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Trumm C.G.,Ludwig Maximilians University of Munich | Haussler S.M.,Ludwig Maximilians University of Munich | Muacevic A.,European Cyberknife Center Munich | Stahl R.,Ludwig Maximilians University of Munich | And 6 more authors.
Journal of Vascular and Interventional Radiology | Year: 2014

Purpose To evaluate technical outcome and safety of computed tomographic (CT) fluoroscopy-guided percutaneous fiducial marker placement before CyberKnife stereotactic radiosurgery. Materials and Methods Retrospective analysis was performed of 196 patients (106 men) undergoing CT fluoroscopy-guided fiducial marker placement in 222 consecutive procedures under local anesthesia from March 2006 to February 2012. Technical success was defined as fiducial marker location in the tumor or vicinity suitable for CyberKnife radiosurgery evaluated on postinterventional planning CT. Complications were classified per Society of Interventional Radiology (SIR). Results One hundred ninety-six patients (age, 61.5 y ± 13.1) underwent percutaneous placement of 321 fiducial markers (mean per tumor, 1.2 ± 0.5; range, 1-4) in 37 primary tumors and 227 metastases in the thorax (n = 121), abdomen (n = 122), and bone (n = 21). Fiducial marker placement was technically successful in all procedures: intratumoral localization in 193 (60.1%), at tumor margin in 50 (15.6%), and outside of tumor in 78 cases (24.3%; mean distance to marker, 0.4 cm ± 0.6; range, 0-2.9 cm). Complications were observed in 63 placement procedures (28.4%), including minor self-limiting pneumothorax (n = 21; SIR class B) and self-limiting pulmonary hemorrhage (n = 35; SIR class A), and major pneumothorax requiring thoracostomy/drainage insertion (n = 14; SIR class D) and systemic toxicity of local anesthetic drug (n = 1; SIR class D). Conclusions CT fluoroscopy-guided percutaneous fiducial marker placement can be performed with high technical success under local anesthesia in various anatomic regions. Although self-limiting in most cases, pneumothorax and pulmonary hemorrhage are frequently observed during fiducial marker implantation into lung tumors. © 2014 SIR.

Furweger C.,Netherlands Cancer Institute | Furweger C.,European Cyberknife Center Munich | Prins P.,Netherlands Cancer Institute | Coskan H.,Netherlands Cancer Institute | Heijmen B.J.M.,Netherlands Cancer Institute
Medical Physics | Year: 2016

Purpose: The "InCise™ multileaf-collimator (MLC)" is the first commercial MLC to be mounted on a robotic SRS/SBRT platform (CyberKnife). The authors assessed characteristics and performance of this novel device in a preclinical five months test period. Methods: Commissioning beam data were acquired with unshielded diodes. EBT3 radiochromic films were employed for measurement of transmission, leaf/bank position accuracy (garden fence) before and after exercising the MLC, for end-to-end testing and further characterization of the beam. The robot workspace with MLC was assessed analytically by transformation to an Euler geometry ("plane," "gantry," and "collimator" angles) and by measuring pointing accuracy at each node. Stability over time was evaluated in picket fence and adapted Winston-Lutz tests (AQA). Results: Beam penumbrae (80%-20%, with 100% = 2 × dose at inflection point for field sizes ≥ 50 × 50 mm2) were 2.2-3.7 mm for square fields in reference condition (source-axis-distance 800 mm, depth 15 mm) and depended on field size and off-axis position. Transmission and leakage did not exceed 0.5%. Accessible clinical workspace with MLC covered non-coplanar gantry angles of [-113°; +112°] and collimator angles of [-100°; +107°], with an average robot pointing accuracy of 0.12 ± 0.09 mm. For vertical beams, garden fence tests exhibited an average leaf positioning error of ≤0.2 mm, which increased by 0.25 and 0.30 mm (banks X1 and X2) with leaves traveling parallel to gravity. After execution of a leaf motion stress routine, garden fence tests showed slightly increased jaggedness and allowed to identify one malfunctioning leaf motor. Total system accuracy with MLC was 0.38 ± 0.05 mm in nine end-to-end tests. Picket fence and AQA tests displayed stable results over the test period. Conclusions: The InCise™ MLC for CyberKnife showed high accuracy and adequate characteristics for SRS/SBRT applications. MLC performance after exercise demands specific quality assurance measures. © 2016 American Association of Physicists in Medicine.

