Nuclear Medicine Pearls

5 Gauss line = 5 mT = 0.005 T

Average background radiation dose to US citizen = 300 mrem

Consider therapeutic abortion if dose to fetus > 10 rad (0.1 Gy)

To categorize area as restricted from general public, average dose rate > 2 mrem/hr

If Tc99m is given to lactating female, cease breast-feeding for 4 days

Terminate breast-feeding altogether after administration of I131 or Ga67

Test for Mo99 contamination in Tc99m samples by using a dose calibrator

Use thin layer chromatography to test for free Tc in Tc99m

Use colorimeter to test for Al in Tc99m MDP

White label I < 0.5 mrem

Yellow < 50 mrem/hr – AND – not > 1 mrem/hr @ 1 meter

Yellow III > 50 mrem/hr – OR – > 1 mrem/hr @ 1 meter

Maximum allowable exposure to family members of patients with I131 = 5 mSv

Risk for congenital defects from radiation to general population significantly increases > 15 rad (150 mGy)

Radiotherapy dose must be > 20% to report to NRC

A well counter does not use a gas-filled chamber to detect radiation levels

Mo99/Tc99m generator operates on principle of transient equilibrium and is state where daughter radionuclide is short than that of parent radionuclide

In secular equilibrium, radioactive daughter’s decay rate is balanced by own decay rate

Risk of congenital defects to fetus significantly increases > 100 mGy

Annual occupational dose equivalent limit to single organ in radiation worker = 50000 mrem (500 mSv).

NaI123 has t1/2 = 13.2 hr

Theraspheres used for unresectable HCC, SIR-Spheres used for liver mets

Dose calibrator QC –

        Geometry: performed at installation

        Constancy: daily (“constantly”)

        Linearity: quarterly

        Accuracy: annually