National Council On Radiation Protection Research Articles

National Council on Radiation Protection (NCRP) 2024 annual meeting: advanced and small modular nuclear power reactors**The authors have confirmed that any identifiable participants in this study have given their consent for publication.

On 25-26 March 2023, the U.S. National Council on Radiation Protection and Measurements (NCRP) held its 2024 annual meeting in Bethesda, Maryland, USA. The NCRP dates from 1929, and this meeting celebrated the 60th anniversary of receiving a U.S. Congressional Charter. For this annual meeting the NCRP felt it was essential to provide a briefing about advanced and small modular nuclear reactors (SMRs). The Journal of Radiological Protection is delighted to publish the following synopsis of material presented at the U.S. NCRP meeting. This synopsis is divided into five sections. The first section provides an overview of the whole meeting together with summaries of two context setting overview papers. The following four sessions of this synopsis are specific to advanced and small modular nuclear power reactors. The meeting also included keynote presentations by three of NCRP annual award recipients. The meeting topical areas were Technology Overview and Critical Issues. The individual papers laid the groundwork to understanding reactor technologies, terminology, and the fundamental concepts and processes for electrical generation. The perspectives of the U.S. Environmental Protection Agency and states, through the Conference of Radiation Control Program Directors were provided. The papers included a discussion of diverse topics including potential emergency preparedness considerations, radiological survey requirements, an evaluation of the future of nuclear power, the economics of reactors (both large and small), and the critical issues identified by the recent National Academies of Sciences' study on advanced reactors. The summary papers were developed to briefly document the major points and concepts presented during the oral papers presented at the 2024 NCRP Annual Meeting. The meeting heralded the dawn of a new era for commercial nuclear power.

Assessment of Radiographic Film Quality in Some Selected Hospitals in Benue State

The essence of diagnostic radiology is to obtain a high quality image with low radiation dose to patient. Since radiology is aimed in producing images which provide adequate information for the clinical purpose with minimum radiation dose to the patient, we seek to assess the high image qualities that are produced in the darkroom. The processing time and the temperature, at which these films were processed, stored and also evaluated, were carried out in the darkroom. Agfa films were used throughout the procedure in four different hospitals, H-1, H-2, H-3 and H-4 and the processing chemicals were observed for the period of a month. Therefore, in H-1, the average temperature was found to be 29oC, average temperature was 26oC in H-2; in H-3, average temperature was 30oC and the average temperature in H-4 was found to be 29oC which all fall above the standard temperature limit (25oC) as recommended by National Council on Radiation Protection (NCRP). From the experimental proceedings in the darkroom, the distance from safelight to workbench, it shows that H-1 and H-2 do not conform to the standard while H-3 and H-4 are in conformity. The result obtained from darkroom fog test shows that, the Optical Density Difference (ODD) for H-1, H-2, H-3 and H-4 was found to be 0.16, 0.07, 0.18 and 0.35 respectively, which were all found to be above the ICRP standard limit (0.05). This implies that, most hospitals in Makurdi operates below the set darkroom practices as recommended by NCRP and ICRP which affects the quality of image as a result of high temperature, poor concentration in processing chemicals and some effect of fogging in the darkroom which needs to be checked.

Determination of Activity Levels 226ra, 232th and 40k in some Soil Samples of Federal Polytechnic Kaltungo Main Campus Using Gamma Ray Spectrometry

This paper presents an investigation on radioactivity level of radioactive elements within Federal Polytechnic Kaltungo Main Campus. A total of forty (40) soil samples were analyzed using Gamma-Ray Spectrometry of 76×76mmNaI (TI) detector crystal with radioactivity activity concentration of potassium (40K), Radium (226Ra) and Thorium (232Th) were determined within the study area. Results obtained showed the highest activity concentration of 40K, 226Ra, and 232Th from locations AB3 (898.7365 Bq/kg), AB3 (107.7457 Bq/kg) and AB2 (243.1510 Bq/kg) respectively. The mean activity of 206.7681 Bq/kg obtained for 40K was seen to be lower than the world average of 420 Bq/kg while the mean activity concentrations of 232Th (95.393 Bq/kg) was above the world average of 50 Bq/kg. These upshots could be attributed to the presence of mountains which surround the polytechnic and the quarry activity taking place close to the polytechnic. Equally, Thorium. 226 Ra also had a lowest mean activity concentration of 43.8600 Bq/kg, which is also lower than the world average of 370 Bq/kg. In-situ dose rate measurement of the study area was also carried out using a Radiation Alert Inspector meter and the background radiation reading obtained was seen to fall within a range of 0.11µsv/hr - 0.21µsv/hr, which did not exceed the 1mSv/yr as recommended by National Council on Radiation Protection (NCRP).

