Treatment for a variety of diseases often requires guidance for the delivery of either a drug or radiation to the disease site. Positron Emission Tomography (PET) can provide three dimensional positioning of the location of positron emitting radioisotopes that can mark a disease site. However, the inversion of the raw emission projection data into a 3D volume is computationally intensive, and this results in a low update or frame rate. In order to be useful in either guiding a surgeon, or some other automated feedback approach, the update/frame rate must be of sufficient speed that the user can effectively control the process. This approach provides a substantial improvement to the frame rate by taking advantage of iterative reconstruction methodologies to shortcut the reconstruction process.