Nuclear Medicine Practices in the 1950s through the Mid-1970s and Occupational Radiation Doses to Technologists from Diagnostic Radioisotope Procedures

Abstract

Data on occupational radiation exposure from nuclear medicine procedures for the time period of the 1950s through the 1970s is important for retrospective health risk studies of medical personnel who conducted those activities. However, limited information is available on occupational exposure received by physicians and technologists who performed nuclear medicine procedures during those years. To better understand and characterize historical radiation exposures to technologists, we collected information on nuclear medicine practices in the 1950s, 1960s, and 1970s. To collect historical data needed to reconstruct doses to technologists, a focus group interview was held with experts who began using radioisotopes in medicine in the 1950s and the 1960s. Typical protocols and descriptions of clinical practices of diagnostic radioisotope procedures were defined by the focus group and were used to estimate occupational doses received by personnel, per nuclear medicine procedure, conducted in the 1950s-1960s using radiopharmaceuticals available at that time. The radionuclide activities in the organs of the reference patient were calculated using the biokinetic models described in ICRP Publication 53. Air kerma rates as a function of distance from a reference patient were calculated by Monte Carlo radiation transport calculations using a hybrid computational phantom. Estimates of occupational doses to nuclear medicine technologists per procedure were found to vary from less than 0.01 μSv (thyroid scan with 1.85 MBq of administered 131I-iodide) to 0.4 μSv (brain scan with 26 MBq of 203Hg-chlormerodin). Occupational doses for the same diagnostic procedures starting in the mid-1960s but using 99mTc were also estimated. The doses estimated in this study show that the introduction of 99mTc resulted in an increase in occupational doses per procedure.

Association of Chromosome Translocation Rate with Low Dose Occupational Radiation Exposures in U.S. Radiologic Technologists

“…Our finding that occupational dose accumulated in the earlier time periods (<1960) was slightly [albeit nonsignificantly ( P > 0.5)] more effective at producing chromosome translocations than dose accumulated more recently, is probably not related to the increasing use of higher energy radioisotope medical procedures in more recent time periods (59, 60). The changes in energy over time in X-ray imaging in our cohort were due to changes in filtration of the X-ray beam, but the changes were too small to have marked effect, since these changes were not between very low-energy and moderate-energy X rays where the largest difference in biological effect would be expected (32).…”

Use of Radiopharmaceuticals in Diagnostic Nuclear Medicine in the United States

“…The administered activity of 131 I-sodium iodide for thyroid imaging before the mid-1970s was about 1.85 MBq (Harper et al 1965; Wagner 1968; Atkins 1975; McAfee and Subramanian 1984; Drozdovitch et al 2014), then gradually increased to 3.7 MBq (Sodee and Early 1975; Irwin et al 1978; Mettler et al 1986; Sisson 1997). The administered activity of 123 I-sodium iodide for thyroid imaging before the late-1970s was estimated to be 3.7 MBq (Robertson 1982; Wagner et al 1986), then gradually increased to 11.1 MBq in the 1980s (Mettler and Guiberteau 1983, Mettler et al 1986; Wagner et al 1995; Park et al 1994, 1997) and to 14.8 MBq in the mid-1990s (Mettler and Guiberteau 1998; Becker et al 1999; Kowalsky and Falen 2004; Balon et al 2006a; Joyce and Swihart 2011).…”

A New Era of Low-Dose Radiation Epidemiology

“…Unlike CT scans, these procedures also present increased occupational radiation exposure levels to the physicians and technologists who perform them [12,13]. Concerns about the higher exposures and risks of cancer and other radiation-related disease risks to medical workers have resulted in the establishment of new retrospective cohort epidemiologic studies for groups, such as cardiologists and radiologic technologists, who perform these procedures [12,14].…”