Flexible geometries for hand-held PET and SPECT cameras

Minimally invasive surgery has spurred development of portable nuclear medicine nonimaging detection products (i.e., probes). Although these probes function well in simple anatomic regions (e.g., extremities), more complicated regions (e.g., head & neck, axilla) can present surgeons with difficulties due to the presence of overlapping tissue activity. Conventional gamma cameras, with large camera heads, are not ideal for intraoperative applications. Due to the bulky camera size, PET and SPECT is difficult to implement in OR settings. Although small gamma cameras may be helpful when a lesion is already identified, surveillance of larger areas (e.g., for peritoneal evaluation) can be difficult due to limited field-of-view. Ideally, the information from small hand-held gamma cameras would be integrated from multiple views taken at arbitrary positions and angles. We present a method of creating an image with 3D information from one or more portable hand-held gamma cameras held in arbitrary positions and angles near a radioactive source (patent pending). The method takes advantage of recent developments in iterative reconstruction algorithms, computer speed, and position sensing devices. Corrections were implemented for inhomogeneous sampling in time and space.