Abstract:
:In order to investigate the relationship between diagnostic accuracy and radiographic image quality, we have developed a dual-film cassette which produces two radiographs simultaneously with a single exposure. One of these radiographs is of standard quality; the second is of lower quality because of degraded spatial resolution and a significantly lower exposure. We have studied the basic physical properties of the standard and low-dose screen-film systems which we use in the dual-film cassette by comparing their beam hardening, scatter fractions, contrasts, modulation transfer functions (MTFs), and Wiener spectra. The x-ray spectrum incident on the low-dose system contained more high-energy photons than that incident on the standard system, and the scatter fractions for the low-dose system were slightly less than or comparable to those for the standard system. While the radiographic contrast produced by the two systems were generally comparable, the standard system had a slightly higher contrast than the low-dose system in some cases. The MTF of the low-dose system was considerably lower than that of the standard system, and the low-dose system had a noise level considerably greater than did the standard system. Phantom images and clinical radiographs indicated that, for the low-dose system, the image quality degraded significantly.
journal_name
Med Physjournal_title
Medical physicsauthors
Higashida Y,Doi K,Lehr JL,MacMahon Hdoi
10.1118/1.595546subject
Has Abstractpub_date
1984-09-01 00:00:00pages
646-52issue
5eissn
0094-2405issn
2473-4209journal_volume
11pub_type
杂志文章相关文献
MEDICAL PHYSICS文献大全abstract::A Monte Carlo method was developed and implemented to simulate x-ray photon transport. Simulations consisted of a pencil beam of monoenergetic photons with energies from 50 to 110 keV incident on water and aluminum slabs. The dependence of scatter fraction and multiple scattering on x-ray energy, scatterer thickness, ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.596268
更新日期:1988-11-01 00:00:00
abstract:PURPOSE:For stereotactic radiosurgery (SRS), accurate evaluation of dose-volume metrics for small structures is necessary. The purpose of this study was to compare the DVH metric capabilities of five commercially available SRS DVH analysis tools (Eclipse, Elements, Raystation, MIM, and Velocity). METHODS:DICOM RTdose ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.14645
更新日期:2020-12-09 00:00:00
abstract::CEA TVS film is a therapy verification film that has been recently introduced in the North American market. This film features linear characteristic curves for photon energies from 137Cs to 18 MV as reported by Cheng and Das [Med. Phys. 23, 1225 (1996)]. In Saskatoon, TVS film was investigated for its application in t...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.598316
更新日期:1998-08-01 00:00:00
abstract:PURPOSE:To identify which physical properties of nanoparticles are correlated with the survival fraction of cells exposed in vitro to low-energy protons in combination with nanoparticles. METHODS:The Geant4 simulation toolkit (version 10.3) was used to model nanoparticles of different sizes (5-50 nm) and materials (Ti...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.12362
更新日期:2017-08-01 00:00:00
abstract:PURPOSE:Polymer-based gel dosimeter (MAGIC type) is a preferable phantom material for PET range verification of proton beam therapy. However, improvement in elemental tissue equivalency (specifically O/C ratio) is very desirable to ensure realistic time-activity measurements. METHODS:Glucose and urea was added to the ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3260844
更新日期:2010-01-01 00:00:00
abstract:PURPOSE:The Small Animal Radiation Research Platform (SARRP) has been developed for conformal microirradiation with on-board cone beam CT (CBCT) guidance. The graphics processing unit (GPU)-accelerated Superposition-Convolution (SC) method for dose computation has been integrated into the treatment planning system (TPS...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.12862
更新日期:2018-05-01 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
pub_type: 杂志文章
doi:10.1118/1.595130
更新日期:1982-09-01 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
pub_type: 杂志文章
doi:10.1118/1.4842556
更新日期:2014-01-01 00:00:00
abstract::Traditionally, short scan helical FDK algorithms have been implemented based on horizontal transaxial slices. However, not every point on the horizontal transaxial slice satisfies Tuy's condition for the corresponding (pi+fan angle) segment of helix, which means that some points on the horizontal slices are incomplete...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1916077
更新日期:2005-06-01 00:00:00
abstract:PURPOSE:High-dose-rate brachytherapy (HDR-BT) is a treatment option for malignant skin diseases compared to external beam radiation therapy, HDR-BT provides improved target coverage, better organ sparing, and has comparable treatment times. This is especially true for large clinical targets with complex topologies. To ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.13975
更新日期:2020-03-01 00:00:00
abstract::Separation of water from fat tissues in magnetic resonance imaging is important for many applications because signals from fat tissues often interfere with diagnoses that are usually based on water signal characteristics. Water and fat can be separated with images acquired at different echo time shifts. The three-poin...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2952644
更新日期:2008-08-01 00:00:00
abstract::With intensity-modulated radiotherapy (IMRT), a variety of user-defined dose distribution can be produced using inverse planning. The generalized equivalent uniform dose (gEUD) has been used in IMRT optimization as an alternative objective function to the conventional dose-volume-based criteria. The purpose of this st...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1897464
更新日期:2005-05-01 00:00:00
abstract:PURPOSE:Fusion of intraprocedure ultrasound and preprocedure CT data is proposed for guidance in percutaneous spinal injections, a common procedure for pain management. CT scan of the lumbar spine is usually collected in a supine position, whereas spinal injections are performed in prone or sitting positions. This lead...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4711753
更新日期:2012-06-01 00:00:00
abstract:PURPOSE:In fractionated radiation therapy, image guidance with daily tomographic imaging becomes more and more clinical routine. In principle, this allows for daily computation of the delivered dose and for accumulation of these daily dose distributions to determine the actually delivered total dose to the patient. How...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3697524
更新日期:2012-04-01 00:00:00
abstract::The introduction of negative pions into cancer therapy has required the construction of large new proton accelerators together with special magnetic systems to form and direct the pion beam to a patient. A summary is presented of the fundamental properties of pions and of the methods used to study the therapeutic beam...