Optimized radiological alert thresholds based on device-dosimetric information to predict peak skin dose between 2 and 4Gy during vascular fluoroscopically guided intervention.

To provide radiologists and physicists with methodological tools to improve patient management after vascular fluoroscopically guided intervention (FGI) by providing optimized thresholds (OT) values that could be used as a surrogate to the thresholds classically proposed by the National Council on Radiation Protection (NCRP) or could be useful to adapt their own substantial radiation dose levels (SRDL) values. PSD of 2000-4000mGy after FGI were calculated for 258 patients with dedicated software. Overall, the kerma and KAP 3D-ROC curves were used to assess the sensitivity (SEN) and specificity (SPE) of NCRP thresholds and OT for each PSD. Kiviat diagram and density curves were plotted for the best SEN/SPE pair of 3D-ROC curves and compared to the NCRP thresholds. OT for both kerma and KAP generating the best SEN/SPE couple for PSD of 2000-4000mGy were obtained. The SEN/SPE couple of each OT was always better than that obtained using NCRP ones. The best OT among all those calculated providing the highest SEN/SPE values for kerma (3020.5mGy) and KAP (741.02Gy.cm2) were obtained when PSD was equal to 3300mGy. We have calculated OT in terms of kerma and KAP based on 3D-ROC curves analysis and peak skin dose calculations that can be obtained to better predict high skin dose. The use of OT that predicted PSD greater than 3000mGy is likely to improve patient follow-up. The methodology developed in this work could be adapted to other institutions in order to better define their own SRDL. • Optimized dose thresholds in terms of kerma and KAP based on 3D-ROC curves analysis and peak skin dose calculations between 2000 and 4000mGy can be obtained to better predict high skin dose. • Patients receiving a peak skin dose between 2000 and 4000mGy have their follow-up enhanced by using the optimized thresholds instead of the NCRP thresholds. • The best-optimized thresholds, corresponding to 3020.5mGy and 741.02Gy.cm2 for kerma and KAP respectively can be used instead of NRCP ones to trigger patient follow-up after fluoroscopically guided vascular interventions.

Optimized radiological alert thresholds based on device dosimetric information and peak skin dose in vascular fluoroscopically guided intervention.

The National Council on Radiation Protection (NCRP) report no. 168 recommended that during fluoroscopically guided interventions (FGIs), each patient should be monitored when one of the following thresholds is reached: an air kerma > 5Gy, a kerma area product (KAP) > 500Gy.cm2, a fluoroscopy time > 60min, or a peak skin dose (PSD) > 3Gy. Whereas PSD is the most accurate metric regarding the prevention of radiological risks, it remains the most difficult parameter to assess. We aimed to evaluate the relevance of the other, more accessible metrics and propose new optimized threshold (OT) for improved patient follow-up. Overall, 108 patients who underwent FGI in which at least one NCRP threshold was reached and PSD was measured were considered. The correlation between all metrics was assessed using principal component analysis (PCA). ROC curves and the sensitivity/specificity of both NCRP and OT to predict PSD > 3Gy were evaluated. The PCA shows that FGI can be decomposed with two components based on time and dose variables. Only KAP and kerma were correlated with PSD. The overall sensitivity and specificity of the new OT regarding KAP (67.6/93.0), kerma (97.3/81.7), and time (62.2/62.0) were better compared with NCRP thresholds (97.3/16.9, 40.5/95.4, and 21.6/74.7). This study shows that fluoroscopy time is not a relevant metric when used to predict PSDs > 3Gy. By adapting KAP and kerma thresholds to predict PSD over 3Gy, patient follow-ups following vascular FGI can be improved. • In vascular fluoroscopically guided interventions, principal component analysis demonstrates that between fluoroscopy time, KAP, and kerma, only the two last were correlated to the peak skin dose. • Optimized thresholds replacing NRCP ones obtained with ROC curves analysis were 85,451μGy.cm2, 2938mGy, and 41min for KAP, kerma, and fluoroscopy time respectively. • Improvements to trigger patient follow-up after vascular fluoroscopically guided interventions may be obtained by using the optimized thresholds.

