Abstract：
:The same calibration grade ionization chamber and electrometer were sequentially sent to all five currently AAPM Accredited Dosimetry Calibration Laboratories (ADCL). A Cesium-137 based check device was utilized to ensure chamber and electrometer factor constancy and showed a maximum deviation of 0.32% (typically less than 0.1%) over the 227 days needed to complete the intercomparison. The chamber and electrometer calibration factor provided by each of the five ADCLs were analyzed for consistency. The maximum percent difference in reported chamber factor between all five ADCLs was 1.40%. The reported electrometer factor had a maximum discrepancy of only 0.50%. System (chamber plus electrometer) factors as provided by three of the five ADCLs had a maximum discrepancy of 1.51%.
journal_name
Med Physjournal_title
Medical physicsauthors
Blackwell CR,McCullough ECdoi
10.1118/1.596880subject
Has Abstractpub_date
1992-01-01 00:00:00pages
207-8issue
1eissn
0094-2405issn
2473-4209journal_volume
19pub_type
杂志文章相关文献
MEDICAL PHYSICS文献大全abstract：:Noise, partial volume (PV) effect, and image-intensity inhomogeneity render a challenging task for segmentation of brain magnetic resonance (MR) images. Most of the current MR image segmentation methods focus on only one or two of the above-mentioned effects. The objective of this paper is to propose a unified framewo...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.1944912
更新日期：2005-07-01 00:00:00
abstract：PURPOSE:Formation of new blood vessels (angiogenesis) in response to hypoxia is a fundamental event in the process of tumor growth and metastatic dissemination. However, abnormalities in tumor neovasculature often induce increased interstitial pressure (IP) and further reduce oxygenation (pO2) of tumor cells. In radiot...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3615164
更新日期：2011-08-01 00:00:00
abstract：PURPOSE:The authors discuss measurement methods and instrumentation useful for the characterization of the gray tracking performance of medical color monitors for diagnostic applications. The authors define gray tracking as the variability in the chromaticity of the gray levels in a color monitor. METHODS:The authors ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4953186
更新日期：2016-07-01 00:00:00
abstract：PURPOSE:To develop a new scintillating fiber-based electronic portal imaging device (EPID) with a high quantum efficiency (QE) while preserving an adequate spatial resolution. METHODS:Two prototypes were built: one with a single pixel readout and the other with an active matrix flat-panel imager (AMFPI) for readout. T...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.13900
更新日期：2020-01-01 00:00:00
abstract：:Various radionuclides have been proposed for systemic tumor therapy. However, in most dosimetric analysis of proposed radionuclides the charged particles are taken into consideration while the potential photons are ignored. The photons will cause undesirable irradiation of normal tissue, and increase the probability o...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.2229428
更新日期：2006-09-01 00:00:00
abstract：PURPOSE:Dynamic 18 F-FDG PET allows quantitative estimation of cerebral glucose metabolism both at the regional and local (voxel) level. Although sensitive to noise and highly computationally expensive, nonlinear least-squares (NLS) optimization stands as the reference approach for the estimation of the kinetic model p...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.13366
更新日期：2019-03-01 00:00:00
abstract：:Single photon emission computed tomography (SPECT) was investigated for imaging on-board radiation therapy machines in order to localize functional and molecular targets. A computer-simulated female NCAT phantom was positioned supine on a flat-top treatment couch. Twenty tumor locations were defined in the upper torso...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3113902
更新日期：2009-05-01 00:00:00
abstract：PURPOSE:The measurement of malignant pleural mesothelioma is critical to the assessment of tumor response to therapy. Current response assessment standards utilize summed linear measurements acquired on three computed tomography (CT) sections. The purpose of this study was to evaluate manual area measurements as an alt...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4810940
更新日期：2013-08-01 00:00:00
abstract：:A systems analysis of reduced dose mammography with scatter removal has quantitatively specified the relationships between the several parameters in mammography systems. While the results are only preliminary in the sense that they need to be proven experimentally, they do seem to provide a good feel for the nature of...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.594540
更新日期：1979-03-01 00:00:00
abstract：:The nucletron Leipzig applicator is designed for (HDR) 192Ir brachy radiotherapy of surface lesions. The dosimetric characteristics of this applicator were investigated using simulation method based on Monte Carlo N-particle (MCNP) code and phantom measurements. The simulation method was validated by comparing calcula...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.1812609
更新日期：2004-12-01 00:00:00
abstract：PURPOSE:To construct a Monte Carlo (MC)-based simulation model for analyzing the dependence of tumor oxygen distribution on different variables related to tumor vasculature [blood velocity, vessel-to-vessel proximity (vessel proximity), and inflowing oxygen partial pressure (pO2)]. METHODS:A voxel-based tissue model c...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4892386
更新日期：2014-09-01 00:00:00
abstract：:Convolution/superposition software has been used to produce a library of photon pencil beam dose matrices. This library of pencil beams is designed to serve as a tool for both education and investigation in the field of radiotherapy optimization. The elegance of this pencil beam model stems from its cylindrical symmet...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.598615
更新日期：1999-07-01 00:00:00
abstract：PURPOSE:In radiotherapy (RT) based on magnetic resonance imaging (MRI) as the only modality, the information on electron density must be derived from the MRI scan by creating a so-called pseudo computed tomography (pCT). This is a nontrivial task, since the voxel-intensities in an MRI scan are not uniquely related to e...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4914158
更新日期：2015-04-01 00:00:00
abstract：:Tissue absorbed dose (D) is a computed result for internal emitters. For fixed geometries, D is calculated by a matrix (S) multiplication of the integrated activity vector (Ã). The last quantity is usually measured by nuclear imaging of activity in various source organs and performing a temporal integration. Ã is the ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4735750
更新日期：2012-06-01 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
pub_type： 杂志文章
doi：10.1118/1.4908223
更新日期：2015-03-01 00:00:00
abstract：PURPOSE:The depth dose of a monoenergetic broad parallel proton beam has been modeled in a number of ways, but evidently not yet for oblique incidence. The purpose of this investigation is to find an accurate analytic formula for this case, which can then be used to model the depth dose of a broad beam with an initial ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3495969
更新日期：2010-11-01 00:00:00
abstract：PURPOSE:In this study, the authors validated a novel respiratory tracking device, the multidimensional respiratory tracking (MDRT) system, that was designed to assist in correcting for respiratory motion in PET/CT images. The authors also investigated a novel PET acquisition technique, smart gating (SG), that enables t...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3523100
更新日期：2011-01-01 00:00:00
abstract：:In this paper, the authors review the field of resolution modeling in positron emission tomography (PET) image reconstruction, also referred to as point-spread-function modeling. The review includes theoretical analysis of the resolution modeling framework as well as an overview of various approaches in the literature...
