Untersuchungen zur Kombination von Brachy- und Röntgentherapie zur Behandlung von Augentumoren
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Date
2022-09-13
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Abstract
Die Brachytherapie mit Ruthenium-106 Applikatoren stellt für intraokulare Tu- moren mit einer Apexhöhe über 6 mm aufgrund der unzureichenden Bestrahlung der Tumorspitze eine Kontraindikation dar. Im Rahmen dieser Arbeit wird ein integriertes Konzept, das die Kombination der Brachytherapie mit externer Röntgen- bestrahlung beinhaltet, zur Behandlung intraokularer Tumoren untersucht. Hierfür wird die kombinierte Therapiemodalität anhand von Patientenfällen, die bereits mit einem Ruthenium-Applikator bestrahlt wurden, simuliert und die Gewichtung der Strahlungsquellen mittels einer Optimierung durch die differentielle Evolution angepasst, sodass die Dosis in den Risikostrukturen minimiert wird. Der Vergleich der Dosis-Volumen-Histogramme der kombinierten Therapieform mit den Dosis- Volumen-Histogrammen der Brachytherapie bestätigt die Vorteile der Integration der externen Röntgenbestrahlung in die Brachytherapie mit dem Ruthenium-106 Applikator in Bezug auf den Schutz der Risikostrukturen und die Homogenität des Dosisprofils im Tumor. Des Weiteren werden als Grundlage für experimentelle Untersuchungen der kombinierten Therapiemodalität die Unsicherheiten der Ab- solutkalibrierung eines Szintillationsdetektors untersucht. Die Messungen liefern erste Hinweise auf die Ursachen der Unsicherheiten, es werden jedoch detaillierte Analysen mit höherer statistischer Aussagekraft benötigt, um die Ergebnisse zu bestätigen.
Brachytherapy with Ru-106 eye applicators is contraindicated for intraocular tumors with an apex height above 6 mm due to insufficient irradiation of the tumor apex. In this work, an integrated concept, consisting of brachytherapy with external X-ray irradiation, is investigated for the treatment of intraocular tumors. For this purpose, the combined therapy modality is simulated using patient cases, which were already irradiated with a ruthenium applicator, and the weights of the radiation sources are adjusted by using optimization through differential evolution so that the dose to the structures at risk is minimized. Comparison of the dose-volume histograms of the combined form of therapy with the dose-volume histograms of brachytherapy only, confirms the advantages of integrating external X-ray irradiation using the ruthenium-106 applicator in terms of protection of the structures at risk and homogeneity of the dose profile in the tumor. Furthermore, as a basis for experimental studies of the combined therapy modality, the uncertainties of the absolute calibration of a scintillation detector are investigated. The measurements provide initial indications of the causes of the uncertainties, but detailed analyses with higher statistical power are needed to confirm the results.
Brachytherapy with Ru-106 eye applicators is contraindicated for intraocular tumors with an apex height above 6 mm due to insufficient irradiation of the tumor apex. In this work, an integrated concept, consisting of brachytherapy with external X-ray irradiation, is investigated for the treatment of intraocular tumors. For this purpose, the combined therapy modality is simulated using patient cases, which were already irradiated with a ruthenium applicator, and the weights of the radiation sources are adjusted by using optimization through differential evolution so that the dose to the structures at risk is minimized. Comparison of the dose-volume histograms of the combined form of therapy with the dose-volume histograms of brachytherapy only, confirms the advantages of integrating external X-ray irradiation using the ruthenium-106 applicator in terms of protection of the structures at risk and homogeneity of the dose profile in the tumor. Furthermore, as a basis for experimental studies of the combined therapy modality, the uncertainties of the absolute calibration of a scintillation detector are investigated. The measurements provide initial indications of the causes of the uncertainties, but detailed analyses with higher statistical power are needed to confirm the results.