Abstract
Background
The advent of EOS imaging has offered clinicians the opportunity to image the whole skeleton in the anatomical standing position with a smaller radiation dose than standard spine roentgenograms. It is known as the fifth modality of imaging. Current NICE guidelines do not recommend EOS scans over x-rays citing: “The evidence indicated insufficient patient benefit in terms of radiation dose reduction and increased throughput to justify its cost”.
Methods
We retrospectively reviewed 103 adult and 103 paediatric EOS scans of standing whole spines including shoulders and pelvis for those undergoing investigation for spinal deformity in a tertiary spinal centre in the UK. We matched this against a retrospective control group of 103 adults and 103 children who underwent traditional roentgenograms whole spine imaging at the same centre during the same timeframe. We aimed to compare the average radiation dose of AP and lateral images between the two modalities. We utilised a validated lifetime risk of cancer calculator (www.xrayrisk.com) to estimate the additional mean risk per study.
Results
In the Adult EOS Group (AEG) the mean estimated effective dose of AP was 0.08 mSv (0.04–0.15) and Lateral 0.06 mSv (0.03–0.14). Conversely in the Adult Roentgenograms Group (ARG) the mean AP was 0.49 mSv (0.15–1.88) and Lateral was 0.29 mSv (0.07–1.20).
In the Paediatric EOS Group (PEG): the mean dose of AP was 0.07 mSv (0.02–0.21) and Lateral 0.04 mSv (0.02–0.11). Conversely Paediatric Roentgenograms Group (PRG) had a mean dose in AP of 0.37 mSv (0.03–5.92) and in lateral of 0.17 mSv (0.03–0.44).
The percentage differences were: ARG:AES AP 613%, ARG:AES Lat 483%, PPG:PEG AP 529%, PRG:PEG Lat 425%. Mean difference 513%.
The additional lifetime cancer risk for AEG was 1 in 176056 for males and 1 in 138696 for females, compared to ARG 1 in 31596 for males and 1 in 24894 for females. In PEG that was 1 in 58207 for boys and 1 in 33367 for girls, compared to PRG 1 in 11860 for boys and 1 in 6797 in girls.
Differences in additional lifetime risk of cancer per scan: ARG:AES Male 557%, Female 557%, PRG:PEG Male 491%, Females 491%.
Conclusion
Standard plain film imaging of the whole spine requires approximately five-times higher doses of radiation compared to dual planar EOS scans. This carries a significant impact when considering the need for repeat imaging on additional lifetime malignancy risk in both children and adults. There is approximately 5-fold increase in risk of cancer for all groups with roentgenograms over EOS.
We directly challenge the NICE guidance and recommend EOS dual planar imaging in favour of plane roentgenograms for investigation of spinal deformity.
