A proposed helmet-PET with a jaw detector enabling high-sensitivity brain imaging

The advanced depth-of-interaction positron emission tomography (PET) detectors have been improved to provide three-dimensionally uniform detector resolution. These detectors allow a geometry that places the detectors very close to imaging subjects, because they can maintain high spatial resolution even in the peripheral region in the field-of-view (FOV) without loss of sensitivity. In this study, we are proposing a helmet-PET geometry consisting of a hemispheric-shaped detector and a jaw detector. The key points of the geometry are the closely positioned detectors and the detector covering the jaw. For each point in the FOV, we calculated the geometrical sensitivity as the relative coverage of the solid angle where the coincidence measurement was possible. We found that the hemispheric-shaped geometry had high sensitivity for the cerebrum region. In addition, the jaw detector significantly improved the sensitivity at the center region of the hemisphere, where the cerebellum is positioned during PET measurement. High sensitivity and quantitative accuracy for the cerebellum region are important especially for functional brain imaging because this region may be used as a reference value in kinetic analysis. Geometrical analysis showed that the proposed geometry has good potential for highly sensitive and accurate measurement of brain functions. In addition, numerical simulations showed the proposed geometry increases image quality especially for the central region.