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Zeitschrift Für Medizinische Physik

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https://www.readbyqxmd.com/read/29463428/swiss-survey-on-hybrid-imaging-cts-doses-in-nuclear-medicine-and-proposed-national-dose-reference-levels
#1
Thiago V M Lima, Silvano Gnesin, Nick Ryckx, Klaus Strobel, Nicolas Stritt, Reto Linder
A multidisciplinary working group led by the Swiss Federal Office of Public Health was formed to plan and perform a nationwide survey of patient radiation exposure from computed tomography (CT) in hybrid devices across Nuclear Medicine departments. The survey included 16 departments (of which 5 were university hospitals) and the submitted responses included 10,673 entries for the 33 different protocols proposed (11 in PET and 22 in SPECT). The working group determined the selection and exclusion criteria applied to the analysis...
February 17, 2018: Zeitschrift Für Medizinische Physik
https://www.readbyqxmd.com/read/29439849/potential-of-metric-homotopy-between-intensity-and-geometry-information-for-multi-modal-3d-registration
#2
Daniel Glodeck, Jürgen Hesser, Lei Zheng
This paper focuses on a novel strategy increasing robustness with respect to local optima when using Mutual Information (MI) in multi-modal image registration. This is realized by integrating additional geometry information in the cost function. Hereby, the main innovation is a generalization of multi-metric registration approaches by means of a metric homotopy. Particularly we realize a method which automatically determines the parameters of the metric homotopy. To construct the cost function independent of the choice of the optimizer, the weighting is defined as a function of one of the metrics instead of optimizer steps...
February 10, 2018: Zeitschrift Für Medizinische Physik
https://www.readbyqxmd.com/read/29429610/automated-ultrafast-kilovoltage-megavoltage-cone-beam-ct-for-image-guided-radiotherapy-of-lung-cancer-system-description-and-real-time-results
#3
Manuel Blessing, Anna Arns, Hansjoerg Wertz, Dzmitry Stsepankou, Judit Boda-Heggemann, Juergen Hesser, Frederik Wenz, Frank Lohr
PURPOSE: To establish a fully automated kV-MV CBCT imaging method on a clinical linear accelerator that allows image acquisition of thoracic targets for patient positioning within one breath-hold (∼15s) under realistic clinical conditions. METHODS AND MATERIALS: Our previously developed FPGA-based hardware unit which allows synchronized kV-MV CBCT projection acquisition is connected to a clinical linear accelerator system via a multi-pin switch; i.e. either kV-MV imaging or conventional clinical mode can be selected...
February 8, 2018: Zeitschrift Für Medizinische Physik
https://www.readbyqxmd.com/read/29426589/determination-of-the-effective-dose-delivered-by-image-guided-radiotherapy-in-head-neck-and-breast-treatments
#4
Mireille Conrad, Grégory Bolard, Marie Nowak, Berardino De Bari, Wendy Jeanneret-Sozzi, Jean Bourhis, Jean-François Germond, François Bochud, Raphaël Moeckli
PURPOSE: Image guided radiotherapy (IGRT) improves patient positioning for treatment delivery at the cost of an additional dose. This work aimed to calculate the effective dose (as an indicator of dose) for head & neck (H&N) and breast IGRT treatments by implementing dose calculation models to determine the dose distributions. METHODS: The kV dose-models were created for the IGRT systems of Elekta Synergy (XVI) and Varian Clinac (OBI) linear accelerators within Philips Pinnacle TPS...
February 6, 2018: Zeitschrift Für Medizinische Physik
https://www.readbyqxmd.com/read/29426588/-magnetic-resonance-imaging-beyond-the-proton-what-does-oxygen-17-mri-have-to-offer
#5
EDITORIAL
Michael Bock
No abstract text is available yet for this article.
February 6, 2018: Zeitschrift Für Medizinische Physik
https://www.readbyqxmd.com/read/29373177/the-quest-for-higher-sensitivity-in-mri-through-higher-magnetic-fields
#6
EDITORIAL
Mark E Ladd
No abstract text is available yet for this article.
