Research Findings

Dosimetry - Occupational Radiation

Photon energy readings in OSL dosimeter filters: an application to retrospective dose estimation for nuclear medicine workers (2018)
 This assessment confirmed the applicability of using ratios of photon energies captured under different filters in personal radiation dosimeters worn by 19 nuclear medicine (NM) technologists to determine whether they performed traditional NM procedures, PET imaging, or a combination of these procedures. The radioisotope used for PET imaging, F-18, produces high energy (511 keV) photons, while the primary isotope used for other NM procedures, Tc-99m, produces moderate energy (140 keV) photons. The copper (Cu) filter removes some of the moderate energy photons and the aluminum (Al) filter removes some of the lower energy photons, while neither filter alters the effect of the high energy photons on the recorded dose. The Al/Cu filter ratios were higher for technologists who only performed traditional NM procedures, lower for those who likely performed only PET scans, and intermediate for technologists who did both. Photon energy ratios will be useful for estimating occupational radiation doses in studies of nuclear medicine technologists with limited information on work history. This method may also be able to distinguish between photon energies from nuclear medicine versus conventional radiation procedures.
A U.S. Multicenter Study of Recorded Occupational Radiation Badge Doses in Nuclear Medicine (2018)
 An assessment of 2618 annual badge dose records for 208 nuclear medicine technologists currently or formerly working at nine U.S. medical institutions revealed that the median annual personal dose equivalent was 2.18 mSv (interquartile range, 1.25-3.47 mSv; mean, 2.69 mSv). While median annual doses remained relatively constant from 1992 to 2015 (range, 1.40-3.30 mSv), the maximum doses increased over time from 8.00 to 13.9 mSv. The doses were well below the current occupational limits and consistent with those reported for nuclear medicine technologists in other countries, but were somewhat higher than doses for other nuclear and general medical workers in the U.S.
Changing Patterns in the Performance of Fluoroscopically Guided Interventional Procedures and Adherence to Radiation Safety Practices in a U.S. Cohort of Radiologic Technologists (2016)
 This paper presents a detailed description of frequencies performed 21 different types of fluoroscopically-guided (FG) interventional procedures, associated work practices, and safety measures used during 1950-2009 by 12,571 radiologic technologists who reported working with FG procedures. This information will be used along with badge dose data to estimate organ-specific radiation doses to assess radiation-related health risks in technologists performing FG procedures.
Historical patterns in the types of procedures performed and radiation safety practices used in nuclear medicine from 1945-2009 (2016)
 Among 4,400 radiologic technologists who worked with radionuclide procedures, the median frequency of diagnostic procedures performed increased from 5 to 30 per week between 1945 and 2009 primarily related to increasing use of cardiac and non-brain PET scans. Except for apron use, which declined over time, use of other radiation safety practices increased substantially.
Use of radiopharmaceuticals in diagnostic nuclear medicine in the United States: 1960-2010 (2015)
 Data were collected from nuclear medicine radiology experts and a comprehensive literature review on the use of radiopharmaceuticals and typical administered activities for nuclear medicine procedures performed during 1960-2010 for use in retrospective reconstruction of occupational and personal medical radiation doses.
Nuclear medicine practices in the 1950s through the mid-1970s and occupational radiation doses to technologists from diagnostic radioisotope procedures (2014)
 Occupational doses to technologists who conducted diagnostic radioisotope procedures during the 1950s to mid-1970s were estimated based on information provided by an expert panel of nuclear medicine radiologists on typical protocols, radioisotopes, and clinical practices used for specific types of procedures over time.
Radiation organ doses received by U.S. radiologic technologists: Estimation methods and findings (2014)
 2.23 million annual badge doses were estimated for years worked during 1916-1997 by 110,000 radiologic technologists who completed at least one cohort survey, using more than 900,000 badge measurements available for 80,000 cohort members and historical literature and archival documents. Badge doses were converted to radiation absorbed doses to twelve organs and tissues using available information on air kerma, protective apron use, and conversion factors for X-irradiation spectra that reflected changes in energy and beam filtration over time.
Organ-specific external dose coefficients and protective apron transmission factors for historical dose reconstruction for medical personnel (2011)
 This paper presents dose conversion coefficients for continuous distributions of radiation energy characteristic of diagnostic medical x-rays as well as for radiation energies from radioisotope procedures, for use in estimating organ-specific doses for medical radiation workers. The dose conversion coefficients were derived for twelve organs and tissues based on three different peak tube potentials (70 kV, 80kV, 90kV), four beam filtration levels, four calendar periods (<1949, 1949-1954, 1955-1968, >=1969) and, for organs potentially protected by a lead apron, three apron possibilities (none, 0.25 mm Pb, 0.50 mm Pb thickness). As described in the paper, dose conversion coefficients were derived for medical x-rays (distributions of energy) by appropriately weighting data for individual energies published by international radiation protection organizations. The conversion of badge dose readings to organ-specific doses for medical personnel vastly improves the reliability of the dose reconstruction.
Estimating historical radiation doses to a cohort of U.S. radiologic technologists (2006)
 This paper describes our early efforts to reconstruct occupational radiation doses among the 90,000 radiologic technologists who completed the baseline survey during the mid-1980s. The dose estimation used available film badge measurements (approximately 350,000) for individual cohort members, information provided by technologists about their work history and protection practices, and measurement and other data from the literature. Dosimetry models estimated annual and cumulative occupational badge doses for each technologist for each year worked from 1916 to 1984, plus absorbed doses to organs and tissues, including bone marrow, breast, thyroid, ovary, testes, lung, and skin.
Status report on estimating historical radiation doses to a cohort of U.S. radiologic technologists (2004)
 Data and physical/statistical models were used to estimate unknown occupational radiation doses to 90,000 members of the U.S. Radiological Technologists cohort who responded to the first major questionnaire conducted in the mid-1980s. The dosimetry estimation used available film-badge measurements (approximately 350,000) for individual cohort members, technologist's responses on their work history/protection practices, and data from published literature. The complete dosimetry model estimates annual and cumulative occupational badge doses (personal dose equivalent) for each technologist for each year worked from 1916 through 1984, as well as absorbed doses to organs and tissues including bone-marrow, female breast, thyroid, ovary, testes, lung and skin. Workers who began work prior to 1950 had significantly higher doses than those first working in later years.