TY - JOUR A1 - Guckenberger, Matthias A1 - Roesch, Johannes A1 - Baier, Kurt A1 - Sweeney, Reinhart A. A1 - Flentje, Michael T1 - Dosimetric consequences of translational and rotational errors in frame-less image-guided radiosurgery N2 - Background: To investigate geometric and dosimetric accuracy of frame-less image-guided radiosurgery (IG-RS) for brain metastases. Methods and materials: Single fraction IG-RS was practiced in 72 patients with 98 brain metastases. Patient positioning and immobilization used either double- (n = 71) or single-layer (n = 27) thermoplastic masks. Pre-treatment set-up errors (n = 98) were evaluated with cone-beam CT (CBCT) based image-guidance (IG) and were corrected in six degrees of freedom without an action level. CBCT imaging after treatment measured intra-fractional errors (n = 64). Pre- and posttreatment errors were simulated in the treatment planning system and target coverage and dose conformity were evaluated. Three scenarios of 0 mm, 1 mm and 2 mm GTV-to-PTV (gross tumor volume, planning target volume) safety margins (SM) were simulated. Results: Errors prior to IG were 3.9 mm± 1.7 mm (3D vector) and the maximum rotational error was 1.7° ± 0.8° on average. The post-treatment 3D error was 0.9 mm± 0.6 mm. No differences between double- and single-layer masks were observed. Intra-fractional errors were significantly correlated with the total treatment time with 0.7mm±0.5mm and 1.2mm±0.7mm for treatment times ≤23 minutes and >23 minutes (p<0.01), respectively. Simulation of RS without image-guidance reduced target coverage and conformity to 75% ± 19% and 60% ± 25% of planned values. Each 3D set-up error of 1 mm decreased target coverage and dose conformity by 6% and 10% on average, respectively, with a large inter-patient variability. Pre-treatment correction of translations only but not rotations did not affect target coverage and conformity. Post-treatment errors reduced target coverage by >5% in 14% of the patients. A 1 mm safety margin fully compensated intra-fractional patient motion. Conclusions: IG-RS with online correction of translational errors achieves high geometric and dosimetric accuracy. Intra-fractional errors decrease target coverage and conformity unless compensated with appropriate safety margins. KW - Medizin KW - Radiosurgery KW - Frame-less KW - Frame-based KW - Stereotactic KW - Image-guidance Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-75669 ER - TY - JOUR A1 - Guckenberger, Matthias A1 - Sweeney, Reinhart A. A1 - Flickinger, John C. A1 - Gerszten, Peter C. A1 - Kersh, Ronald A1 - Sheehan, Jason A1 - Sahgal, Arjun T1 - Clinical practice of image-guided spine radiosurgery - results from an international research consortium JF - Radiation Oncology N2 - Background Spinal radiosurgery is a quickly evolving technique in the radiotherapy and neurosurgical communities. However, the methods of spine radiosurgery have not been standardized. This article describes the results of a survey about the methods of spine radiosurgery at five international institutions. Methods All institutions are members of the Elekta Spine Radiosurgery Research Consortium and have a dedicated research and clinical focus on image-guided radiosurgery. The questionnaire consisted of 75 items covering all major steps of spine radiosurgery. Results Strong agreement in the methods of spine radiosurgery was observed. In particular, similarities were observed with safety and quality assurance playing an important role in the methods of all institutions, cooperation between neurosurgeons and radiation oncologists in case selection, dedicated imaging for target- and organ-at-risk delineation, application of proper safety margins for the target volume and organs-at-risk, conformal planning and precise image-guided treatment delivery, and close clinical and radiological follow-up. In contrast, three major areas of uncertainty and disagreement were identified: 1) Indications and contra-indications for spine radiosurgery; 2) treatment dose and fractionation and 3) tolerance dose of the spinal cord. Conclusions Results of this study reflect the current practice of spine radiosurgery in large academic centers. Despite close agreement was observed in many steps of spine radiosurgery, further research in form of retrospective and especially prospective studies is required to refine the details of spinal radiosurgery in terms of safety and efficacy. KW - vertebral metastases KW - spine