研究目的
To improve image quality in cone-beam CT by developing a weighted rebinned backprojection-filtration algorithm and a hybrid scatter correction method from partially beam-blocked data in a single scan.
研究成果
The proposed wrBPF algorithm and hybrid scatter correction method effectively improve image quality in CBCT by utilizing data redundancy and combining measurement-based and convolution-based approaches, successfully reducing scatter artifacts and enhancing contrast, though noise and ring artifacts increase, and further optimization is needed for clinical practicality.
研究不足
The method requires a full-scan in full-fan mode, may be sensitive to geometric errors like gantry sag, scatter correction is computationally intensive, and ring artifacts may become more pronounced after correction. Beam hardening effects were not initially corrected but addressed later.
1:Experimental Design and Method Selection:
The study involves designing a beam blocker array to partially block X-rays, using a hybrid scatter correction method combining measurement-based and convolution-based approaches, and implementing a weighted rebinned backprojection-filtration (wrBPF) algorithm with butterfly filtering for image reconstruction.
2:Sample Selection and Data Sources:
An anthropomorphic head phantom (Erler-Zimmer GmbH, Germany) and a 3D Shepp-Logan phantom were used as imaged objects. Data were acquired from a circular CBCT scan with 720 projections over 360 degrees.
3:List of Experimental Equipment and Materials:
X-ray tube (100 kVp, 7 mA), flat-panel detector (1024x1024 pixels,
4:4x4 mm2 pixel size), beam blocker array (lead strips on acrylic plate, thickness 3 mm, width 5 mm, vertical length 70 mm, 10 strips with interval 10 mm and period 20 mm), and an object-rotation-type CBCT imaging system (EBSCAN, EBtech Co., KOREA). Experimental Procedures and Operational Workflow:
The beam blocker was placed between the source and object; projections were acquired; scatter was estimated using measurement-based method in blocked regions; convolution kernel parameters were optimized; scatter-corrected projections were reconstructed using wrBPF algorithm with butterfly filtering.
5:Data Analysis Methods:
Image quality was assessed visually and through profiles; scatter-to-primary ratio (SPR) was calculated; comparisons were made with FBP reconstruction and narrow collimation data.
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