A new PET scanner for functional brain imaging based on 2-mm straw detectors

Positron Emission Tomography (PET) is a uniquely valuable imaging modality for functional brain imaging that remains underutilized due to the lack of affordable, high-performance brain PET scanners. We propose a parallax-free, low-cost detector technology that offers high spatial resolution, high sensitivity, 3D position encoding, and simple readout without the use of photomultiplier tubes. The capabilities of the new detector are demonstrated in a new scanner design. The performance of the proposed scanner is explored in Monte Carlo simulations, implemented in MCNP5. The scanner consists of six detector heads arranged hexagonally, each containing thirty-five detector modules, and separated 22 cm from one another. Each module contains a 10×10 array of “straw” detectors, each 50 cm long, 2 mm in diameter and incorporating a thin layer of lead in their wall. Photons interacting in lead generate Compton- and photo-electrons that are subsequently counted in the gas contained within each straw detector. We predict that image resolution is close to 1 mm in all three directions (radial, tangential and axial), and remains uniform to within 15% over the entire transverse field of view (FOV). Sensitivity is 7.8%, for a point source in the center FOV, in the absence of a scattering medium. The transverse variation of sensitivity is on the order of 10%. The scatter fraction is 48% and the peak NECR is 165 kcps, obtained at 17.7 kBq/cc.