Blind Angle and Angular Range Detection in Planar and Limited-View Geometries for Photoacoustic Tomography

In this paper, the relationship between the position of ultrasound transducers from the photoacoustic source and the reconstructed image is investigated. Our studies have shown that the distance of the transducer and its location from the photoacoustic source specifically affects and is closely related to the quality of the reconstructed image of the source. Also, we introduce a concept called blind angle for photoacoustic computed tomography (PACT) that have planar or circular limited-view geometry. Complete and accurate equations of this relationship are presented in this paper for all different 2D photoacoustic geometries. The main source of these equations is the spherically of the ultrasound wave produced by the photoacoustic source. The result of these equations is that depending on the location of the transducers with respect to the photoacoustic source, the characteristics of the reconstructed image and the quality of the reconstruction of each point of the photoacoustic source can be accurately obtained, and the reason for these dependencies is fully explained. The results show that the more transducers receive the ultrasound wave produced by the photoacoustic source at more different angles, the higher the quality of the reconstructed image would become.