Application of ultra-low-dose CT in 3D printing of distal radial fractures

Purpose: To explore the effect of ultra-low-dose computed tomography (CT) on three-dimensional (3D) printing models and the diagnosis of wrist fractures.Method: This study enrolled 76 patients with distal radial fractures (DRFs). All patients underwent 320-row detector CT and were divided randomly into two groups. In Group A, 38 patients were scanned with the standard-dose protocol using a tube voltage of 120 kV and current of 100 mA. In Group B, 38 patients were scanned with the ultra-low-dose protocol using a tube voltage of 80 kV and current of 10 mA. For objective image quality assessment, the noise, CT number, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were measured. Subjectively, two experienced orthopaedic surgeons blinded to the scan parameters evaluated the clarity of the 3D printing model and fracture line using a 3-point scale (the diagnosis was considered acceptable with scores >= 2). The mean radiation dose was calculated. The diagnostic performances for the fractures between the two groups were compared.Results: The effective radiation dose was significantly reduced by 97.1 % in Group B, compared to Group A (0.28 +/- 0.05vs. 9.75 +/- 2.23 mu Sv, respectively). Quantitative objective image quality parameters (e.g., CNR, SNR, and CT numbers) were higher in the standard-dose group (p < 0.001). However, there was no difference in subjective scoring of the 3D printing model. Although the fracture line score was higher in Group A (2.92 +/- 0.27 vs. 2.16 +/- 0.37; p < 0.001), the diagnostic performance of the two groups was consistent (all scores >= 2). There were no statistically significant differences in the sensitivity, specificity or accuracy between standard-dose group and ultra-low-dose group.Conclusions: The ultra-low-dose protocol effectively reduced the radiation dose by 97.1 %, while maintaining the image quality for diagnosis of DRFs. Therefore, this protocol can meet the needs of 3D printing models for preoperative assessments.