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Zeitschrift Für Medizinische Physik

Marius Treutwein, Lothar Schad
No abstract text is available yet for this article.
October 17, 2016: Zeitschrift Für Medizinische Physik
Evelyn Bohrer, Stefan Schäfer, Ulf Mäder, Peter B Noël, Gabriele A Krombach, Martin Fiebich
INTRODUCTION: The trend towards submillisievert CT scans leads to a higher dose fraction of localizer radiographs in CT examinations. The already existing technical capabilities make dose optimization of localizer radiographs worthwhile. Modern CT scanners apply automatic exposure control (AEC) based on attenuation data in such a localizer. Therefore not only this aspect but also the detectability of anatomical landmarks in the localizer for the desired CT scan range adjustment needs to be considered...
October 6, 2016: Zeitschrift Für Medizinische Physik
Wiebke Neumann, Florian Lietzmann, Lothar R Schad, Frank G Zöllner
OBJECTIVES: This work proposes a modular, anthropomorphic MR and CT thorax phantom that enables the comparison of experimental studies for quantitative evaluation of deformable, multimodal image registration algorithms and realistic multi-nuclear MR imaging techniques. METHODS: A human thorax phantom was developed with insertable modules representing lung, liver, ribs and additional tracking spheres. The quality of human tissue mimicking characteristics was evaluated for (1)H and (23)Na MR as well as CT imaging...
September 2, 2016: Zeitschrift Für Medizinische Physik
Thomas Flohr
No abstract text is available yet for this article.
September 2016: Zeitschrift Für Medizinische Physik
Michael Schwerter, Florian Lietzmann, Lothar R Schad
Minimally invasive interventions are frequently aided by 2D projective image guidance. To facilitate the navigation of medical tools within the patient, information from preoperative 3D images can supplement interventional data. This work describes a novel approach to perform a 3D CT data registration to a single interventional native fluoroscopic frame. The goal of this procedure is to recover and visualize a current 2D interventional tool position in its corresponding 3D dataset. A dedicated routine was developed and tested on a phantom...
September 2016: Zeitschrift Für Medizinische Physik
Alexander Gerbershagen, David Meer, Jacobus Maarten Schippers, Mike Seidel
PURPOSE: A first order design of the beam optics of a superconducting proton therapy gantry beam is presented. The possibilities of superconducting magnets with respect to the beam optics such as strong fields, large apertures and superposition of different multipole fields have been exploited for novel concepts in a gantry. Since various techniques used in existing gantries have been used in our first design steps, some examples of the existing superconducting gantry designs are described and the necessary requirements of such a gantry are explained...
September 2016: Zeitschrift Für Medizinische Physik
Eckhart Fröhlich, Juliane Hofmann, Ines Debove, Christoph F Dietrich, Hans Kaarmann, Jan Pauluschke-Fröhlich, Stefan Schmidt, Reinhold Muller
AIM: To replace pictograms with pictocam pictures: A prospective blinded quality improvement study in documenting image orientation and localisation in abdominal ultrasound imaging. MATERIALS AND METHODS: A minicam was mounted on the ultrasound scanhead to record pictocam pictures. The primary examiner produced an ultrasound image together with the routinely embedded pictogram. Subsequently the pictogram was covered by the synchronically taken pictocam picture. Subsequently, the primary examiner assessed the pictograms and the second examiner the pictocam pictures (blinded to the pictogram findings of the primary examiner)...
September 2016: Zeitschrift Für Medizinische Physik
Joachim H X Schrauth, Gunthard Lykowsky, Kathrin Hemberger, Jakob Kreutner, Daniel Weber, Lars Rackwitz, Ulrich Nöth, Peter M Jakob, Daniel Haddad
RATIONALE AND OBJECTIVES: Osteoarthritis (OA) is a degenerative joint disease leading to cartilage deterioration by loss of matrix, fibrillation, formation of fissures, and ultimately complete loss of the cartilage surface. Here, three magnetic resonance imaging (MRI) techniques, dGEMRIC (delayed Gadolinium enhanced MRI of cartilage; dG1=T1,post; dG2=1/T1,post-1/T1,pre), T1ρ,and sodium MRI, are compared in a preclinical in vivo study to evaluate the differences in their potential for cartilage characterization and to establish an examination protocol for a following clinical study...
