Over the past decade, the number of positron emission tomography/computed tomography (PET/CT) imaging procedures has increased substantially. This imaging technique provides accurate functional and anatomical information, particularly for oncological applications. Separately, both PET and CT are considered as high-dose imaging modalities. With the increased use of PET/CT, one could expect an increase in radiation doses to staff and patients. As such, major efforts have been made to reduce radiation dose in PET/CT facilities.

The calculated dose rate from the radioiodine therapy patient should normally include a factor accounting for the attenuation and scatter of patient body tissues. The attenuation factor is currently neglected, and not applied in operational radiation protection. Realistic estimation of radiation dose rate levels from radioiodine therapy patients when properly performed will reduce operational cost and optimise institutional radiation protection practice.

Accurate dose rate estimates is important for radiation protection specialists conducting risk assessments and performing dose reconstruction in cases of accidental exposures.

Objectives: The objectives of this work was to experimentally evaluate the bladder voiding factor effect on the dose rate measured from patients undergoing PET/CT imaging studies using 18F-FDG by directly measuring the dose rate immediately before and after voiding, and compare the results with the current scientific literature.

The objectives of this work were to estimate the amount of fluorine-18 fluorodeoxyglucose (F-FDG) excreted (AFE) in the patient urine during the uptake phase as percentage of the injected activity and to examine the effect of blood glucose levels (BGL) on the excreted amount and whether it varies among men and women using statistical analysis methods. Radiation dose rates were measured at 1 m from 50 patients, 24 men and 26 women, before and after the first void using a calibrated ionization chamber. The F-FDG was injected in the patients using a calibrated automatic dose injection system.