Schlaefer A.,University of Lubeck | Schlaefer A.,TU Hamburg - Harburg | Viulet T.,University of Lubeck | Muacevic A.,European Cyberknife Center Munich | Furweger C.,European Cyberknife Center Munich
Medical Physics | Year: 2013

Purpose: Treatment planning for radiation therapy involves trade-offs with respect to different clinical goals. Typically, the dose distribution is evaluated based on few statistics and dose-volume histograms. Particularly for stereotactic treatments, the spatial dose distribution represents further criteria, e.g., when considering the gradient between subregions of volumes of interest. The authors have studied how to consider the spatial dose distribution using a multicriteria optimization approach. Methods: The authors have extended a stepwise multicriteria optimization approach to include criteria with respect to the local dose distribution. Based on a three-dimensional visualization of the dose the authors use a software tool allowing interaction with the dose distribution to map objectives with respect to its shape to a constrained optimization problem. Similarly, conflicting criteria are highlighted and the planner decides if and where to relax the shape of the dose distribution. Results: To demonstrate the potential of spatial multicriteria optimization, the tool was applied to a prostate and meningioma case. For the prostate case, local sparing of the rectal wall and shaping of a boost volume are achieved through local relaxations and while maintaining the remaining dose distribution. For the meningioma, target coverage is improved by compromising low dose conformality toward noncritical structures. A comparison of dose-volume histograms illustrates the importance of spatial information for achieving the trade-offs. Conclusions: The results show that it is possible to consider the location of conflicting criteria during treatment planning. Particularly, it is possible to conserve already achieved goals with respect to the dose distribution, to visualize potential trade-offs, and to relax constraints locally. Hence, the proposed approach facilitates a systematic exploration of the optimal shape of the dose distribution. © 2013 American Association of Physicists in Medicine.

Staehler M.,Ludwig Maximilians University of Munich | Bader M.,Ludwig Maximilians University of Munich | Schlenker B.,Ludwig Maximilians University of Munich | Casuscelli J.,Ludwig Maximilians University of Munich | And 6 more authors.
Journal of Urology | Year: 2015

Purpose: High dose local stereotactic radiosurgery was performed in select patients to improve local tumor control and overall survival. We report on patients with renal tumors treated with single fraction robotic stereotactic radiosurgery. Materials and Methods: A total of 40 patients with a median age of 64 years who had an indication for nephrectomy and subsequent hemodialysis were entered in a prospective case-control study of single fraction stereotactic radiosurgery. Of the patients 11 had transitional cell cancer and 29 had renal cell cancer. Tumor response, renal function, survival and adverse events were estimated every 3 months. Followup was at least 6 months. Results: A total of 45 renal tumors were treated. Median followup was 28.1 months (range 6.0 to 78.3). The local tumor control rate 9 months after stereotactic radiosurgery was 98% (95% CI 89-99). There was a measurable size reduction in 38 lesions, including complete remission in 19. Renal function remained stable. Using the CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equation median creatinine clearance was 76.8 (range 25.3 to 126.3) and 70.3 ml/minute/1.73 m2 (range 18.6 to 127.3) at baseline and followup, respectively (p = 0.89). Grade I erythrodermia developed in 1 patient, 3 reported grade I fatigue and 2 reported grade I nausea. Nephrectomy was avoided in all cases. Conclusions: Single fraction stereotactic radiosurgery as an outpatient procedure is a treatment modality with short-term safety and efficacy. It avoids treatment related loss of renal function and hemodialysis in select patients with transitional or renal cell cancer. At short followup oncologic results were similar to those of other ablative techniques for renal tumors. To date functional results have been excellent. Further studies are needed to determine the long-term results and limits of stereotactic radiosurgery in this setting. © 2015 American Urological Association Education and Research, Inc.

Stintzing S.,Ludwig Maximilians University of Munich | Hoffmann R.T.,Ludwig Maximilians University of Munich | Heinemann V.,Ludwig Maximilians University of Munich | Kufeld M.,European Cyberknife Center Munich | Muacevic A.,European Cyberknife Center Munich
European Journal of Cancer | Year: 2010

Introduction: Due to advanced chemotherapy regimens, patients presenting with residual liver metastases of colorectal cancer (CRC) has increased. Surgery of residual metastases enhances overall survival, but surgical resection is often limited. Less invasive techniques have been invented to enhance local disease control. We investigated in a selected patient cohort local control of liver metastasis from CRC using robotic radiosurgery. Methods and materials: In this study patients with colorectal liver metastases were prospectively followed after having been treated with single-session radiosurgery using a robotic image-guided device and real-time tumour tracking. The primary end-point was local control (LC); secondary end-points were toxicity, progression-free survival (PFS) and overall survival (OS). Extrahepatic metastases were excluded using a whole body (PET-CT: positron emission tomography computed tomography). Follow up was done by liver MRI every 3 months post-treatment. Results: Fourteen patients (median age 65 years), with a total of 19 colorectal liver metastases were treated with 24 Gy in one fraction. Median follow up was 16.8 months. A one-year LC rate of 87% and a median PFS of 9.2 months were reached. Discussion: Frameless robotic image-guided radiosurgery with real-time tumour tracking as an effective treatment for patients with colorectal liver metastases. This technique enhances the possibilities of multidisciplinary oncological concepts. © 2010 Elsevier Ltd. All rights reserved.

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