A Comparative Study of Continuous Versus Stop-and-Go Scanning in Circular Scanning Photoacoustic Tomography

Photoacoustic tomography (PAT) is a noninvasive hybrid imaging modality providing high contrast and resolution in deep tissue imaging. In a typical PAT system, the photoacoustic (PA) waves are recorded using an ultrasound transducer rotating around the sample. Being economical and easily available, a single-element transducer (SET) is commonly employed. For each laser pulse, the SET collects one time-resolved PA signal, known as an A-line. The acquisition of A-lines in a circular scanning PAT system by a SET can be done in two ways: 1) Stop-and-go scan, and 2) Continuous scan. In this work, we compared the two types of scanning methods in terms of image quality, signal-to-noise ratio (SNR), spatial accuracy, resolution, and scan-time for phantoms and in vivo imaging. We found that the image quality, spatial accuracy, and the SNR did not change in continuous scans, as compared to stop-and-go scans. However, there was a significant decrease in scan time in continuous scans. This improvement in scan time was 2-4 folds for lasers with low pulse repetition rate (10 Hz), and up to 7-12 folds for lasers with higher pulse repetition rate (7 kHz).