The accuracy of SPECT brain activation images: propagation of registration errors.

abstract：:A series of experiments has been carried out in order to characterize a miniannular phased array applicator prior to possible clinical implementation. The energy deposition patterns over the frequency range of 100 to 200 MHz were determined in several human limb models of different complexities by measuring the electr...

journal_title：Medical physics

authors： Guerquin-Kern JL,Hagmann MJ,Levin RL

更新日期：1987-07-01 00:00:00

abstract：PURPOSE:Deformable image registration (DIR) is often validated based on a distance-to-agreement (DTA) criterion of automatically propagated anatomical landmarks that were manually identified. Due to human observer variability, however, the performance of the registration method is diluted. The purpose of this study was...

journal_title：Medical physics

authors： Mencarelli A,van Beek S,van Kranen S,Rasch C,van Herk M,Sonke JJ

更新日期：2012-11-01 00:00:00

abstract：PURPOSE:To develop an individually optimized contrast-enhanced (CE) 4D-computed tomography (CT) for radiotherapy simulation in pancreatic ductal adenocarcinomas (PDA). METHODS:Ten PDA patients were enrolled. Each underwent three CT scans: a 4D-CT immediately following a CE 3D-CT and an individually optimized CE 4D-CT ...

journal_title：Medical physics

authors： Choi W,Xue M,Lane BF,Kang MK,Patel K,Regine WF,Klahr P,Wang J,Chen S,D'Souza W,Lu W

更新日期：2016-10-01 00:00:00

abstract：PURPOSE:In this article, the authors studied the feasibility of estimating regional mechanical properties in cerebral aneurysms, integrating information extracted from imaging and physiological data with generic computational models of the arterial wall behavior. METHODS:A data assimilation framework was developed to ...

journal_title：Medical physics

authors： Balocco S,Camara O,Vivas E,Sola T,Guimaraens L,Gratama van Andel HA,Majoie CB,Pozo JM,Bijnens BH,Frangi AF

更新日期：2010-04-01 00:00:00

abstract：PURPOSE:The aim of this study is to investigate the performance of Sentinel(™), a patient setup verification device based on a laser/camera system, when used on rigid-body phantoms. METHODS:The Sentinel system consists of a scanner unit, containing the laser and the camera, and surface-matching registration software. ...

journal_title：Medical physics

authors： Pallotta S,Marrazzo L,Ceroti M,Silli P,Bucciolini M

更新日期：2012-02-01 00:00:00

abstract：PURPOSE:Intraoperative electron radiation therapy (IOERT) involves the delivery of a high radiation dose during tumor resection in a shorter time than other radiation techniques, thus improving local control of tumors. However, a linear accelerator device is needed to produce the beam safely. Mobile linear accelerators...

journal_title：Medical physics

authors： Marinetto E,Victores JG,García-Sevilla M,Muñoz M,Calvo FÁ,Balaguer C,Desco M,Pascau J

更新日期：2017-10-01 00:00:00

abstract：:Several updated Monte Carlo (MC) codes are available to perform calculations of voxel S values for radionuclide targeted therapy. The aim of this work is to analyze the differences in the calculations obtained by different MC codes and their impact on absorbed dose evaluations performed by voxel dosimetry. Voxel S val...

journal_title：Medical physics

authors： Pacilio M,Lanconelli N,Lo MS,Betti M,Montani L,Torres AL,Coca PM

更新日期：2009-05-01 00:00:00

abstract：:An in vitro radiographic technique which uses saline/iodine displacement has been developed to study the thickness of bone-equivalent and soft-tissue-equivalent materials within atherosclerotic plaques in arterial specimens which have been cut open longitudinally and laid flat. Results concerning the optimization of t...

journal_title：Medical physics

authors： Moreau M,Holdsworth DW,Fenster A

更新日期：1997-01-01 00:00:00

abstract：:Digital tomosynthesis is an imaging technique to produce a tomographic image from a series of angular digital images in a manner similar to conventional focal plane tomography. Unlike film focal plane tomography, the acquisition of the data in a C-arm geometry causes the image receptor to be positioned at various angl...

