Author: Jonathan Cole

Background: The purpose of this study was to verify the feasibility of using the light output from the display monitor to monitor contrast to background ratio (CBR) and optimise image quality in a fluoroscopy system Methods: A standard grey scale pattern (GS2 Leeds test tool) was used to assess image quality for 2 mobile Siemens Cios C-arm units (one with image intensifier and the other with a Flat panel detector (FPD – Cios Flow)). This test tool was placed into a stack of polymethyl methacrylate (PMMA) phantoms simulating a patient equivalent thickness of 10 and 20cm. Fluoroscopic images for the extremity protocol were acquired using low, medium and high dose settings for 7.5pps and continuous modes. The display monitors were checked for quality using the SMPTE pattern before assessing for luminescence (cd/m2) using an X2 Unfors light meter. The incident air kerma rate (Ka,r) at interventional reference point was recorded from the displayed values from each c-arm unit. The luminescence values...

Diagnosis and interventional procedures in healthcare rely heavily on x-ray imaging.However, there are known patient risks associated with the use of x-rays. Therefore,minimising radiation dose to the patient is essential, whilst also retaining adequate clinicalimage quality. Image quality is currently measured using test objects, which cannot bedirectly related to clinical image quality. These measures are also subjective, timeconsuming, and cannot easily be applied to large datasets. The majority of previous researchinto clinical image quality has incorporated quantitative measures of computed tomographyimage quality, with additional work aiming to automate these measures. Preliminaryresearch using quantitative measures of clinical image quality has also been carried out ininterventional radiology and digital mammography. The aim of this study was to develop objective image quality measures for interventionalradiology procedures, to be applied to large numbers of clinical images for use alongsidepatient dose data during system optimisation. This involved a retrospective audit of clinicalimages from Royal Free Hospital, and a phantom study to validate the results. The developedmetrics...

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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