Eddy current disruption: effect on nuclear magnetic resonance coil impedance and power loss.


:We present a theoretical development and experimental verification of a description of power loss and sample resistance for a lossy sample in a nuclear magnetic resonance radio frequency coil for a sample geometry where the eddy current streamlines are disrupted from their usually assumed circular paths. Specifically treated is the case of a lossy hemisphere. The problem is solved for two orientations; with the induction parallel and perpendicular to the flat surface of the hemisphere. Results of this analysis as well as those for the full sphere as presented by Hoult and Lauterbur are compared with observation for a variety of sample conductivities and orientation.


Med Phys


Medical physics


Harpen MD




Has Abstract


1989-09-01 00:00:00












  • Dynamic multiatlas selection-based consensus segmentation of head and neck structures from CT images.

    abstract:PURPOSE:Manual delineation of head and neck (H&N) organ-at-risk (OAR) structures for radiation therapy planning is time consuming and highly variable. Therefore, we developed a dynamic multiatlas selection-based approach for fast and reproducible segmentation. METHODS:Our approach dynamically selects and weights the a...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Haq R,Berry SL,Deasy JO,Hunt M,Veeraraghavan H

    更新日期:2019-12-01 00:00:00

  • FRoG: An independent dose and LETd prediction tool for proton therapy at ProBeam® facilities.

    abstract:PURPOSE:Particle therapy is becoming increasingly available world-wide for precise tumor targeting, its favorable depth dose deposition, and increased biological damage to tumor tissue compared to conventional photon therapy. As demand increases for improved robustness and conformality, next-generation secondary dose c...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Kopp B,Fuglsang Jensen M,Mein S,Hoffmann L,Nyström H,Falk M,Haberer T,Abdollahi A,Debus J,Mairani A

    更新日期:2020-10-01 00:00:00

  • A two-step algorithm for predicting portal dose images in arbitrary detectors.

    abstract::Recently, portal imaging systems have been successfully demonstrated in dosimetric treatment verification applications, where measured and predicted images are quantitatively compared. To advance this approach to dosimetric verification, a two-step model which predicts dose deposition in arbitrary portal image detecto...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: McCurdy BM,Pistorius S

    更新日期:2000-09-01 00:00:00

  • Accelerated helium-ion beams for radiotherapy and stereotactic radiosurgery.

    abstract::A new beam line for radiotherapy and radiosurgery with accelerated helium-ion beams has been set up at the Bevalac. The new treatment room has been equipped with a very precise patient positioner in order to utilize the superior dose localization properties of light-ion beams. The beam spreading and shaping system is ...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Ludewigt BA,Chu WT,Phillips MH,Renner TR

    更新日期:1991-01-01 00:00:00

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

    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

    pub_type: 杂志文章


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

    更新日期:1994-12-01 00:00:00

  • What is the optimum leaf width of a multileaf collimator?

    abstract:UNLABELLED:The following question is investigated: How narrow do the leaves of a multileaf collimator have to be such that further reduction of the leaf width does not lead to physical improvements of the dose distribution. Because of the physical principles of interaction between radiation and matter, dose distributio...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Bortfeld T,Oelfke U,Nill S

    更新日期:2000-11-01 00:00:00

  • The head-scatter factor for small field sizes.

    abstract::The head-scatter factors H were examined for four different linear accelerators and were found to be similar at field sizes larger than 3 x 3 cm2. Sharply reduced values for small collimator openings were observed for all the accelerators. It is concluded that the head-scatter (or collimator-scatter) factor has two ma...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Zhu TC,Bjärngard BE

    更新日期:1994-01-01 00:00:00

  • Sci-Fri PM: Planning-03: Fundamental understanding of the inter-relation of arc range, angular dose rate and MLC leaf position optimization of Intensity Modulated Arc Therapy for a concave target.

    abstract::Intensity Modulated Arc Therapy (IMAT) is a rotational variant of Intensity Modulated Radiation Therapy (IMRT) that can be implemented with or without angular dose rate optimization. The purpose of this study is to determine the inter-relationship among arc range, Multi-Leaf Collimator (MLC) leaf positions and angular...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Oliver M,Chen J,Wong E

    更新日期:2008-07-01 00:00:00

  • Dead time of an anger camera in dual-energy-window-acquisition mode.

    abstract::Two side-by-side energy windows are sometimes employed in quantitative single photon emission computed tomography (SPECT) studies. The count-rate losses at high activities for a GE400AT camera were measured in such a dual-window-acquisition mode by imaging a decaying source composed of a hot sphere within a warm cylin...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Zasadny KR,Koral KF,Swailem FM

