Metrological assessment of image quality in ultrasonic medical diagnostic equipment

Abstract

This paper presents a model for estimating uncertainty of measurement of performance parameters commonly used in the evaluation of ultrasound images. These are axial and lateral resolutions, contrast detail, spherical void, dead zone, image uniformity, measurement system accuracy, display and recording errors, vertical and horizontal distance accuracy, and anechoic object perception. These parameters were measured by two technicians following the recommendations of document IEC/TS 61390:1996, using a phantom, and the model of uncertainty proposed based on the guide to the expression of uncertainty in measurement (BIPM JCGM 100:2008). Moreover, an evaluation was carried out after 1 year to assess changes in the equipment image quality tested. In the assessment of operator influence on measurements, it was found that there is no statistical evidence that measurement results are different among most of the parameters. The results of three parameters were considered different between the two operators: contrast-detail resolution, display and recording errors, and measurement system accuracy. When considering the normalized error in comparison to the measurements made by the same operator under the same conditions in two consecutive years, no parameter showed a difference, given the level of uncertainty practiced. It is noteworthy that the proposed model of uncertainty contributes as an unprecedented way for metrological evaluation of diagnostic imaging by ultrasound.