiac procedures.

Discussion on optimisation below dose limit for public using background-cancer-risk-based approach

To improve a radiological protection system, the lower bound of optimisation was discussed using a newly proposed background-cancer-risk-based approach. This approach provides a new finding that the standard deviation of the background cancer risk in Japan is 7.4 × 10(-5) y(-1). If this risk level corresponding to 1σ can be regarded as a non-concern level, it would be possible that the lower bound of optimisation of radiological protection could be set at 1 mSv y(-1), since the assumed risk of 1 mSv y(-1) is equivalent to ~5 × 10(-5) y(-1) obtained using the overall fatal risk coefficient of 5 % Sv(-1), which is lower than the non-concern level.

Lower Bound of Dose Constraints in Radiological Protection of the Public Taking into Consideration Dose Criteria for Exemption

The International Atomic Energy Agency (IAEA) has published a safety guide, RS-G-1.7, that gives specific values of activity concentration for radionuclides of artificial origin that may be used for bulk amounts of material for the purpose of applying exemption. The primary radiological basis for establishing these values is that the effective doses received by individuals should be of the order of 0.01 mSv or less per year. On the other hand, the International Commission on Radiological Protection (ICRP) has published the new concept of a representative person in Publication 101. This representative person is a hypothetical person exposed to a dose that is representative of the most highly exposed persons in the population. On the basis of the new concept of the ICRP, it is reasonable that, theoretically, the 95th percentile of the distribution of the dose received by the population is lower than the dose constraint, which indicates that the main part of the dose distribution is considerably lower than the dose constraint. Taking into consideration the rationale of IAEA/RS-G-1.7 and the new recommendations for probabilistic dose assessment in ICRP/Pub.101, it is possible to propose that the minimum dose constraint for the optimization of radiological protection of the public should be set to 0.1 mSv/y.

Assessing Dose of the Representative Person for the Purpose of Radiation Protection of the Public and the Optimization of Radiological Protection: Broadening the Process

New York State Department of Health; Division of Environmental Health Investigations; New York State Department of Health; 547 River Street, Room 500; Troy, NY 12180; [email protected] (The opinions expressed in this section are those of the authors and do not represent the official opinion or position of the Journal, the Health Physics Society, or the authors' institutions.)

Optimisation of Radiological Protection and the Design of Nuclear Facilities

The optimisation of protection principle, also called the ALARA principle, is now recognised as the cornerstone of radiological protection programmes implemented by companies and utilities involved in the nuclear industry. The broad aim of optimisation is to find the best use of resources in reducing exposures to individuals and the population. This should take into account both economic and social factors, such as the efficiency of protection, investments and equity in dose distributions. Because the optimisation process is source-related and of predictable nature, it is basically applicable at the design stage of projects where a wide spectrum of protection options are still possible. however, even at a preliminary stage of a project, applying ALARA implies having a fairly good knowledge about the way the equipment and the plant will be operated in the future. This is far from a straightforward task. After a brief review of the basic objectives of the ALARA principle, this paper presents a generic approach for its application at the equipment and installation design stage. The key role of past experience analysis and the use of constraints are outlined and discussed.

Optimisation of Radiological Protection and the Design of Nuclear Facilities

The optimisation of protection principle, also called the ALARA principle, is now recognised as the cornerstone of radiological protection programmes implemented by companies and utilities involved in the nuclear industry. The broad aim of optimisation is to find the best use of resources in reducing exposures to individuals and the population. This should take into account both economic and social factors, such as the efficiency of protection, investments and equity in dose distributions. Because the optimisation process is source-related and of predictable nature, it is basically applicable at the design stage of projects where a wide spectrum of protection options are still possible. however, even at a preliminary stage of a project, applying ALARA implies having a fairly good knowledge about the way the equipment and the plant will be operated in the future. This is far from a straightforward task. After a brief review of the basic objectives of the ALARA principle, this paper presents a generic approach for its application at the equipment and installation design stage. The key role of past experience analysis and the use of constraints are outlined and discussed.

Studies on optimization of radiation protection for patients in diagnostic radiology

For the exposure of patients in diagnostic radiology, individual dose limit does not apply, but optimization of radiological protection may play a major role. This project has been carried out with the purpose of improving the protection of patients in medical diagnostic radiology in China utilizing the principles of optimization. Taking Sichuan, Shandong and Beijing as surveyed areas, we investigated the present situation of the protection of patients. In the survey, the patient doses were classified into practical dose, justified dose and optimized dose to evaluate the influences of managerial and equipment factors separately. The results show that there are some urgent protection problems in X-ray pro­ tection to be solved in the surveyed regions. This paper, however, points out that the prospects of reducing patient doses are encouraging provided that appropriate measures are adopted. For instance, taking proper managerial mea­ sures without radical change of existing equipments may reduce patient doses in chest fluoroscopy and radiography by 40% and 18% respectively ; refitting some equipment may reduce the doses by 82.4% in chest fluoroscospy, 66% in chest radiography, and 80% in barium meal examination of the gastrointestinal (GI) tract. Using chest radiography instead of fluoroscopy supplemented by other protection measures may reduce the doses by 91.7%. Optimization analysis shows that adoption of the above measures conforms to the principle of optimi­ zation of radiation protection.