Development of shielding evaluation and management program for O-ring type linear accelerators.

The shielding parameters can vary depending on the geometrical structure of the linear accelerators (LINAC), treatment techniques, and beam energies. Recently, the introduction of O-ring type linear accelerators is increasing. The objective of this study is to evaluate the shielding parameters of new type of linac using a dedicated program developed by us named ORSE (O-ring type Radiation therapy equipment Shielding Evaluation). The shielding evaluation was conducted for a total of four treatment rooms including Elekta Unity, Varian Halcyon, and Accuray Tomotherapy. The developed program possesses the capability to calculate transmitted dose, maximum treatable patient capacity, and shielding wall thickness based on patient data. The doses were measured for five days using glass dosimeters to compare with the results of program. The IMRT factors and use factors obtained from patient data showed differences of up to 65.0% and 33.8%, respectively, compared to safety management report. The shielding evaluation conducted in each treatment room showed that the transmitted dose at every location was below 1% of the dose limit. The results of program and measurements showed a maximum difference of 0.003 mSv/week in transmitted dose. The ORSE program allows for the shielding evaluation results to the clinical environment of each institution based on patient data.

Occupational orthopedic problems and its relation to personal radiation protection in interventional radiology.

PURPOSE: Several studies report occupational orthopedic problems among interventional cardiologists. These health problems are usually multifactorial. However, the personal protective equipment used should play a major role. An online survey was conducted to determine the frequency of such health problems among interventional radiologists and to correlate them with the use of personal radiation protective clothing. MATERIAL AND METHODS: An anonymous online survey that comprised of 17 questions was sent via e-mail to 1427 members of the German Society for Interventional Radiology (DeGIR) in Germany, Austria and Switzerland. The questions were focused on interventional workload, the use of personal radiation protection apparel and orthopedic problems. Given the different scale levels, the associations between the variables were analyzed using different statistical methods. A significance level of p < 0.05 was chosen. RESULTS: There were 221 survey responders (15.5% response rate). About half of responders (47.7%) suffered from more than five episodes of orthopedic problems during their interventional career. Lumbar spine was involved in 81.7% of these cases, cervical spine in 32.8%, shoulder in 28.5% and knee in 24.7%. Because of orthopedic problems, 16.1% of the responders had to reduce and 2.7% had to stop their interventional practice. The number of affected body regions correlates with the fit of the radiation protection means (p < 0.05, r = 0.135) and the reduction of activity as an interventional radiologist (p < 0.05, r = -0.148). CONCLUSION: Overall, the survey reveals widespread orthopedic problems at several body regions among interventional radiologists, associated with the fit of radiation protection systems, among other factors. A connection between the orthopaedic complaints and the radiation protection system used could not be established.

Secondary proton buildup in space radiation shielding.

The risk posed by prolonged exposure to space radiation represents a significant obstacle to long-duration human space exploration. Of the ion species present in the galactic cosmic ray spectrum, relativistic protons are the most abundant and as such are a relevant point of interest with regard to the radiation protection of space crews involved in future long-term missions to the Moon, Mars, and beyond. This work compared the shielding effectiveness of a number of standard and composite materials relevant to the design and development of future spacecraft or planetary surface habitats. Absorbed dose was measured using Al2O3:C optically stimulated luminescence dosimeters behind shielding targets of varying composition and depth using the 1 GeV nominal energy proton beam available at the NASA Space Radiation Laboratory at the Brookhaven National Laboratory in New York. Absorbed dose scored from computer simulations performed using the multi-purpose Monte Carlo radiation transport code FLUKA agrees well with measurements obtained via the shielding experiments. All shielding materials tested and modeled in this study were unable to reduce absorbed dose below that measured by the (unshielded) front detector, even after depths as large as 30 g/cm2. These results could be noteworthy given the broad range of proton energies present in the galactic cosmic ray spectrum, and the potential health and safety hazard such space radiation could represent to future human space exploration.

Potential risk assessment: a model for quality evaluation in fluoroscopy-guided interventional procedures.