    更新日期:1993-07-01 00:00:00

  • Statistical variability and confidence intervals for planar dose QA pass rates.

    abstract:PURPOSE:The most common metric for comparing measured to calculated dose, such as for pretreatment quality assurance of intensity-modulated photon fields, is a pass rate (%) generated using percent difference (%Diff), distance-to-agreement (DTA), or some combination of the two (e.g., gamma evaluation). For many dosimet...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Bailey DW,Nelms BE,Attwood K,Kumaraswamy L,Podgorsak MB

    更新日期:2011-11-01 00:00:00

  • Technical note: Signal resolution increase and noise reduction in a CCD digitizer.

    abstract::Increasing output resolution is assumed to improve noise characteristics of a CCD digitizer. In this work, however, we have found that as the quantization step becomes lower than the analog noise (present in the signal before its conversion to digital) the noise reduction becomes significantly lower than expected. Tha...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: González A,Martínez JA,Tobarra B

    更新日期:2004-03-01 00:00:00

  • Neutron energies in medical electron accelerator rooms.

    abstract::Two experimental methods are described for obtaining average energies of neutron spectra produced by an electron accelerator in a medical treatment room. In the first method, the dose equivalent is measured by means of indium activation foils in an Andersson-Braun moderator. Fluences are determined by the usual activa...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: LaRiviere PD

    更新日期:1985-11-01 00:00:00

  • Cascaded systems analysis of the 3D noise transfer characteristics of flat-panel cone-beam CT.

    abstract::The physical factors that govern 2D and 3D imaging performance may be understood from quantitative analysis of the spatial-frequency-dependent signal and noise transfer characteristics [e.g., modulation transfer function (MTF), noise-power spectrum (NPS), detective quantum efficiency (DQE), and noise-equivalent quanta...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Tward DJ,Siewerdsen JH

    更新日期:2008-12-01 00:00:00

  • ALTIS: A fast and automatic lung and trachea CT-image segmentation method.

    abstract:PURPOSE:The automated segmentation of each lung and trachea in CT scans is commonly taken as a solved problem. Indeed, existing approaches may easily fail in the presence of some abnormalities caused by a disease, trauma, or previous surgery. For robustness, we present ALTIS (implementation is available at http://lids....

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Sousa AM,Martins SB,Falcão AX,Reis F,Bagatin E,Irion K

    更新日期:2019-11-01 00:00:00

  • A unified material decomposition framework for quantitative dual- and triple-energy CT imaging.

    abstract:PURPOSE:Many clinical applications depend critically on the accurate differentiation and classification of different types of materials in patient anatomy. This work introduces a unified framework for accurate nonlinear material decomposition and applies it, for the first time, in the concept of triple-energy CT (TECT)...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Zhao W,Vernekohl D,Han F,Han B,Peng H,Yang Y,Xing L,Min JK

    更新日期:2018-07-01 00:00:00

  • On effective dose for radiotherapy based on doses to nontarget organs and tissues.

    abstract:PURPOSE:The National Council for Radiation Protection and Measurement (NCRP) published estimates for the collective population dose and the mean effective dose to the population of the United States from medical imaging procedures for 1980/1982 and for 2006. The earlier report ignored the effective dose from radiothera...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Uselmann AJ,Thomadsen BR

    更新日期:2015-02-01 00:00:00

  • A water phantom controller for automated acquisition of linac beam parameters.

    abstract::Three-dimensional water phantoms are routinely used when acquiring the data necessary to commission medical linear accelerators. A new water phantom controller has been developed at our institution that is unique in several aspects. The water phantom controller is based on an IBM XT compatible computer. This has been ...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Schmid MG,Morris RL

    更新日期:1989-01-01 00:00:00

  • Computerized detection of lung nodules through radiomics.

    abstract:PURPOSE:Lung cancer is a major cause of cancer deaths, and the 5-year survival rate of stage IV lung cancer patients is only 2%. However, the 5-year survival rate of stage I lung cancer patients significantly increases to 50%. As such, spiral computed tomography (CT) scans are necessary to diagnose high-risk lung cance...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Ma J,Zhou Z,Ren Y,Xiong J,Fu L,Wang Q,Zhao J

    更新日期:2017-08-01 00:00:00

  • Diffuse-diffuse photon coupling via nonscattering void in the presence of refractive index mismatch on the void boundary.

    abstract::It is well established that the diffusion approximation (DA) is valid for light propagation in highly scattering media, but it breaks down in nonscattering void regions. The methods that handle the void with refractive index matched boundary were previously developed. For the void with refractive index mismatched boun...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Lee JH,Kim S,Kim YT

    更新日期:2004-08-01 00:00:00

  • Automated detection of pulmonary nodules in PET/CT images: Ensemble false-positive reduction using a convolutional neural network technique.

    abstract:PURPOSE:Automated detection of solitary pulmonary nodules using positron emission tomography (PET) and computed tomography (CT) images shows good sensitivity; however, it is difficult to detect nodules in contact with normal organs, and additional efforts are needed so that the number of false positives (FPs) can be fu...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Teramoto A,Fujita H,Yamamuro O,Tamaki T

    更新日期:2016-06-01 00:00:00

  • Fourier transform infrared imaging and small angle x-ray scattering as a combined biomolecular approach to diagnosis of breast cancer.

