EOS low dose 2D/3D X-ray imaging system


The taking of images such as X-rays is very important to help guide the treatment of many orthopaedic conditions. There are some conditions where it can be beneficial to take an image that is weight-bearing, full body, or three-dimensional (3D). One example of such a condition is scoliosis. Scoliosis is a 3D deformity of the spine. It is characterised by a curve from side to side. With this curve there is also a change in the normal front to back curves of the spine and some twisting. This distorts the rib cage and may give the patient a rib hump. The size, stiffness and cosmetic consequences of the curve change over time. Scoliosis usually develops during childhood and adolescence. When the condition has no clear underlying cause, it is referred to as ‘idiopathic’, which is the most common type of scoliosis. It has been estimated that adolescent idiopathic scoliosis occurs in 1-3% of children between 10 and 16 years of age. Scoliosis is also seen in adults.

Medical management aims to prevent the scoliosis from worsening or to straighten the spine in more severe cases. The treatment plan is often determined by the severity of the curvature and the patient’s age. This necessitates periodic monitoring of curve progression. The repeated monitoring results in a high dose of radiation exposure with conventional X-ray imaging devices. An alternative imaging device which can be used in conditions like scoliosis is the EOS 2D/3D X-ray imaging system, which is a new digital radiography system, capable of providing uninterrupted full-body, weight-bearing digital 2D and 3D imaging in a single scan with a low radiation dose.

The aim of this project is to assess the benefits, adverse effects and cost-effectiveness of the EOS 2D/3D X-ray imaging system compared with conventional X-ray devices for monitoring and evaluation of scoliosis and other relevant orthopaedic conditions.


Three controlled trials were identified for the assessment of the comparative clinical effectiveness of EOS.  Two studies compared EOS with film X-ray imaging and one study compared EOS with CR. The included studies were small, but of reasonable quality. All found image quality to be comparable or better with EOS overall and radiation dose (entrance surface dose) was significantly lower with EOS for all images. No other outcomes were reported and there was no evidence of patient health benefits from the facilities offered by EOS such as the ability to scan a full body image, removing the need for digital stitching, or the ability to take PA and lateral images simultaneously so that a 3D image can be produced. 

The cost effectiveness analysis found that overall the health benefits estimated from EOS as a result of radiation dose reductions are very small.  Given the higher price of the EOS equipment, patient throughput is a major determinant of the cost-effectiveness of EOS.  Using the estimates of patient throughput at national level from the HES data suggests that EOS is not cost-effective for any of the indications considered.  When health benefits from EOS relate only to reduced radiation dose, patient throughput in the region of 15,100 to 26,500 (corresponding to a workload of 60 to 106 patient appointments per working day) for EOS compared to a throughput of only 7,530 for CR (corresponding 30 patient appointments per working day) is needed to achieve an ICER of £30,000 per QALY.  EOS can only be shown to be cost-effective when compared to CR if the utilisation for EOS is about twice the utilisation of CR, which is unlikely.  If EOS were able to generate health benefits as a result of any changes in therapy as clinicians respond to any changes in the nature and quality of the EOS image compared to standard X-ray, then these may be sufficient for EOS to be considered cost-effective.

Conducted by: CRD and the Centre for Health Economics, University of York

Further details

Project page on NIHR HTA Programme website

Related guidance

Commissioned to inform NICE DG1: The EOS 2D/3D imaging system. London: National Institute for Clinical Excellence; 2011


McKenna C, Wade R, Faria R, Yang H, Stirk L, Gummerson N, Sculpher M, Woolacott N. EOS 2D/3D X-ray imaging system:
a systematic review and economic evaluation
. Health Technol Assess 2012;16(14)

Wade R, Yang H, McKenna C, Faria R, Gummerson N, Woolacott N. A systematic review of the clinical effectiveness of EOS 2D/3D X-ray imaging system. Eur Spine J 2013;22(2):296-304


Commissioned by the NIHR HTA Programme on behalf of NICE's Diagnostic Assessment process. Diagnostics technologies guidance is designed to help the NHS adopt efficient and cost effective medical diagnostic technologies more rapidly and consistently.