Modified time-of-flight based calibration approach for ultrasonic computed tomography.

In the previous paper [11], a method for geometrical and transducer-time-delay auto-calibration of an ultrasonic computed tomography (USCT) system has been described, aiming at calibration of individual ultrasonic (US) transducer positions. The present contribution describes a novel modification of the method utilizing the particular USCT system concept: the exactly known spatial relations among transducers grouped in each of the transducer array systems (TASes). The algorithms used for the calibration remain based on the principles similar to the global positioning system (GPS) navigation, however, the positions and orientations of complete TASes are calibrated, rather than individual positions of transducers.

Calibrating an ultrasonic computed tomography system using a time-of-flight based positioning algorithm.

This paper presents a method for geometrical and time-delay auto-calibration of an ultrasonic computed tomography (USCT) system. The algorithms used for the calibration are based on the principles similar to the global positioning system (GPS) navigation. Ultrasonic transmitters and receivers in USCT can be viewed like satellite transmitters and mobile receiver units in GPS.

Comparison of wave-equation versus measurement-processing transducer calibration for ultrasonic transmission tomography.

The contribution deals with the first step in using proper wave-equation based ultrasound propagation model in image reconstruction from the ultrasonic computed tomography data. Particularly, it compares the transducer calibration results obtained via direct measurement of the empty image field and consequential data processing based on a simple direct-propagation model with the simulation results obtained via solving the single-frequency wave equation under proper border conditions reflecting the realistic measurement geometry. The results show a reasonable qualitative agreement when a certain degree of phase-shifted coupling from the transmitting transducer elements to the neighbouring elements of the transducer field is admitted.