Negativity artifacts analysis in back-projection based photoacoustic tomography

Abstract

Photoacoustic tomography (PAT) is a fast-evolving biomedical imaging modality in recent years, which has unique applications in a range of biomedical fields. In PAT, image reconstruction is a critical step to produce high-quality optical absorption images from photoacoustic projections. To date, algorithms based on back projection are the most widely used image reconstruction techniques due to their simplicity and computational efficiency. However, images reconstructed by back projection contain negative intensities, which have no physical meanings and are essentially undesired artifacts. Here we study the formation mechanism, fundamental causes of the negativity artifacts in backprojection based PAT. Results show that limited detector bandwidth and limited view angle are two fundamental causes of the negativity artifacts. When the bandwidth of the detector is limited, back-projection signals will be distorted due to the loss of frequency contents and negativity artifacts thus occur. When the view angle of the detector is limited, photoacoustic signals propagating in three-dimensional space cannot be captured completely, resulting in negativity artifacts. This work provides a comprehensive understanding of the characteristics of negativity artifacts, which may promote the development of artifact-free image reconstruction algorithms.