A quality assurance program describes all procedures necessary to maintain proper and consistent equipment operation. The goal is to keep the diagnostic quality of the ultrasound image at a consistently high level and to maintain patient and operator safety.
All clinical ultrasound facilities should have a good quality assurance program. Indeed, having a robust QA program is now a requirement for all accredited departments. The AIUM has an excellent document that describes in detail the components of a good QA program. You can access it here.
I have also created the three-part video series below that provides a good overview of quality assurance.
Also, a thorough explanation of statistical parameters such as Sensitivity, Specificity, Positive Predictive Value, and Negative Predictive Value is provided below in Part 3 of the Quality Assurance videos.
Non-uniformity due to malfunctioning transducer crystal(s)
An overview of QA and an explanation of testing devices
Gray scale QA testing with tissue mimicking phantoms
Statistical parameter concepts (e.g., sensitivity, specificity, PPV & NPV)