Health Physics

Vetter, Richard J.; Bushberg, Jerrold T.; Mettler, Fred A.

doi: 10.1097/HP.0000000000001239pmid: 32118678

Abstract The National Council on Radiation Protection and Measurements (NCRP) held its 55th Annual Meeting 1-2 April 2019 in Bethesda, Maryland. The 2019 meeting was a special year for NCRP as it marked the 90th Anniversary of the founding of the predecessor organization, US Advisory Committee on X-Ray and Radium Protection. Leaders for the scientific portion of the meeting were Fred A. Mettler, Jr., M.D. (Chair), University of New Mexico School of Medicine; Jerrold T. Bushberg, Ph.D. (Co-Chair), University of California Davis; and Richard J. Vetter, Ph.D. (Co-Chair), Mayo Clinic. The meeting was designed to explore important areas of inquiry associated with use of ionizing radiation relevant to radiation protection, addressing frequently asked questions and concerns from both members of the public and radiation professionals. The meeting was organized into six sessions plus three honorary lectures and a special presentation. This paper summarizes the scientific content of the six sessions and is based on the notes of the co-chairs and the slides of the speakers. The three honorary lectures are included as other papers in this issue.

Coleman, C. Norman

doi: 10.1097/HP.0000000000001240pmid: 32039927

Abstract On the occasion of the 90th anniversary of National Council on Radiation Protection and Measurements (NCRP) and its 55th anniversary since being Congressionally Chartered, the theme of “Providing Best Answers to Your Most Pressing Questions about Radiation” is most appropriate. The question proposed here is, “What are the new frontiers for the NCRP with its breadth of talent and expertise in the rapidly evolving era of precision medicine?” Three closely related themes are presented for new applications of radiation science for research and career opportunities: (1) introduction of the new concept of defining radiation dose in biological perturbations in addition to physical dose, particularly for cancer treatment; (2) assessment of early biomarkers of radiation injury for mass casualty exposure (biodosimetry) to guide triage and for clinical application to guide radiation therapy; and (3) proposal to expand opportunities for radiation professionals, including consideration of a new training program within NCRP’s “Where are the radiation professionals?” initiative that trains radiation oncologists as molecular radiation epidemiologists.

Roessler, Genevieve S.; Baes, Fred; Classic, Kelly

doi: 10.1097/HP.0000000000001238pmid: 32118679

Abstract The Health Physics Society (HPS) conceived of the idea of an online “Ask the Experts” (ATE) feature in 1999 when the Society created its website. ATE features are popular now, but at that time it was a novel idea, so there was no assurance it would succeed. Now 20 y later, the HPS considers its ATE feature a success and the most valuable service the Society offers for the public. Nearly 13,000 questions have been submitted to the feature. They come both from members of the public and from health physicists. All have been answered personally by radiation safety experts. While it is important to answer questions personally, it is recognized that the most far-reaching impact of the feature is the written material on the ATE section of the website, which is provided for people searching for answers to their concerns and questions. Posted material includes frequently asked questions, summary papers on topics of interest, and links to other pertinent information. This is in addition to answers to a select group of submitted questions. To enhance the information search, all postings, including answers to questions, have headlines. These serve as keywords that facilitate website searches. The feature, managed by one lead editor, 20 topic editors, and more than 300 experts, draws over one million visitors per year. This statistic suggests that a substantial number of people are finding answers to their questions on the site and, therefore, do not need to submit personal questions. ATE editors have learned much about effective interaction with questioners, especially members of the public. Most important, answers should show compassion, present the bottom line first, be brief, and use plain language. Heavy reliance on peer-reviewed documents adds to the credibility of the information. Questions from the public cover a wide range of subjects; however, by far the most frequent deal with medical exposures, especially computed tomography procedures. Other questions deal with a wide range of concerns including products from Japan, granite countertops, radon, smoke detectors, luggage and whole-body scanners, and radiation exposure from airline travel. Another major concern is exposure to nonionizing radiation sources such as cell phones, radar, ultraviolet radiation, lasers, and power lines. Examples are provided of the most intriguing questions that have come to the ATE feature and the answers provided by the experts.

Bouville, André

doi: 10.1097/HP.0000000000001237pmid: 32118680

Abstract The process of nuclear fission, which was discovered in 1938, opened the door to the production of nuclear weapons, which were used in 1945 by the United States against Japan in World War II, and to the detonation of >500 nuclear weapons tests in the atmosphere by the United States, the former Soviet Union, the United Kingdom, China, and France from 1946–1980. Hundreds of radionuclides, most of them short-lived, were produced in the atmospheric tests. The radioactive clouds produced by the explosions were usually partitioned between the troposphere and the stratosphere: the activity that remained in the troposphere resulted in local and regional fallout, consisting mainly of short-lived radionuclides and in relatively high doses for the populations residing in the vicinity of the test site, whereas the activity that reached the stratosphere returned to the ground with a half-life of ~1 y and was composed of long-lived radionuclides that contaminated all uncovered materials on Earth to a small extent and led to low-level irradiation of the world population for decades or more. The health effects resulting from exposure to radioactive fallout constitute, in most cases, small excesses over baseline rates for thyroid cancer and leukemia. An extra 49,000 cases of thyroid cancer would be expected to occur among the US population from exposure to radioactive fallout from the atmospheric nuclear weapons tests that were conducted at the Nevada Test Site in the 1950s. In addition, there could be as many as 11,000 deaths from non-thyroid cancers related to fallout from all atmospheric tests that were conducted at all sites in the world, with leukemia making up 10% of the total. Public concern arose in part from the secrecy that surrounded the nuclear testing programs and, for a long time, the poor communication regarding the consequences of the tests, both in terms of radiation doses and of health effects. Sociological and political pressures contributed to the establishment of programs of compensation for radiation exposures and evidence of radiation-induced diseases in countries that incurred significant fallout from nuclear weapons testing.