Knowledge, Attitude, and Practice (KAP) of Radiographic Protection by Dental Undergraduate and Endodontic Postgraduate Students, General Practitioners, and Endodontists.

The aim of this study is to evaluate the knowledge, attitude, and perception of radiation hazard and preventive measures among dental undergraduate students, general practitioners, endodontic postgraduate students, and endodontists in Saudi Arabia. Multiple choice questions questionnaires were distributed among undergraduate and endodontic postgraduate dental students, general practitioners, and endodontists in the colleges of dentistry in Saudi Arabia, government hospitals, and private clinics. The questionnaire included sociodemographic data, assessment of the knowledge of radiation physics and biology, assessment of the practice of dental radiography, and assessment of knowledge of radiation protection. Chi-square test was used for individual and multiresponse analysis. Level of statistical significance was set at P ≤ 0.05. Three hundred and twenty-nine responded to the questionnaire. More than half of the respondents agreed that dental X-ray is hazardous to health (60.79%), and 68.1% were familiar with ALARA (as low as reasonably achievable) principle. However, only 34% are familiar with the recommendations of the National Council on Radiation Protection (NCRP) and International Commission on Radiological Protection (ICRP). The use of lead apron and thyroid collar for patients' protection from X-ray radiation was practiced among endodontic postgraduate students more frequently as well as those who are proactive in the academic field. Undergraduate students, endodontic postgraduate students, and endodontists in the academic field were the most aware towards radiation reduction measures. The use of the preventive measures needs to be emphasized more among general practitioners, endodontic postgraduate students, and endodontists especially in governmental hospitals and private sectors.

ANALYSIS OF URINARY EXCRETION DATA FROM THREE PLUTONIUM-CONTAMINATED WOUNDS AT LOS ALAMOS NATIONAL LABORATORY.

The National Council on Radiation Protection (NCRP)-156 Report proposes seven different biokinetic models for wound cases depending on the physicochemistry of the contaminant. Because the models were heavily based on experimental animal data, the authors of the report encouraged application and validation of the models using bioassay data from actual human exposures. Each of the wound models was applied to three plutonium-contaminated wounds, and the models resulted in a good agreement to only one of the cases. We then applied a simpler biokinetic model structure to the bioassay data and showed that fitting the transfer rates from this model structure yielded better agreement with the data than does the best-fitting NCRP-156 model. Because the biokinetics of radioactive material in each wound is different, it is impractical to propose a discrete set of model parameters to describe the biokinetics of radionuclides in all wounds, and thus each wound should be treated empirically.

Estimation of induced air activity in 30 MeV proton accelerator: Comparative study of Monte Carlo simulations and analytical calculations

The induced radioactivity concentrations of 41Ar, 13N, and 15O in air in 30 MeV proton accelerator vaults has been estimated using Fluka Monte Carlo simulations and National Council on Radiation Protection (NCRP) 144 based analytical methods. The results obtained by these methods are compared and discussed. It is found that analytical calculations using NCRP 144 guidelines underestimate the 41Ar concentrations about three times while 15O concentrations are overestimated about ten times when compared to Monte Carlo estimates. However, the 13N concentrations estimated by both the methods are found to be in good agreement. It is seen that the analytical calculations ignore the significantly large contribution of 41Ar formation by the neutrons above thermal energy. The overestimation of 15O is caused by the large cross-section value assigned in the analytical calculations.

Structural Shielding Design of a 6 MV Flattening Filter Free Linear Accelerator: Indian Scenario.

