Novel design solutions for dedicated portable brain positron emission tomography systems with improved performance facilitate emergency and interventional image-guided surgery as well as advanced diagnostics of clinically impaired patients with neurodegenerative diseases. We report a novel portable MVT-based All-Digital helmet PET system with a hemispherical detector arrangement based on the Multi Voltage Threshold technology. It has a transverse and axial field of view (FOV) of 200 and 124 mm, respectively. It allows to scan subjects in a standing, sitting, and lying position. We evaluated the performance of the system according to NEMA standards. The scanner exhibits a noise equivalent count rate peak of $mathbf {(151pm 2)}$