imagequality – Fluoroscopy Users' Group

FLUG 2017 – IPEM Evidence Based QA Working Party – Fluoroscopy and Fluorography – image quality; Daniel Shaw

23rd November 201728th December 2017 By Jonathan Cole Comment Closed

Background There is little evidence in peer reviewed literature to support the efficacy of many of the tests of x-ray equipment performed routinely by medical physics departments. Current guidance is based on the substantial experience of the members of working parties involved in writing IPEM report 91 and the IPEM report 32 series. The aim of this working party is to produce evidence that would support any future revisions of IPEM Reports 91 and 32. The specific focus of this workstream is on the efficacy of routine tests in fluoroscopy and fluorography. Methods A pro-forma for data collection was devised, tested and revised by the working party. The final pro-forma contained fields to collect data relating to all tests routinely undertaken on fluoroscopy and fluorography equipment. The fields were designed to accept simple pass/fail or the quantitative result, whichever was most appropriate for each specific test. The pro-forma was developed in such a way that as much or as little information could...

FLUG 2017 – A Novel Quantitative Measurement of Image Quality in Fluoroscopy; Patrick Kenny

23rd November 201728th December 2017 By Jonathan Cole Comment Closed

Measuring image quality on modern flat panel fluoroscopy systems is challenging. Accurate measurements using the Leeds TO10 must use a small range of prescribed settings of beam quality (kV & added copper). Often these are not always easily achieved on newer systems. Also, TO10 analysis involves estimating the Threshold Contrast Index HT(A), which is a subjective estimate of the image’s signal to noise ratio. It is the inverse of the product of the square root of the disc area times its nominal contrast, as derived from Rose’s model of imaging. Finally, a typical measurement error of about 15% is associated with such an estimate of HT(A). More recently we are beginning to use the NEMA XR-27 protocol in which ‘for-processing’ images can be used to calculate MTF, NNPS & DQE etc. However, while representing a welcome development, such measurements do not address the effects of image processing applied prior to image presentation. It is in some ways an interim...

FLUG 2017 – Digital Angiography: Hunting for Ghosts; David Costello

23rd November 20176th January 2018 By Jonathan Cole Comment Closed

Low dose Angiography (LDA) systems rely on significant recursive filtration (aka temporal averaging) to maintain image quality. The use of this type of processing is specific to the imaging application (cardiac, neuro, vascular…) and can be varied by the system vendor. In situations of rapid motion, such processing can have a detrimental effect on images obtained, producing temporal ghosting. LDA enables the use of lower kV and mAs resulting in lower patient and staff doses. It also allows manufacturers to overcome output limitations when using smaller focal spots. While the benefits are clear very little work has been carried out in relation to the drawbacks of this approach. This work aims to examine the impact of recursive filtration on moving targets in LDA systems. Common test objects such as the Leeds Test Objects do not allow for the dynamic assessment of Image ghosting. In this study, a modified NEMA Cardiology Phantom and an in-house linear motion phantom were used...

FLUG 2017 – Assessment of the detectability of a moving guidewire in fluoroscopically-guided procedures using a mathematical model observer; Nick Ryckx

23rd November 201728th December 2017 By Jonathan Cole Comment Closed

Presentation to come Background Fluoroscopically-guided procedures are among the most irradiating medical interventions using ionising radiation. As such, a fair amount of pressure is put on reducing patient dose, either by adapting the protocols implemented in the units, or by heavy technical upgrades allowing for online image processing and subsequent patient exposure reduction. The downside is a potential loss in image information content, leading to either longer procedure times or, worse, increased volumes of injected contrast medium. To our knowledge, there is no existing quantity able to properly assess the visibility of moving structures in fluoroscopic images. This work proposes a new method to measure image quality using a clinically relevant detection task in dynamic conditions. Methods Our test object consists of a 3 mm thick and 250 mm wide PMMA square plate, with a 1 mm deep groove along one of the diagonals. The groove is used to straighten a 0.014” thick coronary guidewire. The plate is attached to a dedicated motion...

FLUG 2017 – Development of a software based on an anthropomorphic image atlas for image quality optimization in interventional radiology: initial results for 3D angiography; Michaël Gautier

23rd November 201728th December 2017 By Jonathan Cole Comment Closed

Purpose To provide a protocol optimization software helping radiologist to tailor image quality (IQ) in Interventional Radiology (IR) thanks to an anthropomorphic images atlas. Method and materials For the four most representative anatomic areas of our clinical practice (liver, pelvis, lung, spleen), five reference protocols were set-up in our interventional radiology system (Innova IGS 540, GE Healthcare, Buc, France) with different IQ/dose preferences from low dose to high Image Quality (IQ). These preferences were defined by adjusting the Automatic Dose Rate and Image Quality (ADRIQ) strategy, the detail level and the rotation speed for 3DA sequences. For these 20 protocols, 3D angiography images were acquired on an anthropomorphic phantom (PBU-60, Kyoto Kagaku). All acquired images were qualitatively validated by a senior radiologist. These images were implemented in a home-made software (ProtoEnhanceIR) in order to optimize protocols by displaying the anthropomorphic images and associated Peak Skin Dose (PSD). The radiologist has the ability to select the most suitable protocols in regard...