CT Images of the Scapula Taken with Reduced dose can Yield Segmented Models of Sufficient Accuracy - A Pilot Study - Abstract
Introduction: 3D imaging techniques are increasingly being used for pre-operative planning and the production of patient specific implants or guides. In orthopedics and traumatology these images are segmented out of CT scans as they provide the best quality bone images. However, these CT scans expose patients to high dosages of ionizing radiation which has a baleful influence on their health. In this pilot study we investigate the influence of tube current reduction on the segmentation accuracy of the scapula.
Materials and methods: A human cadaver was CT scanned multiple times while reducing tube current amperage. The images were segmented using 2 different segmentation methods (n=28). Subsequently the scapula was dissected and all soft tissues were removed. An optical laser scan of the dissected scapula was aligned and compared with the segmented meshes of the different CT scans. Radiation dosage, 3D distance, volume and other parameters were analyzed.
Results: All segmented meshes differed statistically significantly from the optical scan (p<0.001). Apart from one, all meshes had a larger volume than the reference mesh (n=27). The average 3D deviation varied between 1.17 mm (Max) -0.759mm (Min) and the total average 3D deviation was -0.45mm (+/- 0.38mm SD).
The mesh accuracy remained fairly constant with diminishing tube currents. Radiation dosages were reduced from 7.1 to 0.3 mSv. Only the automatically generated meshes, corresponding with the lowest tube currents, had large surface deviations. The semi-automatically generated meshes had deviation values within normal averages.
Conclusion: CT Tube current can be largely reduced without losing the surface segmentation accuracy of segmented scapula meshes.