Influence of eye movement on lens dose and optic nerve target coverage during craniospinal irradiation.

Autor: Hoeben BAW; Department of Radiation Oncology, University Medical Center Utrecht, Utrecht, the Netherlands.; Princess Máxima Center for Pediatric Oncology, Utrecht, the Netherlands., Seravalli E; Department of Radiation Oncology, University Medical Center Utrecht, Utrecht, the Netherlands., Wood AML; Princess Máxima Center for Pediatric Oncology, Utrecht, the Netherlands.; Radboud University, Nijmegen, the Netherlands., Bosman M; Department of Radiation Oncology, University Medical Center Utrecht, Utrecht, the Netherlands., Matysiak WP; Department of Radiation Oncology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands., Maduro JH; Princess Máxima Center for Pediatric Oncology, Utrecht, the Netherlands.; Department of Radiation Oncology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands., van Lier ALHMW; Department of Radiation Oncology, University Medical Center Utrecht, Utrecht, the Netherlands., Maspero M; Department of Radiation Oncology, University Medical Center Utrecht, Utrecht, the Netherlands., Bol GH; Department of Radiation Oncology, University Medical Center Utrecht, Utrecht, the Netherlands., Janssens GO; Department of Radiation Oncology, University Medical Center Utrecht, Utrecht, the Netherlands.; Princess Máxima Center for Pediatric Oncology, Utrecht, the Netherlands.
Jazyk: angličtina
Zdroj: Clinical and translational radiation oncology [Clin Transl Radiat Oncol] 2021 Aug 29; Vol. 31, pp. 28-33. Date of Electronic Publication: 2021 Aug 29 (Print Publication: 2021).
DOI: 10.1016/j.ctro.2021.08.009
Abstrakt: Purpose: Optic nerves are part of the craniospinal irradiation (CSI) target volume. Modern radiotherapy techniques achieve highly conformal target doses while avoiding organs-at-risk such as the lens. The magnitude of eye movement and its influence on CSI target- and avoidance volumes are unclear. We aimed to evaluate the movement-range of lenses and optic nerves and its influence on dose distribution of several planning techniques.
Methods: Ten volunteers underwent MRI scans in various gaze directions (neutral, left, right, cranial, caudal). Lenses, orbital optic nerves, optic discs and CSI target volumes were delineated. 36-Gy cranial irradiation plans were constructed on synthetic CT images in neutral gaze, with Volumetric Modulated Arc Therapy, pencil-beam scanning proton therapy, and 3D-conventional photons. Movement-amplitudes of lenses and optic discs were analyzed, and influence of gaze direction on lens and orbital optic nerve dose distribution.
Results: Mean eye structures' shift from neutral position was greatest in caudal gaze; -5.8±1.2 mm (±SD) for lenses and 7.0±2.0 mm for optic discs. In 3D-conventional plans, caudal gaze decreased Mean Lens Dose (MLD). In VMAT and proton plans, eye movements mainly increased MLD and diminished D98 orbital optic nerve (D98 OON ) coverage; mean MLD increased up to 5.5 Gy [total ΔMLD range -8.1 to 10.0 Gy], and mean D98 OON decreased up to 3.3 Gy [total ΔD98 OON range -13.6 to 1.2 Gy]. VMAT plans optimized for optic disc Internal Target Volume and lens Planning organ-at-Risk Volume resulted in higher MLD over gaze directions. D98 OON became ≥95% of prescribed dose over 95/100 evaluated gaze directions, while all-gaze bilateral D98 OON significantly changed in 1 of 10 volunteers.
Conclusion: With modern CSI techniques, eye movements result in higher lens doses and a mean detriment for orbital optic nerve dose coverage of <10% of prescribed dose.
Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(© 2021 The Author(s).)
Databáze: MEDLINE
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