Timing-error-difference calibration using reciprocal signals.
Timing errors in transmission and reception electronic channels of medical ultrasound imaging systems are generally smaller than one-tenth of a wavelength and do not influence the focusing quality of the system. However, these errors influence the performance of the near-field-signal-redundancy algorithm for correcting phase-aberrations generated by speed heterogeneity in the medium due to its high sensitivity to errors. The effect of timing errors is to make the transmission and reception phase-aberration profiles different. When the difference is much smaller than the period of the signal, an algorithm has been proposed in a previous work to measure the average of the transmission and reception phase-aberration profiles, and it can be used as an approximation to correct phase-aberrations on both transmission and reception. However, when the difference is large, the transmission and reception phase-aberration profiles need to be measured separately. In this paper, several algorithms that use reciprocal signals are proposed to measure the difference profile of the transmission and reception phase-aberration profiles. Their performances are theoretically analyzed, simulated, and experimentally tested. From the measured average and difference profiles, the transmission and reception phase-aberration profiles can be derived separately and used to correct phase-aberrations on transmission and reception, respectively.
Li
Yue
Y
Information and Communication Technologies Center, Commonwealth Scientific and Industrial Research Organisation, Marsfield, NSW, Australia. yue.li@csiro.au
D000465:Algorithms; D001315:Australia; D002138:Calibration; D007089:Image Enhancement / Q000379:methods* / Q000592:standards*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods* / Q000592:standards*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013997:Time Factors; D014463:Ultrasonography / Q000295:instrumentation / Q000379:methods* / Q000592:standards*