Title: Replacing conventional spine radiographs with dual energy x-ray absorptiometry in children with suspected reduction in bone density
Funder: Department of Health (England)

Abstract: Background Children are at a higher lifetime risk of radiation-induced complications than are adults. Radiation exposure must be kept to a minimum. Conventional radiographs are obtained to assess spine morphometry, while dual energy x-ray absorptiometry (DXA) of the spine is traditionally used to measure bone density. Many children will have both investigations, necessitating appointments within two areas of the Radiology Department. In 2009 our Trust performed 1130 DXA scans on 457 children (45% of a random selection also had spine radiographs). UK background radiation dose is 6 to 20uSv/day; a single radiograph of the lumbar spine 1,000uSv; whole body DXA less than 1uSv. DXA is used in adults but not in children to assess spine morphometry. A similar role in children should be investigated. Aims 1) To conduct a study comparing diagnostic accuracy and observer reliability of iDXA to those of conventional spine radiography for vertebral crush fractures 2) To determine whether bone density can reliably be measured from lateral iDXA scans by comparing with values obtained from AP scans 3)To evaluate patient and carer acceptance of iDXA compared to conventional radiography 4) To model the patient and carer pathway for the two diagnostic protocols 5) To model the radiation and cost savings of iDXA scans. Members of the public will be involved both in developing and in determining the best means of administering the questions required to meet aims 3 and 4 above. Plan of Investigation 1) Over an 18-month period, children presenting to our Department for both iDXA and spine radiographs because of suspected reduction in bone density will be recruited. 2) Children will have AP and lateral spine iDXA scans and lateral spine radiographs on the same day. 3) Morphometric interpretation of iDXA scans will be performed blinded to, then compared with findings on spine radiographs. 4) Diagnostic accuracy and image quality of iDXA will be determined (radiography = gold standard) 5) Inter and intra observer reliability will be calculated 6) We will determine patient / carer acceptance, dose reduction, cost effectiveness and feasibility of iDXA to replace spine radiographs in the context of children presenting with suspected reduced bone density and vertebral fracture(s). Potential Impact Children with suspected reduced bone density have spine radiographs to exclude fractures. Many require repeated follow-up examinations e.g. those with osteogenesis imperfecta - OI (at least yearly spine radiographs throughout childhood) or those on long-term steroids. Locally, for the OI group alone, this is at least 200 lateral radiographs a year. These children also have regular (twice yearly) iDXA scans to objectively determine bone density. If iDXA can replace spine radiographs in this group (even without considering other potential clinical indications), then population radiation exposure will be significantly reduced, with the added advantages of a one-stop visit to the Radiology Department and potential cost savings to the NHS.


Research activity codes: 4.2 EVALUATION OF MARKERS AND TECHNOLOGIES
Health categories: MUSCULOSKELETAL