Collimator interchange system for adaptive cardiac imaging in C-SPECT

Use of a small field of view can greatly improve the imaging performance of cardiac SPECT systems, compared to using conventional whole-body SPECT system that use a large field of view for cardiac imaging. To maximize the benefits, however, it is important to locate the heart and place it accurately into the small FOV. To achieve high performance across the general population, a system must provide imaging configurations optimized for different size and location of the heart and the size of the patient. Because of the critical role the collimator plays in SPECT, it would be ideal if a dedicated collimator could be used for each of the different patient groups. The ability to exchange collimators without moving the patient can enable serial studies with different imaging options while preserving anatomic registration. We developed a slit exchange system for the slit-slat collimator of the C-SPECT cardiac platform. The full-scale prototype, a precision link conveyor following a curved, body contouring path, allows four distinct transaxial collimation options and can be expanded further. The collimators can be exchanged in 10 seconds without disturbing the patient, allowing truly adaptive clinical SPECT imaging The positioning precision for all elements of the system is within 0.1 mm and has shown no degradation over 100,000 complete revolutions of the conveyor - well above the expected usage for a clinical system. We believe that the rapid and precise operation allowing optimal collimation for different imaging tasks is an important technological step for SPECT.