Effects of Mechanical Alignment Errors on Compton Scatter Imaging

The development of a prototypc Compton scaltering camera based on two 1 cm3 cubic 3-D position scnsitivc CZT detectors is iindcrway in our laboratory. As a practical problem, the mechanical alignmcnt error may be larger than the 1 mm detector position rcsolution. This paper investigates thc cffccts of any possible mechanical alignmcnt error on the reconstructed images by Montc Carlo simulations. Our simulation results show that a minor misalignmcnt can cause a significant distortion in the reconstructcd iinagc. Any alignment error will lead to a systematic error if the mcchanical misalignment is not compensated for. Since the alignmcnt error can causc a distinguishable distortion, system parameters can be adjusted during the image rcconstruction procedurc until an optimal image is obtained. In this manner, the mechanical alignmcnt error can be automatically determined and compensated for. Our rcsults indicatc that any distortion due to alignment error can be eliminated and cnsure the angular resolution remains only limited by the two detectors cncrgy and position resolutions. position rcsolution. In this papcr, cffects of any possible mechanical alignment error on the final reconstructed imagcs are invcstigated by Monte Carlo simulation. An automatic approach to calibrate the alignment error is proposed and tested using Monte Carlo simulated data.