Least-Squares Estimation of Imaging Parameters for an Ultrasonic Array Using Known Geometric Image Features

Ultrasonic array images are adversely affected by errors in the assumed or measured imaging parameters. For non-destructive testing and evaluation, this can result in reduced defect detection and characterization performance. In this paper, an autofocus algorithm is presented for estimating and correcting imaging parameter errors using the...

Time to threshold (TT), a safety parameter for heating by diagnostic ultrasound

Activities in the standardisation of medical ultrasonic imaging and monitoring devices have been undertaken to ensure the safe application and to provide the user with tools to perform risk-to-benefit analysis. Internationally, agreement has not been reached to implement a system based on a physical quantity such as temperature rise. Therefore,...

New contrast parameter to qualify 1D and 2D arrays

A Figure-of-Merit for the performance of any medical array is defined, which is new in the field of medical imaging: the object contrast parameter. This contrast parameter quantifies the contrast between an on-axis object and its surroundings and as such is closely related to the visibility of an object. Its behaviour as a function of depth...

Ultrasonic characterization of defects in steel using Multi-SAFT imaging and neural networks

Due to the recent improvements in nondestructive inspection (NDI) techniques, even small or weak inhomogeneities can be detected and discrimination between critical and non-critical defects becomes more crucial. In practice, welded regions of steel components are of special interest. Characterizing a detected inhomogeneity may be done by using...

Angle-dependent backscatter from the arterial wall

The anisotropic nature of intra-arterial echographic images is reported, and the source of this anisotropy is investigated using postmortem human iliac arteries. A 27 MHz transducer, mounted on an ultrasonic microscope, is used to quantify the angular dependence of the backscatter power versus the angle of incidence, and these results are...

Backward ray tracing for ultrasonic imaging

Focused ultrasonic beams frequently pass one or more media interfaces, strongly affecting the ultrasonic beamshape and focusing. A computer program, based on backward ray tracing was developed to compute the shape of a corrected focusing mirror. This shape is verified with another program; then the mirror is constructed by CNC (computerized...