Is Grey Level a Suitable Alternative to Low-Contrast Penetration as a Serial Measure of Sensitivity in Computerised Ultrasound Quality Assurance?
The aim of this study was to test the hypothesis that grey levels are a suitable alternative measure of sensitivity in ultrasound imaging quality assurance, as there are several caveats in the use of penetration depth. In a primary cohort of nine probes, where measurements had been made for 6 to 34 mo, both penetration depth and mean grey level fell below tolerance for six probes; both penetration depth and mean grey level remained within tolerance for three probes. In a secondary cohort where a measurement programme had been in place for a shorter period, grey level and/or penetration depth fell below tolerance in 15 of 66 probes; the sensitivity and specificity of at least 10% loss of grey level in predicting >5% loss in penetration depth were 91% and 93%, respectively. A loss of grey level accompanies a loss of penetration and provides a suitable alternative measure of sensitivity.
Radiation Protection & Radiology Physics, United Lincolnshire Hospitals NHS Trust, Greetwell Road, Lincoln, UK. Electronic address: nick.dudley@ulh.nhs.uk.
Nicholas J
NJ
Dudley
Medical Physics & Clinical Engineering, Nottingham University Hospitals NHS Trust, Derby Road, Nottingham, UK.
Nicholas M
NM
Gibson
D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D019047:Phantoms, Imaging; D011786:Quality Control; D012680:Sensitivity and Specificity; D014463:Ultrasonography / Q000379:methods*
Grey level; Penetration; Quality assurance; Sensitivity; Ultrasound