OpenABC: An Open-Source Active Breathing Control System for Low-Resource Centers

Abstract

Respiratory motion management during radiation therapy can improve delivery to a moving target and spare normal tissue. However, current gating or breath-hold motion management methods are often expensive and inaccessible to low-to-middle income countries (LMICs). We propose developing a low-cost breath-hold and gating system that provides audio visual-feedback to patients while monitoring respiratory motion. An open-source system, called open active breathing control (OpenABC), was developed consisting of a micro-processor (Raspberry Pi 3) and a motion sensor (MPU-6050, InvenSense Inc) to generate breathing traces with audiovisual projector for patient feedback and monitoring display for radiation delivery control. An algorithm was developed in Python to convert motion sensor signal to a respiratory trace for direct comparison between a commercial system (RPM™). OpenABC was demonstrated on a phantom and volunteer and univariate-linear-regression and Bland-Altman analysis was performed. A low-cost projector was used to provide visual feedback for a patient in treatment position and a web-interface will be used to provide real-time monitoring (over WiFi) for treatment control. Total cost for OpenABC system is under $100 USD. Monitoring of periodic phantom motion show excellent agreement between commercial and OpenABC (r = 0.99, p<0.0001, bias = 0.0±0.9mm, 95%-confidence-interval = -1.7 to 1.7mm) and volunteer motion shows good agreement of irregular breathing motion (r = 0.94, p<0.0001, bias = -0.2±0.5mm, 95%-confidence-interval = -1.1 to 0.7mm). Mean motion differences at maximum, average and minimum traces for the phantom were 0.2±0.1mm, 0.1±0.6mm, and 0.1±0.1mm respectively. Mean motion differences at maximum, average and minimum traces for the volunteer were 0.4±0.2mm, 0.3±0.5mm, and 0.4±0.3mm respectively. Motion period time differences for phantom and volunteer were 0.07±0.06s and 0.08±0.14s respectively. Real-time feedback was successfully provided via a projector and monitoring system. We demonstrated feasibility of an open-source accelerometer/gyroscope-based system for active breathing control for motion gating or breath-hold radiation treatments, called OpenABC. Future work will further develop OpenABC to have user friendly GUIs, standardize use protocols and showing proof-of-concept implementation, in collaboration with Rayos Contra Cancer (RCC) and Radiating Hope, in cancer centers in Bolivia that would benefit from motion management in their clinics.Tabled 1Abstract 2878; Table; Motion difference (OpenABC - RPM™)Mean ± SDPeriod (s)Max (mm)Average (mm)Min (mm)Phantom-0.07 ± 0.06-0.2 ± 0.1-0.1 ± 0.6-0.1 ± 0.1Volunteer-0.08 ± 0.140.4 ± 0.2-0.3 ± 0.5-0.4 ± 0.3 Open table in a new tab