Respiratory triggered 4D cone-beam computed tomography: a novel method to reduce imaging dose

Area of Science:

• Medical Imaging
• Radiotherapy Physics
• Computed Tomography

Background:

• 4D cone-beam computed tomography (4D CBCT) is crucial for image-guided radiotherapy.
• Reducing imaging dose in 4D CBCT is essential to minimize patient exposure.
• Conventional 4D CBCT methods do not actively utilize respiratory signals to optimize dose.

Purpose of the Study:

• To introduce and evaluate a novel Respiratory Triggered 4D Cone-Beam Computed Tomography (RT 4D CBCT) method.
• To assess the potential of RT 4D CBCT in reducing imaging dose without compromising image quality.
• To compare the performance of RT 4D CBCT against conventional 4D CBCT techniques.

Main Methods:

• Simulated 3600 CBCT projections of a thorax phantom were used to create datasets for comparison.
• Respiratory triggered (RT 4D CBCT) and conventional 4D CBCT acquisition schemes were simulated.
• Image quality was assessed by comparing reconstructed images to a ground truth dataset; imaging dose was determined by projection count.

Main Results:

• Phase-based sorting in RT 4D CBCT reduced imaging dose by 47% with less than 4% image quality degradation.
• Displacement-based sorting in RT 4D CBCT achieved a 57% dose reduction but resulted in 26% worse image quality.
• RT 4D CBCT demonstrated significant dose reduction potential.

Conclusions:

• RT 4D CBCT, particularly with phase-based sorting, offers a viable method for dose reduction in 4D CBCT.
• Comparable image quality is maintained with phase-based RT 4D CBCT.
• Further optimization is needed for displacement-based RT 4D CBCT to improve image quality.