Generator eluate QC

Question 1

Describe radioactivity calibration

Answer 1

• assay eluate
• using tongs, place the vial of eluate in the dose calibrator, and ensure it is measured on the 99m-Tc setting
• The specific activity is calculated
• record the activity and concentation in NMIS or log book

Question 2

Describe visual inspection

Answer 2

• Eluate should be inspected for:
• Particulate matter, clarity, color
• Eluate should be clear and colorless
• do not use if cloudy or contains particles

Question 3

Describe the radionuclidic purity test

Answer 3

• 99-Mo breakthrough
• ensures no 99-Mo contamination in the 99m-Tc eluate
• 99-Mo is a radionuclide impurity and results in:
• Increased radiation dose to patient
• poor image quality
• The activity of 99Mo is divided by the activity of the 99m-Tc to obtain a ratio

Question 4

Describe the minimum requirement of 99-Mo Breakthrough

Answer 4

• Performed after first elution of a new generator
• clinically, often done after each elution

Question 5

Explain the 99-Mo breakthrough limits

Answer 5

• USP limit: maximum 0.15 kBq of 99-Mo/MBq of 99m-Tc
• Canadian Limit: 0.03kBq/MBq according to the CNSC
• If at any time the ration exceeds 0.03 kBq/MBq of 99m-Tc, the eluate must not be used
• Generally, if ratio is <0.038 at time of elution, it will be acceptable for injection of ~12 hours

Question 6

Describe the 99-Mo breakthrough test procedure

Answer 6

• requires a 99-Moly sheild, shields 99m-Tc photons
• Eluate vial in a specifically designed lead pot (~6mm thick),and place in the dose calibrator (Remove the pastic dipper/insert)
• Set the dose calibrator to measure 99-Mo

Question 7

What are some reasons for eluate QC failure

Answer 7

• External contamination on outside moly sheild
• wrong isotope selection
• worn or dented moly sheild (99m-Tc photons escape)

Question 8

Describe radionuclide contaminants

Answer 8

• Fission produced 99Mo cancontainnother extraneous radionuclide contaminants
• 131-I, 103-Ru, 89-Sr, 90-Sr
• These tests are performed by the manufacturer and the limits for these contaminants are strict

Question 9

Describe chemical purity or aluminum breakthrough testing

Answer 9

• Must be performed after every elution
• ensures no aluminum ion (Al3) present in the 99m-Tc eluate

Question 10

Describe what Al3 chemical impurity results in:

Answer 10

• Poor image quality due to labelling problems
• In preparing 99m-Tc Sulfur Colloid- too much aluminum ion will cause aggregation results: lung uptake
• Can cause technetium-aluminum particles to form result:liver uptake
• interferes with the labelling of RBCs causing agglutination (clumping)

Question 11

Describe how the aluminum break through test is done

Answer 11

• Most common method is: colormetric spot test
• a small drop of 99m-Tc eluate placed on a strip of filter paper that contains a color indicator
• a small drop of aluminum standardof a known concentration (1-ug/ml) is placed on the opposite ende of the filter paper
• aluminum reacts with the indicator producing a pink color
• the intensity is proportional to the amount of A3 present
• USP limit: 10 ug Al3/ml of 99m-Tc
• Do not use eluate does not pass the test

Question 12

Describe the sterility test

Answer 12

• Aspetic technique should be followed when eluting the generator and whenever withdrawing pertechnetate fromthe vial
• Retrospective sterility testing should be performed monthly

Question 13

Describe pH testing

Answer 13

• Performed by manufacturer level
• The pH of the eluate should be between 4.5-7.5
• The pH of the eluate is usually 5.5
• Can be performed quantitatively with pH paper