IEC/TS 62791 Ed. 2.0 en:2022

Ultrasonics - Pulse-echo scanners

Low-echo sphere phantoms and method for performance testing of grey-scale medical ultrasound scanners applicable to a broad range of transducer types

IEC TS 62791:2022 defines terms and specifies methods for quantifying detailed imaging performance of real-time, ultrasound B-mode scanners.

Detail is assessed by imaging phantoms containing small, low-echo spherical targets in a tissue-mimicking background and analysing sphere detectability. Specifications are given for phantom properties.

In addition, procedures are described for acquiring images, conducting qualitative analysis of sphere detectability, and carrying out quantitative analysis by detecting sphere locations and computing their contrast-to-noise ratios.

With appropriate choices in design, results can be applied, for example:

• to assess the relative ability of scanner configurations (scanner make and model, scan head and console settings) to delineate the boundary of a tumour or identify specific features of tumours;
• to choose scanner control settings, such as frequency or the number and location of transmit foci, which maximize spatial resolution;
• to detect defects in probes causing enhanced sidelobes and spurious echoes.

The types of transducers used with these scanners include:

• a) phased arrays,
• b) linear arrays,
• c) convex arrays,
• d) mechanical sector scanners,
• e) 3-D probes operating in 2-D imaging mode, and
• f) 3-D probes operating in 3-D imaging mode for a limited number of sets of reconstructed 2-D images.

The test methodology is applicable for transducers operating in the 1 MHz to 23 MHz frequency range.

IEC TS 62791:2022 cancels and replaces the first edition published in 2015. This edition constitutes a technical revision.

This edition includes the following significant technical changes with respect to the previous edition:

• a) It introduces necessary corrections to the analysis methods; these have been published in the literature.
• b) It increases the range of contrast levels of low-echo spheres in phantoms that meet this Technical Specification. Previous specification was -20 dB, but two additional levels, -6 dB and either -30 dB or, if possible, -40 dB, are now specified.
• c) It includes a wider range of uses of the methodology, including testing the effectiveness of scanner pre-sets for specific clinical tasks and detecting flaws in transducers and in beamforming.
• d) It decreases the manufacturing cost by decreasing phantoms' dimensions and numbers of low-echo, backscattering spheres embedded in each phantom.