A rotating beam-blocker method for cone beam CT scatter correction.

Area of Science:

• Medical Imaging
• Radiological Physics

Background:

• Cone beam CT (CBCT) is essential in clinical settings, but scatter artifacts degrade image quality.
• Effective scatter correction methods are crucial for expanding CBCT applications.

Purpose of the Study:

• To introduce a rotating beam-blocker (RBB) method for CBCT scatter correction and image reconstruction within a single scan.
• To evaluate the RBB method in both full- and half-fan scan scenarios.

Main Methods:

• The RBB features alternating open and blocked regions for simultaneous projection acquisition.
• Scatter signals from blocked projections correct open projections.
• The Feldkamp-Davis-Kress algorithm reconstructs 3D images from corrected projections.
• Performance was assessed using head and pelvis phantoms with and without bowtie filters, measuring CT number error, spatial nonuniformity (SNU), and contrast-to-noise ratio (CNR).

Main Results:

• CT number error was drastically reduced: from >200 HU to <5 HU (head, no bowtie) and >160 HU to <4 HU (head, full bowtie).
• Pelvis phantom showed similar improvements: >250 HU to <12 HU (no bowtie) and >190 HU to <10 HU (half bowtie).
• Scatter correction led to >79% SNU decrease and >2x CNR increase.

Conclusions:

• The RBB method enables high-quality CBCT imaging in a single scan, improving accuracy for image-guided interventions.
• The RBB's efficiency in minimizing time delay between projections prevents motion-induced mismatches, making it ideal for thoracic and abdominal imaging.