Final answer:
A desirable quality for a radioisotope used for medical imaging of a specific organ is a short half-life, as it allows for a shorter waiting time before the patient can be considered safe from radiation exposure.
Step-by-step explanation:
The distance that radioisotopes travel through matter increases in order from alpha to gamma particles. For medical imaging of a specific organ, a desirable quality for a radioisotope would be a short half-life. A short half-life means that the radioisotope decays quickly, allowing for a shorter waiting time before the patient can be considered safe from radiation exposure.