This study presented a model applied for potential risk assessment in an interventional radiology setting. The model of potential risk assessment (MARP) consisted of the creation of a scale of indicators ranging from 0 to 5. The radiation levels were categorized according to gender, kind of procedure, value of kerma air product (Pka), and accumulated radiation dose (mGy). The MARP model was applied in 121 institutions over 8 y. A total of 201 656 patient radiation doses (Dose-area product and accumulated kerma) data were launched into the system over time, with an average of 22 406 doses per year. In the context of the workers (cardiologists, radiographers, and nurses) monitored during the MARP application, 8007 cases (with an average of 890 per year) of occupational radiation doses were recorded. This study showed a strategy for quality evaluation in fluoroscopy using a model with a compulsory information system for monitoring safety.

Society and Nuclear Energy: What Is the Role for Radiological Protection?

ABSTRACT: The harm that society expects from ionizing radiation does not match experience. Evidently there is some basic error in this assumption. A reconsideration based on scientific principles shows how simple misunderstandings have exaggerated dangers. The consequences for society are far-reaching. The immediate impact of ionizing radiation on living tissue is destructive. However, this oxidative damage is similar to that produced during normal metabolic activity where the subsequent biological reaction is not only protective but also stimulates enhanced protection. This adaptation means that the response to oxidative damage depends on past experience. Similarly, social reaction to a radiological accident depends on the regulations and attitudes generated by the perception of previous instances. These shape whether nuclear technology and ionizing radiation are viewed as beneficial or as matters to avoid. Evidence of the spurious damage to society caused by such persistent fear in the second half of the 20 th century suggests that these laws and attitudes should be rebased on evidence. The three stages of radiological impact-the initial physical damage, the subsequent biological response, and the personal and social reaction-call on quite different logic and understanding. When these are confused, they lead to regulations and public policy decisions that are often inept, dangerous, and expensive. One example is when the mathematical rigor of physics, appropriate to the immediate impact, is misapplied to the adaptive behavior of biology. Another, the tortured historical reputation of nuclear technology, is misinterpreted as justifying a radiological protection policy of extreme caution.Specialized education and closed groups of experts tend to lock in interdisciplinary misperceptions. In the case of nuclear technology, the resulting lack of independent political confidence endangers the adoption of nuclear power as the replacement for fossil fuels. In the long term, nuclear energy is the only viable source of large-scale primary energy, but this requires a re-working of public understanding.

Replace the Linear No-threshold Model with a Risk-informed Targeted Approach to Radiation Protection.

ABSTRACT: The linear no-threshold (LNT) model may be useful as a simple basis for developing radiation protection regulations and standards, but it bears little resemblance to scientific reality and is probably overly conservative at low doses and low dose rates. This paper is an appeal for a broader view of radiation protection that involves more than just optimization of radiation dose. It is suggested that the LNT model should be replaced with a risk-informed, targeted approach to limitation of overall risks, which include radiation and other types of risks and accidents/incidents. The focus should be on protection of the individual. Limitation of overall risk does not necessarily always equate to minimization of individual or collective doses, but in some cases it might. Instead, risk assessment (hazards analysis) should be performed for each facility/and or specific job or operation (straightforward for specialized work such as radiography), and this should guide how limited resources are used to protect workers and the public. A graded approach could be used to prioritize the most significant risks and identify exposure scenarios that are unlikely or non-existent. The dose limits would then represent an acceptable level of risk, below which no further reduction in dose would be needed. Less resources should be spent on ALARA and tracking small individual and collective doses. Present dose limits are thought to be conservative and should suffice in general. Two exceptions are possibly the need for a lower (lifetime) dose limit for lens of the eye for astronauts and raising the public limit to 5 mSv y -1 from 1 mSv y -1 . This would harmonize the public limit with the current limit for the embryo fetus of the declared pregnant worker. Eight case studies are presented that emphasize how diverse and complex radiation risks can be, and in some cases, chemical and industrial risks outweigh radiation risks. More focus is needed on prevention of accidents and incidents involving a variety of types of risks. A targeted approach is needed, and commitments should be complied with until they are changed or exemptions are granted. No criticism of regulators or nuclear industry personnel is intended here. Protection of workers and the public is everyone's goal. The question is how best to accomplish that.

Radioprotection issues in uraniferous minerals collections with reference to an actual case.

