The custom algorithm for the noninvasive CyberKnife system, designed to monitor eye position during radiotherapy

• Autorzy: Skrobała Agnieszka , Łuczko Szymon , Ginter Józef , Matuszewski Krzysztof

Identyfikatory

DOI

10.2478/pjmpe-2025-0009

• Języki publikacji: EN

Abstrakty

EN

Introduction: Radiotherapy using the CyberKnife (CK) system for treating eye tumors requires tracking skull movements and immobilizing the eye. This study aims to develop a custom algorithm for a noninvasive eye position monitoring system in the CK framework. Material and Methods: Retrospective data were analyzed from 13 patients treated with CK over five fractions. Eye immobilization was achieved using two guides above the patient’s head, with a black dot as the fixation eye. Camera recording was used to analyze pupil movements. A Python-based algorithm was developed to calculate eye position angles relative to the desired direction. A Quality Index (QI) was defined as the Common Area (CA) ratio of the 80% isodose and Planning Target Area (PTA) to the isodose area shifted by eye movement. For simplicity, only horizontal eye movement (angle ϕ) was considered. Dose distribution and CT data were processed in ImageJ, and a script calculated CA values for all integer ϕ angles. MediaPipe was used to map facial landmarks, estimate iris contours, and track pupil center positions on the XY plane. Results: The algorithm analyzed camera recording during fractions of radiation, issuing visual and auditory warnings when gaze angles exceeded 20°. Instantaneous and average QI values were also monitored, with violations prompting controlled therapy interruptions. Analysis of 7 patients showed effective eye tracking. Two patients struggled to maintain their gaze, leading to frequent warnings. For six recordings, issues arose due to missing facial landmarks, 90° image rotations, or partially closed eyes. Conclusion: The custom algorithm provides real-time eye movement analysis and can enhance treatment quality monitoring in CK-based eye tumor therapy.

Słowa kluczowe

EN

stereotactic radiotherapy; eye tumor; movement tracking; CyberKnife

• Wydawca: Polskie Towarzystwo Fizyki Medycznej
• Czasopismo: Polish Journal of Medical Physics and Engineering
• Rocznik: 2025
• Tom: Vol. 31, Iss. 1
• Strony: 92--98
• Opis fizyczny: Bibliogr. 10 poz., rys., tab.

Twórcy

autor

Skrobała Agnieszka

• Department of Electroradiology, Poznan University of Medical Science, Poznan, Poland
• Department of Medical Physics, Greater Poland Cancer Centre, Poznan, Poland

• https://orcid.org/0000-0003-0539-9041

autor

Łuczko Szymon

• Department of Biomedical Physics, Faculty of Physics, University of Warsaw, Warsaw, Poland

autor

Ginter Józef

• Department of Biomedical Physics, Faculty of Physics, University of Warsaw, Warsaw, Poland

• https://orcid.org/0000-0001-7581-5296

autor

Matuszewski Krzysztof

• Department of Medical Physics, Greater Poland Cancer Centre, Poznan, Poland

• https://orcid.org/0000-0002-9119-8985

Bibliografia

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• 3. Caujolle J-P, Mammar H, Chamorey E, et alP. Proton beam radiotherapy for uveal melanomas at Nice teaching hospital: 16 years' experience. International Journal of Radiation Oncology, Biology, Physics. 2010;78(1):98-103. https://doi.org/10.1016/j.ijrobp.2009.07.1688
• 4. Zehetmayer M, Kitz K, Menapace R, et al. Local tumor control and morbidity after one to three fractions of stereotactic external beam irradiation for uveal melanoma. Radiother Oncol. 2000;55(2):135-144. https://doi.org/10.1016/s0167-8140(00)00164-x
• 5. Schmelter V, Schneider F, Guenther SR, et al. Local recurrence in choroidal melanomas following robotic-assisted radiosurgery (CyberKnife). Ocular Oncology and Pathology, 2022;8(4-6):221-229. https://doi.org/10.1159/000527915
• 6. Schneider CA, Rasband WS, Eliceiri KW. NIH Image to ImageJ: 25 years of image analysis. Nature Methods. 2012;9(7):671-675. https://doi.org/10.1038/nmeth.2089
• 7. Daftari IK, Petti PL, Larson DA, et al. A noninvasive eye fixation monitoring system for CyberKnife radiotherapy of choroidal and orbital tumors. Medical Physics. 2009;36(3):719-724. https://doi.org/10.1118/1.3070537
• 8. Bogner J, Petersch B, Georg D, et al. A noninvasive eye fixation and computer-aided eye monitoring system for linear accelerator-based stereotactic radiotherapy of uveal melanoma. International Journal of Radiation Oncology Biology Physics. 2003;56(4),1128-1136. https://doi.org/10.1016/s0360-3016(03)00280-3
• 9. Kheir WJ, Stinnett SS, Meltsner S, et al. Novel frameless LINAC radiosurgery solution for uveal melanoma. Frontiers in Oncology. 2024;14:1365197. https://doi.org/10.3389/fonc.2024.1365197
• 10. Iskanderani O, Béliveau-Nadeau D, Doucet R, et al. Reproducibility of a noninvasive system for eye positioning and monitoring in stereotactic radiotherapy of ocular melanoma. Technol Cancer Res Treat. 2017;16:352-356. https://doi.org/10.1177/1533034617690979

Uwagi

Opracowanie rekordu ze środków MNiSW, umowa nr POPUL/SP/0154/2024/02 w ramach programu "Społeczna odpowiedzialność nauki II" - moduł: Popularyzacja nauki (2025).