Member Only – Page 4 – Fluoroscopy Users' Group

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...

FLUG 2017 – Business Meeting; FLUG team

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

Elections due The Chair (Jonathan Cole) is up for re-election. Nominations were invited from anyone else who wishes to stand. Constitutional amendments An amendment was passed to add a quorum for certain actions to the constitution. ...

FLUG 2017 – Assessment of Fluoroscopy Mode on the Varian TrueBeam Linear Accelerator; Claire Jerrom

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

The X-Ray Imaging System on Varian TrueBeam Linear Accelerators can be used to acquire fluoroscopic images to aid radiotherapy treatment planning and verification. Six Varian TrueBeam units were installed in the Radiotherapy Department at Guy's Cancer Centre in June 2016. The fluoroscopy programmes were tested on three of the units during the commissioning period, and were deemed to be unsuitable for clinical use at that time due to the high skin dose rates and poor image quality. The radiotherapy department planned to use the fluoroscopy mode to observe lung tumour motion by screening the patient for a period of several breathing cycles using a low frame rate and with the beam collimated to the area of interest in the lung. Screening would be performed in AP and LAT orientations prior to the delivery of each radiotherapy fraction. Additional measurements were carried out in March 2017 to investigate the fluoroscopy programmes further, with the eventual aim of bringing these programmes into...

FLUG 2017 – Dose variation in Barium/water soluble swallow studies; Leanne Royle

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

Barium swallows continue to prove their usefulness in a wide range of diagnosis and within Guys and ST Thomas’ Trust are the most common fluoroscopy procedure performed. They are performed mostly by the junior registrars and discussed with senior consultants to come to a useful conclusion to aid in the diagnosis or ongoing management of the patient. There is a general protocol registrars use to complete a study, which we are taught early in our training. However this varies depending on the clinical indication and question to be answered. As fluoroscopy is a dynamic test, the patterns of practice change in real time depending on the findings of the study. As with any fluoroscopic investigation, screening time has to be considered alongside the need for diagnostic images. Our project investigates the range of doses in over 400 barium/water soluble swallows performed within our trust over the period January to June 2017. We have reviewed the indications and protocols used with...

FLUG 2017 – The effect of higher pulse rates on radiation dose and detection of aspiration and penetration in video fluoroscopy; Hazel Gray

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

Introduction: Videofluoroscopic swallow studies (VFSS) are used to assess the risk of airway compromise in patients with dysphagia. There is evidence to suggest that the optimisation of pulse rates in VFSS is paramount to the accurate detection of aspiration and penetration 1. This has implications for food and fluid viscosity and texture recommendations2, as well as length of stay and patient mortality3. This study aims to analyse the effect of higher pulse rates in VFSS on the detection of aspiration and patient dose. Objectives: 1) To optimise techniques and assess the effects of higher pulse rates on the detection of airway compromise events in VFSS for patients with dysphagia 2) To compare the patient radiation doses between teams A and B using different protocols and pulse rates Methodology: A prospective analysis of VFSS footage was collected over two rounds of the study between September 2016 and July 2017. Team B continued with their protocol of 7.5pps and team A started a protocol using 30pps. A radiation...

FLUG 2017 – Validation of peak skin doses calculated by an open source skin dose mapping software package; Debbie Harries

23rd November 20178th January 2018 By Jonathan Cole Comment Closed

Purpose: To assess the accuracy of estimates of peak skin dose (PSD) obtained from an open source (openSkin, as integrated into OpenREM) skin dose mapping software package and the accuracy of estimates of peak reference point air kerma obtained from a commercially available (DoseWatch, GE Healthcare©) dose management package. Materials and Methods: A 32 x 32 x 20 cm PMMA phantom was subject to a series of simple fluoroscopic and acquisition exposures in a Siemens Artis Zee cardiac catheter laboratory. Direct measurements of PSD were obtained using either an RTI T20 solid state dose meter or 35 x 43 cm Gafchromic XR-type film fixed to the exposed surface of the PMMA phantom. These measurements were then compared with the PSD values calculated by openSkin under conditions of matched-phantom geometry. The PSD measurements were also compared with the peak reference point air kerma values calculated by the DoseWatch cumulative incidence map, a feature of the commercially available DoseWatch dose management package. Results: The DoseWatch...

FLUG 2017 – Potential utility of linking staff dose records to RDSR patient dose records – early impressions; Siân Vaughan

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

The Ray Safe electronic staff dosimeter has been adopted by Philips Healthcare and integrated into its latest interventional x-ray units. These units are able to pick up the staff member wearing the dosimeter and assign the dose that they receive to the precise part of the examination as defined by the DICOM RDSR patient dose report. The staff doses are then exported in a format similar to a patient dose report. This work will present early findings of using this system, including pitfalls of implementation along with early analysis of data showing how staff dose may be analysed in conjunction with gantry geometry and patient dose. One interesting analysis has been the production of gantry angulation 'heat maps' showing at what angulation staff are receiving most dose - this may be of use for staff dose optimisation efforts. The system may also facilitate impact assessments of staff dose reduction strategies, such as the StarBoard radial armboard system. The longer term...