A proposed enhancement to the in air sensitivity test for ultrasound quality assurance

Abstract

PurposeA number of guidelines for ultrasound quality assurance recommend the use of the in air reverberation depth as a proxy measure for sensitivity. The test is quantised, i.e. it depends on the brightness of the deepest in air reverberation. The aim of this study was to investigate a possible enhancement to the test, where the gain is reduced to determine the “reverberation threshold”. MethodsThe test was introduced in several ultrasound departments. Results were audited to determine agreement with annual tests of sensitivity using a tissue mimicking test object. ResultsThe new test was performed on 100 probes. A change in reverberation threshold was demonstrated in 9 probes; 8 of these also had changes in penetration and/or grey level in a tissue mimicking test object. Reduced penetration but no change in reverberation threshold was seen in 2 probes. ConclusionsThe reverberation threshold provides a simple enhancement to the in air sensitivity test. Periodic sensitivity testing with a tissue mimicking test object remains important.