Radiation Absorbed Dose to the Basal Ganglia from Dopamine Transporter Radioligand 18F-FPCIT

• Published in: BioMed research international Vol. 2014; no. 2014; pp. 1 - 5
• Main Authors: Robeson, William, Dhawan, Vijay, Ma, Yilong, Bjelke, David, Margouleff, Claude, Chaly, Thomas, Eidelberg, David
• Format: Journal Article
• Language: English
• Published: Cairo, Egypt Hindawi Puplishing Corporation 01.01.2014; Hindawi Publishing Corporation
• Subjects: Adult; Basal Ganglia - diagnostic imaging; Dopamine Plasma Membrane Transport Proteins - chemistry; Fluorodeoxyglucose F18 - administration & dosage; Humans; Ligands; Positron-Emission Tomography; Radiation Dosage; Radiography; Radiopharmaceuticals - administration & dosage; Urinary Bladder - diagnostic imaging; Urinary Bladder - metabolism
• ISSN: 2314-6133; 2314-6141
• DOI: 10.1155/2014/498072

Our previous dosimetry studies have demonstrated that for dopaminergic radiotracers, 18F-FDOPA and 18F-FPCIT, the urinary bladder is the critical organ. As these tracers accumulate in the basal ganglia (BG) with high affinity and long residence times, radiation dose to the BG may become significant, especially in normal control subjects. We have performed dynamic PET measurements using 18F-FPCIT in 16 normal adult subjects to determine if in fact the BG, although not a whole organ, but a well-defined substructure, receives the highest dose. Regions of interest were drawn over left and right BG structures. Resultant time-activity curves were generated and used to determine residence times for dosimetry calculations. S-factors were computed using the MIRDOSE3 nodule model for each caudate and putamen. For 18F-FPCIT, BG dose ranged from 0.029 to 0.069 mGy/MBq. In half of all subjects, BG dose exceeded 85% of the published critical organ (bladder) dose, and in three of those, the BG dose exceeded that for the bladder. The BG can become the dose-limiting organ in studies using dopamine transporter ligands. For some normal subjects studied with F-18 or long half-life radionuclide, the BG may exceed bladder dose and become the critical structure.