Effective dose estimation for oncological and neurological PET/CT procedures

Area of Science:

• Nuclear Medicine
• Radiological Sciences
• Medical Imaging

Background:

• Patient effective dose (ED) varies across different Positron Emission Tomography/Computed Tomography (PET/CT) procedures.
• Understanding dose contributions from both PET radiopharmaceuticals and CT is crucial for radiation safety.

Purpose of the Study:

• To retrospectively evaluate patient effective dose (ED) for diverse PET/CT protocols using various radiopharmaceuticals.
• To determine the relative contributions of PET radiotracers and CT to the total ED in different scan types.

Main Methods:

• Retrospective review of 210 patient PET/CT studies across Torso, Whole Body (WB), Head and Neck Tumor (HNT), and Brain protocols.
• Utilized various radiopharmaceuticals including 18F-FDG, 11C-CHOL, 18F-FDOPA, 11C-MET, and 18F-florbetapir.
• Calculated ED using conversion factors applied to radiotracer activity and CT dose-length product.

Main Results:

• Mean ED ranged from 4.6 mSv (Brain PET/CT with 18F-FDOPA) to 20.0 mSv (WB-18F-FDG).
• CT was the primary dose contributor for body protocols (62-77% ED), while PET radiopharmaceuticals dominated brain protocols (74-89% ED).
• Scan length and patient positioning significantly impacted CT ED in 18F-FDG PET/CT (p < 0.01).

Conclusions:

• The mean effective dose for body and brain PET/CT protocols varies significantly based on radiopharmaceutical and scan type.
• CT is the main source of radiation dose for body PET/CT, whereas the PET radiopharmaceutical is the primary contributor for brain PET/CT.
• Optimizing scan parameters and radiopharmaceutical selection can help manage patient effective dose in PET/CT imaging.