Quality Control

Question 1

1. Measurement of Dose

Answer 1

a. Done with dose calibrator, NRC requires dose be within 10% of intended dose

Question 2

2. Mo99 Breakthrough

Answer 2

a. Radionuclide purity
b. Mo-99 decays via beta minus gives off 740 & 780 kev photons, Too much Mo-99 in eluant increases pt dose
c. Determine Mo-99 level each time generator used = NRC guideline < 0.15 uCi per 1.0 mCi Tc-99m

Question 3

3. Alumina Breakthrough (121H, 44M)

Answer 3

a. Chemical purity
b. Maximum acceptable = 10 micrograms per ml of eluate
c. Aluminum (Al3+) interferes with proper formation of Tc-99m pharmaceuticals
d. Tc-Aluminum particles can cause hepatic uptake
e. Cause aggregation of sulfur colloid – lung uptake

Question 4

4. Technetium Dioxide (47M)

Answer 4

a. The eluate from a generator is Tc-99m Pertechnetate (TcO4 +7)
b. Must reduce to valence of +3/+4/+5 to combine with kit preparation (done with stannous chloride)
c. Reactive (reduced) Technetium may become hydrolyzed forming technetium dioxide - Tc Dioxide is insoluble
d. To check for presence of Tc Dioxide use thin layer chromatography

Question 5

5. Dose Calibrator (123Huda)

Answer 5

a. Constancy: checked daily, Measures precision/reproducibility of dose calibrator, Done with long T1/2 sources (Co-57, Ba-133, and Cs-137)
b. Linearity: Checked quarterly, Measure decay of Tc-99m over 72 hours
c. Accuracy: Checked annually

Question 6

6. Field Uniformity (123Huda)

Answer 6

a. Checks the gamma camera’s ability to reproduce a uniform field
b. Performed daily – Nonuniformities > 10% unacceptable
c. Flood Source: either Co-57 or Tc-99m

Question 7

7. Kit Preparation Problems

Answer 7

a. If O 2 gets into vial then stannous ion is hydrolyzed & prevents reduction of TcO4 = free TcO4 in preparation = Colloid formation = activity in liver (especially with bone scan)