journal_title：Medical physics

authors： Rakowski JT,Dennis MJ

更新日期：2006-08-01 00:00:00

abstract：PURPOSE:The availability of accurate and simple models for the estimation of x-ray spectra is of great importance for system simulation, optimization, or inclusion of photon energy information into data processing. There is a variety of publicly available tools for estimation of x-ray spectra in radiology and mammograp...

journal_title：Medical physics

authors： Sisniega A,Desco M,Vaquero JJ

更新日期：2014-01-01 00:00:00

abstract：PURPOSE:To develop a pharmacokinetic modelfree framework to analyze the dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) data for assessment of response of brain metastases to radiation therapy. METHODS:Twenty patients with 45 analyzable brain metastases had MRI scans prior to whole brain radiation thera...

journal_title：Medical physics

authors： Farjam R,Tsien CI,Lawrence TS,Cao Y

更新日期：2014-01-01 00:00:00

abstract：PURPOSE:This paper provides a comparison between a fast, commercial, in-patient Monte Carlo dose calculation algorithm (GPUMCD) and geant4. It also evaluates the dosimetric impact of the application of an external 1.5 T magnetic field. METHODS:A stand-alone version of the Elekta™ GPUMCD algorithm, to be used within th...

journal_title：Medical physics

authors： Ahmad SB,Sarfehnia A,Paudel MR,Kim A,Hissoiny S,Sahgal A,Keller B

更新日期：2016-02-01 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：PURPOSE:To correct for the deviations of the detector response when typical radiation detectors are used under non-reference conditions, factor kNR was calculated from the known energy dependence of the detector response at photon energies from 10 keV upwards and from clinical photon spectra within a large water phanto...

journal_title：Medical physics

authors： Chofor N,Poppe B,Harder D

更新日期：2012-06-01 00:00:00

abstract：:Myocardial beta adrenergic receptor (beta-AR) concentration can substantially decrease in congestive heart failure and significantly increase in chronic volume overload, such as in severe aortic valve regurgitation. Positron emission tomography (PET) with an appropriate ligand-receptor model can be used for noninvasiv...

journal_title：Medical physics

authors： Salinas C,Muzic RF Jr,Ernsberger P,Saidel GM

更新日期：2007-01-01 00:00:00

abstract：:Subsecond single-slice, multi-slice or cone-beam spiral computed tomography (SSCT, MSCT, CBCT) offer great potential for improving heart imaging. Together with the newly developed phase-correlated cardiac reconstruction algorithms 180 degrees MCD and 180 degrees MCI [Med. Phys. 27, 1881-1902 (2000)] or related algorit...

journal_title：Medical physics

authors： Kachelriess M,Sennst DA,Maxlmoser W,Kalender WA

更新日期：2002-07-01 00:00:00

abstract：:A general expression is derived for the NMR signal from a fluid undergoing random directional flow such as encountered within the microcirculation. The dependence of the echo amplitude on flow velocity, sample morphology, and experimental parameters are described in terms of a temporal velocity autocorrelation functio...

journal_title：Medical physics

authors： Kennan RP,Gao JH,Zhong J,Gore JC

更新日期：1994-04-01 00:00:00

abstract：PURPOSE:Computerized liver extraction from hepatic CT images is challenging because the liver often abuts other organs of a similar density. The purpose of this study was to develop a computer-aided measurement of liver volumes in hepatic CT. METHODS:The authors developed a computerized liver extraction scheme based o...

journal_title：Medical physics

authors： Suzuki K,Kohlbrenner R,Epstein ML,Obajuluwa AM,Xu J,Hori M

更新日期：2010-05-01 00:00:00

abstract：PURPOSE:To develop a novel aperture-based algorithm for volumetric modulated are therapy (VMAT) treatment plan optimization with high quality and high efficiency. METHODS:The VMAT optimization problem is formulated as a large-scale convex programming problem solved by a column generation approach. The authors consider...

journal_title：Medical physics

authors： Men C,Romeijn HE,Jia X,Jiang SB

更新日期：2010-11-01 00:00:00

abstract：:We investigated the utility of three manual planimetric methods to quantify carotid plaque volume. A single observer measured 15 individual plaques from 15 three-dimensional (3D) ultrasound (3D US) images of patients ten times each using three different planimetric approaches. Individual plaque volumes were measured (...

