Accuracy analysis of three-dimensional bone surface models of the forearm constructed from multidetector computed tomography data.

摘要

BACKGROUND: We developed an original computer program that simulates upper limb reconstruction surgery using three-dimensional (3D) bone models constructed from computed tomography (CT) data. However, the accuracy of a bone model has not been clarified, and radiation exposure from CT scanning posed a concern. The purpose of this study was to investigate the appropriate CT parameters required to reduce radiation exposure while maintaining the accuracy of 3D models of the forearm bones. METHODS: Twelve dry forearm bones were used to investigate the accuracy of 3D bone models created from two different CT parameters. The accuracy was evaluated by measuring: (a) the discrepancy between the models constructed from low- and normal-dose CT parameters; (b) the error between actual surface data derived by a contact-type coordinate measuring machine and a 3D bone model; and (c) the difference between a 3D bone model constructed from a bare dry bone and a model constructed from the same bone embedded in a radio-opaque soft tissue substitute. CT dose index (CTDI) and dose-length product (DLP) were recorded to evaluate the radiation exposure. RESULTS: The mean error between bone models constructed from two different CT parameters was 0.04 mm. CTDI and DLP for the normal-radiation dose condition were 9.3 and 563 mGy/cm and those for the low-radiation dose condition were 0.3 and 18 mGy/cm, respectively. The mean error between the bone models and scanning data from contact measurement was 0.45 mm. The mean error between a 3D model constructed from a dry bone and that constructed from the same bone embedded in a radio-opaque soft tissue substitute was 0.06 mm. CONCLUSIONS: 3D bone models constructed from low-radiation dose CT data demonstrated the same level of accuracy as those constructed from normal-radiation dose data. The present simulation system can produce 3D bone models with one-thirtieth of the normal radiation dose in the forearm.