January 17, 2018: Zeitschrift Für Medizinische Physik
https://www.readbyqxmd.com/read/29338903/clinical-workflow-optimization-to-improve-4dct-reconstruction-for-toshiba-aquilion-ct-scanners
#7
P Freislederer, C Heinz, H von Zimmermann, S Gerum, F Roeder, M Reiner, M Söhn, C Belka, K Parodi
Respiratory motion remains a source of major uncertainties in radiotherapy. Respiratory correlated computed tomography (referred to as 4DCT) serves as one way of reducing breathing artifacts in 3D-CTs and allows the investigation of tumor motion over time. The quality of the 4DCT images depends on the data acquisition scheme, which in turn is dependent on the vendor. Specifically, the only way Toshiba Aquilion LB CT scanners can reconstruct 4DCTs is a cycle-based reconstruction using triggers provided by an external surrogate signal...
January 12, 2018: Zeitschrift Für Medizinische Physik
https://www.readbyqxmd.com/read/29336934/determination-of-recombination-and-polarity-correction-factors-ks-and-kp-for-small-cylindrical-ionization-chambers-ptw-31021-and-ptw-31022-in-pulsed-filtered-and-unfiltered-beams
#8
Gregor Bruggmoser, Rainer Saum, Rafael Kranzer
The aim of this technical communication is to provide correction factors for recombination and polarity effect for two new ionization chambers PTW PinPoint 3D (type 31022) and PTW Semiflex 3D (type 31021). The correction factors provided are for the (based on the) German DIN 6800-2 dosimetry protocol and the AAPM TG51 protocol. The measurements were made in filtered and unfiltered high-energy photon beams in a water equivalent phantom at maximum depth of the PDD and a field size on the surface of 10cm×10cm...
January 11, 2018: Zeitschrift Für Medizinische Physik
https://www.readbyqxmd.com/read/29275899/analysis-of-the-treatment-plan-evaluation-process-in-radiotherapy-through-eye-tracking
#9
A Kyroudi, K Petersson, M Ozsahin, J Bourhis, F Bochud, R Moeckli
BACKGROUND AND PURPOSE: Treatment plan evaluation is a clinical decision-making problem that involves visual search and analysis in a contextually rich environment, including delineated structures and isodose lines superposed on CT data. It is a two-step process that includes visual analysis and clinical reasoning. In this work, we used eye tracking methods to gain more knowledge about the treatment plan evaluation process in radiation therapy. MATERIALS AND METHODS: Dose distributions on a single transverse slice of ten prostate cancer treatment plans were presented to eight decision makers...
December 21, 2017: Zeitschrift Für Medizinische Physik
https://www.readbyqxmd.com/read/29233600/noise-reduction-in-flair2-images-using-total-generalized-variation-gaussian-and-wiener-filtering
#10
René Schranzer, Alexander Rauscher, Evelin Haimburger, Kristian Bredies, Gernot Reishofer, Günther Grabner
PURPOSE: Multiplication of FLAIR and T2-weighted MRI scans results in images (called FLAIR2) with an improved contrast-to-noise ratio (CNR) for multiple sclerosis (MS) lesions but with a reduced signal-to-noise ratio (SNR). Denoising of these images may therefore further improve FLAIR2 image quality. The purpose of this work is to present a systematic investigation of FLAIR2 image denoising methods using Gaussian, Wiener and Total Generalized Variation (TGV) filtering approaches. MATERIALS AND METHODS: T2-weighted and FLAIR data of four MS patients were used...
