same animal for development of a new drug you have to monitor the animal multiple time points over a time course of a couple months at least so the radiation dose can kill the animal and it doesn't give you enough information as well because x-rays sometimes does not provide enough information right you have to have the functional information to make your to test the efficacy of the drug further acoustic tomography is simultaneously analogous to MRI in pet so this is one example on this site we can see the hemodynamic contrast