Establishment and validation of cyberknife irradiation in a syngeneic glioblastoma mouse model

CyberKnife stereotactic radiosurgery (CK-SRS) precisely delivers radiation to intracranial tumors. However, the underlying radiobiological mechanisms at high single doses are not yet fully understood. Here, we established and evaluated the early radiobiological effects of CK-SRS treatment at a single dose of 20 Gy after 15 days of tumor growth in a syngeneic glioblastoma-mouse model. Exact positioning was ensured using a custom-made, non-invasive, and trackable frame. One superimposed target volume for the CK-SRS planning was created from the fused tumor volumes obtained from MRIs prior to irradiation. Dose calculation and delivery were planned using a single-reference CT scan. Six days after irradiation, tumor volumes were measured using MRI scans, and radiobiological effects were assessed using immunofluorescence staining. We found that CK-SRS treatment reduced tumor volume by approximately 75%, impaired cell proliferation, diminished tumor vasculature, and increased immune response. The accuracy of the delivered dose was demonstrated by staining of DNA double-strand breaks in accordance with the planned dose distribution. Overall, we confirmed that our proposed setup enables the precise irradiation of intracranial tumors in mice using only one reference CT and superimposed MRI volumes. Thus, our proposed mouse model for reproducible CK-SRS can be used to investigate radiobiological effects and develop novel therapeutic approaches

Vulnerability of the groundwater

Om de kwetsbaarheid van het grondwater in Nederland voor verontreiniging te karakteriseren, zijn voor het afdekkende pakket gelegen boven het eerste watervoerend pakket kaarten samengesteld met informatie over enkele bodemkenmerken, die van invloed zijn op de uitspoeling. Hierbij werd onderscheid gemaakt tussen de niet met water verzadigde deklaag en het resterende, waterverzadigde deel van het afdekkend pakket. De grens tussen beide delen van de deklaag werd hierbij gelegd bij de gemiddeld laagste grondwaterstand (GLG). Door deze benaderingswijze is het mogelijk om inzicht te verkrijgen in de kwetsbaarheid van zowel het zeer ondiepe grondwater als van het grondwater in het bovenste watervoerende pakket.DGM/DWB-