journal_title:Medical physics
pub_type: 杂志文章,评审
doi:10.1118/1.594868
更新日期:1981-05-01 00:00:00
abstract:PURPOSE:Total and regional body composition are important indicators of health and mortality risk, but their measurement is usually restricted to controlled environments in clinical settings with expensive and specialized equipment. A method that approaches the accuracy of the current gold standard method, dual-energy ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.14492
更新日期:2020-12-01 00:00:00
abstract:PURPOSE:Silicon photodetectors are of significant interest for use in positron emission tomography (PET) systems due to their compact size, insensitivity to magnetic fields, and high quantum efficiency. However, one of their main disadvantages is fluctuations in temperature cause strong shifts in gain of the devices. P...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4903889
更新日期:2015-01-01 00:00:00
abstract::Statistical image reconstruction (SIR) methods have shown potential to substantially improve the image quality of low-dose x-ray computed tomography (CT) as compared to the conventional filtered back-projection (FBP) method. According to the maximum a posteriori (MAP) estimation, the SIR methods are typically formulat...
journal_title:Medical physics
pub_type: 杂志文章,评审
doi:10.1002/mp.13123
更新日期:2018-10-01 00:00:00
abstract::This paper describes a multileaf collimator, designed to obtain irregularly shaped neutron fields, that fits into an existing fixed field-size collimator system. The shape of the desired portal field is obtained by appropriately setting the position of each leaf of the collimator. The collimator consists of 40 polyeth...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.596084
更新日期:1987-03-01 00:00:00
abstract::A system for measuring two-dimensional (2D) dose distributions in orthogonal anatomical planes in the cranium was developed and used to evaluate the accuracy of coplanar conformal therapy using ExacTrac image guidance. Dose distributions were measured in the axial, sagittal, and coronal planes using a CIRS (Computeriz...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2955751
更新日期:2008-08-01 00:00:00
abstract:PURPOSE:X-ray fluorescence (XRF) is a promising technique with sufficient specificity and sensitivity for identifying and quantifying features in small samples containing high atomic number (Z) materials such as iodine, gadolinium, and gold. In this study, the feasibility of applying XRF to early breast cancer diagnosi...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4863510
更新日期:2014-03-01 00:00:00
abstract:PURPOSE:The extensive use of computed tomography (CT) in diagnostic procedures is accompanied by a growing need for more accurate and patient-specific dosimetry techniques. Optically stimulated luminescent dosimeters (OSLDs) offer a potential solution for patient-specific CT point-based surface dosimetry by measuring a...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4914398
更新日期:2015-04-01 00:00:00
abstract:BACKGROUND:Deep learning methods for radiomics/computer-aided diagnosis (CADx) are often prohibited by small datasets, long computation time, and the need for extensive image preprocessing. AIMS:We aim to develop a breast CADx methodology that addresses the aforementioned issues by exploiting the efficiency of pre-tra...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.12453
更新日期:2017-10-01 00:00:00
abstract::We have reexamined the problem of estimating the luminal area of an elliptically shaped coronary artery cross section from two or more radiographic diameter measurements. The expected error is found to be much smaller than the maximum potential error. In the cases of two orthogonal views, closed form expressions have ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.596296
更新日期:1988-07-01 00:00:00
abstract::A restricted angular scattering model for electron penetration in dense media is presented. In the model, the Fermi-Eyges transport equation is modified through the addition of an extra term which may be interpreted as representing an apparent force opposing the scattering of electrons into wider angles. The introduct...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.596747
更新日期:1991-01-01 00:00:00
abstract::A calculation is described that enables the rapid assessment of dose rate at various points of interest within the eye (lens, optic nerve, etc.) for the treatment of choroidal melanoma by plaque therapy. 125I seeds are used as the radiation source. The location of the plaque and its associated seeds relative to the ey...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.596234
更新日期:1988-05-01 00:00:00
abstract::The authors are investigating the concept of a direct-conversion flat-panel imager with avalanche gain for low-dose x-ray imaging. It consists of an amorphous selenium (a-Se) photoconductor partitioned into a thick drift region for x-ray-to-charge conversion and a relatively thin region called high-gain avalanche rush...
journal_title:Medical physics
pub_type: 杂志文章,评审
doi:10.1118/1.3002314
更新日期:2008-12-01 00:00:00
abstract:PURPOSE:Scattered radiation remains to be a major cause of image quality degradation in Flat Panel Detector (FPD)-based Cone-beam computed tomography (CBCT). We have been investigating a novel two-dimensional antiscatter grid (2D-ASG) concept to reduce scatter intensity, and hence improve CBCT image quality. We present...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.12724
更新日期:2018-02-01 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
pub_type: 杂志文章
doi:10.1118/1.1586453
更新日期:2003-07-01 00:00:00
abstract::The widespread application of positron emission tomography (PET) in clinical oncology has driven this imaging technology into a number of new research and clinical arenas. Increasing numbers of patient scans have led to an urgent need for efficient data handling and the development of new image analysis techniques to ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2432404
更新日期:2007-02-01 00:00:00