Our work investigated the radioprotection implications associated with the possession of a collection of uraniferous minerals. Considering different scenarios, we developed (and applied to an actual collection) specific formulas for radiation doses evaluation. We discussed the shielding necessary to reduce the gamma irradiation down to the required values. A mathematical model was developed to estimate the minimum air flow rate to reduce the radon air concentration below the reference values. The radiation risks associated to the handling of single specimens was also addressed, including hand skin irradiation and shielding capabilities of surgical lead gloves. Finally, we discussed the radiation risks associated to the exhibition of a single specimen. The results, compared to the safety standards of the EU Directive 13/59, show that the exhibition of uraniferous samples with activity of a few MBq do not need specific radioprotection requirements nor for the involved personnel nor for visitors.

Phantom study of a self-shielded X-ray bone age assessment instrument against scattered radiation in children.

Hand-wrist radiography is the most common and accurate method for evaluating children's bone age. To reduce the scattered radiation of radiosensitive organs in bone age assessment, we designed a small X-ray instrument with radioprotection function by adding metal enclosure for X-ray shielding. We used a phantom operator to compare the scattered radiation doses received by sensitive organs under three different protection scenarios (proposed instrument, radiation personal protective equipment, no protection). The proposed instrument showed greater reduction in the mean dose of a single exposure compared with radiation personal protective equipment especially on the left side which was proximal to the X-ray machine (≥80.0% in eye and thyroid, ≥99.9% in breast and gonad). The proposed instrument provides a new pathway towards more convenient and efficient radioprotection.

Estimation of internal-exposure contribution in radiation dose exposure for boron neutron capture therapy.

Although boron neutron capture therapy (BNCT) causes minor damage to normal cells owing to the nuclear reactions induced by neutrons with major elements of tissues such as hydrogen and nitrogen, it is useful to estimate the accurate exposure dose for radiation protection. This study aims to estimate the contribution of internal exposure in radiation exposure dose for BNCT. The study was performed by referring to clinical studies at a reactor-based BNCT facility on the basis of computational dosimetry. Five irradiation regions of head and neck were selected for the estimation. The results suggest that external exposure occurred primarily in and around the irradiation field. Furthermore, during the exposure dose estimation in BNCT, internal exposure was found to be not negligible, implying that the irradiation regions in treatment planning must be considered for avoiding damage to certain critical organs that are susceptible to internal exposure.

Occupational dose measurement in interventional cardiology practice.

Ensuring the safety of healthcare workers in interventional cardiology necessitates effective monitoring of occupational radiation exposure. This study aims to assess the accuracy of the over-apron single dosimetric approach compared with double dosimetric methods and explore the relationship between under-apron and over-apron doses. This investigation showed that the prescribed annual dose constraint of 20 mSv year-1 was not exceeded by the maximum annual occupational doses determined by dosimetric algorithms, which were 0.13 ± 0.02, 0.15 ± 0.02 and 0.27 ± 0.04 mSv, respectively. The study demonstrated excellent statistically significant correlations among single and double dosimetric algorithms and between direct under-apron and over-apron doses. Consequently, single dosimetric algorithms could effectively estimate doses for double dosimetric algorithms, highlighting the limited added value of under-apron measurements. These findings significantly impact the practice of interventional cardiology in Sri Lanka, playing a crucial role in enhancing radiation protection measures.

Characterizing imaging radiation risk in a population of 8918 patients with recurrent imaging for a better effective dose.

An updated extension of effective dose was recently introduced, namely relative effective dose ( E r ), incorporating age and sex factors. In this study we extended E r application to a population of about 9000 patients who underwent multiple CT imaging exams, and we compared it with other commonly used radiation protection metrics in terms of their correlation with radiation risk. Using Monte Carlo methods, E r , dose-length-product based effective dose ( E DLP ), organ-dose based effective dose ( E OD ), and organ-dose based risk index ( RI ) were calculated for each patient. Each metric's dependency to RI was assessed in terms of its sensitivity and specificity. E r showed the best sensitivity, specificity, and agreement with RI (R2 = 0.97); while E DLP yielded the lowest specificity and, along with E OD , the lowest sensitivity. Compared to other metrics, E r provided a closer representation of patient and group risk also incorporating age and sex factors within the established framework of effective dose.

