Calculating the Activity in a 99Mo/99mTc Generator
Let us take a more in depth look at how 99Mo decays to 99mTc, specifically predicting the amount of activity in the generator and how much 99mTc should be in the eluate
- Most important is to remember that we are dealing with the decay formula in a modified fashion that will help us determine the activities levels of 99Mo and 99mTc
- Given the formula on the left for both 99Mo and 99mTc the decay factor of one hour can be calculated, which is 0.990 and 0.891 respectively
- From the question on the right the problem determines what the decay factor is from a 3.5 Ci generator after 68 hours of decay
- The amount of activity that remains is 1.71 mCi of 99Mo
- Once you have the 99Mo activity you must use the above formula to find the activity of 99mYc
- The amount of activity is 1.64 Ci, but this is not the final step
- Because 10% of 99mTc decays by internal conversion you must multiple 0.9 to get the true 99mTc activity
- The final Ci amount is 1.5
