Which slot scanning device is best for low-dose radiographs in pediatric scoliosis? A pilot study

Abstract

Purpose: Studies have demonstrated a higher lifetime risk of cancer in AIS patients compared to age-matched controls. An asynchronous slot scan feature with ultra-small angle tomosynthesis reconstruction recently became available at our institution. Thus, we aimed to compare the performance of this new technology to the existing biplanar slot scanner for scoliosis imaging using standard dose settings.

Methods: All scoliosis patients under 18 years old from a single institution who underwent diagnostic imaging with both the asynchronous (True2Scale) and biplanar imaging system (EOS®) were included. Overall image quality was independently reviewed using a previously published method. Anthropomorphic phantom evaluations and dose measurements were conducted, with effective doses compared between systems. A computerized model based on phantom data estimated standardized patient effective doses.

Results: 40 imaging studies from 20 patients met the inclusion criteria. ICC for overall image quality was 0.88, with weighted-Cohen's Kappa analysis showing very high agreement (κ = 0.873). On average, patients imaged with the asynchronous system received 0.23 ± 0.15 (median: 0.10) mSv in each study, while patients imaged with the biplanar system received 0.12 ± 0.05 (median: 0.13) mSv. A bootstrap Welch's t-test showed a significant difference in mean radiation doses (p = 0.038, mean difference = 0.11 mSv, T2S higher than EOS). AP dose analysis showed no significant difference (p = 0.196), with the asynchronous system at 0.07 ± 0.03 (median: 0.07) mSv and biplanar at 0.06 ± 0.02 (median: 0.05) mSv.

Conclusions: Both technologies with standard dose parameters provided comparable image quality. While the asynchronous system delivers slightly higher radiation doses, both systems expose patients to less than annual background radiation (3 mSv) and standard 2-view scoliosis imaging doses. Larger studies are warranted to confirm these pilot findings.

Level of evidence: III-retrospective cohort study.

Keywords: Asynchronous slot scan; Biplanar slot scanner; Image quality; Radiation dose; Scoliosis.