Image Reconstruction Analysis for Positron Emission Tomography with Heterostructured Scintillators

Abstract

<p>The concept of structure engineering has been proposed for the exploration of the next generation of radiation detectors with improved performance. A Time Of Flight Positron Emission Tomography (TOF-PET) scanner with heterostructured scintillators with a pixel size of 3.0×3.1×15 mm<sup>3</sup> was simulated. The heterostructures consisted of alternating layers of BGO as a dense material with high stopping power and plastic as a fast light emitter. Using the GATE simulation toolkit, a detector time resolution was calculated as a function of the deposited and shared energy in both materials on an event-by-event basis. We saw that while sensitivity was reduced to 32% for 100 µm thick plastic layers and 52% for 50 µm, the CTR distribution improved to 204±49 ps and 220±41 ps respectively, compared to 276±9 ps for bulk BGO. We divided the events into three groups based on their CTR and modeled them with different Gaussian TOF kernels. On a NEMA IQ phantom, the heterostructures had better contrast recovery in early iterations, while on the other hand, BGO achieved a better Contrast-to-Noise Ratio (CNR) after the 10th - 15th iteration due to the higher sensitivity. The developed simulation and reconstruction methods constitute new tools for evaluating different detector designs with complex time responses.</p>