Abstract:
PURPOSE:The aim of this research was to explore x-ray beam parameters with intent to optimize pediatric x-ray settings in the cardiac catheterization laboratory. This study examined the effects of peak x-ray tube voltage (kVp) and of copper (Cu) x-ray beam filtration independently on the image quality to dose balance for pediatric patient sizes. The impact of antiscatter grid removal on the image quality to dose balance was also investigated. METHODS:Image sequences of polymethyl methacrylate phantoms approximating chest sizes typical of pediatric patients were captured using a modern flat-panel receptor based x-ray imaging system. Tin was used to simulate iodine-based contrast medium used in clinical procedures. Measurements of tin detail contrast and flat field image noise provided the contrast to noise ratio. Entrance surface dose (ESD) and effective dose (E) measurements were obtained to calculate the figure of merit (FOM), CNR2/dose, which evaluated the dose efficiency of the x-ray parameters investigated. The kVp, tube current (mA), and pulse duration were set manually by overriding the system's automatic dose control mechanisms. Images were captured with 0, 0.1, 0.25, 0.4, and 0.9 mm added Cu filtration, for 50, 55, 60, 65, and 70 kVp with the antiscatter grid in place, and then with it removed. RESULTS:For a given phantom thickness, as the Cu filter thickness was increased, lower kVp was favored. Examining kVp alone, lower values were generally favored, more so for thinner phantoms. Considering ESD, the 8.5 cm phantom had the highest FOM at 50 kVp using 0.4 mm of Cu filtration. The 12 cm phantom had the highest FOM at 55 kVp using 0.9 mm Cu, and the 16 cm phantom had highest FOM at 55 kVp using 0.4 mm Cu. With regard to E, the 8.5 and 12 cm phantoms had the highest FOM at 50 kVp using 0.4 mm of Cu filtration, and the 16 cm phantom had the highest FOM at 50 kVp using 0.25 mm Cu. Antiscatter grid removal improved the FOM for a given set of x-ray conditions. Under aforesaid optimal settings, the 8.5 cm phantom FOM improved by 24% and 33% for ESD and E, respectively. Corresponding improvements were 26% and 24% for the 12 cm phantom and 6% and 15% for the 16 cm phantom. CONCLUSIONS:For pediatric patients, using 0.25-0.9 mm Cu filtration in the x-ray beam while maintaining 50-55 kVp, depending on patient size, provided optimal x-ray image quality to dose ratios. These settings, adjusted for x-ray tube loading limits and clinically acceptable image quality, should provide a useful strategy for optimizing iodine contrast agent based cardiac x-ray imaging. Removing the antiscatter grid improved the FOM for the 8.5 and 12 cm phantoms, therefore grid removal is recommended for younger children. Improvement for the 16 cm phantom declined into the estimated margin of error for the FOM; the need for grid removal for older children would depend on practical feasibility in the clinical environment.
journal_name
Med Physjournal_title
Medical physicsauthors
Gislason AJ,Davies AG,Cowen ARdoi
10.1118/1.3488911subject
Has Abstractpub_date
2010-10-01 00:00:00pages
5258-69issue
10eissn
0094-2405issn
2473-4209journal_volume
37pub_type
杂志文章相关文献
MEDICAL PHYSICS文献大全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::An automated technique for the alignment of right and left breast images has been developed for use in the computerized analysis of bilateral breast images. In this technique, the breast region is first identified in each digital mammogram by use of histogram analysis and morphological filtering operations. The anteri...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.597307
更新日期:1994-03-01 00:00:00
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
pub_type: 杂志文章
doi:10.1118/1.3254189
更新日期:2009-12-01 00:00:00
abstract:PURPOSE:Signal encoding in magnetic particle imaging (MPI) is achieved by moving a field-free point (FFP) through the region of interest. One way to increase the sensitivity of the method is to scan the region of interest with a field-free line (FFL) instead of the FFP. Recently, the first feasible FFL coil setup was i...