radiosurgery KW - methods KW - questionnaire Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-138006 VL - 6 IS - 172 ER - TY - THES A1 - Guckenberger, Matthias T1 - Analyse des Hitzeschocks bei Neisseria meningitidis mit DNA-Microarrays T1 - Analysis of the heat shock response of Neisseria meningitidis with DNA microarrays N2 - Das Gram negative Bakterium Neisseria meningitidis ist weltweit ein bedeutender Erreger der bakteriellen Meningitis. Obwohl das ausschließlich humanpathogene Bakterium in bis zu 25% der Europäischen Bevölkerung die oberen Atemwege als harmloser Kommensale besiedelt, kommt es unter bestimmten, noch nicht ganz verstandenen Bedingungen zu einer klinisch manifesten Infektion. In dieser Arbeit wurde die neue Technologie der DNA Mikroarray Technologie für die Untersuchung des Transkriptoms bei Neisseria meningitidis etabliert. Untersucht wurde die Reaktion von N. meningitidis auf einen Hitzeschock, eine plötzliche Steigerung der Temperatur. Während einer Infektion wird das Bakterium durch induziertes Fieber sehr ähnlichen Bedingungen ausgesetzt. Im Ergebnis erlaubten die RNA Expressionsanalysen nicht nur eine sichere Unterscheidung deregulierter Gene von Genen mit konstanter Expression, sondern es konnte auch das Ausmaß der Deregulation exakt bestimmt werden. Die Daten der DNA Mikroarray Experimente wurden mit der etablierten Technik der RT-PCR exakt bestätigt. Bei den Hitzeschock-Versuchen mit Neisseria meningitidis konnten zahlreiche ORFs als Hitzeschock-Gene identifiziert werden. Die Funktion dieser Gene, darunter groEL/groES und dnaJ/dnaK, war bereits bei anderen Organismen beschrieben worden, was die Qualität und Reproduzierbarkeit der Ergebnisse unterstreicht. Es konnte gezeigt werden, dass die Intensität des Hitzeschocks und damit die Deregulation der Hitzeschock-Gene mit steigender Temperatur zunimmt. Eine Erklärung für dieses interessante Ergebnis wäre, dass mit Steigerung der Temperatur der Schaden im Bakterium zunimmt und dadurch auch mehr Hitzeschock Proteine zur Reparatur benötigt werden. Daneben wurde erstmals die transkriptionelle Beeinflussung von Genen aus dem Bereich der Transformation durch einen Hitzeschock gefunden. Diese Daten konnten durch einen phänotypischen Nachweis der Verminderung der Transformationsaktivität von Meningokokken nach einem Hitzeschock bestätigt werden. Diese neue Technik wird eine der Schlüsseltechnologien für die Forschung in der postgenomischen Ära sein. Viele Fragen in dem noch lückenhaften Wissen über die Pathologie von Neisseria meningitidis sollen sich in Zukunft mit Hilfe der DNA Mikroarrays beantworten lassen. N2 - The Gram negative bacteria Neisseria meningitidis is a major pathogen of meningitis throughout the world. Although N. meningitidis can be found in the upper airway of up to 30% of European population, it is unclear what exactly causes a clinical infection. Here we established the new technique of DNS microarrays to examine the transcriptional response of N. meningitidis to a rapid increase of temperature, a heat shock. During an infection, the bacteria could encounter similar stress situations when causing high fever. Using rising temperatures from 37oC up to 45oC an increasing number of the 59 selected N. meningitidis ORFs showed dereglulation. Deregulated and not deregulated ORFs were successfully confirmed using semi quantitative RT-PCR. Among these upregulated ORFs there were already known heat shock genes like groEL / groES and dnaJ / dnaK and the alternative sigma factors rpoD and rpoH. These ORFs showed an increasing upregualtion with rising temperatures. An explanation for this interesting result could be that higher temperatures cause more damage to the bacteria and therefore more heat shock proteins are needed for repair. The heat shock response of E. coli has been analysed using whole genome DNS microarrays and these data were in very good concordance with our results. This proofs the excellent quality of the data produced with N. meningitidis DNS microarrays. Besides we found a number of ORFs to be downregulated confronted with high temperatures during heat shock: Mainly ORFs of aerobic and anaerobic metabolism but also ORFs pilM – pilQ. A deregulation after heat shock of these 5 ORFs has not been reported before. These pil ORFs are essential for assembly of type IV pili. Type IV pili are responsible for binding of free DNS, the first step in the process of transformation. A downregulation of these ORFs should be followed