Ultrahigh-resolution Small Animal SPECT Imaging Study Based On A Novel Parallel Hole-pinhole Collimator

Small animal SPECT is a significant branch of small animal molecular imaging,which plays a key role in disease mechanism study and the clinical drug development.And it has been one of the mainstream trends to develop ultrahigh resolution small animal SPECT systems under the pressure of improving imaging qualities.This dissertation aims to design a novel ultrahigh resolution small animal SPECT system,which can achieve 0.1 mm to 0.2 mm resolution.The dissertation focouses on the design and evaluation of the proposed novel collimator.To improve the overlap and DOI effect in the pinhole collimator,the design of parallel hole-pinhole collimator is proposed for the first time in this dissertation,and an analytical model is built for the parameters design.The Monte Carlo simulation package GATE is used to buildup the model and peform simulation,simulation results provethat the system has a level of 0.15 mm ultrahigh resolutionperformance.For imaging performance test,a real single-hole collimator model has been made according to the design,and an experimental platform hasalso been built up for the testing purpose.With the projection data and the analytical projection model that has been built,system geometry calibration is applied.The dissertation also provides two different methodsto evaluate the resolution performance of the collimator with single-angle projection data,and both of the two methods get consistent results.The experiment results validate the system can achieveultrahigh resolution.A multi-hole collimator has been designed based on single-hole collimator.By comparing the sampling performance with different scanning orbits under the multi-hole collimator system,an adapted scanning orbits is given in this dissertation.In conclusion,a novel parallel hole-pinhole collimator has been designed in this dissertation,experiment and simulation results demonstrat that the system can achieve the level of 0.15 mm ultrahigh resolution.Methods of how to design a parallel hole-pinhole collimator has been given by the work of this dissertation,which can be instructive to how toimprove spatial resolution of small animal SPECT.