This type of PET/CT scanning achieves the images through tracing the proteins found on the surface of prostate cancer cells. These proteins are referred to as PMSA (Prostate Specific Membrane Antigen). Until fairly recently, the available radiotracers have not been the kind that will bind to prostate cancer cells. However, this changed when some new radiotracers appeared on the market, FDA-approved, and today there are several available.