Equipment is the first of its kind in the world and will help researchers develop better bone-healing techniques
What is special about the Adora Radiostereometry (RSA) System? Although radiostereometry RSA has been in use for more than 30 years, its use is limited to a few specialised centres. This is largely because the radiographic setup for RSA is complex, and quite different from standard radiography. Analysis of the results is also difficult.
The Adora RSA (NRT Nordisk Rontgen Teknik A/S, Aarhus, Denmark) system is the first x-ray system worldwide to be custom designed to make Radiostereometry easier. While it has been built to ensure reliable and precise RSA it is also capable of carrying out all standard radiographic examinations required in a busy hospital setting.
The Adora RSA automatically positions both x-ray tubes for the stereo RSA examination, which significantly helps the radiographer and greatly increases the reliability of the exams. This ensures excellent radiographs on all occasions and avoids poor or unanalysable examinations.
The fundamental accuracy of the RSA technique relies on measurement of the implanted beads which are made of tantalum and vary in size between 0.5 and 1.0mm. In the past RSA has used x-ray film or Computed Radiography (CR) cassettes for imaging. Both of these need to be scanned in special machines before assessment by the computer and this introduces significant errors in the measurements. Direct digital radiography (DDR) uses cassettes with fixed detectors that send the information directly to the computer. DDR therefore removes the need for film processing/developing, which removes the errors produced by film or CR scanning as well as giving the radiographer rapid feedback for assessing the quality of the radiographs. The ADORA RSA uses compact (lightweight) DDR detectors of a similar size to film cassettes. Pictured here is the Canon CXDI-50C [figure 1], which is used for DDR.
Tests in Aberdeen have shown that these detectors provide very precise measurement of the tantalum markers. Indeed millimetre sized markers have been determined to a precision of a few microns (thousandths of a millimetre). As DDR rejects fewer images, it allows use of lower patient x-ray exposures to obtain good quality radiographs.
What will be the benefits of Adora RSA for patients?
- It will be possible to measure the normal rates of healing of a range of different fractures which will guide the development of new treatments.
- Rapid testing of the effects of new implants or drug treatments on fracture healing can be achieved. This will speed up the introduction of the treatment for the genera public.
- We hope that it may be possible in the longer term for many hospitals to have use of the Adora RSA system due to its simplicity of use. This would allow RSA to guide the management of many more fracture patients.
Hospital Imaging and Radiology Europe Vol. 5 No 4 – winter 2010