Reduction of Radiation Exposure to Patients and Professionals by Reducing the Administered Activity of 18F-Fluorodeoxyglucose in a Positron-emission Tomography/Computed Tomography Study

Aim: With increased clinical indications for positron-emission tomography/computed tomography (PET/CT) and repeated PET/CT scans, there is a need to reduce the radiation burden to the patient, professionals as well as public. This requires a redefining of the workflow and the 18-F-fluorodeoxyglucose (18F-FDG) administered activity. The objective of our study is to observe the impact of strike out reduction of administered activity on the radiation exposure to personnel and public, as well as the absorbed dose to the patient with no compromise on image quality by increasing the image acquisition time.

Materials and Methods: Nineteen patients evaluated in this study (11 males, 8 females) were put into two groups, namely, A and B. Patients in Group A (n = 10) were administered with 18F-FDG equivalent to the recommended dose (7-8 MBq/kg body weight) whereas patients in Group B (n = 9) were administered with 18F-FDG equivalent to half the recommended dose (3-4MBq/kg body weight). The exposure rates from the patients at the body surface and 100 cm distance were measured immediately and 1 h postinjection.

Results: The average surface dose rate and 100 cm dose rate of the adult patients immediately postinjection for patients of Group A were 0.94 ± 0.19 mSv/h and 0.057 ± 0.007 mSv/h, and for Group B were 0.34 ± 0.24 mSv/h and 0.031 ± 0.01 mSv/h.

Conclusion: This study suggests that reduction in injected 18F-FDG activity reduces the radiation exposure rate from the patient, absorbed dose to the patient with reportable image quality.