Real-Time Infrared Motion Tracking Analysis for Patients Treated With Gated Frameless Image Guided Stereotactic Radiosurgery

Abstract

The transition from frame-based brain stereotactic radiosurgery (SRS) to frameless delivery is supported by realtime intrafraction monitoring to ensure accurate delivery. The purpose of this study is to characterize these real-time motion traces in a large cohort of patients treated with frameless gated brain SRS and to develop patient-specific predictions of tolerance violations. Methods and Materials: SRS patients treated on the Gamma Knife Icon were immobilized using a device-specific thermoplastic head mask. A motion marker was fixed to the patient's nose, with gating and cone beam computed tomography (CBCT)-based corrections to the treatment at excursions from baseline exceeding 1.5 mm. The traces of 1446 fractions were analyzed according to magnitude (932 unique treatment plans for 462 unique individual patients), directional distribution of displacement, and stability. A neural network model was developed to predict interruptions based on a subset of trace data. Results: The average displacement of the marker in the first fraction of all patients was 0.62 AE 0.25 mm with beam CBCT corrections, which would otherwise be modeled at 0.96 AE 0.96 mm without intrafraction motion correction (P < .0001). Twenty-nine percent of fractions delivered were interrupted, of which the Z-axis (superoinferior) motion was the largest contributor to excursion. Baseline corrections significantly compensated for the magnitude of motion in all 3 dimensions (P < .01). The motion relative to the first acquired CBCT was on average seen to consistently increase with treatment time, with the minimum P value occurring at 61.3 minutes. The neural network prediction model was able to predict treatment interruptions with 84% sensitivity on the first 5-minute sample of the trace. Conclusions: Corrections to marker position significantly decreased marker excursions in all 3 axes compared with a single CBCT alignment. Patient-specific modeling may aid in the optimization of cases selected for frameless radiosurgery to increase the accuracy of planned delivery.

Stereotactic Radiosurgery and Stereotactic Body Radiotherapy in the Management of Oligometastatic Disease

“…This technique became known as SRS. As imaging evolved to routinely incorporate computed tomography and then magnetic resonance imaging, the applicability and availability of SRS also increased, with the option now for frameless SRS [9,10].…”

Long term outcomes with linear accelerator stereotactic radiosurgery for treatment of jugulotympanic paragangliomas

“…Although cumulatively more time is spent on patient setup and verifying initial positional accuracy with multifaction regimens compared to single fraction regimens, beam‐on time for each fraction is shorter with a multifraction regimen than a single‐fraction regimen, assuming the same dose rate. Patient motion during beam‐on time increases with increasing treatment time and degrades the positional accuracy of treatment, highlighting the importance of minimizing beam‐on time with each treatment session 24‐26 . Thus, frameless linac‐based SRS delivered over multiple fractions is an attractive treatment option for the management of JTPs in these patients, and this series lends support to this treatment strategy with evidence of long‐term efficacy.…”

“…Given the elderly and frail patient population often referred for SRS for JTPs, immobilization for a prolonged period of time may be intolerable and may require sedation. Additionally, longer treatment time is associated with increased intrafraction patient motion, which may lead to decreased treatment accuracy 24‐26 . Improved imaging modalities and image‐guided techniques over the past few decades have allowed for linac‐based SRS to be delivered over multiple fractions of shorter individual treatment duration and without use of a rigid stereotactic headframe.…”

Patient perspectives on frame versus mask immobilization for gamma knife stereotactic radiosurgery

“…25 Further investigations of the intrafraction motion monitoring system associated with the mask immobilization device will also likely increase confidence in its use. 26 When clinically appropriate, the experiences and preferences of patients in this study could inform immobilization used for future patients undergoing GK SRS.…”