Respiratory motion guided four dimensional cone beam computed tomography: encompassing irregular breathing.

Area of Science:

• Medical Imaging
• Radiotherapy Physics
• Image Reconstruction

Background:

• Four dimensional cone beam computed tomography (4D CBCT) is limited by under-sampled projections due to respiratory motion.
• Conventional 4D CBCT systems lack feedback mechanisms to adapt acquisition to patient breathing patterns.
• Existing methods struggle with projection data clustering, impacting image quality and radiation dose.

Purpose of the Study:

• To develop and validate a practical algorithm for respiratory motion guided 4D CBCT (RMG-4DCBCT) using real patient breathing data.
• To optimize gantry velocity and projection timing for evenly spaced projections across the respiratory cycle.
• To evaluate the trade-offs between image quality, acquisition time, and imaging dose in RMG-4DCBCT.

Main Methods:

• Implemented a novel algorithm for RMG-4DCBCT to dynamically regulate gantry motion and projection acquisition based on real-time respiratory signals.
• Simulated a realistic RMG-4DCBCT system using 112 breathing traces from 24 lung cancer patients.
• Quantified image noise and streaking artifacts by reconstructing data from phantom studies, comparing RMG-4DCBCT with conventional methods.

Main Results:

• RMG-4DCBCT achieved optimal trade-offs between image quality, acquisition time, and patient dose.
• Approximately 50% reduction in imaging dose was observed for RMG-4DCBCT compared to conventional 4D CBCT at equivalent image quality and acquisition time.
• Image quality, measured by signal-to-noise ratio, improved by an average of 63% with RMG-4DCBCT for the same imaging dose.
• Acquisition times were reduced to under 60 seconds using modern C-arm CBCT systems.

Conclusions:

• The developed RMG-4DCBCT algorithm effectively addresses projection clustering in 4D CBCT using real patient breathing data.
• RMG-4DCBCT offers significant improvements in image quality and/or reductions in radiation dose for patients undergoing CT imaging.
• This advancement paves the way for more efficient and safer CBCT imaging in clinical practice.