A novel method for the gain conversion factor estimation in quality assessment of ultrasound diagnostic systems

Quality Assessment (QA) of ultrasound (US) equipment is of primary importance since US diagnostic systems are used in a wide range of medical applications. Among the recommended test parameters, maximum depth of penetration, local dynamic range and spatial resolution are usually estimated in the literature through the Gray Scale Mapping Function (GSMF) that, for some methods, requires the US system's gain to be provided in dB. Since many US systems in the market provide the gain in arbitrary units (au), a novel automatic method for the assessment of the gain conversion factor to dB has been proposed and investigated in the present study. According to the definition, if the diagnostic system provides the overall gain in au, the abovementioned factor is the conversion unit from au to dB, while it is a dimensionless coefficient if the gain is directly given in dB. Data have been collected on a gray scale US phantom displaying the contrast targets at three different depths as well as by varying both the operating frequency of the phased array probe used and the dynamic range settings. Based on the promising preliminary results, further studies will be carried out on a higher number of diagnostic systems and probe models to improve the automatic method and deepen the method uncertainty investigation.