Fluoro-2-deoxy-D-glucose (18F-FDG) positron slowing down, annihilation, and electron capture absorbed doses in female patients

Background: 18-F fluoro-2-deoxy-D-glucose (F-18-FDG) is the most common tracer in whole-body positron emission tomography (PET) imaging for cancer. The diagnostic information gained from a F-18-FDG is beneficial, but the administration of radioactive material always comes with an increased risk of secondary cancer. The objective of this paper was to calculate the effective dose for F-18-FDG injected patients considering the specific contribution from positron slowing down, positron annihilation, and electron capture mechanisms. Materials and Methods: The dose for various organs was estimated by using the Monte Carlo (MC) method. The Medical Internal Radiation Dose (MIRD) female phantom was used for the simulations and the effective doses to various organs from internal exposure from a(18)F-FDG injection were calculated using a biokinetic model and International Commission on Radiological Protection (ICRP) publication 128 provided data. Calculated doses were compared with measured doses found in published studies. Results: The dose for each organ is dependent on the F-18 decay mode. The total effective dose is 6.73 mSv when the administered activity is 185 MBq. Positron annihilation leads to the highest average effective dose at 3.57 mSv. The effective doses for positron slowing and electron capture gammas are 2.99 and 0.17 mSv, respectively. The urinary bladder, followed by the brain and heart, have the highest absorbed doses. The calculated doses for a female patient are in good agreement with published measured data. Conclusions: The results presented here can be used to scale the dose measured by a dosimeter to estimate the patient's absorbed dose. Tracking the cumulative effective dose from medical procedures is an important aspect of managing the care of cancer patients to ensure regulatory limits are not exceeded.