Radiation dosimetry of 18F-FDG PET/CT: incorporating exam-specific parameters in dose estimates

Abstract

BackgroundWhole body fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) is the standard of care in oncologic diagnosis and staging, and patient radiation dose must be well understood to balance exam benefits with the risk from radiation exposure. Although reference PET/CT patient doses are available, the potential for widely varying total dose prompts evaluation of clinic-specific patient dose. The aims of this study were to use exam-specific information to characterize the radiation dosimetry of PET/CT exams that used two different CT techniques for adult oncology patients and evaluate the practicality of employing an exam-specific approach to dose estimation.MethodsWhole body PET/CT scans from two sets of consecutive adult patients were retrospectively reviewed. One set received a PET scan with a standard registration CT and the other a PET scan with a diagnostic quality CT. PET dose was calculated by modifying the standard reference phantoms in OLINDA/EXM 1.1 with patient-specific organ mass. CT dose was calculated using patient-specific data in ImPACT. International Commission on Radiological Protection publication 103 tissue weighting coefficients were used for effective dose.ResultsOne hundred eighty three adult scans were evaluated (95 men, 88 women). The mean patient-specific effective dose from a mean injected 18F-FDG activity of 450 ± 32 MBq was 9.0 ± 1.6 mSv. For all standard PET/CT patients, mean effective mAs was 39 ± 11 mAs, mean CT effective dose was 5.0 ± 1.0 mSv and mean total effective dose was 14 ± 1.3 mSv. For all diagnostic PET/CT patients, mean effective mAs was 120 ± 51 mAs, mean CT effective dose was 15.4 ± 5.0 mSv and mean total effective dose was 24.4 ± 4.3 mSv. The five organs receiving the highest organ equivalent doses in all exams were bladder, heart, brain, liver and lungs.ConclusionsPatient-specific parameters optimize the patient dosimetry utilized in the medical justification of whole body PET/CT referrals and optimization of PET and CT acquisition parameters. Incorporating patient-specific data into dose estimates is a worthwhile effort for characterizing patient dose, and the specific dosimetric information assists in the justification of risk and optimization of PET/CT.

Effective dose estimation for oncological and neurological PET/CT procedures

“…Others demonstrated an increase in CT dose when moving from a standard protocol to a diagnostic protocol [22] or from low-dose protocols to contrast-enhanced protocols [23]. Willowson et al [8] showed that PET ED decreases from 6.3 to 6.0 mSv when ED is scaled to individual patient weight.…”

Application of 82Sr/82Rb generator in neurooncology

“…A coefficient for calculating an effective dose is 1.26 μSv/MBq using the tissue‐weighting factor of the International Commission on Radiological Protection (International Commission on Radiological Protection (ICRP), ). So, the total effective dose was 1.0–1.9 mSv per single injection in compare, for example, with about 7–9 mSv from injected 18 F‐FDG activity 370–450 MBq (Marti‐Climent et al, ; Quin, Dauer, Pandit‐Taskar, Scholder, & Dauer, ).…”

Biodistribution and Radiation Dosimetry of the Integrin Marker 64Cu-BaBaSar-RGD2 Determined from Whole-Body PET/CT in a Non-human Primate

“…In Table 4, we compared the radiation doses of 64 Cu-BaBaSar-RGD 2 with a few other PET probes including 18 F-galacto-RGD [9], 18 F-FDG [27], and 64 Cu-RGD 4 [28]. The absorbed doses in the heart, and brain were much lower for 64 Cu-BaBaSar-RGD 2 than those for 18 F-FDG.…”