A new approach to very high resolution mini-brain PET using a small number of large detectors

A novel very-high-resolution positron emission tomography (PET) using only a small number of large detectors in a circular ring format with collimating apertures is proposed, and a design example is given. The proposed system is ideally suited for very-high-resolution brain imaging, i.e. close to 2 mm FWHM (full width at half maximum) resolution, and can be converted to a medium-resolution system by simply changing the size of the collimating aperture if higher-sensitivity operation is desired. The basic concept of the system design is the optimization of the detector size and system diameter. The former relates to the detection efficiency and photon spillage and penetration to adjacent crystals, while the latter (system diameter) relates to the overall system sensitivity. Since conventional sampling schemes are unlikely to satisfy the sampling requirements for such a system where only a small number of large detectors are arranged in a circular ring format, a sequentially arranged collimating aperture rotating-ring detector (SCARD) scheme has been developed. This scheme makes it possible to sample the object space finely enough for image reconstruction