Radiation protection in CT-guided interventions: does real-time dose visualisation lead to a reduction in radiation dose to participating radiologists? A single-centre evaluation.

AIM: To evaluate if real-time dose visualisation during computed tomography (CT)-guided interventions leads to a reduction in radiation dose to participating radiologists. MATERIALS AND METHODS: The individual radiation dose radiologists are exposed to during CT interventions was measured using dedicated dosimeters (RaySafe i2-system, Unfors RaySafe GmbH, Billdal, Sweden) worn over the usual radiation protective apron. Initially, only the total radiation dose was measured, without visualisation (control group). In the following study period, the radiation dose was shown to participants on a live screen in real-time (experimental group). In both groups, the dose was recorded in 1-second intervals. The results collected were evaluated by comparison using descriptive statistics and mixed-effect models. In particular, the variables experience, gender, role, and position during the intervention were analysed. RESULTS: In total, 517 measurements of 304 interventions (n=249 with and n=268 without live screen) performed by 29 radiologists acting as interventionalists or assistants were analysed. All CT-guided interventions were performed percutaneously, the majority of which (n=280) were microwave ablations (MWA). Radiation doses in the group without visualisation were comparable with usual dose rates for the corresponding intervention type. The mean total radiation dose was reduced by 58.1% (11.6 versus 4.86 µSv) in the experimental group (p=0.034). The highest reduction of 78.5% (15.55 versus 3.35 µSv) was observed in radiologists with the role of assistant (p=0.002). Sub-analysis showed significant dose reduction (p<0.0001) for the use of live screen in general; considering all variables, the role "assistant" alone had a statistically significant influence (p=0.002). CONCLUSION: The real-time visualisation of active radiation dose during CT interventions leads to a relevant reduction in radiation dose to participating radiologists.

Radiation shielding assessment for interventional radiology personnel: Geant4 dosimetry of lead-free compositions.

The inherent biological hazards associated with ionizing radiation necessitate the implementation of effective shielding measures, particularly in medical applications. Interventional radiology, in particular, poses a unique challenge as it often exposes medical personnel to prolonged periods of high x-ray doses. Historically, lead and lead-based compounds have been the primary materials employed for shielding against photons. However, the drawbacks of lead, including its substantial weight causing personnel's inflexibility and its toxicity, have raised concerns regarding its long-term impact on both human health and the environment. Barium tantalate has emerged as a promising alternative, due to its unique attenuation properties against low-energy x-rays, specifically targeting the weak absorption area of lead. In the present study, we employ the Geant4 Monte Carlo simulation tool to investigate various formulations of barium tantalate doped with rare earth elements. The aim is to identify the optimal composition for shielding x-rays in the context of interventional radiology. To achieve this, we employ a reference x-ray spectrum typical of interventional radiology procedures, with energies extending up to 90 keV, within a carefully designed simulation setup. Our primary performance indicator is the reduction in air kerma transmission. Furthermore, we assess the absorbed doses to critical organs at risk within a standard human body phantom protected by the shield. Our results demonstrate that specific concentrations of the examined rare earth impurities can enhance the shielding performance of barium tantalate. To mitigate x-ray exposure in interventional radiology, our analysis reveals that the most effective shielding performance is achieved when using barium tantalate compositions containing 15% Erbium or 10% Samarium by weight. These findings suggest the possibility of developing lead-free shielding solutions or apron for interventional radiology personnel, offering a remarkable reduction in weight (exceeding 30%) while maintaining shielding performance at levels comparable to traditional lead-based materials.

Directional vector visualization of scattered rays in mobile c-arm fluoroscopy.