be lowered synthesis of type IV pili and therefore decreased transformation activity. As expected, after exposure to a heat shock the transformation activity of Neisseria meningitidis was lowered up to 10% of normal activity. Summarizing, we successfully established the promising technique of DNS microarrays for Neisseria meningitidis, a technique that hopefully will proof as a beneficial tool for examining bacterial pathogenesis and finding new ways of treatment or prevention. KW - Neisseria KW - meningitidis KW - Hitzeschock KW - Microarray KW - Genom KW - Neisseria KW - meningitidis KW - heat KW - shock KW - Microarray Y1 - 2003 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-8952 ER - TY - JOUR A1 - Gerszten, Peter C. A1 - Sahgal, Arjun A1 - Sheehan, Jason P. A1 - Kersh, Ronald A1 - Chen, Stephanie A1 - Flickinger, John C. A1 - Quader, Mubina A1 - Fahim, Daniel A1 - Grills, Inga A1 - Shin, John H. A1 - Winey, Brian A1 - Oh, Kevin A1 - Sweeney, Reinhart A. A1 - Guckenberger, Matthias T1 - A multi-national report on methods for institutional credentialing for spine radiosurgery JF - Radiation Oncology N2 - Background: Stereotactic body radiotherapy and radiosurgery are rapidly emerging treatment options for both malignant and benign spine tumors. Proper institutional credentialing by physicians and medical physicists as well as other personnel is important for the safe and effective adoption of spine radiosurgery. This article describes the methods for institutional credentialing for spine radiosurgery at seven highly experienced international institutions. Methods: All institutions (n = 7) are members of the Elekta Spine Radiosurgery Research Consortium and have a dedicated research and clinical focus on image-guided spine radiosurgery. A questionnaire consisting of 24 items covering various aspects of institutional credentialing for spine radiosurgery was completed by all seven institutions. Results: Close agreement was observed in most aspects of spine radiosurgery credentialing at each institution. A formal credentialing process was believed to be important for the implementation of a new spine radiosurgery program, for patient safety and clinical outcomes. One institution has a written policy specific for spine radiosurgery credentialing, but all have an undocumented credentialing system in place. All institutions rely upon an in-house proctoring system for the training of both physicians and medical physicists. Four institutions require physicians and medical physicists to attend corporate sponsored training. Two of these 4 institutions also require attendance at a non-corporate sponsored academic society radiosurgery course. Corporate as well as non-corporate sponsored training were believed to be complimentary and both important for training. In 5 centers, all cases must be reviewed at a multidisciplinary conference prior to radiosurgery treatment. At 3 centers, neurosurgeons are not required to be involved in all cases if there is no evidence for instability or spinal cord compression. Backup physicians and physicists are required at only 1 institution, but all institutions have more than one specialist trained to perform spine radiosurgery. All centers believed that credentialing should also be device specific, and all believed that professional societies should formulate guidelines for institutions on the requirements for spine radiosurgery credentialing. Finally, in 4 institutions radiation therapists were required to attend corporate-sponsored device specific training for credentialing, and in only 1 institution were radiation therapists required to also attend academic society training for credentialing. Conclusions: This study represents the first multi-national report of the current practice of institutional credentialing for spine radiosurgery. Key methodologies for safe implementation and credentialing of spine radiosurgery have been identified. There is strong agreement among experienced centers that credentialing is an important component of the safe and effective implementation of a spine radiosurgery program. KW - cyberknife radiosurgery KW - advanced technology KW - conformal radiotherapy KW - clinical trials KW - quality assurance KW - credentialing KW - spine tumors KW - stereotactic body radiotherapy KW - spine Radiosurgery KW - paraspinal tumors KW - intensity modulated radiotherapy KW - ACR practice guidelines KW - radiation therapy Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-131485 