Technical and dosimetric realization of in vivo x-ray microbeam irradiations at the Munich Compact Light Source.

abstract：PURPOSE:Motion is a major confound of image quality in MRI. A method of retrospectively correcting the effects of rotations and translations on the acquired k-space data is presented. METHODS:In two phantom experiments of well-controlled translation and rotation, two MRI-compatible infrared cameras recorded motion dat...

journal_title：Medical physics

authors： Marxen M,Marmurek J,Baker N,Graham SJ

更新日期：2009-12-01 00:00:00

abstract：PURPOSE:The biologically effective dose (BED) of temporary brachytherapy treatments is a function of both chosen radionuclide (R) and implant duration (T). This study endeavored to evaluate BED delivered to the tumor volume and surrounding ocular structures as a function of plaque position (P), prescription dose, R, an...

journal_title：Medical physics

authors： Gagne N,Rivard M

更新日期：2012-06-01 00:00:00

abstract：:In Monte Carlo simulations of light transport in tissues, a grid system is set up to score physical quantities. This study of cylindrically symmetrical problems found that the optimized radial and angular positions for the averaged physical quantities in each grid element are off-center. The error of the extrapolated ...

journal_title：Medical physics

authors： Wang L,Jacques SL

更新日期：1994-07-01 00:00:00

abstract：:Compared with slice-by-slice approaches for SPECT reconstruction, three-dimensional iterative methods provide a more accurate physical model and an improved SPECT image. Clinical application of these methods, however, is limited primarily to their computational demands. This paper investigates the methods for approxim...

journal_title：Medical physics

authors： Gilland DR,Jaszczak RJ,Riauka TA,Coleman RE

更新日期：1997-09-01 00:00:00

abstract：:The dosimetry protocols DIN 6800-2 and AAPM TG-51, both based on the absorbed dose to water concept, are compared in their theoretical background and in their application to electron dosimetry. The agreement and disagreement in correction factors and energy parameters used in both protocols will be shown and discussed...

journal_title：Medical physics

authors： Dohm OS,Christ G,Nüsslin F,Schüle E,Bruggmoser G

更新日期：2001-11-01 00:00:00

abstract：PURPOSE:In C-arm computed tomography (CT), the field of view (FOV) is often not sufficient to acquire certain anatomical structures, e.g., a full hip or thorax. Proposed methods to extend the FOV use a fixed detector displacement and a 360° scan range to double the radius of the FOV. These trajectories are designed for...

journal_title：Medical physics

authors： Herbst M,Schebesch F,Berger M,Choi JH,Fahrig R,Hornegger J,Maier A

更新日期：2015-05-01 00:00:00

abstract：:An optimization analysis of digital fluoroscopy has been carried out using (signal/noise)2/dose as a figure of merit. Three signal detection tasks have been considered: (i) small iodine-containing blood vessels; (ii) regions of fat; and (iii) microcalcifications. The effects of x-ray beam filtration and kilovoltage on...

journal_title：Medical physics

authors： Zamenhof RG

更新日期：1982-09-01 00:00:00

abstract：:Molecular imaging is the direct or indirect noninvasive monitoring and recording of the spatial and temporal distribution of in vivo molecular, genetic, and/or cellular processes for biochemical, biological, diagnostic, or therapeutic applications. Molecular images that indicate the presence of malignancy can be acqui...

journal_title：Medical physics

authors： Munley MT,Kagadis GC,McGee KP,Kirov AS,Jang S,Mutic S,Jeraj R,Xing L,Bourland JD

更新日期：2013-10-01 00:00:00

abstract：PURPOSE:Intensity modulated proton therapy (IMPT) of head and neck (H&N) cancer patients may be improved by plan adaptation. The decision to adapt the treatment plan based on a dose recalculation on the current anatomy requires a diagnostic quality computed tomography (CT) scan of the patient. As gantry-mounted cone be...

journal_title：Medical physics

authors： Landry G,Nijhuis R,Dedes G,Handrack J,Thieke C,Janssens G,Orban de Xivry J,Reiner M,Kamp F,Wilkens JJ,Paganelli C,Riboldi M,Baroni G,Ganswindt U,Belka C,Parodi K

更新日期：2015-03-01 00:00:00

abstract：PURPOSE:The purpose of this study is to quantify the change in monthly VMAT quality assurance (QA) and determine the tests to maintain consistent delivery with a baseline. METHODS:VMAT monthly QA has been performed for over 14 months on two Elekta Synergy LINACs. A baseline was established at acceptance and the monthl...

