The impact of anatomical changes during photon or proton based radiation treatment on tumor dose in glioblastoma dose escalation trials. (November 2021)

• Record Type: Journal Article
• Authors: Hessen, Eline D.; Makocki, Sebastian; van der Heide, Uulke A.; Jasperse, Bas; Lutkenhaus, Lotte J.; Lamers, Emmy; Damen, Eugène; Troost, Esther G.C.; Borst, Gerben R.
• Is Part Of: Radiotherapy and oncology. Volume 164(2021)
• Page Start: 202
• Page End: 208
• Publication Date: 2021-11
• Subjects: MR0 Radiotherapy planning MRI -- MR1 Additional MRI -- T1w T1-weighted MRI sequence -- T1w_c T1-weighted MRI sequence after administration of gadolinium contrast agent -- GTR Gross total resection -- STR Subtotal resection -- SIB simultaneous integrated boost -- GTV Gross Tumor Volume -- CTV Clinical Target Volume -- PTV Planning Target Volume -- ΔCoverage change in coverage in percentage points -- ΔV<71.25Gy change in CTV not receiving the minimal accepted dose of 71.25 Gy -- ΔDmin change in near minimum dose -- ΔD95% change in dose received by 95% of the CTV volume -- MGMT O6-methylguanine-DNA methyltransferase; Glioblastoma -- Anatomical changes -- Radiotherapy -- Repeated MRI -- Target volume changes -- Dose escalation trials; Oncology -- Periodicals; Radiotherapy -- Periodicals; Tumors -- Periodicals; Medical Oncology -- Periodicals; Neoplasms -- radiotherapy -- Periodicals; Radiotherapy -- Periodicals; Radiothérapie -- Périodiques; Cancérologie -- Périodiques; Tumeurs -- Périodiques; Electronic journals; 616.9940642
• DOI: 10.1016/j.radonc.2021.09.022
• Languages: English
• ISSNs: 0167-8140

Abstract

Highlights: Twenty-four glioblastoma patients received an additional MRI during radiotherapy. Photon- and proton-based dose escalated treatment plans were simulated. For 12.5% of the patients the dose coverage and minimum dose decreased dramatically. No major differences between the photon and proton treatment plans were found. Abstract: Purpose/Objective: Most dose-escalation trials in glioblastoma patients integrate the escalated dose throughout the standard course by targeting a specific subvolume. We hypothesize that anatomical changes during irradiation may affect the dose coverage of this subvolume for both proton- and photon-based radiotherapy. Material and Methods: For 24 glioblastoma patients a photon- and proton-based dose escalation treatment plan (of 75 Gy/30 fr) was simulated on the dedicated radiotherapy planning MRI obtained before treatment. The escalated dose was planned to cover the resection cavity and/or contrast enhancing lesion on the T1w post-gadolinium MRI sequence. To analyze the effect of anatomical changes during treatment, we evaluated on an additional MRI that was obtained during treatment the changes of the dose distribution on this specific high dose region. Results: The median time between the planning MRI and additional MRI was 26 days (range 16–37 days). The median time between the planning MRI and start of radiotherapy was relatively short (7 days, range 3–11 days). In 3 patients (12.5%) changes were observed which resulted in a substantial deterioration of both the photon and proton treatment plans. All these patients underwent a subtotal resection, and a decrease in dose coverage of more than 5% and 10% was observed for the photon- and proton-based treatment plans, respectively. Conclusion: Our study showed that only for a limited number of patients anatomical changes during photon or proton based radiotherapy resulted in a potentially clinically relevant underdosage in the subvolume. Therefore, volume changes during treatment are unlikely to be responsible for the negative outcome of dose-escalation studies.