Noninvasive referencing of intraocular tumors for external beam radiation therapy using optical coherence tomography: A proof of concept

Abstract

The tumor referencing method presented in combination with the statistical eye model introduced in the past has the potential to enable noninvasive treatment and may improve quality, efficacy, and flexibility of external beam radiotherapy of intraocular tumors.

Optical eye tracking system for real‐time noninvasive tumor localization in external beam radiotherapy

“…Comparable mean values (0.35 • ) were reported by Rüegsegger et al for azimuthal rotations. 16 Significant correlation was found between the error magnitude and the deviation of the phantom cornea center with respect to the treatment room isocenter. A substantially higher misalignment (up to 1.46 mm) was measured for imposed elevation rotation with respect to azimuth (up to 0.11 mm) and torsion (up to 0.50 mm), thus resulting in a higher error.…”

“…Such a value represents an improvement with respect to the 15 Hz reported by Petersch et al 14 Moreover, the computational time required by our template matching based approach for torsion detection (median value: 14.40 ms) is significantly smaller than the one reported by Rüegsegger (mean value: 94-25 ms). 16 Higher frequencies could be achieved with the proposed ETS by using a smaller iris ROI in the torsional eye detection method, but further testing should be made in order to verify the method robustness.…”

“…The proposed algorithm outperforms the OCT-based approach which features torsional accuracies ranging between 0.52 • and 0.79 • . 16 Experimental testing on healthy subjects was carried out to test the method robustness against changes in pupil size under different lighting conditions. The ROI selection on the peripheral part of the iris region makes the algorithm robust with respect to pupil dilatation and constriction.…”

“…Rüegsegger et al have recently developed a prototype device for tridimensional (3D) intraocular tumor localization based on optical coherence tomography (OCT). 16 During planning CT acquisition and irradiation, the anterior eye topography is extracted using OCT. Topography and ocular CT are registered, and 3D tumor local coordinates are computed using a statistical eye model adapted to the specific patient anatomy. 17 Reported results show high accuracy in eye rotation detection, but the computational performance of the system currently prevents real-time monitoring.…”

Feasibility study of a non-invasive eye fixation and monitoring device using a right-angle prism mirror for intensity-modulated radiotherapy for choroidal melanoma

“…There are other reports of systems involving advanced mechanisms, such as OCT or tracking systems. They have higher prediction accuracy regarding tumor location [32, 33]; however, these systems require expensive special materials. For predicting tumor position and for reducing the dose to the anterior segment, our study is adequate for clinical use.…”