Question

A diphosphonate kit contian 180 mCi of Tc99m in 30 ml when it is prepared at 8am. Immediately, a 20 mCi dose is withdrawn for a bone scan. if the patient arrives late at 9:30 and half the volume is accidentally discharged, how much volume from the kit must now be added to the syringe to correct the dose to 20 mCi? (no other doses have been withdrawn meanwhile, and the decay factor for 1.5 hrs is 0.841)

a. 1.5 ml
b. 2.0 ml
c. 2.3 ml
d. 2.5 ml
e. 2.7 ml

Answer 1

To correct the dose to 20 mCi, 240 ml from the kit must be added to the syringe.

Step-by-step explanation:

To find the volume from the kit that must now be added to the syringe to correct the dose to 20 mCi, we need to understand the concept of radioactive decay and use the decay factor given.

Initially, the kit contained 180 mCi of Tc99m in 30 ml, and a 20 mCi dose was withdrawn for a bone scan. Therefore, there is now 180 - 20 = 160 mCi of Tc99m left in the kit.

To calculate the volume that needs to be added, we can set up the following proportion: (Volume to be added) / 30 ml = 160 mCi / 20 mCi.

Simplifying the proportion gives (Volume to be added) = (30 ml * 160 mCi) / 20 mCi = 240 ml.

Therefore, the volume from the kit that must now be added to the syringe is 240 ml