journal_title：Medical physics

authors： Stenbeck J,Oves S,Gebreamlak W,Alkhatib H

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:Recent advances in compressed sensing (CS) enable accurate CT image reconstruction from highly undersampled and noisy projection measurements, due to the sparsifiable feature of most CT images using total variation (TV). These novel reconstruction methods have demonstrated advantages in clinical applications wh...

journal_title：Medical physics

authors： Niu T,Zhu L

更新日期：2012-07-01 00:00:00

abstract：:We are developing computerized feature extraction and classification methods to analyze malignant and benign microcalcifications on digitized mammograms. Morphological features that described the size, contrast, and shape of microcalcifications and their variations within a cluster were designed to characterize microc...

journal_title：Medical physics

authors： Chan HP,Sahiner B,Lam KL,Petrick N,Helvie MA,Goodsitt MM,Adler DD

更新日期：1998-10-01 00:00:00

abstract：:A method is proposed for realistic simulation of the breast ductal network as part of a computer three-dimensional (3-D) breast phantom. The ductal network is simulated using tree models. Synthetic trees are generated based upon a description of ductal branching by ramification matrices (R matrices), whose elements re...

journal_title：Medical physics

authors： Bakic PR,Albert M,Brzakovic D,Maidment AD

更新日期：2003-07-01 00:00:00

abstract：:In prostate seed implants, radioactive seeds are implanted into the prostate through a guiding needle with the help of a template and real-time imaging. The ideal locations of the guiding needles and the relative positions of the seeds in each needle are determined before the implantation under the assumption that the...

journal_title：Medical physics

authors： Nath S,Chen Z,Yue N,Trumpore S,Peschel R

更新日期：2000-05-01 00:00:00

abstract：:The effective energy of the x-ray beam from linear accelerators changes as a function of the position in the beam due to nonuniform filtration by the flattening filter. In this work, the transmittance through a water column was measured in good geometry and the beam quality characterized in units of HVL in water. Meas...

journal_title：Medical physics

authors： Hanson WF,Berkley LW,Peterson M

更新日期：1980-03-01 00:00:00

abstract：:We discuss a formalism for clinical proton beam dosimetry based on the use of ionization chamber absorbed dose-to-water calibration and beam quality correction factors. A quantity kQ, the beam quality correction factor, is defined which corrects the absorbed dose-to-water calibration factor ND,w in a reference beam of...

journal_title：Medical physics

authors： Vatnitsky SM,Siebers JV,Miller DW

更新日期：1996-01-01 00:00:00

abstract：:Multi-instrument activity estimation and decay correction techniques were developed for radionuclide mixtures, motivated by the desire for accurate quantitation of Tc-94m positron emission tomography (PET) studies. Tc-94m and byproduct Tc isotopes were produced by proton irradiation of enriched Mo-94 and natural Mo ta...

journal_title：Medical physics

authors： Smith MF,Daube-Witherspoon ME,Plascjak PS,Szajek LP,Carson RE,Everett JR,Green SL,Territo PR,Balaban RS,Bacharach SL,Eckelman WC

更新日期：2001-01-01 00:00:00

abstract：:Intraoperative three-dimensional reconstruction of seed locations during prostate brachytherapy for purposes of immediate computation of radiation dosimetry is an active area of current investigation, including methods which use multiple fluoroscopic projections. A simulation study using seed locations extracted from ...

journal_title：Medical physics

authors： Su Y,Davis BJ,Herman MG,Robb RA

更新日期：2004-05-01 00:00:00

abstract：PURPOSE:To compare and evaluate intensity-based registration methods for computation of serial x-ray mammogram correspondence. METHODS:X-ray mammograms were simulated from MRIs of 20 women using finite element methods for modeling breast compressions and employing a MRI/x-ray appearance change model. The parameter con...

journal_title：Medical physics

authors： Pinto Pereira SM,Hipwell JH,McCormack VA,Tanner C,Moss SM,Wilkinson LS,Khoo LA,Pagliari C,Skippage PL,Kliger CJ,Hawkes DJ,Silva IM

更新日期：2010-09-01 00:00:00

abstract：:When an (exposure) calibrated ionization chamber is used for the determination of absorbed dose from a photon beam, the reading of the instrument must be multiplied by a number of factors, one of which is an attenuation correction for phantom material displaced by the chamber. the magnitude of this correction must dep...