Detailed structural shielding of primary and secondary barriers for a 6 MV medical linear accelerator (LINAC) operated with flattening filter (FF) and flattening filter free (FFF) modes are calculated. The calculations have been carried out by two methods, one using the approach given in National Council on Radiation Protection (NCRP) Report No. 151 and the other based on the monitor units (MUs) delivered in clinical practice. Radiation survey of the installations was also carried out. NCRP approach suggests that the primary and secondary barrier thicknesses are higher by 24% and 26%. respectively, for a LINAC operated in FF mode to that of a LINAC operated in both FF and FFF modes with an assumption that only 20% of the workload is shared in FFF mode. Primary and secondary barrier thicknesses calculated from MUs delivered on clinical practice method also show the same trend and are higher by 20% and 19%, respectively, for a LINAC operated in FF mode to that of a LINAC operated in both FF and FFF modes. Overall, the barrier thickness for a LINAC operated in FF mode is higher about 20% to that of a LINAC operated in both FF and FFF modes.

PD4-04 USE OF FLUOROSCOPY AND POTENTIAL LONG-TERM RADIATION EFFECTS ON CATARACT FORMATION

INTRODUCTION AND OBJECTIVES: The increased use of fluoroscopy exposes practicing urologists to frequent radiation exposure. The human eye is a highly radiosensitive part of the body and long-term exposure to radiation can initiate cataract formation. Many physicians now wear lead lined glasses for safety. We explored the radiation exposure of urologists at our institution to determine whether they are at an increased risk for cataract formation. METHODS: A retrospective review of a multi-surgeon, prospectively maintained database of fluoroscopic cases between 10/ 2013 to 10/2014 identified a total of 691 cases. The screening time, kV and mA were recorded from all cases in the operating room. The procedures were performed by different subspecialties of urology and included stent insertion, ureteroscopic lithotripsy, and percutaneous nephrolithotomy. We calculated the radiation dosimetry of urologists through the methods described by the National Council on Radiation Protection (NCRP) and extrapolated the dose exposure to determine risk of cataract formation. For the calculated dosimetry, technical specifications of the GE OEC 990 mobile C-arm unit were used. The surgeon was assumed to be standing at a distance of 75 cm with a scattering angle of 45 degrees to estimate the radiation dose to the surgeon’s eye. RESULTS: The average fluoroscopic time was 35.35 seconds per case. The average tube potential and tube current was 89.69 kV and 1.96 mA, respectively. Pediatric urologists used the least amount of fluoroscopic time, 11.86 seconds per case (p 1⁄4 0.0047). Endourology fellowship trained urologists utilized the longest time of fluoroscopy, 70.33 seconds per case (p < 0.0001), while non-endourologists utilized 27.24 seconds per case (p < 0.0001). This may be related to the complexity of the cases. The tube potential and current for endourology cases were recorded as 91.34 kV and 1.81 mA (p1⁄40.11). The total number of endourology cases over the past year was 131. Using this data, we then calculated the estimated radiation dose to the eyes for the most highly exposed urologists at our institution to be 5.64 mGy per case. For the past year, the total estimated cumulative dose would then be 738.84 mGy. CONCLUSIONS: Yearly eye exposure limits are currently defined at 150 mSv by the NCRP. Over the past year, our highest exposed urologists compiled an estimated dose of 0.5% of the annual limit. We conclude that fluoroscopy is a safe method in the urological field. With the use of newer radiation technologies and sensible radiation principles, the risk to the surgeon is diminishing.

Construction Shielding Design for Medical X-Ray Imaging Equipment

There are analytic methods for designing protective barriers however, they lack sufficient efficiency and considering the NCRP (National Council on Radiation Protection and measurements) reports, designing mechanical protective barrier in order to protect the initial x-ray radiation and absorption of the ray quality of such radiation is different. In this study, computer software was designed to calculate the needed barrier with high accuracy. For proper determination of thickness of the protective barrier, relevant information about curves of radiation weakness, dose limit and other items should be entered. This program was done in windows and designed in such a way that the operator works easily, flexibility of the program is acceptable and its accuracy and sensitivity is high. Meanwhile sometimes shielding is more than what required which lacks technical standards and cost effectiveness. When the application index is contrasting zero, thickness of NCRP49 calculation is about 20% less than the calculated rate done by the method of this study. The multi radiation sources in a single room are considered and non guaranteed radiation of NCRP hypothesis is removed. Difference between the theoretical and calculated rates of this method is X2 =10-5 which indicates accuracy and high efficiency of this software.

