TAM-C - Topics in Health Physics Centennial Ballroom 300C 09:30 - 11:00
|
| Chair(s): Ben Edwards
|
| |
TAM-C.1
09:30 National Academies' Study on Radioactive Sources, Applications and Alternative Technologies O Kosti*, National Academies
Abstract: The U.S. National Academies of Sciences, Engineering, and Medicine, at the request of Sandia National Laboratories, assessed the status of applications of radioactive sources and alternative (nonradioisotopic) technologies in the United States and internationally. The assessment will be used to inform existing and future activities under the National Nuclear Security Administration (NSSA) Office of Radiological Security program to reduce the current use of high-risk radiological materials and promote alternative technologies.
The study found that while radioactive sources continue to be used broadly, both nationally and internationally, no new applications of high-risk and moderate-risk radioactive sources have emerged during the past 10 to 15 years. However, data tracked in the United States indicate that the number of Category 1 and Category 2 sources has increased over the past 12 years by about 30 percent. The U.S. government and the international community have taken actions to strengthen the security and accountability of radioactive sources primarily for high-risk sources. Security and accountability for Category 3 sources have been a lower priority, making them more vulnerable to unauthorized transactions and theft. In addition, recent modeling analyses of radiological events and real-life events conclude that even small radiation releases and exposures below the levels that can cause immediate harm may have serious and long-term socioeconomic consequences. The study report recommends that the International Atomic Energy Agency, the U.S. Nuclear Regulatory Commission, and other organizations should consider reframing their source categorization schemes to account for both (a) probabilistic health impacts such as development of cancer later in life and (b) economic and social impacts. In parallel, the U.S. Nuclear Regulatory Commission should phase in tracking of Category 3 sources to help increase accountability for owning these sources and regulating their use.
Progress with developing and adopting alternative technologies has been uneven across different applications and radionuclides. The most notable progress is the worldwide adoption of x-ray technologies to replace the use of cesium-137 for blood and research irradiation. In the United States, that progress was facilitated in large part by financial incentives provided by the government. Also, in high- and many middle-income countries linear accelerators have almost entirely replaced cobalt-60 teletherapy. For most applications, however, there are no broadly accepted replacement technologies. A progressive transition to alternative technologies is taking place in sterilization applications, with the use of electron-beam (e-beam) technologies in medical device sterilization increasing during the past 10 to 15 years both domestically and internationally. For some applications, for example well logging, no suitable replacement technology has been developed.
The study also found that consideration and adoption of alternative technologies for medical applications such as cancer therapy in low- and middle-income countries should take into account stark disparities in access to healthcare and resources. For example, adoption of alternative technologies for cancer therapy in some low- and middle-income countries has had unintended negative impacts on patient care because of lack of trained workforce, required resources, and infrastructure to make these alternatives viable options. In situations in which local resources and infrastructure cannot support alternatives, efforts should instead focus on enhancing security and assisting with infrastructure building
The National Academies report can be accessed free of charge here: https://www.nap.edu/catalog/26121
|
TAM-C.2
09:45 An Evaluation of Nuclear Regulatory Commission and Agreement States Future Directives TM Jue*, California Department of Public Health
; Z Gulshan, California Department of Public Health; H Akhavanik, Nuclear Regulatory Commission
Abstract: This year, the Nuclear Regulatory Commission (NRC) Division of Materials Safety, Security, State and Tribal Programs (NMSS) has developed a nuclear materials working group to evaluate the significant changes in the nuclear industry by specifically evaluating new scenarios for example, (All states become agreement states, limited workforce, removal radiological source material, new licensing emerging technologies, changes in radiation program due to pandemic, (online inspections) etc. that is changing the radiation industry radiation protection programs. These examples will impact the NRC technical advisory such as training programs, IMPEP, rulemaking activities etc. on how the NRC will advise and or regulate radiological material in agreement states and non-agreement states.
Currently there are 39 agreement states that have signed formal agreements with NRC to regulate certain byproduct, source material and small quantities of special nuclear material. The NRC assists intended non agreement states to become agreements states and provides technical assistance to agreement states in reviewing the adequacy to protect the public health and safety of their program. In addition, the NRC and agreement states have jointly discussed new regulations, regulatory guidance and other regulatory initiatives.
The objective of this presentation is to provide outreach communication to an intended health physics audience that manages radiation protection programs to provide feedback to move forward with new NRC recommendations and directives.
|
TAM-C.3
10:00 The current problems in the quantification of radition exposure J Sabol*, Police Academy of the Czech Republic in Prague
Abstract: There are too many quantities currently in use in radiation protection. Many of them are not readily measurable and are applied incorrectly to the assessment of both stochastic and deterministic biological effects caused by radiation exposure. This is especially related to the quantity of effective dose which can only be used up to something like 500 mSv since above this level deterministic effects (tissue reactions) could take place. The paper is analyzing the present inconsistencies of the radiation quantities and suggests some changes regarding this system which should be much simpler and based on readily measurable quantities. The emphasis are reflecting the need for separate quantities for the assessment of stochastic and deterministic effects which should be considered separately.
|
TAM-C.4
10:15 Regulator requirement of smoke detector OY Al_Somali*, Saudi Aramco
Abstract: A smoke detector is a device that senses to smoke, typically as an indicator of fire. Also known as smoke alarms, generally issue an audible or visual alarm. Smoke detectors perform a life-saving function in the event of fire. Smoke detectors are now more common as fire safety requirements. These smoke detectors are housed in plastic enclosures, typically shaped like a disk about 150 millimeters (6 in) in diameter and 25 millimeters (1 in) thick, but shape and size vary. The US National Fire Protection Association reports 0.53 deaths per 100 fires in homes with working smoke alarms compared to 1.18 deaths without (2009–2013).
