Effects of mechanical alignment errors on Compton scatter imaging

The development of a prototype Compton scattering camera based on two 1 cm/sup 3/ cubic 3-D position sensitive CZT detectors is underway in our laboratory. As a practical problem, the mechanical alignment error may be larger than the 1 mm detector position resolution. This paper investigates the effects of any possible mechanical alignment error on the reconstructed images by Monte Carlo simulations. Our simulation results show that a minor misalignment can cause a significant distortion in the reconstructed image. Any alignment error will lead to a systematic error if the mechanical misalignment is not compensated for. Since the alignment error can cause a distinguishable distortion, system parameters can be adjusted during the image reconstruction procedure until an optimal image is obtained. In this manner, the mechanical alignment error can be automatically determined and compensated for. Our results indicate that any distortion due to alignment error can be eliminated and ensure the angular resolution remains only limited by the two detectors energy and position resolutions.