journal_title：Medical physics

authors： Landry A,Ainsworth C,Blake C,Spence JD,Fenster A

更新日期：2007-04-01 00:00:00

abstract：PURPOSE:Although small animal image-guided radiotherapy (SA-IGRT) systems are used increasingly in preclinical research, tools for performing routine quality assurance (QA) have not been optimized and are not readily available. Robust, efficient, and reliable QA tools are needed to ensure the accuracy and reproducibili...

journal_title：Medical physics

authors： Anvari A,Poirier Y,Sawant A

更新日期：2018-07-01 00:00:00

abstract：:The intensity of Compton scattered photons is directly proportional to the electron density of a substance; therefore it is possible to detect changes in electron density by this noninvasive method. The source-detector geometry has been varied to study the effects of geometry on the calculated electron density values,...

journal_title：Medical physics

authors： Huddleston AL,Sackler JP

更新日期：1985-01-01 00:00:00

abstract：:We employed an elastic reservoir filled with tissue-equivalent fluid as an x-ray beam filter for exposure equalization. The filter is designed to be placed between the upper compression plate and the breast. During compression, it will conform to the shape of the peripheral region of the breast and fill the space betw...

journal_title：Medical physics

authors： Lam KL,Chan HP

更新日期：1990-03-01 00:00:00

abstract：:A single-field rotational total skin electron irradiation technique has recently been developed at the McGill University for treatment of skin malignancies. The dose received by a given surface point during rotation in a uniform large electron field depends on the radius of rotation of the surface point, on the local ...

journal_title：Medical physics

authors： Pla C,Heese R,Pla M,Podgorsak EB

更新日期：1984-07-01 00:00:00

abstract：:Purpose To investigate narrow, elongated magnetically focused proton beams and compare their properties with passively collimated beams using Monte Carlo simulation. METHODS:We performed Geant4 Monte Carlo simulations involving a single quadrapole focusing magnet, thereby creating a flattened beam with an elongated e...

journal_title：Medical physics

authors： McAuley G,Barnes S,Wroe A,Slater J

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:Efficacy of tuberculosis (TB) treatment is often monitored using chest radiography. Monitoring size of cavities in pulmonary tuberculosis is important as the size predicts severity of the disease and its persistence under therapy predicts relapse. The authors present a method for automatic cavity segmentation i...

journal_title：Medical physics

authors： Maduskar P,Hogeweg L,de Jong PA,Peters-Bax L,Dawson R,Ayles H,Sánchez CI,van Ginneken B

更新日期：2014-07-01 00:00:00

abstract：PURPOSE:Two ultra-high-resolution (UHR) computed tomography (CT) scanners are clinically available. One is achieved by a CT system with a 0.25 mm × 160 row detector (Detector-UHR), whereas the other is with a 0.6 mm × 32 row detector with in-plane comb filtering in a dual source CT (Comb-UHR). We compared radiation dos...

journal_title：Medical physics

authors： Kawashima H,Ichikawa K,Takata T,Nagata H,Hoshika M,Akagi N

更新日期：2020-02-01 00:00:00

abstract：:A method is described for calibration of 192Ir high-dose-rate (HDR) brachytherapy afterloading systems. Since NIST does not offer calibration of ionization chambers with the gamma-ray spectrum of iridium-192, an interpolation procedure is employed, using calibrations above (137Cs, 662 keV) and below (250 kVcp, 146-keV...

journal_title：Medical physics

authors： Goetsch SJ,Attix FH,Pearson DW,Thomadsen BR

更新日期：1991-05-01 00:00:00

abstract：PURPOSE:To compare how the inclusion of the uncertainties in dose and optical density affects the results of the calibration of Gafchromic(®) EBT3 radiochromic films. METHODS:Five methods of least square minimization were compared for calibration of radiochromic films. These differed in the way in which the uncertaint...

journal_title：Medical physics

authors： Garcia LI,Azorin JF

更新日期：2013-07-01 00:00:00

abstract：:We designed a novel force/torque moment transducer with six degrees of freedom. This new sensor is used for measuring the forces and torque moments exerted by static magnetic resonance imaging (MRI) fields on various medical implants, instruments, and ballistic shell fragments. To determine the location of strongest e...

journal_title：Medical physics

authors： Planert J,Modler H,Vosshenrich R

更新日期：1996-06-01 00:00:00