SU‐D‐210‐01: Automated Depth of Penetration Measurements for Quality Assurance in Ultrasound

Abstract

Purpose:Subjective assessment of image quality metrics is a current limitation of most ultrasound quality assurance (QA) programs. Here, depth of penetration (DOP) assessments for sensitivity checks are routinely done. We demonstrate the performance of an automated method for DOP measurement for ultrasound QA.Methods:Subjective DOP was assessed by examining an image of a QA phantom and determining the depth where the echo data fades into noise. To assess DOP objectively, a phantom image was recorded followed by a second, “noise image” with the transducer held in air. Phantom and noise images were laterally averaged; the DOP was the depth where phantom image pixel value intersected 1.4X noise image values. During annual QA, DOP was evaluated subjectively by a single observer on a number of probes and compared with objective DOP measurements. Additionally, the objective method's measurement variance and sensitivity to transmit power was examined using a linear‐array transducer. To examine variance, the DOP measurement was repeated with 25 phantom images recorded at uncorrelated planes with transmit power at either 100% or 1%. DOP was also measured as the transmit power was varied in fine steps between 0.1% and 100%.Results:Agreement within 10% of the mean DOP was found between objective and subjective methods for most cases. A small number of cases showed a difference between 10% and 18%. Using the linear‐array, DOP was found to fall off as a power law with the transmit power. At 100% and 1% transmit power, the standard deviation of the DOP measurement was found to be 0.9 mm at DOP's of 8.16 and 6.30 mm on average.Conclusion:Objective image quality assessment is necessary to improve the utility of routine ultrasound QA. We found that objective DOP measurements show good agreement with subjective assessments of DOP while showing little variance.