TH-C-332-02: First Implementation of High-Resolution Dual-Detector Region-Of-Interest Cone-Beam Computed Tomography (ROI-CBCT) for a Rotating C-Arm Gantry System

Purpose: Region‐of‐interest cone‐beam computed tomography (ROI‐CBCT) has the potential to reduce integral dose while providing higher‐resolution data in the ROI. Previous work used rotating object geometries. We have implemented an ROI‐CBCT system on a clinical rotating C‐arm gantry system and have developed methods for combining high‐resolution projection data within the ROI and low‐resolution, low‐dose data outside the ROI. Method and Materials: High‐resolution ROI projection data were acquired of a coronary stent placed in a rabbit using a custom‐made, high‐sensitivity, microangiographic‐fluoroscope (HSMAF) detector (35 micron pixels), attached to the C‐arm of a clinical fluoroscopic gantry. Full field‐of‐view (FFOV), low‐resolution data were acquired at the same dose as the HSMAF (standard‐dose) and at a lower dose using a commercial flat‐panel detector (FPD) (194 micron pixels). HSMAF data were spatially registered with FPD data using cross‐correlation techniques. The lower‐dose FPD pixel values were matched to the HSMAF values using linear regression. During reconstruction, HSMAF data were used within the ROI, while corrected lower‐dose FPD data were used outside the ROI. Reconstructions were performed with HSMAF/lower‐dose‐FPD and standard‐dose‐FPD data using geometric calibration data, Parker weights, a Shepp‐Logan filter, and a Feldkamp algorithm, generating 512 × 512 × 512 volumes (25 micron voxels). Results: The dual‐detector ROI‐CBCT reconstruction exhibits greater detail than that of the FPD alone. The full‐width‐at‐half‐maxima of line profiles of stent struts (100 micron diameter) are approximately 150 and 290 microns for the dual‐detector and FPD data, respectively. No truncation artifacts are visible. The integral dose of the dual‐detector system is 54% that of the standard‐dose FPD for this experiment. Conclusion: High‐resolution 3D images of stents implanted in a rabbit are successfully obtained using a new rotating‐gantry dual‐detector ROI‐CBCT system. Resolution is significantly higher and integral dose is lower with ROI‐CBCT compared to the standard FPD approach. (Support: NIH‐Grants R01‐NS43924, R01‐EB002873, Toshiba‐Medical‐Systems‐Corporation).