journal_title:Medical physics
pub_type: 信件
doi:10.1118/1.3447726
更新日期:2010-07-01 00:00:00
abstract:PURPOSE:To obtain on-treatment volumetric patient anatomy during respiratory gated volumetric modulated arc therapy (VMAT). METHODS:On-board imaging device integrated with Linacs offers a viable tool for obtaining patient anatomy during radiation treatment delivery. In this study, the authors acquired beam-level kV im...
journal_title:Medical physics
pub_type: 信件
doi:10.1118/1.4794925
更新日期:2013-04-01 00:00:00
abstract:PURPOSE:To evaluate a three-equation three-unknown dual-energy quantitative CT (DEQCT) technique for determining region specific variations in bone spongiosa composition for improved red marrow dose estimation in radionuclide therapy. METHODS:The DEQCT method was applied to 80/140 kVp images of patient-simulating lumb...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4870378
更新日期:2014-05-01 00:00:00
abstract::The goal is to perform geometric studies on cone-beam CT scanning along a three-dimensional (3D) spiral of variable radius. First, the background for variable radius spiral cone-beam scanning is given in the context of electron-beam CT/micro-CT. Then, necessary and sufficient conditions are proved for existence and un...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1751251
更新日期:2004-06-01 00:00:00
abstract:PURPOSE:A detailed analysis of 2728 intensity modulated proton therapy (IMPT) fields that were clinically delivered to patients between 2007 and 2013 at Paul Scherrer Institute (PSI) was performed. The aim of this study was to analyze the results of patient specific dosimetric verifications and to assess possible corre...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4964449
更新日期:2016-11-01 00:00:00
abstract:PURPOSE:Examine the use of TomoDose for Tomotherapy quality assurance. METHODS:Baseline TomoDose profiles are acquired annually in accordance with TG-148. During monthly quality assurance, TomoDose is irradiated with a static beam and referenced to baseline. Differences between superimposed profiles are evaluated mont...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4735202
更新日期:2012-06-01 00:00:00
abstract:PURPOSE:The authors previously introduced a methodology to generate a realistic three-dimensional (3D), high-resolution, computer-simulated breast phantom based on empirical data. One of the key components of such a phantom is that it provides a means to produce a realistic simulation of clinical breast compression. In...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3637500
更新日期:2011-10-01 00:00:00
abstract::A high sensitivity (HS) model of radiochromic film is receiving increasing use. The film's linear sensitometric response in the range of 0.5-40 Gy would make this film an ideal candidate for complex dosimetry applications that require tissue equivalence. This study investigates the potential use for clinical dosimetry...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1883565
更新日期:2005-04-01 00:00:00
abstract:PURPOSE:To demonstrate the feasibility of a three-plenoptic camera projection, scintillation-based dosimetry system for measuring three-dimensional (3D) dose distributions of static photon radiation fields. METHODS:Static x-ray photon beams were delivered to a cubic plastic scintillator volume embedded within acrylic ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.14213
更新日期:2020-08-01 00:00:00
abstract::It is known that motion of an object imaged by magnetic resonance imaging leads to errors and artifacts in the image. This effect is especially important when a pulse sequence with long echo time (TE) and long TR is used to provide T2-weighted images. We have modified the usual spin warp imaging pulse sequence in a wa...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.596026
更新日期:1987-07-01 00:00:00
abstract:PURPOSE:Different low-signal correction (LSC) methods have been shown to efficiently reduce noise streaks and noise level in CT to provide acceptable images at low-radiation dose levels. These methods usually result in CT images with highly shift-variant and anisotropic spatial resolution and noise, which makes the par...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.12855
更新日期:2018-05-01 00:00:00
abstract::Respiratory motion can produce misregistration errors between CT and PET images in cardiac PET/CT imaging. The objective of this study was to determine if manual registration of a single-phase end-expiration CT scan to the PET image would eliminate respiratory-induced artifacts. Listmode data from 71 cardiac PET patie...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2965988
更新日期:2008-07-01 00:00:00
abstract::Breast density is a strong predictor of the failure of mammography screening to detect breast cancer and is a strong predictor of the risk of developing breast cancer. The many imaging options that are now available for imaging dense breasts show great promise, but there is still the question of determining which wome...