VL - 8 IS - 158 ER - TY - JOUR A1 - Hardcastle, Nicholas A1 - Tomé, Wolfgang A. A1 - Cannon, Donald M. A1 - Brouwer, Charlotte L. A1 - Wittendorp, Paul W. H. A1 - Dogan, Nesrin A1 - Guckenberger, Matthias A1 - Allaire, Stéphane A1 - Mallya, Yogish A1 - Kumar, Prashant A1 - Oechsner, Markus A1 - Richter, Anne A1 - Song, Shiyu A1 - Myers, Michael A1 - Polat, Bülent A1 - Bzdusek, Karl T1 - A multi-institution evaluation of deformable image registration algorithms for automatic organ delineation in adaptive head and neck radiotherapy JF - Radiation Oncology N2 - Background: Adaptive Radiotherapy aims to identify anatomical deviations during a radiotherapy course and modify the treatment plan to maintain treatment objectives. This requires regions of interest (ROIs) to be defined using the most recent imaging data. This study investigates the clinical utility of using deformable image registration (DIR) to automatically propagate ROIs. Methods: Target (GTV) and organ-at-risk (OAR) ROIs were non-rigidly propagated from a planning CT scan to a per-treatment CT scan for 22 patients. Propagated ROIs were quantitatively compared with expert physician-drawn ROIs on the per-treatment scan using Dice scores and mean slicewise Hausdorff distances, and center of mass distances for GTVs. The propagated ROIs were qualitatively examined by experts and scored based on their clinical utility. Results: Good agreement between the DIR-propagated ROIs and expert-drawn ROIs was observed based on the metrics used. 94% of all ROIs generated using DIR were scored as being clinically useful, requiring minimal or no edits. However, 27% (12/44) of the GTVs required major edits. Conclusion: DIR was successfully used on 22 patients to propagate target and OAR structures for ART with good anatomical agreement for OARs. It is recommended that propagated target structures be thoroughly reviewed by the treating physician. KW - intensity-modulated radiotherapy KW - megavoltage computed-tomography KW - cancer KW - variability KW - strategies KW - risk Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-134756 VL - 7 IS - 90 ER - TY - JOUR A1 - Colvill, Emma A1 - Booth, Jeremy A1 - Nill, Simeon A1 - Fast, Martin A1 - Bedford, James A1 - Oelfke, Uwe A1 - Nakamura, Mitsuhiro A1 - Poulsen, Per A1 - Worm, Esben A1 - Hansen, Rune A1 - Ravkilde, Thomas A1 - Rydhög, Jonas Scherman A1 - Pommer, Tobias A1 - af Rosenschold, Per Munck A1 - Lang, Stephanie A1 - Guckenberger, Matthias A1 - Groh, Christian A1 - Herrmann, Christian A1 - Verellen, Dirk A1 - Poels, Kenneth A1 - Wang, Lei A1 - Hadsell, Michael A1 - Sothmann, Thilo A1 - Blanck, Oliver A1 - Keall, Paul T1 - A dosimetric comparison of real-time adaptive and non-adaptive radiotherapy: a multi-institutional study encompassing robotic, gimbaled, multileaf collimator and couch tracking JF - Radiotherapy and Oncology N2 - Purpose: A study of real-time adaptive radiotherapy systems was performed to test the hypothesis that, across delivery systems and institutions, the dosimetric accuracy is improved with adaptive treatments over non-adaptive radiotherapy in the presence of patient-measured tumor motion. Methods and materials: Ten institutions with robotic(2), gimbaled(2), MLC(4) or couch tracking(2) used common materials including CT and structure sets, motion traces and planning protocols to create a lung and a prostate plan. For each motion trace, the plan was delivered twice to a moving dosimeter; with and without real-time adaptation. Each measurement was compared to a static measurement and the percentage of failed points for gamma-tests recorded. Results: For all lung traces all measurement sets show improved dose accuracy with a mean 2%/2 mm gamma-fail rate of 1.6% with adaptation and 15.2% without adaptation (p < 0.001). For all prostate the mean 2%/2 mm gamma-fail rate was 1.4% with adaptation and 17.3% without adaptation (p < 0.001). The difference between the four systems was small with an average 2%/2 mm gamma-fail rate of <3% for all systems with adaptation for lung and prostate. Conclusions: The investigated systems all accounted for realistic tumor motion accurately and performed to a similar high standard, with real-time adaptation significantly outperforming non-adaptive delivery methods. KW - Robotic tracking KW - Gimbaled tracking KW - MLC tracking KW - Couch tracking KW - Organ motion Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-189605 VL - 119 IS - 1 ER -