FLUG 2024 – Visualising Recursive Filtration: practical methods; Emily Smith
We have established a simple, low-cost, practical method to visualise the lag / recursive filtration present in fluoroscopy images. Using a high-contrast test object on a rotating stand, the signal in a fixed ROI is measured as the test object passes through. The reduction in signal in subsequent frames gives an indication of the ‘recovery time’ i.e. the number of frames before the signal returns to background levels.
This can be visualised graphically and used to characterise the lag / strength of recursive filtration on clinical fluoroscopy programmes. Where image export is not possible, the method still enables a quick visual check to see if lag is visible. This has benefits for optimisation and potential routine constancy testing.
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