TY - THES A1 - Stumm, Tobias T1 - Vergleich verschiedener Bestrahlungstechniken am Beispiel unterschiedlicher Hirntumore - eine retrospektive Planungsstudie T1 - Comparison of different radiation techniques at the example of different brain tumors - a retrospective planning study N2 - Die Patientenbestrahlung stellt eine wichtige Therapiesäule in der onkologischen Behandlung von Hirntumoren dar. Das Hauptaugenmerk wird dabei auf die Erreichung einer vorgegebenen Zieldosis im Tumorgebiet und die ausreichende Schonung von sensiblen Strukturen gerichtet. Wir verglichen insgesamt 4 Bestrahlungstechniken untereinander, welche in ihrer Segmentierung und Feldzahl variiert werden können: KoPlanar (Komplettbestrahlung in einer Ebene), KoPlanar+1 (Bestrahlung in einer Ebene mit einem Zusatzfeld in einer anderen Ebene), 2-Ebenen (Bestrahlung auf 2 unterschiedliche Ebenen verteilt), Quasi-Isotrop (Bestrahlung mit Zentralstrahlen in mehreren unterschiedlichen Ebenen). Die Feldzahl kann zwischen wenigen Feldern (9F oder 10F) und vielen Feldern (15F oder 16F) gewählt werden. Die Segmentanzahl wird entweder bei 64 oder 120 Segmenten festgelegt, alternativ wurde eine freie Optimierung der Feldfluenz ermöglicht. Dabei zeigte die Quasi-Isotrope Technik eindeutige und signifikante Vorteile gegenüber allen anderen Techniken sowohl bei niedrigen als auch hohen Feldzahlen. Die koplanare Bestrahlung schnitt bei unserer Auswertung am schlechtesten ab. Die 2-Ebenen Technik und KoPlanar+1 Technik können bei hohen Feldzahlen als gleichwertig betrachtet werden, bei niedrigen Feldzahlen zeigt die KoPlanar+1 Technik Vorteile. Aus unserer Sicht sollten die unentschiedenen Vergleiche in weiteren Studien untersucht werden, die das Patientengut weiter einengen. Weiterhin wäre eine Erweiterung der Untersuchungen auf die schneller applizierbaren nonkoplanaren Volumetric Arc –Techniken (VMAT) wünschenswert. N2 - Radiation therapy is an important option in the oncological treatment of brain tumors. The main focus is on achieving a specified target dose in the tumor area and on adequate protection of sensitive structures. We compared 4 irradiation techniques with each other, which were varied in their segmentation and in the number of fields: KoPlanar (complete irradiation in one level), KoPlanar + 1 (irradiation in one level with an additional field in another level), 2-levels (irradiation on 2 different planes distributed), quasi-isotropic (irradiation with central rays in several different planes). The number of fields were varied (9F/10F or 15F/16F). The number of segments was set to either 64 or 120 segments; alternatively, the field fluence was optimized without any restriction. The quasi-isotropic technique showed clear and significant advantages over all other techniques with both low and high field numbers. The KoPlanar technique was inferior to the other techniques in our evaluation. The 2-level technique and the KoPlanar + 1 technique can be regarded as equivalent in the case of high numbers of fields; the KoPlanar + 1 technique is beneficial for low numbers of fields. From our point of view, the non-conclusive comparisons should be examined in further studies with a more consistent patient population. Furthermore, future investigations should include the non-coplanar volumetric arc techniques (VMAT) which can be applied more quickly. KW - Bestrahlung KW - Gliome KW - IMRT KW - nonkoplanar KW - DMPO Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-217733 ER - TY - THES A1 - Kraus, Pia T1 - Behandlungsergebnisse maligner Nasenhaupt- und Nebenhöhlentumore T1 - Therapeutic results of patients with cancer ot the nasal and sinunasal cavities N2 - Ziel der Dissertation ist es, die Behandlungsergebnisse von Patienten mit malignen Nasenhaupt- und Nebenhöhlentumore, die zwischen Februar 1990 bis März 2014 unter kurativer Zielsetzung in der Klinik für Strahlentherapie des Universitätskrankenhauses Würzburg behandelt wurden, zu analysieren. Vor 2007 kam eine 3D-CRT Technik zum Einsatz, danach eine IMRT-Bestrahlung, in primärer oder postoperativer Form. Eine Verminderung der Überlebensrate ergab sich bei hohem Gesamttumorvolumen (>60ml), bei primäre Bestrahlung, bei Infiltration des Subkutangewebes, bei einer Fernmetastasierung im Verlauf und wenn keine komplette Remission erreicht wurde. Eine Verschlechterung der lokalen Tumorkontrolle wurde durch ein hohes Gesamttumorvolumen (>60ml) verursacht. Eine Chemotherapie zog keinen Vorteil in den Überlebenszeiten und der lokalen Tumorkontrolle nach sich. Die postoperative Radiotherapie ist die häufigste und zu bevorzugende Therapiemodalität. N2 - To analyse the therapeutic results of patients with malignant cancer of the nasal an paranasal sinuses is the objective of this thesis. Those patients were treated under curative terms in the department of radiotheray in the university hosptial Würzburg between Febuary 1990 and March 2014. Before 2007 a 3D-CRT technique was used, afterwards a IMRT technique. A reduction of survival rates was produced with large tumor volumes (>60ml), with primary radiation, with infiltration of subcutaneous tissue, with distant metastases and if no complete remission was achieved. Local control rates were downgraded by large tumor volumens (>60ml). No positive effects on local control and overall survival were attained by the application of a chemotherapy. Postoperative radiotherapy is the most common and preferred therapeutic modality. KW - Strahlentherapie KW - Radiotherapy KW - IMRT KW - Nasenhaupthöhlentumore KW - Nasennebenhöhlentumore KW - Gesamttumorvolumen Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-160525 ER - TY - JOUR A1 - Holubyev, Konstyantyn A1 - Bratengeier, Klaus A1 - Gainey, Mark A1 - Polat, Bülent A1 - Flentje, Michael T1 - Towards automated on-line adaptation of 2-Step IMRT plans: QUASIMODO phantom and prostate cancer cases JF - Radiation Oncology N2 - Background The standard clinical protocol of image-guided IMRT for prostate carcinoma introduces isocenter relocation to restore the conformity of the multi-leaf collimator (MLC) segments to the target as seen in the cone-beam CT on the day of treatment. The large interfractional deformations of the clinical target volume (CTV) still require introduction of safety margins which leads to undesirably high rectum toxicity. Here we present further results from the 2-Step IMRT method which generates adaptable prostate IMRT plans using Beam Eye View (BEV) and 3D information. Methods Intermediate/high-risk prostate carcinoma cases are treated using Simultaneous Integrated Boost at the Universitätsklinkum Würzburg (UKW). Based on the planning CT a CTV is defined as the prostate and the base of seminal vesicles. The CTV is expanded by 10 mm resulting in the PTV; the posterior margin is limited to 7 mm. The Boost is obtained by expanding the CTV by 5 mm, overlap with rectum is not allowed. Prescription doses to PTV and Boost are 60.1 and 74 Gy respectively given in 33 fractions. We analyse the geometry of the structures of interest (SOIs): PTV, Boost, and rectum, and generate 2-Step IMRT plans to deliver three fluence steps: conformal to the target SOIs (S0), sparing the rectum (S1), and narrow segments compensating the underdosage in the target SOIs due to the rectum sparing (S2). The width of S2 segments is calculated for every MLC leaf pair based on the target and rectum geometry in the corresponding CT layer to have best target coverage. The resulting segments are then fed into the DMPO optimizer of the Pinnacle treatment planning system for weight optimization and fine-tuning of the form, prior to final dose calculation using the collapsed cone algorithm. We adapt 2-Step IMRT plans to changed geometry whilst simultaneously preserving the number of initially planned Monitor Units (MU). The adaptation adds three further steps to the previous isocenter relocation: 1) 2-Step generation for the geometry of the day using the relocated isocenter, MU transfer from the planning geometry; 2) Adaptation of the widths of S2 segments to the geometry of the day; 3) Imitation of DMPO fine-tuning for the geometry of the day. Results and conclusion We have performed automated 2-Step IMRT adaptation for ten prostate adaptation cases. The adapted plans show statistically significant improvement of the target coverage and of the rectum sparing compared to those plans in which only the isocenter is relocated. The 2-Step IMRT method may become a core of the automated adaptive radiation therapy system at our department. KW - Prostate carcinoma KW - IMRT KW - IGRT KW - Adaptation Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-96818 UR - http://www.ro-journal.com/content/8/1/263 ER - TY - JOUR A1 - Bratengeier, Klaus A1 - Holubyev, Kostyantyn T1 - Anisotropy of dose contributions-an instrument to upgrade real time IMRT and VMAT adaptation? JF - Medical Physics N2 - Purpose: To suggest a definition of dose deposition anisotropy for the purpose of ad hoc adaptation of intensity modulated arc therapy (IMRT) and volumetric arc therapy (VMAT), particularly in the vicinity of important organs at risk (OAR), also for large deformations. Methods: Beam's-eye-view (BEV) based fluence warping is a standard adaptation method with disadvantages for strongly varying OAR shapes. 2-Step-adaptation overcomes these difficulties by a deeper analysis of the 3D properties of adaptation processes, but requires separate arcs for every OAR to spare, which makes it impractical for cases with multiple OARs. The authors aim to extend the 2-Step method to arbitrary intensity modulated plan by analyzing the anisotropy of dose contributions. Anisotropy was defined as a second term of Fourier transformation of gantry angle dependent dose contributions. For a cylindrical planning target volume (PTV) surrounding an OAR of varying diameter, the anisotropy and the dose-normalized anisotropy were analyzed for several scenarios of optimized fluence distributions. 2-Step adaptation to decreasing and increasing OAR diameter was performed, and compared to a usual fluence based adaptation method. For two clinical cases, prostate and neck, the VMAT was generated and the behavior of anisotropy was qualitatively explored for deformed organs at risk. # Results: Dose contribution anisotropy in the PTV peaks around nearby OARs. The thickness of the "anisotropy wall" around OAR increases for increasing OAR radius, as also does the width of 2-Step dose saturating fluence peak adjacent to the OAR K. Bratengeier et al., "A comparison between 2-Step IMRT and conventional IMRT planning," Radiother. Oncol. 84, 298-306 (2007)]. Different optimized beam fluence profiles resulted in comparable radial dependence of normalized anisotropy. As predicted, even for patient cases, anisotropy was inflated even more than increasing diameters of OAR. Conclusions: For cylindrically symmetric cases, the dose distribution anisotropy defined in the present work implicitly contains adaptation-relevant information about 3D relationships between PTV and OAR and degree of OAR sparing. For more complex realistic cases, it shows the predicted behavior qualitatively. The authors claim to have found a first component for advancing a 2-Step adaptation to a universal adaptation algorithm based on the BEV projection of the dose anisotropy. Further planning studies to explore the potential of anisotropy for adaptation algorithms using phantoms and clinical cases of differing complexity will follow. KW - modulated arc therapy KW - 2-step IMRT KW - radiation-therapy KW - online adaption KW - prostate-cancer KW - plans KW - IMAT KW - tracking KW - radiotherapy KW - adaption KW - IMRT KW - VMAT Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-186833 VL - 43 IS - 11 ER -