Comparison of different methods for shielding design in computed tomography

The purpose of this work is to compare different methods for shielding calculation in computed tomography (CT). The BIR-IPEM (British Institute of Radiology and Institute of Physics in Engineering in Medicine) and NCRP (National Council on Radiation Protection) method were used for shielding thickness calculation. Scattered dose levels and calculated barrier thickness were also compared with those obtained by scatter dose measurements in the vicinity of a dedicated CT unit. Minimal requirement for protective barriers based on BIR-IPEM method ranged between 1.1 and 1.4 mm of lead demonstrating underestimation of up to 20 % and overestimation of up to 30 % when compared with thicknesses based on measured dose levels. For NCRP method, calculated thicknesses were 33 % higher (27-42 %). BIR-IPEM methodology-based results were comparable with values based on scattered dose measurements, while results obtained using NCRP methodology demonstrated an overestimation of the minimal required barrier thickness.

PANEL SESSION ON INTERNATIONAL PERSPECTIVES ON THE FUTURE OF NUCLEAR POWER

The 2009 National Council on Radiation Protection (NCRP) Annual Meeting provided an opportunity to exchange viewpoints and consider current information regarding the evolution of selected commercial nuclear power trends worldwide. Within the overall topical context of radiation-related regulation, focus was placed on activities in the United Kingdom, Japan, and the United States, although general global developments were reviewed to some extent. This paper provides the reader with a sense of these activities as described by the authors and presenters: David Bennett (Environmental Agency, United Kingdom), Alan Hanson (AREVA), Shojiro Matsuura (Japan Nuclear Safety Research Association), and Alexander Marion (Nuclear Energy Institute).

Radiation Exposure Dose Trends and Radiation Dose Reduction Strategies in Medical Imaging

Since the discovery of x-rays, many investigations of radiation effects on humans have taken place. From the discovery of severe x-ray dermatitis near the end of 1896, the multiple radiation burns endured by Thomas Edison's assistant, Clarence Dally, to the establishment of early radiation regulation in 1929, radiation exposure has been a continuing concern. Studies from the 1940s to the 1960s looked at effects such as leukemia and other cancers that appeared to be caused by exposure to radiation; outcomes of these studies resulted in increased regulation, establishment of dose tolerances and the development of the National Council on Radiation Protection (NCRP). Since the 1960s, similar studies have continued resulting in stricter dose limits. However, a recent resurgence of radiation exposure injuries led to this literature review that revealed a gap in the literature concerning the radiation practices and continued education of today's radiologic technologists. Through this review, recommendations for dose reduction strategies are included.

An estimation of the annual effective dose to the Canadian population from medical CTexaminations

This study was carried out to assess the annual per capita effective dose frommedical diagnostic procedures using computed tomography (CT) in Canada.Relevant data concerning the nature and the frequency of various diagnostic CTexaminations were obtained from the reports on Medical Imaging in Canada andDiagnostic Services in Ontario. Doses associated with examinations of differenttypes were based primarily on typical effective doses used in the National Councilon Radiation Protection and Measurements Report 160 with considerations oflimited dose information surveyed in Canada. The results show that the per capitaannual effective dose from diagnostic CT exams was 0.74 mSv in 2006, up from0.19 mSv in 1991. This significant increase in population radiation dose from CTscans is due mainly to a more than doubling in the examination rate and to ahigher radiation dose per procedure from the newer generation of multi-detectorCTs.

Radiation exposure in emergency physicians working in an urban ED: a prospective cohort study

Objective The National Council on Radiation Protection (NCRP) limits health care–associated occupational exposures to radiation to 5000 mrem/y. Previous studies suggested that emergency physicians were not exposed over this limit. Their relevance to contemporary practice is unknown. We hypothesized that emergency physicians are currently exposed to radiation levels above the NCRP limits. Methods This prospective cohort study was conducted at an urban, academic, level I trauma center emergency department (ED). Thermoluminescent dosimeter radiation badges were placed on the torso and ring finger of all physicians staffing the ED during May 2008. Thermoluminescent dosimeter badges were affixed to 8 portable phones that are carried by physicians in the ED 24 hours a day. At the end of the study period, exposure dose for each subject was estimated. Results Seventy-five physicians enrolled in the study; 41 residents worked a median of 94 hours and 34 attendings worked a median of 54 hours. Compliance for physician badge wearing was 99%, ring wearing was 98%, and phone wearing was 100%. Two subjects had detectable levels of radiation on their torso thermoluminescent dosimeters of 4 and 1 mrem, respectively. One phone badge had a detectable level of 1 mrem. The annual extrapolated exposure for the subject with the highest radiation level would have been 50 mrem, below the 5000 mrem exposure limit for health care workers. Conclusion Emergency physicians working in an urban, academic, level I trauma center ED do not appear to be at risk of exceeding the NCRP dose limits for ionizing radiation exposure to their torso or extremities.

