Image Reconstruction Analysis for Positron Emission Tomography with
Heterostructured Scintillators
Abstract
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 mm3 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.