    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

    pub_type: 杂志文章


    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

  • Toward a statistically relevant calibration end point for prostate seed implants.

    abstract::Interstitial brachytherapy for carcinoma of the prostate is achieved through the use of a configuration of radioactive seeds placed in a manner that delivers a customized, reasonably uniform dose to the target volume. Accurate dose delivery depends on both precise seed placement and reliable seed strength in the impla...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Rosenzweig DP,Schell MC,Yu Y

    更新日期:2000-01-01 00:00:00

  • Analytical considerations of beam hardening in medical accelerator photon spectra.

    abstract::Beam hardening is a well-known phenomenon for therapeutic accelerator beams passing through matter in narrow beam geometry. This study assesses quantitatively the magnitude of beam hardening of therapeutic beams in water. A formal concept of beam hardening is proposed which is based on the decrease of the mean attenua...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Kleinschmidt C

    更新日期:1999-09-01 00:00:00

  • Calculation of photon dose distributions in an inhomogeneous medium using convolutions.

    abstract::A formulation of the single energy photon transport problem is cast in the form of a series of convolutions over the primary fluence distribution with invariant kernels. A method is developed for compensating for the variant intervoxel attenuation in the scattered dose distribution by means of an invariant correction ...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Boyer AL,Mok EC

    更新日期:1986-07-01 00:00:00

  • A novel 3D printing method for accurate anatomy replication in patient-specific phantoms.

    abstract:PURPOSE:A novel 3D printing method has been developed, which employs human CT images to construct patient specific phantoms by controlling the filament extrusion rate. METHODS:An in-house software was developed comprising pixel-by-pixel (PbP) reading of the Hounsfield Units (HU) values in the original patient DICOM im...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Okkalidis N

    更新日期:2018-10-01 00:00:00

  • Neutron and gamma spectroscopy for clinical dosimetry.

    abstract::Neutron and photon energy spectra were measured in different depths and lateral positions in tissue-equivalent phantoms exposed to a therapeutical 14.1 MeV neutron beam. Intensity weighted mass energy absorption coefficients were derived for application in ionization chamber dosimetry in mixed neutron-gamma fields. Th...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Schmidt R,Magiera E,Scobel W

    更新日期:1980-09-01 00:00:00

  • Advanced statistical techniques applied to comprehensive FTIR spectra on human colonic tissues.

    abstract:PURPOSE:Colon cancer is a major public health problem due to its high disease rate and death toll worldwide. The use of FTIR microscopy in the field of cancer diagnosis has become attractive over the past 20 years. In the present study, the authors investigated the potential of FTIR microscopy to define spectral change...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Zwielly A,Mordechai S,Sinielnikov I,Salman A,Bogomolny E,Argov S

    更新日期:2010-03-01 00:00:00

  • Design and evaluation of an MRI-compatible linear motion stage.

    abstract:PURPOSE:To develop and evaluate a tool for accurate, reproducible, and programmable motion control of imaging phantoms for use in motion sensitive magnetic resonance imaging (MRI) appli cations. METHODS:In this paper, the authors introduce a compact linear motion stage that is made of nonmagnetic material and is actua...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Tavallaei MA,Johnson PM,Liu J,Drangova M

    更新日期:2016-01-01 00:00:00

  • Robust experiment design for estimating myocardial beta adrenergic receptor concentration using PET.

    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

    pub_type: 杂志文章


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

    更新日期:2007-01-01 00:00:00

  • Tolerance design of patient-specific range QA using the DMAIC framework in proton therapy.

    abstract:PURPOSE:To implement the DMAIC (Define-Measure-Analyze-Improve-Control) can be used for customizing the patient-specific QA by designing site-specific range tolerances. METHODS:The DMAIC framework (process flow diagram, cause and effect, Pareto chart, control chart, and capability analysis) were utilized to determine ...

    journal_title:Medical physics

    pub_type: 杂志文章


    authors: Rah JE,Shin D,Manger RP,Kim TH,Oh DH,Kim DY,Kim GY

    更新日期:2018-02-01 00:00:00