128: Radiation Exposure in Emergency Physicians Working in an Urban Emergency Department: A Prospective Cohort Study

The National Council on Radiation Protection (NCRP) has established limits on health care associated occupational exposures to radiation of 5000 mrem/year. While prior studies suggest that emergency physicians were not exposed over this limit, their relevance to contemporary practice is unknown. Due to increased radiographic imaging in the emergency department (ED), we hypothesized that resident and attending emergency physicians are currently exposed to radiation levels above the acceptable limits for health care workers.

A comparison of shielding calculation methods for multi-slice computed tomography (CT)systems

Currently in the UK, shielding calculations for computed tomography (CT) systems arebased on the BIR–IPEM (British Institute of Radiology and Institute of Physics inEngineering in Medicine) working group publication from 2000. Concerns have been raisedinternationally regarding the accuracy of the dose plots on which this method depends andthe effect that new scanner technologies may have. Additionally, more recent shieldingmethods have been proposed by the NCRP (National Council on Radiation Protection)from the USA. Thermoluminescent detectors (TLDs) were placed in three CT scannerrooms at different positions for several weeks before being processed. Patient workload anddose data (DLP: the dose length product and mAs: the tube current–time product) werecollected for this period. Individual dose data were available for more than 95% ofpatients scanned and the remainder were estimated. The patient workload datawere used to calculate expected scatter radiation for each TLD location by boththe NCRP and BIR–IPEM methods. The results were then compared to themeasured scattered radiation. Calculated scattered air kerma and the minimumrequired lead shielding were found to be frequently overestimated compared to themeasured air kerma, on average almost five times the measured scattered air kerma.

PREDICTION OF RENAL CONCENTRATIONS OF DEPLETED URANIUM AND RADIATION DOSE IN GULF WAR VETERANS WITH EMBEDDED SHRAPNEL

Mobilization of uranium (U) from embedded depleted uranium (DU) metal fragments in Gulf War veterans presents a unique exposure scenario for this radioactive and nephrotoxic metal. In a cohort of exposed veterans, urine U concentrations measured every two years since 1993 persistently range from 10 to over 500 times normal levels, indicating that embedded DU fragments give rise to chronic, systemic exposure to U. Health effects of this exposure are not fully known, but clinical surveillance of these soldiers continues in light of animal studies showing that U released from implanted DU pellets results in tissue accumulation of U. The biokinetic model for uranium recommended by the International Commission on Radiological Protection was used to predict kidney U concentrations and tissue radiation doses in veterans with DU shrapnel based on their urine U excretion. Results suggest that kidney U concentrations in some individuals reached their peak within six years after the war, while in others, concentrations continue to increase and are approaching 1 ppm after 10 y. These results are consistent with urine biomarker tests of renal proximal tubular cell function and cytotoxicity which have shown elevated mean urinary protein excretion indicative of functional effects in veterans with high urine U concentrations (> or =0.10 microg g(-1) creatinine). Predicted lifetime effective radiation dose from DU released to the blood for the highest exposed individual in this cohort was substantially less than the National Council on Radiation Protection (NCRP) limit for occupational exposure. These results provide further support for current health protection guidelines for DU, which are based on the metal's chemical rather than its radiological toxicity. In light of the potential for continued accumulation of U in the kidney to concentrations approaching the traditional guidance level of 3 ppm U, these results indicate the need for continued surveillance of this population for evidence of developing renal dysfunction.

Radiation Exposure and Cancer: Case Study

Received for publication April 27, 2001, and accepted for publica-tion August 29, 2001.Abbreviations: ALARA, as low as reasonably achievable; BEIR,Biological Effects of Ionizing Radiation; ICRP, InternationalCommission on Radiation Protection; NCRP, National Council onRadiation Protection and Measurements; UNSCEAR, UnitedNations Scientific Committee on the Effects of Atomic Radiation.