Smoke detectors contain radioactive sources that could be in a form of Am-241, Pu-238, Pu-239, Kr-85 and others radionuclides which are long lived alpha emitters. The risk of harm from radiation exposure from smoke detectors is considered to be low. Alpha radiation, which is emitted by the radioactive source used to make the detector operate, will not even penetrate through air for more than a few centimetres and is therefore contained within the chamber of the detector. Gamma radiation emitted by the source is of low which is substantially shielded by the detector housing. As a rule of thumped, gamma radiation intensity decreases rapidly with increasing distance from the source.
It should be noted that the actual dose received from the detector would be much less since the Am-241 source for example is shielded by the metal chamber and a person would not normally be at a distance of one meter from the smoke detector for any length of time. The probability of the source being removed from the tamperproof chamber and then swallowed is extremely remote. The internal radiation hazard is therefore minimal.
This presentation will outline:
• Health risk of the radioactive material contained within the smoke detectors and benefits of having the devices.
• Household disposal method
• Regulatory requirements,
• National authority, Nuclear and Radiological Regulatory Commission (NRRC)
• International Atomic Energy Agency (IAEA)
• U.S. Nuclear Regulatory Commission (NRC) & U.S. Environmental Protection Agency
• Australian Radiation Protection and Nuclear Safety Agency (ARPNSA)
• UK Guidance & Environmental Authorisations (Scotland) Regulations
• Canadian Nuclear Safety Commission
|
TAM-C.5
10:30 A Phantom Study of X-ray Fluorescence Measurements of Iron, Zinc, and Selenium in Subcutaneous Blood Pool V Mahjan*, California State University, Fresno
; MR Gherase, California State University, Fresno
Abstract: Monitoring essential trace elements in the human body is an important part of clinical metabolic health assessment. Rapid, non-invasive, non-destructive, and low-dose monitoring of trace elements can be achieved by x-ray fluorescence (XRF) measurements. Past XRF studies concerned detection and quantitation of zinc (Zn) in nails, selenium (Se) in skin, or strontium (Sr) in bone. XRF detection of iron (Fe), Zn, and Se in the subcutaneous blood pool was investigated. The method is as a non-invasive alternative to current clinical measurements using inductively coupled plasma mass spectrometry (ICP-MS). Six water solutions containing Fe, Zn, and Se in 5, 10, 15, 20, 25, and 30 μg/g concentrations placed in small polyethylene plastic vials mimicked the skin and subcutaneous capillary blood pool. Spatially selective excitation of the elements in the solution was performed by employing a small (1.5-mm lateral size) x-ray beam produced by an integrated x-ray tube and polycapillary x-ray lens system. A silicon-based x-ray detector, a positioning stage, and a grazing-incidence method developed in our lab were used to acquire three 300-s x-ray spectra for each concentration. Spectral Kα peak area measurements yielded a calibration line for each element. Calibration line slope and peak area uncertainty values were used to compute detection limits of (7.04+/-0.04), (4.5+/-0.2), and (3.9+/-0.2) μg/g for Fe, Zn, and Se, respectively. The normal levels of Fe, Zn, and Se concentrations in human blood are roughly 10, 5, and 0.1 μg/g, respectively. Therefore, Fe and Zn measurements are feasible, but Se level assessment is likely not possible. Future work will assess radiation dose costs and the effects of varying skin x-ray attenuation on detection and concentration measurements.
|
TAM-C.6
10:45 X-ray Fluorescence Measurements of Strontium Concentration in a Lamb Bone Sample MR Gherase, California State University, Fresno
; M Berrios*, California State University, Fresno
Abstract: Strontium (Sr) is an essential element found in the human bone in concentrations of 0.1 to 0.3 mg per gram of calcium. Low doses of dietary Sr were shown to reduce bone demineralization due to osteoporosis in animal studies. Bone Sr measurement was also demonstrated to improve the accuracy of human bone mineral content in dual x-ray absorptiometry (DXA) studies. In vivo bone Sr measurements can be performed using x-ray fluorescence (XRF) methods. Human bone Sr detectability at low radiation doses was demonstrated in past XRF studies, but accurate Sr concentration determination from measurement data remains elusive. The Sr content of superficial cortical bone from a lamb leg was probed using an optimal grazing-incidence XRF method developed in our lab. The lamb bone Sr concentration of 0.33 mg/g was determined using the XRF data from plaster-of-Paris samples doped with Sr. Further, the lamb bone and three overlying leather samples of 1.8-, 2.3-, and 2.5-mm thickness mimicked in vivo human bone measurements. Analysis of the XRF data indicated that Sr Kβ/Kα ratio can be used as a metric of soft tissue x-ray attenuation, a key ingredient in establishing a methodology for accurate bone Sr concentration measurements.
|