December 9, 2017: Zeitschrift Für Medizinische Physik
https://www.readbyqxmd.com/read/29107440/the-technological-basis-for-adaptive-ion-beam-therapy-at-medaustron-status-and-outlook
#11
Markus Stock, Dietmar Georg, Alexander Ableitinger, Andrea Zechner, Alexander Utz, Marta Mumot, Gabriele Kragl, Johannes Hopfgartner, Joanna Gora, Till Böhlen, Loïc Grevillot, Peter Kuess, Phil Steininger, Heinz Deutschmann, Stanislav Vatnitsky
The ratio of patients who need a treatment adaptation due to anatomical variations at least once during the treatment course is significantly higher in light ion beam therapy (LIBT) than in photon therapy. The ballistic behaviour of ion beams makes them more sensitive to changes. Hence, the delivery of LIBT has always been supported by state of art image guidance. On the contrary CBCT technology was adapted for LIBT quite late. Adaptive concepts are being implemented more frequently in photon therapy and also efficient workflows are needed for LIBT...
October 27, 2017: Zeitschrift Für Medizinische Physik
https://www.readbyqxmd.com/read/29054678/excitation-characteristic-of-a-bipolar-stimulus-for-broadband-stimulation-in-measurements-of-electrically-evoked-auditory-potentials
#12
Oliver C Dziemba, Thomas Hocke, Alexander Müller, Holger Kaftan
OBJECTIVE: The aim of this study was to determine the optimum electrical stimulation mode for the measurement of electrically evoked potentials. To quantify the broadband excitation electrically evoked compound action potentials were recorded in cochlear implant recipients. The full width half maximum was determined for spread of excitation along the electrode array. DESIGN: Prospective clinical study. STUDY SAMPLE: The study sample consisted of 20 adult cochlear implant users...
October 17, 2017: Zeitschrift Für Medizinische Physik
https://www.readbyqxmd.com/read/29033293/ct-and-mri-slice-separation-evaluation-by-labview-developed-software
#13
Giuseppe Acri, Barbara Testagrossa, Angela Sestito, Lilla Bonanno, Giuseppe Vermiglio
The efficient use of Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) equipment necessitates establishing adequate quality-control (QC) procedures. In particular, the accuracy of slice separation, during multislices acquisition, requires scan exploration of phantoms containing test objects. To simplify such procedures, a novel phantom and a computerised LabView-based procedure have been devised, enabling determination the midpoint of full width at half maximum (FWHM) in real time while the distance from the profile midpoint of two progressive images is evaluated and measured...
October 13, 2017: Zeitschrift Für Medizinische Physik
https://www.readbyqxmd.com/read/29033292/-dosimetric-verification-of-mammosite-treatment-plans-using-monte-carlo-simulations-and-measurements-with-a-2d-ionization-chamber-array
#14
Moritz Budde, Irenäus A Adamietz, Holger Sommer, Horst Hermani
The surgical removal of a breast tumour is often followed by postoperative irradiation of the surrounding tissue with a radioactive source (brachytherapy). When performing the MammoSite procedure, a spherical silicone balloon is inserted and filled with a NaCl solution. In a period of about five days in several sessions an iridium-192 source with high activity travels through a catheter into the balloon (afterloading) to irradiate the tumour cells remaining in the cavity. In this study, dose distributions of a MammoSite applicator are investigated based on measurements with a 2D detector array, Monte Carlo simulations and calculations with BrachyVision...
October 12, 2017: Zeitschrift Für Medizinische Physik
https://www.readbyqxmd.com/read/29031916/image-guided-adaptive-external-beam-radiation-therapy-for-cervix-cancer-evaluation-of-a-clinically-implemented-plan-of-the-day-technique
#15
Martin Buschmann, Katarina Majercakova, Alina Sturdza, Stephanie Smet, Dina Najjari, Michaela Daniel, Richard Pötter, Dietmar Georg, Yvette Seppenwoolde
BACKGROUND: Radiotherapy for cervix cancer is challenging in patients exhibiting large daily changes in the pelvic anatomy, therefore adaptive treatments (ART) have been proposed. The aim of this study was the clinical implementation and subsequent evaluation of plan-of-the-day (POTD)-ART for cervix cancer in supine positioning. The described workflow was based on standard commercial equipment and current quality assurance (QA) methods. MATERIALS AND METHODS: A POTD strategy, which employs a VMAT plan library consisting of an empty bladder plan, a full bladder plan and a motion robust backup plan, was developed...
