Advancing Patient Accommodation on the Elekta Gamma Knife Esprit Radiosurgery Platform: Evaluation of a Clinically Improved Hdmm Camera-Arm Position
Abstract
Purpose
To characterize the angular dependence of the Elekta Gamma Knife Esprit High Definition Motion Management (HDMM) system and examine the feasibility of non-standard camera angles for the treatment of larger patients.
Methods
To establish a reference, reflective markers placed on a Velmex motion phantom were positioned at the headrest location on the treatment couch to evaluate temporal latency and spatial accuracy at the default camera-arm position (60o). Two additional camera-arm positions (70o and 74o) were then evaluated against the reference. Temporal performance was assessed by observing gating event execution and spatial performance by introducing known displacements of varying magnitude (±0.5 mm, ±1.0 mm, ±1.5 mm) in the lateral direction. A clinically relevant camera-arm position was further evaluated to maximize height above the treatment couch. Finally, the camera-arm operating limit corresponding to the angle where HDMM tracking of infrared markers was lost, was assessed.
Results
Temporal latency and spatial accuracy remained consistent up to the operating limit. Both the 70o and 74o camera-arm positions executed < 200 ms gating events, consistent with the reference. The spatial accuracy of the 60o (reference), 70o, and 74o camera-arm positions was ±0.018 mm, ±0.021 mm, and ±0.019 mm, respectively. The 74o camera-arm angle maximized height above the couch at 54.4 cm. The 75o camera-arm position was found to be the operating limit as infrared marker tracking was lost.
Conclusion
The HDMM system had clinically acceptable performance for all camera angles evaluated up to the operating limit, maintaining both temporal latency and spatial accuracy compared to the standard position. The proposed clinically improved 74o camera-arm position remains below the operating limit, maintains performance and allows for improved line-of-sight, thereby potentially accommodating larger patients.