OCCUPATIONAL PER‐PATIENT RADIATION DOSE FROM A CONSERVATIVE PROTOCOL FOR VETERINARY ¹⁸F‐FLUORODEOXYGLUCOSE POSITRON EMISSION TOMOGRAPHY

Abstract

The occupational external radiation dose to human medical personnel from positron emission tomography (PET) radiopharmaceuticals has been documented, but to date no corresponding veterinary staff dose data are available. Electronic personal dosimeters (EPDs) were used in this study to measure the per-patient external radiation doses to veterinary staff using a PET/CT (PET combined with computed tomography) protocol in which the patient radiopharmaceutical dose was injected after anesthetic induction. Radiation doses were recorded for the nuclear medicine technologists, the on-duty anesthesiology technologist, and an occasional observer from 19 veterinary (18) F-fluorodeoxyglucose PET/CT studies. Patient mass range was 2.8 to 61.0 kg (22.3 kg mean) and injected activity averaged 6 MBq kg(-1) . The dose range received by nuclear medicine technologists per procedure was 0-30 μSv (9.1 μSv mean), by anesthetists 1-22 μSv (8.2 μSv mean), and by the observer 0-2 μSv (0.5 μSv mean). In both feline and canine studies, placement of the EPD on staff was a significant predictor of radiation dose. Additional significant predictors of staff radiation dose from canine studies included job position and injected activity. The per-patient occupational radiation doses to veterinary PET/CT technologists were slightly greater than those reported for human nuclear medicine PET/CT technologists, but were comparable to estimated radiation doses for nurses caring for nonambulatory human PET/CT patients. Efforts toward maintaining staff radiation doses as low as reasonably achievable (ALARA) will be important as veterinary PET/CT caseload increases.

A Proposed Simple Model for Estimating Occupational Radiation Dose to Staff from Veterinary 18F-FDG Pet Procedures

“…The dose model developed is based on a 4-mo study that monitored external radiation doses to staff with DMC 2000S electronic personal dosimeters (MGP Instruments of Mirion Technologies, Smyrna, GA) (Martinez 2011;Martinez et al 2012). The proposed 18 F-FDG model, three equidistant point sources within a soft tissue cylinder, assumes that a staff member will stand either at one end of the patient or at the side of the patient at the midway point (Fig.…”

“…The support and anesthetic monitoring protocol at Colorado State University includes placement of an arterial line to facilitate measurement of direct blood pressure; two additional venous lines for administering intravenous fluids, drugs, and 18 F-FDG; and an indwelling urinary catheter in canine patients (Martinez et al 2012). The animal's urinary catheter bag is placed in a lead-shielded container at the rear of the scanner.…”

“…Multiple studies have been conducted concerning radiation dose to human hospital personnel from PET radiopharmaceuticals (McCormick and Miklos 1993;Chiesa et al 1997;McElroy 1998;Benetar et al 2000;Linemann et al 2000;Biran et al 2004;Guillet et al 2005;Roberts et al 2005;Robinson et al 2005;Zeff and Yester 2005;Dalianis et al 2006;Seierstad et al 2007;Carson et al 2009;Demir et al 2010;Leide-Svegborn 2010), but to date only one parallel study has been conducted for veterinary personnel (Martinez 2011;Martinez et al 2012). Unlike human patients who typically undergo the PET/CT procedure awake (Boellaard et al 2010), veterinary patients need to be anesthetized to ensure the animal remains immobile for optimal image acquisition.…”

“…Animal patients under anesthesia require more intensive monitoring than human patients, meaning that veterinary staff are likely to be exposed to radiation for longer periods of time per patient than staff caring for human patients. On the other hand, administered activities (dosages) are generally smaller for animal patients because they weigh less on average than human patients (Martinez et al 2012). Additionally, the patient throughput at a veterinary clinic (currently about 25 procedures performed every quarter at CSU) is much less than at a human imaging center (up to 30 patients a day) (Zanzonico et al 2008).…”

“…Prior data consisting of 25 scans (16 dogs, eight cats, and one sheep) were used in development of the model (Martinez 2011;Martinez et al 2012). The primary objective in model development was to provide a reference for comparing veterinary PET imaging protocols.…”