Patient Bed Design for an Integrated SPECT-CT Dedicated Mammotomography System

This study investigates the significant challenges and tradeoffs associated with designing a patient positioning system for a novel, compact SPECT-CT system dedicated to 3D breast and chest wall imaging. The primary challenge is to maintain patient comfort while optimally positioning the patient for maximal chest wall imaging, given the physical and geometric dimensions of the dual-modality system. The dedicated breast SPECT system comprises a 16times20cm² CZT-based gamma camera attached to a versatile gantry, capable of varying polar tilt, radial distance and azimuth. The dedicated breast cone beam CT system, initially designed here without dynamic polar tilt, includes a tungsten target source and a 20times25cm² CsI(Tl) detector laterally offset from the central ray, separated by a 60cm SID. The integrated imaging system with a common field-of-view is positioned below the custom-designed, 3-dimensionally flexible bed positioning system. An additional consideration of the bed is that it is radio-opaque, which minimizes both emission contamination from the patient's body into the transmission CT system, while simultaneously minimizing any X-ray scatter onto the patient's body. This preliminary implementation and investigation indicates the need for novel camera trajectories to satisfy both chest wall proximity imaging and patient comfort. The effects of breast volume imaged within the common FOV and table angles, which are assumed to correspond to patient comfort, are examined. A manufactured galvanized steel prototype demonstrates the practicability of the bed.