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Dual resolution cone beam breast CT: A feasibility study

2009; Wiley; Volume: 36; Issue: 9Part1 Linguagem: Inglês

10.1118/1.3187225

2473-4209

Lingyun Chen, Youtao Shen, Chao‐Jen Lai, Tao Han, Yuncheng Zhong, S Ge, Xinming Liu, Tianpeng Wang, Wei Yang, Gary J. Whitman, Chris C. Shaw,

Advanced X-ray and CT Imaging

Purpose: In this study, the authors investigated the feasibility of a dual resolution volume‐of‐interest (VOI) cone beam breast CT technique and compared two implementation approaches in terms of dose saving and scatter reduction. Methods: With this technique, a lead VOI mask with an opening is inserted between the x‐ray source and the breast to deliver x‐ray exposure to the VOI while blocking x rays outside the VOI. A CCD detector is used to collect the high resolution projection data of the VOI. Low resolution cone beam CT (CBCT) images of the entire breast, acquired with a flat panel (FP) detector, were used to calculate the projection data outside the VOI with the ray‐tracing reprojection method. The Feldkamp–Davis–Kress filtered backprojection algorithm was used to reconstruct the dual resolution 3D images. Breast phantoms with and smaller microcalcifications (MCs) were imaged with both FP and FP‐CCD dual resolution CBCT systems, respectively. Two approaches of implementing the dual resolution technique, breast‐centered approach and VOI‐centered approach, were investigated and evaluated for dose saving and scatter reduction with Monte Carlo simulation using a GEANT4 package. Results: The results showed that the breast‐centered approach saved more breast absorbed dose than did VOI‐centered approach with similar scatter reduction. The MCs in fatty breast phantom, which were invisible with FP CBCT scan, became visible with the FP‐CCD dual resolution CBCT scan. Conclusions: These results indicate potential improvement of the image quality inside the VOI with reduced breast dose both inside and outside the VOI.