journal_title:Medical physics
pub_type: 杂志文章,评审
doi:10.1118/1.4935141
更新日期:2015-12-01 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
pub_type: 杂志文章
doi:10.1118/1.1487861
更新日期:2002-07-01 00:00:00
abstract:PURPOSE:The focus of this work was the demonstration and validation of VirtuaLinac with clinical photon beams and to investigate the implementation of low-Z targets in a TrueBeam linear accelerator (Linac) using Monte Carlo modeling. METHODS:VirtuaLinac, a cloud based web application utilizing Geant4 Monte Carlo code,...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4861818
更新日期:2014-02-01 00:00:00
abstract::A conceptual design is presented showing that, by judiciously choosing the beryllium target thickness and the backstop material, improvements can be achieved in dose-rate, skin sparing, and penetration of neutron beams generated by the same proton accelerator. ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.594748
更新日期:1980-09-01 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
pub_type: 杂志文章
doi:10.1118/1.3395579
更新日期:2010-05-01 00:00:00
abstract::When a catheter is inserted through an artery, the wall shear stress increases and the secondary flow exhibits an increased number of instantaneous vortices. These effects become more evident when the annular gap between the catheter and the artery becomes more narrow. Accordingly it is suggested that these factors ma...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.596448
更新日期:1990-09-01 00:00:00
abstract:PURPOSE:Flattening filter free (FFF) beams generated by medical linear accelerators have recently started to be used in radiotherapy clinical practice. Such beams present fundamental differences with respect to the standard filter flattened (FF) beams, making the generally used dosimetric parameters and definitions not...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4754799
更新日期:2012-10-01 00:00:00
abstract::Head-scatter factors of symmetric square and rectangular fields (field center on the central beam axis) defined by the upper (Y) and lower (X) jaws for 6 and 15 MV photon beams from 2300CD and 600C accelerators (Varian Associates, Inc., Palo Alto, CA) were measured, as well as those for fields shaped by the Y jaws and...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.597617
更新日期:1995-08-01 00:00:00
abstract:PURPOSE:The standardized uptake value (SUV) is a quantitative measure of FDG tumor uptake frequently used as a tool to monitor therapeutic response. This study aims to (i) assess the reproducibility and uncertainty of SUV max and SUV mean, due to purely statistical, i.e., nonbiological, effects and (ii) to establish th...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3578604
更新日期:2011-05-01 00:00:00
abstract:PURPOSE:The purpose of this study was to evaluate the effect of various computed tomography (CT) thresholds on trapping volumetric measurements by multidetector CT in chronic obstructive pulmonary disease (COPD). METHODS:Twenty-three COPD patients were scanned with a 64-slice CT scanner in both the inspiratory and exp...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4813906
更新日期:2013-08-01 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:PURPOSE:To improve the dose homogeneity in patch-field proton therapy using beam current modulation. METHODS:MCNPX simulations were performed for various configurations of the Mevion S250 beamline. Spread-out Bragg peak (SOBP) dose distributions were calculated, and lateral and distal dose profiles were extracted for ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4735806
更新日期:2012-06-01 00:00:00
abstract::The aim of the current study was to (a) provide normalized dose data for the estimation of the radiation dose from upper gastrointestinal tract contrast (UGIC) studies carried out to infants and (b) estimate the average patient dose and risks associated with radiation from UGIC examinations performed in our institutio...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2181297
更新日期:2006-04-01 00:00:00
abstract:PURPOSE:Diffusion magnetic resonance imaging (MRI) in combination with functional MRI promises a whole new vista for scientists to investigate noninvasively the structural and functional connectivity of the human brain-the human connectome, which had heretofore been out of reach. As with other imaging modalities, diffu...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3700166
更新日期:2012-05-01 00:00:00
abstract::Heating rate (HR) patterns in cylindrical structures were studied with inhomogeneous limb phantoms. These phantoms, arm and thigh models consisting of fat, bone, and muscle material, were heated with Clini-Therm L, M, and MS applicators at 915 MHz. The thigh model is 18 cm in diameter with 2.65-cm-thick fat on the out...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.596627
更新日期:1991-11-01 00:00:00