September 2016: Zeitschrift Für Medizinische Physik
Franziska Renner
Monte Carlo simulations are regarded as the most accurate method of solving complex problems in the field of dosimetry and radiation transport. In (external) radiation therapy they are increasingly used for the calculation of dose distributions during treatment planning. In comparison to other algorithms for the calculation of dose distributions, Monte Carlo methods have the capability of improving the accuracy of dose calculations - especially under complex circumstances (e.g. consideration of inhomogeneities)...
September 2016: Zeitschrift Für Medizinische Physik
Ndimofor Chofor, Dietrich Harder, Hans-Joachim Selbach, Björn Poppe
The application of various radiation detectors for brachytherapy dosimetry has motivated this study of the energy dependence of radiation quality correction factor kQ,M, the quotient of the detector responses under calibration conditions at a (60)Co unit and under the given non-reference conditions at the point of measurement, M, occurring in photon brachytherapy. The investigated detectors comprise TLD, radiochromic film, ESR, Si diode, plastic scintillator and diamond crystal detectors as well as ionization chambers of various sizes, whose measured response-energy relationships, taken from the literature, served as input data...
September 2016: Zeitschrift Für Medizinische Physik
Johannes Thoelking, Yuvaraj Sekar, Jens Fleckenstein, Frank Lohr, Frederik Wenz, Hansjoerg Wertz
PURPOSE: Online verification and 3D dose reconstruction on daily patient anatomy have the potential to improve treatment delivery, accuracy and safety. One possible implementation is to recalculate dose based on online fluence measurements with a transmission detector (TD) attached to the linac. This study provides a detailed analysis of the influence of a new TD on treatment beam characteristics. METHODS: The influence of the new TD on surface dose was evaluated by measurements with an Advanced Markus Chamber (Adv-MC) in the build-up region...
September 2016: Zeitschrift Für Medizinische Physik
Verónica García-Vázquez, Eugenio Marinetto, Pedro Guerra, Manlio Fabio Valdivieso-Casique, Felipe Ángel Calvo, Eduardo Alvarado-Vásquez, Claudio Vicente Sole, Kirby Gannett Vosburgh, Manuel Desco, Javier Pascau
Intraoperative electron radiation therapy (IOERT) involves irradiation of an unresected tumour or a post-resection tumour bed. The dose distribution is calculated from a preoperative computed tomography (CT) study acquired using a CT simulator. However, differences between the actual IOERT field and that calculated from the preoperative study arise as a result of patient position, surgical access, tumour resection and the IOERT set-up. Intraoperative CT imaging may then enable a more accurate estimation of dose distribution...
August 23, 2016: Zeitschrift Für Medizinische Physik
Stephan Helmbrecht, Wolfgang Enghardt, Fine Fiedler, Marc Iltzsche, Guntram Pausch, Carlo Tintori, Thomas Kormoll
Positron emission tomography (PET) is a means of imaging the β(+)-activity produced by the radiation field in ion beam therapy and therefore for treatment verification. Prompt γ-rays that are emitted during beam application challenge the detectors and electronics of PET systems, since those are designed for low and medium count rates. Typical PET detectors operated according to a modified Anger principle suffer from multiple events at high rates. Therefore, in-beam PET systems using such detectors rely on a synchronization of beam status and measurement to reject deteriorated data...
August 20, 2016: Zeitschrift Für Medizinische Physik
Reinhard Rzanny, Norman Stutzig, Patrick Hiepe, Alexander Gussew, Hans-Alexander Thorhauer, Jürgen R Reichenbach
PURPOSE: The objective of the study was to investigate the reproducibility of exercise induced pH-heterogeneity by splitting of the inorganic phosphate (Pi) signal in the corresponding (31)P-MRS spectra and to compare results of this approach with other fiber-type related markers, like phosphocreatine/adenosine triphosphate (PCr/ATP) ratio, and PCr-recovery parameters. MATERIAL AND METHODS: Subjects (N=3) with different sportive background were tested in 10 test sessions separated by at least 3 days...