Previous radiation protection-measure studies for medical staff who perform X-ray fluoroscopy have employed simulations to investigate the use of protective plates and their shielding effectiveness. Incorporating directional information enables users to gain a clearer understanding of how to position protective plates effectively. Therefore, in this study, we propose the visualization of the directional vectors of scattered rays. X-ray fluoroscopy was performed; the particle and heavy-ion transport code system was used in Monte Carlo simulations to reproduce the behavior of scattered rays in an X-ray room by reproducing a C-arm X-ray fluoroscopy system. Using the calculated results of the scattered-ray behavior, the vectors of photons scattered from the phantom were visualized in three dimensions. A model of the physician was placed on the directional vectors and dose distribution maps to confirm the direction of the scattered rays toward the physician when the protective plate was in place. Simulation accuracy was confirmed by measuring the ambient dose equivalent and comparing the measured and calculated values (agreed within 10%). The directional vectors of the scattered rays radiated outward from the phantom, confirming a large amount of backscatter radiation. The use of a protective plate between the patient and the physician's head part increased the shielding effect, thereby enhancing radiation protection for the physicians compared to cases without the protective plate. The use of directional vectors and the surrounding dose-equivalent distribution of this method can elucidate the appropriate use of radiation protection plates.

On methods for radiometric surveying in radiotherapy bunkers.

Radiometric surveys in radiotherapy bunkers have been carried out in Brazil for many years, both by the same radiotherapy facility for verification of shielding as by the regulatory agency for licensing and control purposes. In recent years, the Intensity Modulated Radiation Therapy (IMRT) technique has been gradually incorporated into many facilities. Therefore, it has been necessary to consider the increased leakage component that has an important impact on the secondary walls. For that, a radiometric survey method has been used that considers an increased 'time of beam-on' for the secondary walls. In this work we discuss two methods of doing this: the first considers that this 'time of beam-on' affects the sum of the two components, leakage and scattered. In another method it is considered that only the leakage component is affected by this extended 'time of beam-on'. We compare the methods and show that for secondary walls withU= 1 the first method overestimates dose rates by important percentages and for secondary walls withU< 1 it can both overestimate or underestimate the dose rates, depending on the parameters of the project. An optimized procedure is proposed, according to the use factor (U) of the secondary wall to be measured.

Assessment of dosimetric approaches in evaluating radiation exposure for interventional cardiologists in Sri Lanka.

Interventional cardiologists face significant radiation exposure during interventional cardiology procedures. Therefore, this study focuses on assessing radiation exposure among interventional cardiologists during their procedures. Specifically, it aims to determine the effectiveness of both single and double dosimeter methods in estimating annual occupational radiation doses. This research holds pioneering significance as it represents the very first study undertaken in Sri Lanka. Thirteen interventional cardiologists performed 486 interventional cardiology procedures over three months in three different healthcare institutes. Active Hp(10) dosimeters were placed to measure radiation exposure. Effective doses were calculated using single and double dosimetric algorithms. Annual occupational doses were assessed on an operator basis. Statistical analyses were conducted to assess algorithmic differences and dose variations using the Kruskal-Wallis test and linear regression. The highest annual occupational dose for each dosimetric algorithm received as 2.00 ± 0.24 mSv, 2.29 ± 0.48 mSv, 3.35 ± 0.71 mSv, and 2.64 ± 0.42 mSv, respectively, and remained below the recommended safety limit of 20 mSv/year. The Kruskal-Wallis test revealed no significant differences in the effective doses among double dosimetric algorithms, as well as between single and double dosimetric algorithms (p > 0.05). Linear regression showed strong correlations among various algorithms, demonstrating consistency. The findings of this study hold significant effects on interventional cardiology practice in Sri Lanka, enhancing radiation safety and monitoring.

Assessment of Radiation Doses to the General Public around Nuclear Power Plants Based on Representative Person Concept.

ABSTRACT: The International Commission on Radiological Protection recommended that the representative person concept should be used in radiation dose assessment of the general public to specify exposed individuals. The objective of this study is to assess radiation doses of the residents around nuclear power plants (NPPs) in relation to the introduction of the representative person concept. Critical group candidates and representative agro-livestock product producing areas were selected around a NPP site by considering radioactive effluents and regional meteorological data, geographical information, etc. A total of five exposure scenarios, including adult (non-fishery, fishery, and commuter), 10-y-old, and 1-y-old groups, were selected for the dose assessment. Generally, radiation doses were higher for 1-y-old, 10-y-old, and adult groups, in that sequence. There was no significant difference among the radiation doses by occupation in adult groups. Radiation dose results calculated by applying the representative person concept and dose assessment method currently used in Korea were compared. Application of the representative person concept results in lower radiation dose by 68.2% due to consideration of actual residential and agro-livestock product producing areas for the radiation dose assessment, by 13.3% due to the application method of habit data for dose calculation, and by 33.3% due to representative value of the dose results. Finally, considering all the factors above, radiation dose calculated by the current dose assessment method was 8.16 × 10 -2 mSv y -1 , while that calculated using the representative person concept was 1.40 × 10 -2 mSv y - 1 (82.8% lower). The results of this study can be used as reference data when introducing the representative person concept to the regulatory systems in Korea.

