A novel respiratory surrogate system with table motion correction and visual feedback for computed tomography

Area of Science:

• Medical Imaging
• Radiotherapy Physics
• Respiratory Motion Management

Background:

• Respiratory motion poses a significant challenge in radiotherapy computed tomography (CT), impacting treatment accuracy.
• Existing clinical surrogate and coaching systems often suffer from inaccuracies due to table motion or sag, limiting their effectiveness in deep inspiration breath-hold (DIBH) CT and four-dimensional CT (4DCT).

Purpose of the Study:

• To evaluate a novel motion-corrected surrogate and feedback system designed to improve breathing quality in DIBH and 4DCT.
• To assess the system's ability to compensate for table motion and enhance patient breath-hold stability and breathing regularity.

Main Methods:

• Phantom tests were conducted to evaluate table sag compensation under varying loads (up to 104 kg).
• Patient data (n=2 for DIBH, n=3 for 4DCT) were analyzed for plateau stability and baseline shifts.
• A volunteer study (n=10) compared audio and visual feedback for DIBH breath-hold stability and 4DCT breathing regularity.

Main Results:

• The novel system effectively reduced table sag impact in phantom tests, limiting baseline shifts to -0.2 mm.
• In patients, the system improved DIBH signal stability (plateau drift: -0.2 mm/s vs. -0.8 mm/s) and reduced 4DCT baseline shifts (-0.2 mm vs. -1.7 mm).
• Visual feedback in volunteers enhanced DIBH reproducibility (SD: 0.5 mm vs. 1.1 mm with audio) and unified irregular 4DCT breathers.

Conclusions:

• The novel motion-corrected system successfully compensated for table motion across phantom, patient, and volunteer measurements.
• The system demonstrated strong performance in DIBH feedback scenarios, improving breath-hold stability.
• Further optimization is needed for the system's performance in 4DCT feedback scenarios.