August 12, 2016: Zeitschrift Für Medizinische Physik
Uwe Schneider, Roger A Hälg, Tony Lomax
PURPOSE: One of the essential elements of an epidemiological study to decide if proton therapy may be associated with increased or decreased subsequent malignancies compared to photon therapy is an ability to estimate all doses to non-target tissues, including neutron dose. This work therefore aims to predict for patients using proton pencil beam scanning the spatially localized neutron doses and dose equivalents. METHODS: The proton pencil beam of Gantry 1 at the Paul Scherrer Institute (PSI) was Monte Carlo simulated using GEANT...
August 11, 2016: Zeitschrift Für Medizinische Physik
Åsmund Kjørstad, Marc Regier, Jens Fiehler, Jan Sedlacik
In 2006, a novel method for extracting functional ventilation-weighted lung images using MRI was published. The method exploited the naturally occurring density changes in the lung during breathing and the resulting images showed a clear clinical potential. A decade later, the method has been adapted and further developed by several research groups and has led to many encouraging pre-clinical studies, both in animals and in humans. In this paper we show the development of the method and summarize the current state-of-the-art, aiming to both inform and motivate students and researchers with an interest in this exciting field...
August 10, 2016: Zeitschrift Für Medizinische Physik
C Bäumer, B Ackermann, M Hillbrand, F-J Kaiser, B Koska, H Latzel, A Lühr, S Menkel, B Timmermann
AIM: To verify the consistency of dose and range measurement in an interinstitution comparison among German proton therapy institutions which use the pencil-beam scanning technique. METHODS: Following a peer-to-peer approach absorbed dose and range have been intercompared in several missions at two hosting centers with two or three visiting physics teams of participating institutions using their own dosimetry equipment. A meta-analysis has been performed integrating the results of the individual missions...
July 15, 2016: Zeitschrift Für Medizinische Physik
Alexander Solle, Carsten Wanke, Lilli Geworski
Ga-68-labeled radiotracers, particularly used for the detection of neuroendocrine tumors by means of Ga-68-DOTA-TATE or -DOTA-TOC or for the diagnosis of prostate cancer by means of Ga-68-labeled antigens (Ga 68-PSMA), become increasingly important. In addition to the high sensitivity and specificity of these radiopharmaceuticals, the short-lived radionuclide Ga-68 offers almost ideal nuclear characteristics for use in PET. Ga-68 is obtained from a germanium-gallium-generator system, so that the availability of Ga-68-labeled radiotracers is independent of an on-site-cyclotron regardless of the short half-life of Ga-68 of about 68minutes...
July 15, 2016: Zeitschrift Für Medizinische Physik
Manuela C Felix, Gerhard Glatting, Frank A Giordano, Marc A Brockmann, Frederik Wenz, Jens Fleckenstein
PURPOSE: In radiation therapy of small animals treatment depths range from a few millimetres to several centimetres. In order to spare surrounding organs at risk steep dose gradients are necessary. To minimize the treatment time, and therefore the strain to the animals, a high dose rate is required. A description how these parameters can be optimized through an appropriate choice of collimators with different source surface distances (SSD) as well as different materials and geometries is presented...
June 16, 2016: Zeitschrift Für Medizinische Physik
Thorsten Frenzel, Michael Gerhard Kaul, Thomas Michael Ernst, Johannes Salamon, Maria Jäckel, Udo Schumacher, Andreas Krüll
AIMS: Radiotherapy of small laboratory animals (SLA) is often not as precisely applied as in humans. Here we describe the use of a dedicated SLA magnetic resonance imaging (MRI) scanner for precise tumor volumetry, radiotherapy treatment planning, and diagnostic imaging in order to make the experiments more accurate. METHODS AND MATERIALS: Different human cancer cells were injected at the lower trunk of pfp/rag2 and SCID mice to allow for local tumor growth. Data from cross sectional MRI scans were transferred to a clinical treatment planning system (TPS) for humans...
June 13, 2016: Zeitschrift Für Medizinische Physik
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