Extremity Cone Beam CT imaging demonstrates value of weight-bearing scans

Commercially launched in early 2017, the Carestream OnSight 3D Extremity System is a Cone Beam Computed Tomography (CBCT) scanner designed for point-of-care extremity imaging in weight-bearing patient position for orthopedic clinics, imaging centres, specialty offices, hospitals and emergency departments. The system uses a high-performance amorphous-Silicon (a-Si(H)) flat-panel detector and a unique three-source X-ray tube design. This detector allows for the rapid acquisition of X-ray projections, which helps minimize the negative impact of patient motion. The three-source X-ray tube was designed to reduce the “cone beam” artifact that has traditionally impacted large volume CBCT reconstructions as reported in scientific literature.
The detector and source rotate around the patient’s anatomy, acquiring a multitude of projections from different angles, axially and rotationally.  The images are then reconstructed into a 3D volume using advanced software reconstruction techniques. This produces high resolution volumetric 3D images that have the same spatial resolution in any plane.

Cobalt Health, a leading UK medical charity, has installed the world’s first Carestream OnSight 3D Extremity Cone Beam CT system at their Imaging Centre in Cheltenham, Gloucestershire UK.

Founded in 1964, Cobalt provides a wide range of oncology services across the south-western UK counties of Herefordshire,Worcestershire and Gloucestershire. Cobalt has a history of early investment in new technologies such as MRI and PET/CT. A long-standing Carestream customer, Cobalt was the first facility in the UK and Ireland to implement the Carestream MyVue Patient Portal and currently has both Carestream Vue RIS and Vue PACS installed. Peter Sharpe, CEO of Cobalt Health said: ‘As a charity we’re very used to introducing new technology to support our patients and referring clinicians and this seemed like an ideal opportunity. The Carestream OnSight 3D Extremity CBCT scanner really fitted very nicely, particularly in supporting our orthopedic clinics. It provides something that we couldn’t offer previously, in terms of image resolution and flexibility; it seemed like a really good fit.’ ‘It provides you with true weight bearing images, high resolution and low radiation dose. I think there’s a huge opportunity to embed it in the patIent pathway in A&E and orthopaedic clinics across the UK.’ To introduce the benefits of the OnSight system to the patient pathway, Cobalt held a series of evening seminars where they showed case studies and orthopedic surgeons demonstrated how patients could benefit from the cone beam CT system. ‘It’s the best way of marketing the new technique,’ said Peter Sharpe. ‘The referrers need to come and understand how it works, what the image quality is, and what the benefits are.’

One-stop clinics

Cobalt runs regular one-stop clinics with orthopedic surgeons who refer their patients on the same day for X-rays, MRI or CT scans. Roisin Dobbin-Stacey, PET CT and CT Manager for Cobalt Health explained: ‘The Carestream On-Sight 3D CBCT doesn’t discriminate; it’s not just for sports injuries or for one-stop clinics, it will be available to all patients.’ ‘The weight-bearing feet and ankle exams that we’ve been doing, on people of all ages, have been made considerably easier; it only takes 25 seconds to get these incredible images. They step into the scanner and all they have to do is keep still for 25 seconds.’
‘In the past, when you had a patient who said they had a pain in their foot or ankle when they were walking or running, you would lie them down and do a CT scan and it wouldn’t show anything. You can now put them into the CBCT scanner and see the true condition of a patient who’s got all their weight going through that joint and you can see the difference; you can see why they’ve got that pain.’
‘The dose, of course, is something else that is talked about a lot; referrers ask why they would send their patient for a CT scan when they can have an X-ray; but actually if a patient is having a CBCT scan, the dose is only slightly higher than with an X-ray, and it’s a weight bearing exam. And it’s a lot less than with a CT, so that again is very encouraging.’

Exquisite detail
Consultant Radiologist, Prof. Iain Lyburn, has had a very positive experience with the Carestream OnSight 3D scanner. ‘It’s very high quality, very high resolution,’ he said. ‘The detail is exquisite, so you can see very small bony defects, very small osteophytes, with great clarity. It’s also much quicker than some other investigations, taking less than a minute for many body parts, so you get a cross sectional slice through  the area in a relatively quick time.’ ‘We recently examined a young man with hind foot pain and, whereas an MRI scan showed some edema, with the Carestream CBCT image you could see the bony detail wit absolutely exquisite clarity and what we hadn’t appreciated properly was an ill-defined irregularity around the os trigonum, which was the cause of the pain. It was a very small detail that you couldn’t pick up on the MRI, these small fragments of bone causing the pain. It was very helpful. We had another patient with pain below the ankle joint whose MRI showed some edema across the joint in the calcaneum, so we thought that was probably the cause of the pain. Remember the MRI would be done with the patient lying supine with their ankle on the bed, whereas with the CBCT the patient was standing in the functional  position, and what it highlighted beautifully was a protuberance in the subtalar joint.We could see the impingement far more clearly demonstrated because of the way the image was taken and realized that it was going to be the cause of the symptoms. There was possibly a suspicion of it on the MRI with the edema, but having the cone beam CT showing it in position clarified that that was the source of the symptoms. And that might change the management of the patient, because many times we would do a plain radiograph, see how the patient gets on then get them back.With the Carestream OnSight CBCT you would get the diagnosis straight away and would see most fractures earlier than you would on an X-ray. In imaging, as with many other aspects of medical technology, you’ll look back in a few year’s and see that the Carestream CBCT is irreplaceable.’

Plug and play
Installing the OnSight 3D Extremity system at Cobalt’s Imaging Centre was straightforward, as Roisin Dobbin-Stacey explained. ‘Planning and getting the room ready for delivery of the equipment was very easy; the room size had to be a minimum of 8 feet by 12 feet (Ed. 2.5m x 3.7m). The equipment arrived, it was brought up in the lift, wheeled in and plugged into a 240 volt socket. It literally is plug and play!’ ‘The Carestream engineers were fantastic, they got it all up and running within a couple of days, and the Apps training was brilliant. I think the system itself, how it’s been designed, is so user friendly. As a radiographer you want something that’s easy to use, and for me it’s fantastic, it’s such good fun to use. Cobalt CEO Peter Sharpe summed up his feelings about the Carestream OnSight CBCT system: ‘we have no regrets. It’s an excellent device, it works well and uptime has been 100 percent. It’s easy to use, patients love it and the image quality is superb so yes, it’s been a great investment.’

Carestream Healthwww.carestream.com