4D cone-beam computed tomography (CBCT) using a moving blocker for simultaneous radiation dose reduction and scatter...

Area of Science:

• Medical Imaging
• Radiation Oncology
• Image Reconstruction

Background:

• Four-dimensional (4D) x-ray cone-beam computed tomography (CBCT) is crucial for precise lung cancer radiation therapy.
• Repeated 4D CBCT acquisitions increase radiation dose and suffer from scatter contamination, degrading image quality.
• Current methods struggle to balance dose reduction and image quality preservation.

Purpose of the Study:

• To develop and evaluate a novel method combining a moving blocker (MB) with motion-compensated reconstruction for simultaneous dose reduction and scatter correction in 4D CBCT.
• To assess the impact of the proposed 4D MB technique on image quality and radiation dose compared to conventional 4D CBCT.
• To investigate the potential of 4D MB for dose reduction without compromising diagnostic image quality.

Main Methods:

• Proposed a 4D moving blocker (4D MB) technique integrated with motion-compensated reconstruction for 4D CBCT acquisition.
• The 4D MB reduces x-ray flux and simultaneously collects scatter information for scatter estimation and correction.
• Employed total-variation (TV) constraint and motion-compensated temporal constraint for reconstruction to handle undersampled data.

Main Results:

• Simulations using the 4D NCAT phantom demonstrated that 4D MB with motion-compensated reconstruction achieved a 1/3 dose reduction.
• The 4D MB method resulted in a 37% SSIM improvement and 55% RMSE reduction compared to standard 4D CBCT without scatter correction.
• 4D reconstruction using 4D MB data outperformed 3D TV reconstruction, showing 28% SSIM and 34% RMSE improvements.

Conclusions:

• The proposed 4D MB technique effectively reduces radiation dose by one-third in 4D CBCT while enhancing image quality.
• This method offers a promising solution for improving lung cancer radiotherapy by addressing dose and image quality concerns simultaneously.
• Further studies with physical phantoms and patient data are warranted to explore the full potential of 4D MB for clinical applications.