journal_title：Medical physics

authors： Cunningham JR,Sontag MR

更新日期：1980-11-01 00:00:00

abstract：PURPOSE:To perform radiomic analysis of primary tumors extracted from pretreatment contrast-enhanced computed tomography (CE-CT) images for patients with oropharyngeal cancers to identify discriminant features and construct an optimal classifier for the characterization and prediction of human papilloma virus (HPV) sta...

journal_title：Medical physics

authors： Bagher-Ebadian H,Lu M,Siddiqui F,Ghanem AI,Wen N,Wu Q,Liu C,Movsas B,Chetty IJ

更新日期：2020-02-01 00:00:00

abstract：:Functional single photon emission computed tomography (SPECT) images of brain activation are based on a comparison of base line and activation images. The correctness of the functional images depends, among other factors, on the accurate spatial registration (alignment) of the base line and activation image data. The ...

journal_title：Medical physics

authors： Sychra JJ,Pavel DG,Chen Y,Jani A

更新日期：1994-10-01 00:00:00

abstract：PURPOSE:In this work the performance of a compact multiresolution and multicontrast x-ray phase system based on edge illumination is investigated. It has been designed for small animal imaging and with a limited footprint for ease of deployment in laboratories. METHODS:The presented edge illumination system is based o...

journal_title：Medical physics

authors： Massimi L,Meganck JA,Towns R,Olivo A,Endrizzi M

更新日期：2020-10-27 00:00:00

abstract：PURPOSE:To evaluate the patient positioning accuracy and reproducibility of two commercially available immobilization systems for Stereotactic Body Radiotherapy (SBRT) treatment. METHODS:Forty one patients with lung (n=21) or liver (n=20) malignancies were assigned to one of the two immobilization devices: Elekta ster...

journal_title：Medical physics

authors： Cao M,Cao N,Cardenes H,Fakiris A,Desrosiers C,Das I

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:The appearance of parenchymal∕stromal patterns in mammography have been characterized as having a Wiener power spectrum with an inverse power-law shape described by the exponential parameter, β. The amount of fibroglandular tissue, which can be quantified in terms of volumetric breast density (VBD), influences ...

journal_title：Medical physics

authors： Mainprize JG,Tyson AH,Yaffe MJ

更新日期：2012-08-01 00:00:00

abstract：:Cone-beam computed tomography systems have been developed to provide in situ imaging for the purpose of guiding radiation therapy. Clinical systems have been constructed using this approach, a clinical linear accelerator (Elekta Synergy RP) and an iso-centric C-arm. Geometric calibration involves the estimation of a s...

journal_title：Medical physics

authors： Cho Y,Moseley DJ,Siewerdsen JH,Jaffray DA

更新日期：2005-04-01 00:00:00

abstract：:In this work, gray-scale invariant ranklet texture features are proposed for false positive reduction (FPR) in computer-aided detection (CAD) of breast masses. Two main considerations are at the basis of this proposal. First, false positive (FP) marks surviving our previous CAD system seem to be characterized by speci...

journal_title：Medical physics

authors： Masotti M,Lanconelli N,Campanini R

更新日期：2009-02-01 00:00:00

abstract：:Fourier transform infrared (FTIR) microspectroscopic imaging and small angle x-ray scattering (SAXS) were combined to investigate the supramolecular structure of collagen from 27 tissue sections from patients undergoing mastectomy, excisional biopsy, or mammoplasty. Both techniques were correlated by matching the scat...

journal_title：Medical physics

authors： Ooi GJ,Fox J,Siu K,Lewis R,Bambery KR,McNaughton D,Wood BR

更新日期：2008-05-01 00:00:00

abstract：PURPOSE:State of the art to access radiofrequency (RF) heating near implants is computer modeling of the devices and solving Maxwell's equations for the specific setup. For a set of input parameters, a fixed result is obtained. This work presents a theoretical approach in the alternating current (ac) limit, which can p...

journal_title：Medical physics

authors： Ballweg V,Eibofner F,Graf H

更新日期：2011-10-01 00:00:00

abstract：:A study of the objective imaging characteristics of a new asymmetric screen-film system is presented herein. The system is characterized by high x-ray absorption asymmetric screens, and a low-noise, high-contrast asymmetric film having near-zero crossover. Comparisons are made with the imaging characteristics of two w...

journal_title：Medical physics

authors： Van Metter R,Dickerson R

更新日期：1994-09-01 00:00:00