Origin Ensemble Algorithm based Doppler Broadening Effect Correction for CZT Compton Camera in Prompt Gamma Imaging: A Monte Carlo Study

In this paper, we firstly study the effect of Doppler broadening on deposited energy and Compton scattering angle for the 4.44 MeV gamma-rays. We measured and fitted the models of the Doppler broadening effect, as well as compared them with theoretical calculations. Then we presented two kinds of approaches (i.e. unidirectional and bidirectional) to correct the Doppler broadening effect via OE with different sampling distribution. Finally, we evaluated the performance of these correction methods for prompt gamma imaging. The corrections with Lorenz distribution of methods □ and □ (i.e. unidirectional and bidirectional) have the best performance on the Doppler broadening correction compared with Gaussian and uniform distribution. Both the calculated model obtained by theoretical formula and fitting model based on the measurement data can realize effective correction. After the correction, the signal-to-noise ratio of the reconstructed image is improved, and the peak prediction is closer to the true value. Moreover, the results of the Doppler broadening correction have a narrower full width at half maximum, which is corresponding to the expected theoretical prediction. The results show that the Doppler broadening correction can further reduce the inherent point spread function of the Compton reconstruction, and improve the accuracy of the reconstruction.