A Cost-effective Breath-hold Coaching Camera System for Patients Undergoing External Beam Radiotherapy

Area of Science:

• Medical Physics
• Radiation Oncology
• Imaging Technology

Background:

• Organ motion during radiation therapy, especially in the breast, lung, abdomen, and pelvis, significantly impacts dose delivery accuracy.
• Respiration-induced motion is managed using strategies like breath-hold (BH) to improve geometric precision.
• Limited availability of surface guidance systems and in-bunker coaching capacity necessitates innovative solutions for BH patient preparation.

Purpose of the Study:

• To develop and evaluate a cost-effective time-of-flight (ToF) camera for coaching radiotherapy patients undergoing breath-hold (BH) procedures.
• To enable patient confidence-building and practice of BH outside the treatment bunker.
• To address the challenge of limited in-bunker coaching time due to high patient throughput.

Main Methods:

• The ToF camera's absolute and relative accuracy were tested.
• Camera responsiveness was evaluated under varying environmental conditions (lighting, temperature).
• Performance was compared against the Elekta Active Breathing Coordinator (ABC) system, and usability was assessed with volunteers.

Main Results:

• Initial non-linearity in distance measurement was corrected retrospectively.
• Relative accuracy was within ± 2 mm using a motion phantom.
• The camera demonstrated robustness to lighting and temperature changes, with comparable results to the Elekta ABC system for lung volume and surface distance changes during BH.
• Volunteers successfully maintained BH within ± 1 mm tolerance.

Conclusions:

• A cost-effective ToF camera is feasible for pre-treatment patient coaching.
• This approach can save valuable linear accelerator (LINAC) and imaging system time.
• The system enhances patient confidence and adherence to breath-hold techniques, improving radiation therapy precision.