Assessing digital tomosynthesis for paediatric sacroiliac joint imaging

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Nirula, Gina
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Objective: To assess the use of digital tomosynthesis (DT) as an alternative imaging modality to radiography for the imaging of paediatric sacroiliac (SI) joints. Methods: Three anthropomorphic pelvis phantoms were imaged using DT at three dose levels: equivalent to the dose incurred in radiography (tube current-time product of 0.32 mAs), almost double the dose incurred in radiography (0.63 mAs) and the default dose setting of the DT system (1.6 mAs). Radiographs of the phantoms were also acquired for comparison. Six radiologists were asked to compare DT images to radiographs and rate DT as either better, the same or worse than radiography. Results: An exact Chi-square test was performed on the data and showed no significant difference in preference for DT between the three phantoms (exact p-value = 0.3389). There was a significant difference in preference for DT between radiologists as well as between the three dose settings (exact p-value = 0.0095 and 0.0001, respectively). At a mAs of 0.32 there is no clear preference for DT, however as mAs increases so does preference for DT. Conclusions: DT shows promise as a possible imaging alternative to radiography, although at dose levels higher than radiography. DT may prove advantageous in SI joints imaging if it reduces the need for subsequent computed tomography imaging which is typically used when radiography yields equivocal results.