QA: Quality Assurance, Accuracy, Precision and Phantoms

When an instrument such as an MRI scanner is installed and handed over to the user, a series of acceptance tests is often carried out by the customer (Och et al., 1992; McRobbie and Quest, 2002; Och et al., 1992). The vendor’s installation engineer will also have carried out extensive testing, according to the manufacturer’s protocols, using phantoms (test objects), to ensure the instrument is operating within the specification of the manufacturer. For MRI these may include signalto-noise ratio, spatial resolution and uniformity tests, gradient calibration, ensuring image artefacts are below certain levels. Quality assurance (QA, sometimes called quality control) is used here to denote an ongoing process of ensuring the instrument continues to operate satisfactorily (Barker and Tofts, 1992; Firbank

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