Optimisation of ultrasound equipment using a phantom as part of the Annual Quality Assurance Program (QA)
Justyna Janus, Medical Physics Department, University Hospitals of Leicester
Introduction
The UHL Ultrasound Physics Quality Assurance (QA) Annual Program performs a complete set of tests using a test phantom to check for deterioration of equipment performance. However, this testing does not optimise the probes pre-set for its clinical applications. Here, we present a different QA approach where an ultrasound phantom was used to optimise and measure the performance of ultrasound probes used for vascular applications, enabling the best resolution required for its clinical use and providing measurements to inform uncertainty of measurement parameters.
Materials and Methods
Several probes and machines were tested individually. Settings including pre-set application, gain, focus, TGC and probe working frequency were optimised to achieve the best quality image. The resolution testing was undertaken by the UHL Medical Physics staff for ultrasound QA, with pre-set optimisation and consensus from three AVS clinical vascular scientists using a tissue-mimicking ultrasound phantom (CIRS Multi-Purpose Multi-Tissue Ultrasound Phantom Model 040GSE). The testing was performed under normal ultrasound room conditions with dimmed lighting and reference images saved to PACS. The caliper accuracy routinely checked at annual QA was determined with specific attention to the most detailed measurements performed clinically for temporal artery imaging using the L8-18 hockey-stick probe.
Result
Optimised settings for each ultrasound machine and probe were recorded and saved for routine clinical use. Recording the specific axial and lateral resolutions enabled the definition of the smallest structures that can be visualised as a separate individual structure and therefore measurable. This assures that clinically significant small measurements fall within an achievable resolution range.
Conclusion
An ultrasound phantom can be a useful tool helping to achieve the best performance of the ultrasound system and ensure that units in clinical measurements are achievable, with a known value for the uncertainty of measurement, therefore improving the quality of the diagnostic service provided to patients.