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PURPOSE Solid and necrotic brain tumors respond to radiosurgery, although necrotic lesions often contain a significant proportion of hypoxic cells which cannot become reoxygenated during the short overall treatment time of single dose application. In addition to the direct cytotoxic action, delayed vascular occlusion followed by ischemic tumor cell death(More)
BACKGROUND AND PURPOSE Stereotactic radiosurgery with an adapted linear accelerator (linac-SRS) is an established therapy option for brain metastases, benign brain tumors, and arteriovenous malformations. We intended to investigate whether the dosimetric quality of treatment plans achieved with a CyberKnife (CK) is at least equivalent to that for linac-SRS(More)
PURPOSE To find out whether the use of stereotactic techniques for fractionated radiotherapy reduces toxicity to the endocrine and visual system in patients with benign perioptic tumors. PATIENTS AND METHODS From 1993 to 2009, 29 patients were treated with fractionated stereotactic radiotherapy. The most frequent tumor types were grade I meningioma (n =(More)
PURPOSE Methyl-[11C]L-methionine ([11C]MET) positron emission tomography (PET) in brain tumors reflects amino acid transport and has been shown to be more sensitive than magnetic resonance imaging in stereotactic biopsy planning. It remains unclear whether the increased [11C]MET uptake is limited to solid tumor tissue or even detects infiltrating tumor(More)
OBJECTIVE The immediate effects of deep brain stimulation (DBS) on subcortical neurons of its target region are controversial. METHODS We measured the regional normalized resting cerebral metabolic rate of glucose (nCMRGlc) with 18-fluorodeoxyglucose (FDG) and PET in 12 patients with Parkinson disease (PD) and bilateral DBS of the subthalamic nucleus(More)
OBJECTIVE AND IMPORTANCE To demonstrate the usefulness of positron emission tomography-magnetic resonance imaging (MRI) coregistration for differentiation of radiation necrosis and recurrent tumor in stereotactic planning. CLINICAL PRESENTATION T1-weighted MRI scans of a 43-year-old woman revealed a contrast-enhancing lesion 4 years after open removal of(More)
We have developed a densitometric method for measuring the isocentric accuracy and the accuracy of marking the isocentre position for linear accelerator based radiosurgery with circular collimators and room lasers. Isocentric shots are used to determine the accuracy of marking the isocentre position with room lasers and star shots are used to determine the(More)
A new approach is presented for unwarping geometrical distortions in echo planar imaging (EPI)-based statistical parametrical maps (SPM). With the developed method, a substantial reduction of geometrical distortions in the order of 5-15 mm down to a residue of approximately 1-2 mm was possible, thus allowing reliable activation localization and, hence,(More)
A method for the fully computerized determination and optimization of positions of target points and collimator sizes in convergent beam irradiation is presented. In conventional interactive trial and error methods, which are very time consuming, the treatment parameters are chosen according to the operator's experience and improved successively. This time(More)
BACKGROUND The management of deep-seated cerebral cavernous malformations (CCMs) is still controversial. Although surgery remains the treatment of choice in patients with recurrent hemorrhage, patients with CCMs located in the brainstem are in many cases not eligible for resection due to high procedure-related morbidity and mortality. We evaluated the(More)