October 11, 2017: Zeitschrift Für Medizinische Physik
https://www.readbyqxmd.com/read/29031915/experimental-and-monte-carlo-based-determination-of-the-beam-quality-specifier-for-tomotherapyhd-treatment-units
#16
S Howitz, M Schwedas, T Wiezorek, K Zink
Reference dosimetry by means of clinical linear accelerators in high-energy photon fields requires the determination of the beam quality specifier TPR20,10, which characterizes the relative particle flux density of the photon beam. The measurement of TPR20,10 has to be performed in homogenous photon beams of size 10×10cm(2) with a focus-detector distance of 100cm. These requirements cannot be fulfilled by TomoTherapy treatment units from Accuray. The TomoTherapy unit provides a flattening-filter-free photon fan beam with a maximum field width of 40cm and field lengths of 1...
October 11, 2017: Zeitschrift Für Medizinische Physik
https://www.readbyqxmd.com/read/29030203/characterization-and-clinical-evaluation-of-a-novel-2d-detector-array-for-conventional-and-flattening-filter-free-fff-imrt-pre-treatment-verification
#17
Yuvaraj Sekar, Johannes Thoelking, Miriam Eckl, Irakli Kalichava, Dwi Seno Kuncoro Sihono, Frank Lohr, Frederik Wenz, Hansjoerg Wertz
BACKGROUND AND PURPOSE: The novel MatriXX(FFF) (IBA Dosimetry, Germany) detector is a new 2D ionization chamber detector array designed for patient specific IMRT-plan verification including flattening-filter-free (FFF) beams. This study provides a detailed analysis of the characterization and clinical evaluation of the new detector array. MATERIAL AND METHODS: The verification of the MatriXX(FFF) was subdivided into (i) physical dosimetric tests including dose linearity, dose rate dependency and output factor measurements and (ii) patient specific IMRT pre-treatment plan verifications...
October 10, 2017: Zeitschrift Für Medizinische Physik
https://www.readbyqxmd.com/read/28969957/reference-conditions-for-ion-chamber-based-hdr-brachytherapy-dosimetry-and-for-the-calibration-of-high-resolution-solid-detectors
#18
Andreas A Schoenfeld, Katrin Büsing, Björn Delfs, Ndimofor Chofor, Ping Jiang, Dietrich Harder, Björn Poppe, Kay C Willborn
The aim of this study has been to develop a two-step method of in-phantom dosimetry around a brachytherapy (192)Ir photon source. The first step is to measure the absorbed dose rate to water with a calibrated ionization chamber under reference conditions, the second to cross-calibrate, under these conditions, small solid-state detectors such as silicon diodes, synthetic diamond or scintillation detectors suited for spatially resolved dose rate measurements at other, particularly at smaller source axis distances in the water phantom...
September 29, 2017: Zeitschrift Für Medizinische Physik
https://www.readbyqxmd.com/read/28939288/pet-mr-hybrid-imaging
#19
EDITORIAL
Harald H Quick
No abstract text is available yet for this article.
September 19, 2017: Zeitschrift Für Medizinische Physik
https://www.readbyqxmd.com/read/28869164/the-output-factor-correction-as-function-of-the-photon-beam-field-size-direct-measurement-and-calculation-from-the-lateral-dose-response-functions-of-gas-filled-and-solid-detectors
#20
Daniela Poppinga, Björn Delfs, Jutta Meyners, Dietrich Harder, Björn Poppe, Hui Khee Looe
The first aim of this study has been to extend the systematic experimental study of the field size dependence of the output factor correction for three micro-ionization chambers (PTW 31014, PTW 31022 and IBA Razor chamber), two silicon diodes (PTW 60017 and IBA Razor Diode) and the synthetic diamond detector microDiamond (PTW 60019) in a 6 MV photon beam down to an effective field side length of 2.6mm, and to summarize the present knowledge of this factor by treating it as a function of the dosimetric field size...
August 28, 2017: Zeitschrift Für Medizinische Physik
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