journal_title：Medical physics
pub_type： 杂志文章,评审
doi：10.1118/1.4800806
更新日期：2013-06-01 00:00:00
abstract：:Previous ultrasound tomography work conducted by our group showed a direct correlation between measured sound speed and physical density in vitro, and increased in vivo sound speed with increasing mammographic density, a known risk factor for breast cancer. Building on these empirical results, the purpose of this work...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.2964092
更新日期：2008-09-01 00:00:00
abstract：PURPOSE:The aim of this study is to understand the characteristics of secondary electrons generated from the interaction of gold nanoparticles (GNPs) with x-rays as a function of nanoparticle size and beam energy and thereby further the understanding of GNP-enhanced radiotherapy. METHODS:The effective range, deflectio...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3539623
更新日期：2011-02-01 00:00:00
abstract：PURPOSE:To develop a computer-driven and thus less user-dependent method, allowing for a simple and straightforward generation of a Monte Carlo (MC) beam model of a scanned proton and carbon ion beam delivery system. METHODS:In a first step, experimental measurements were performed for proton and carbon ion energies i...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.14647
更新日期：2020-12-07 00:00:00
abstract：PURPOSE:It is very important for calculation of clinical indices and diagnosis to detect thyroid nodules from ultrasound images. However, this task is a challenge mainly due to heterogeneous thyroid nodules with distinct components are similar to background in ultrasound images. In this study, we employ cascade deep co...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.12134
更新日期：2017-05-01 00:00:00
abstract：:The absorbed dose values determined with the Exradin and PTW-Markus plane-parallel chambers were compared to the values obtained with the ferrous sulphate dosimetry for a number of the Philips SL25 and the Therac 20 electron beams. For the plane-parallel chambers, the cavity-gas calibration factor Ngaspp, was derived ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.597800
更新日期：1996-03-01 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
pub_type： 杂志文章
doi：10.1118/1.597853
更新日期：1996-06-01 00:00:00
abstract：:Monte Carlo simulations of x-ray beams typically take parameters of the electron beam in the accelerating waveguide to be free parameters. In this paper, a methodology is proposed and implemented to determine the energy, spectral width, and beam divergence of the electron source. All treatment head components were rem...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3070547
更新日期：2009-03-01 00:00:00
abstract：PURPOSE:Many biological objects, including neuronal dendrites, blood vasculature, airways, phylogenetic trees, produce tree structured data. Current methods of analysis either ignore the complex structure of trees or use distance-based methods which limit the scope of multivariate modeling. METHODS:We propose a branch...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.12751
更新日期：2018-03-01 00:00:00
abstract：PURPOSE:To demonstrate an objective approach to determining if a negative report from the Radiological Physics Center (RPC) of greater than 10% error is valid or has clinical significance. METHODS:The discrepancy involved the clinical activity (mgRaEq) of Cs-137 sources, some manufactured by 3M and some by Amersham. M...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4735271
更新日期：2012-06-01 00:00:00
abstract：PURPOSE:This report describes upgrades and performance characterization of an experimental benchtop cone-beam x-ray fluorescence computed tomography (XFCT) system capable of determining the spatial distribution and concentration of metal probes such as gold nanoparticles (GNPs). Specifically, a high-power (~3 kW) indus...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.13138
更新日期：2018-10-01 00:00:00
abstract：PURPOSE:To develop a method of using two-dimensional (2D) magnetic resonance thermometry, and three-dimensional (3D) Gaussian modeling to predict the volume, shape, and location of 1 day postoperative T1w high-intensity focused ultrasound lesions in medication refractory tremor patients; thereby facilitating a better c...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.13868
更新日期：2019-12-01 00:00:00
abstract：PURPOSE:Hip fracture is a serious health problem and textural methods are being developed to assess bone quality. The authors aimed to perform textural analysis at femur on high-resolution digital radiographs compared to three-dimensional (3D) microarchitecture comparatively to bone mineral density. METHODS:Sixteen ca...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3528125
更新日期：2011-01-01 00:00:00
