A Low-Cost Belt-Based Respiratory Gating System for Veterinary Radiotherapy
Abstract
Purpose
Motion management plays a critical role in radiation therapy for thoracic and abdominal tumors, where respiratory motion can significantly compromise treatment precision. Among available motion-mitigation techniques, respiratory gating offers distinct advantages for anesthetized veterinary patients. This work describes the development and evaluation of an in-house, low-cost respiratory belt–based gating system compatible with Elekta linear accelerators.
Methods
A Vernier Go Direct® respiratory belt (Vernier® Science Education, Beaverton, OR) was used to acquire respiratory signals at 20Hz, which were transmitted wirelessly via Bluetooth to a laptop at the treatment console through a USB hub connected by a wall-embedded Ethernet extension. An in-house Python software was developed to acquire and process respiratory signals and to generate gating commands sent to the Response™ gating module, which in turn controlled linac beam delivery. End-to-end system latency was measured using a CIRS dynamic thorax phantom (Model 008A, CIRS Inc., Norfolk, VA). SBRT plan QA passing rates were evaluated with and without gating using patient-specific respiratory signals on the SRS-MapCHECK® phantom.
Results
The belt-based respiratory gating system was successfully implemented at minimal cost. A user-friendly software was developed for wireless signal acquisition, real-time visualization, automated threshold selection, and gating control. Live baseline drift compensation was incorporated to enable expiration-phase gating, which occupied approximately two-thirds of the respiratory cycle. The measured end-to-end beam-on and beam-off delays were 0.20 ± 0.02 and 0.05 ± 0.02s, respectively. Respiratory-gated QA passing rates showed marginal decreases compared to non-gated measurements (98.0±0.8% vs. 99.4±0.6% at 3%/2mm).
Conclusion
A low-cost, user-friendly, and low-latency respiratory gating system compatible with Elekta linear accelerators was successfully developed and validated. This system enables reliable respiratory-synchronized beam delivery and has the potential to reduce treatment margins, improve dose conformity, and enhance the safety of high-dose radiotherapy for thoracic and abdominal tumors in veterinary patients.