Cochran, Lainy D.; Eckert, Aubrey C.; Hunt, Brian; Kraus, Terry

doi: 10.1097/HP.0000000000001133pmid: 31985513

Abstract An interlaboratory effort has developed a probabilistic framework to characterize uncertainty in data products that are developed by the US Department of Energy Consequence Management Program in support of the Federal Radiological Monitoring and Assessment Center. The purpose of this paper is to provide an overview of the probability distributions of input variables and the statistical methods used to propagate and quantify the overall uncertainty of the derived response levels that are used as contours on data products due to the uncertainty in input parameters. Uncertainty analysis results are also presented for several study scenarios. This paper includes an example data product to illustrate the potential real-world implications of incorporating uncertainty analysis results into data products that inform protective action decisions. Data product contours that indicate areas where public protection actions may be warranted can be customized to an acceptable level of uncertainty. The investigators seek feedback from decision makers and the radiological emergency response community to determine how uncertainty information can be used to support the protective action decision-making process and how it can be presented on data products.

Alharshan, Gharam A.

doi: 10.1097/HP.0000000000001143pmid: 31855594

Abstract In the field of gamma-ray spectroscopy with high-purity germanium detectors, used to measure the activity when the sample to be measured has low radioactivity, volumetric sources are widely used. To determine the sample activity, the full-energy peak efficiency is needed. Bulk sources are very common for low-level radioactivity measurements in activation analysis and environmental samples. The main problem with these measurements is that coincidence effects are large for close source-detector geometries. Ignoring these effects can lead to an error typically of a factor of 2 in the determination of 60Co and 88Y activity, which was used in this work in the calibration process. Extensive experimental readings have been carried out, and bulk gamma aqueous sources containing several radionuclides covering the energy range from 60 to 1,840 keV were used. By comparison, the experimental (present work) and theoretical (published) full-energy peak efficiency values are in good agreement; the overall percentage error is less than 6%.

Peplow, Douglas E.

doi: 10.1097/HP.0000000000001136pmid: 31658161

Abstract The specific gamma-ray dose constant represents the gamma effective dose rate due to a point source of unit activity of a given nuclide at 1 m. New tabulations of specific gamma-ray dose constants have been made using current gamma emission data from the SCALE 6.2.3 software package and International Commission on Radiological Protection Publication 107, combined with the effective dose per fluence conversion coefficients (antero-posterior orientation) of International Commission on Radiological Protection Publication 116. SCALE data cover 1,264 nuclides, and International Commission on Radiological Protection Publication 107 data include 1,192 nuclides, with only 777 nuclides in common between the two sets.

Kudo, Takashi; Inano, Akihiro; Midorikawa, Sanae; Kubo, Hitoshi; Hayashi, Kino; Nakashima, Sawako; Fukushima, Chizu; Maeda, Kazuya; Oriuchi, Noboru; Irie, Shin; Yamashita, Shunichi; Kusuhara, Hiroyuki

Root, Caitlin M.; DeVol, Timothy A.; Sinclair, Robert R.; Martinez, Nicole E.

doi: 10.1097/HP.0000000000001147pmid: 31985514

Abstract The radiation safety culture of those working in university open-source radioactive material laboratories was assessed by conducting both surveys and behavioral observations. Baseline results (n = 82, 89% response rate) of assessed safety culture categories indicated safety practices and safety compliance were the most in need of improvement. Specific training based on these results was provided to laboratory members at Princeton University, with creative signage and a safety newsletter posted in and around laboratories for reinforcement, in a targeted effort to improve the radiation safety culture. Signage posted utilized pop cultural memes and other engaging graphics designed to raise awareness of appropriate safety practices and the minimum laboratory attire expected while working in radioactive material laboratories. Postintervention results (n = 38, 43% response rate) indicated improvement in 4 out of the 10 safety culture indicators considered as well as fewer instances of improper safety practices. Collaborative techniques and increased communication between researchers and radiation safety staff appear to have initiated an improvement in the radiation safety culture in open-source radioactive material laboratories at Princeton University.

Brost, Eric; Prather, Andrew; Naik, Himani; Jafari, Mary Ellen

doi: 10.1097/HP.0000000000001159pmid: 32126060

Abstract Radioactive seed localization procedures, using 125I seeds of typical activity 3.7 MBq and higher, are performed to localize nonpalpable lesions in the breast for surgical excision and pathology analysis. This study evaluated the use and dosimetry of 125I seeds of activity <3.7 MBq in radioactive seed localization procedures through retrospective health record review, Monte Carlo simulation, and experimental detection. An average seed strength at the time of specimen excision of 2.48 ± 0.629 MBq was used in 295 radioactive seed localization procedures at Gundersen Health System in La Crosse, Wisconsin, US. The average explanted seed activity served as a basis for Monte Carlo simulation of an 125I IsoAid Advantage seed embedded in soft tissue, which scored the dose deposited to soft tissue. Tabulated values of the dose to postsurgical residual tissue as a function of explanted tumor radius were shown and compared with previously published results. Use of seeds of activity from 1.44 to 3.7 MBq at the time of excision did not adversely affect seed detection and excision. The absorbed dose to residual tissue calculated using Monte Carlo was an average of 1.4 times larger than previously published results when scaled to identical seed strengths. This study demonstrates that seeds of activity <3.7 MBq can be used for radioactive seed localization procedures with no loss in efficacy and a benefit of reduced radiation dose to patients. This is important because the estimated radiation dose to residual tissue is approximately 1.4 times higher than previously indicated.