A report on a survey among Portuguese Association of Interventional Cardiology associates regarding ionizing radiation protection practices in national interventional cath-labs.

INTRODUCTION AND OBJECTIVES: Concerns surrounding the consequences of ionizing radiation (IR) have increased in interventional cardiology (IC). Despite this, the ever-growing complexity of diseases as well as procedures can lead to greater exposure to radiation. The aim of this survey, led by Portuguese Association of Interventional Cardiology (APIC), was to evaluate the level of awareness and current practices on IR protection among its members. METHODS: An online survey was emailed to all APIC members, between August and November 2021. The questionnaire consisted of 50 questions focusing on knowledge and measures of IR protection in the catheterization laboratory. Results were analyzed using descriptive statistics. RESULTS: From a response rate of 46.9%, the study obtained a total sample of 159 responses (156 selected for analysis). Most survey respondents (66.0%) were unaware of the radiation exposure category, and only 60.4% reported systematically using a dosimeter. A large majority (90.4%) employed techniques to minimize exposure to radiation. All participants used personal protective equipment, despite eyewear protection only being used frequently by 49.2% of main operators. Ceiling suspended shields and table protectors were often used. Only two-thirds were familiar with the legally established limit on radiation doses for workers or the dose that should trigger patient follow-up. Most of the survey respondents had a non-certified training in IR procedures and only 32.0% had attended their yearly occupational health consultation. CONCLUSIONS: Safety methods and protective equipment are largely adopted among interventional cardiologists, who have shown some IR awareness. Despite this, there is room for improvement, especially concerning the use of eyewear protection, monitoring, and certification.

The Effect of a Suspended Radiation Protection System on Occupational Radiation Doses During Infrarenal EVAR Procedures: A Randomised Controlled Study.

OBJECTIVE: To compare the protective effect of Zero Gravity (ZG) with conventional radiation protection during endovascular aneurysm repair (EVAR). Secondly, user experience was surveyed with a questionnaire on ergonomics. METHODS: This was a single centre, prospective, randomised, two arm trial where 71 consecutive elective infrarenal EVAR procedures were randomised into two groups: (1) operator using ZG and assistant using conventional protection (n = 36), and (2) operator and assistant using conventional radiation protection (n = 35). A movable floor unit ZG system consists of a lead shield (1.0 mm Pb equivalent) for the front of the body and 0.5 mm Pb equivalent acrylic shielding for the head and neck. The ZG also includes arm flaps of 0.5 mm Pb equivalent covering the arm up to the elbow. Deep dose equivalent values, Hp(10) were measured with direct ion storage dosimeters (DIS) placed on various anatomical regions of the operator (axilla, chest, abdomen, and lower leg). Personal dose equivalent values, Hp(3) to eye lenses were measured in the operating and assisting surgeon using thermoluminescence dosimeters. The study was registered at the US National Institute of Health #NCT04078165. RESULTS: Protection with the standard protection was superior in chest (0.0 vs. 0.1 µSv), abdomen (0.0 vs. 0.6 µSv), and lower leg (0.4 vs. 2.2 µSv) (p < .001). On the other hand, the ZG system yielded better shielding for the axilla (1.5 vs. 0.0 µSv) and eyes (6.3 vs. 1.1 µSv) of the operator. The use of ZG hampered the deployment of ancillary shields, which is particularly relevant for protection of the assisting surgeon. Users found ZG more cumbersome than conventional garments, it also impaired communication and reduced field of view. CONCLUSION: Both ZG and conventional radiation protection reduced radiation exposure. Conventional protection allows better manoeuvrability at the price of wider exposure of the upper arm and axilla. ZG indirectly impaired protection of the assistant.