A patient is scheduled for a PET study tomorrow morning. The radiopharmaceutical to be used is fluorine-18 fluorodeoxyglucose. The physical half-life of F-18 is approximately:
- A 20 minutes
- B 110 minutes ✓
- C 6 hours
- D 8 days
Correct answer: B. 110 minutes
Explanation
F-18 has a physical half-life of about 110 minutes (1.8 hours), long enough to allow production at a cyclotron, transport to the PET facility, radiopharmaceutical synthesis, uptake time in the patient, and imaging, while still permitting same-day decay. O-15 has a half-life of about 2 minutes, C-11 about 20 minutes, and Ga-68 about 68 minutes. I-131, with a half-life near 8 days, belongs to therapy rather than routine PET imaging.
Reference: Christensen's Introduction to the Physics of Diagnostic Radiology, 4th ed.
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