Individually optimized contrast-enhanced 4D-CT for radiotherapy simulation in pancreatic ductal adenocarcinoma.

abstract：:A simple approach was developed that calculates the output factors and tissue maximum ratio of an asymmetric field at any point within the open field, and specifically both at the central axis (when the jaws do not shadow it) and at the effective center of the open field, using the existing tables for symmetric fields...

journal_title：Medical physics

authors： Rosenberg I,Chu JC,Saxena V

更新日期：1995-01-01 00:00:00

abstract：PURPOSE:The purpose of the paper was to use a virtual phantom to identify a set of radiomic features from T1-weighted and T2-weighted magnetic resonance imaging (MRI) of the brain which is stable to variations in image acquisition parameters and to evaluate the effect of image preprocessing on radiomic features stabili...

journal_title：Medical physics

authors： Bologna M,Corino V,Mainardi L

更新日期：2019-11-01 00:00:00

abstract：:Luminance scatter fractions were measured for patients and phantoms in various regions of the chest film. Scatter fractions were found to be highly variable, being quite high in the regions of the chest with a large equivalent tissue thickness (e.g. mediastinum, chest wall, and subdiaphragmatic areas). For example, ap...

journal_title：Medical physics

authors： Niklason LT,Sorenson JA,Nelson JA

更新日期：1981-09-01 00:00:00

abstract：OBJECTIVES:To evaluate the performance of RapidArc® (Eclipse 10.0.28) and SmartArc® (Pinnacle 9.0) radiotherapy plans for lung stereotactic body radiation therapy (SBRT) in terms of dosimetric plan quality, delivery efficiency, inhomogeneity corrections and accuracy of dose delivery using a custom-built heterogeneity i...

journal_title：Medical physics

authors： Fakir H,Hoover D,Chen JZ

更新日期：2012-07-01 00:00:00

abstract：:A 4 x 500 mm2 "cloverleaf" low energy germanium detector array has been assembled for the purpose of in vivo bone lead measurement through x-ray fluorescence. Using 109Cd as an exciting source, results are reported from a leg phantom simulating measurement of lead in a human tibia. For high activity (4.0-4.4 GBq) and ...

journal_title：Medical physics

authors： Fleming DE,Mills CE

更新日期：2007-03-01 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

authors： Glide-Hurst CK,Duric N,Littrup P

更新日期：2008-09-01 00:00:00

abstract：PURPOSE:To examine schemes to grade the severity of metal susceptibility artifacts on image quality using cardiac MRI pulse sequences. METHODS:A post-thoracotomy patient was simulated with a stainless steel sternal wire (Syneture,MA; size=6, diameter=48mm), placed securely on an ACR MRI phantom. Phantom was scanned on...

journal_title：Medical physics

authors： Joyner D,Rivard A,Craft D,Liu T,Callaway S,James J

更新日期：2012-06-01 00:00:00

abstract：:The dose received in the buildup region outside the primary beam has been measured for 60Co gamma rays and 6- and 18-MV X rays. The variation of this dose with field size and depth was evaluated. The effect of blocking trays and the importance of their design was determined. ...

journal_title：Medical physics

authors： Horton JL

更新日期：1984-05-01 00:00:00

abstract：:A filtered backprojection algorithm is developed for single photon emission computed tomography (SPECT) imaging with an astigmatic collimator having a displaced center of rotation. The astigmatic collimator has two perpendicular focal lines, one that is parallel to the axis of rotation of the gamma camera and one that...

journal_title：Medical physics

authors： Wang H,Smith MF,Stone CD,Jaszczak RJ

更新日期：1998-08-01 00:00:00

abstract：PURPOSE:To correlate the Cole relaxation frequencies obtained from measurements of the electrical properties of breast tissue to the presence or absence of cancer. METHODS:Four-lead impedance measurements were obtained on ex vivo specimens extracted during surgery from 187 volunteer patients. Data were acquired with a...

journal_title：Medical physics

authors： Gregory WD,Marx JJ,Gregory CW,Mikkelson WM,Tjoe JA,Shell J

更新日期：2012-07-01 00:00:00

abstract：PURPOSE:To find an upper bound on the maximum dose reduction possible for any reconstruction algorithm, analytic or iterative, that result from the inclusion of the data statistics. The authors do not analyze noise reduction possible from prior knowledge or assumptions about the object. METHODS:The authors examined th...

journal_title：Medical physics

authors： Hsieh SS,Chesler DA,Fleischmann D,Pelc NJ

更新日期：2016-03-01 00:00:00

abstract：PURPOSE:Coronary x-ray computed tomography angiography (CCTA) is used to non-invasively assess coronary artery geometry and has, combined with computational modeling, demonstrated the potential to identify physiologically significant lesions. These measurements require robust and accurate coronary imaging and delineati...

journal_title：Medical physics

authors： Contijoch F,Stayman JW,McVeigh ER

更新日期：2017-07-01 00:00:00

abstract：PURPOSE:Computed tomography (CT) intrascanner and interscanner variability has not been well characterized. Thus, the purpose of this study was to examine the within-run, between-run, and between-scanner precision of physical dosimetry-related measurements collected over the course of 1 yr on three different makes and ...

journal_title：Medical physics

authors： Mathieu KB,McNitt-Gray MF,Zhang D,Kim HJ,Cody DD

更新日期：2010-08-01 00:00:00

abstract：PURPOSE:Adding magnetic resonance (MR)-derived information to standard transrectal ultrasound (TRUS) images for guiding prostate biopsy is of substantial clinical interest. A tumor visible on MR images can be projected on ultrasound (US) by using MR-US registration. A common approach is to use surface-based registratio...

journal_title：Medical physics

authors： van de Ven WJ,Hu Y,Barentsz JO,Karssemeijer N,Barratt D,Huisman HJ

更新日期：2015-05-01 00:00:00

abstract：:Due to practical limitations such as inter- and intraleaf transmission, nondivergent leaf end design, and leaf scatter, multileaf collimators (MLCs) are unable to accurately produce the ideal fluence patterns generated by inverse planning systems. Consequently, low dose regions receive substantially more radiation tha...

journal_title：Medical physics

authors： Popple RA,Fiveash JB,Brezovich IA

更新日期：2007-10-01 00:00:00

abstract：PURPOSE:Wide bore CT scanners use extended field-of-view (eFOV) reconstruction algorithms to attempt to recreate tissue truncated due to large patient habitus. Radiation therapy planning systems rely on accurate CT numbers in order to correctly plan and calculate radiation dose. This study looks at the impact of eFOV r...

journal_title：Medical physics

authors： Cheung JP,Shugard E,Mistry N,Pouliot J,Chen J

更新日期：2019-02-01 00:00:00

abstract：:Reported MOSFET measurements concern mostly external radiotherapy and in vivo dosimetry. In this paper, we apply the technique for absolute dosimetry in the context of HDR brachytherapy using an 192Ir source. Measured radial dose rate distributions in water for different planes perpendicular to the source axis are pre...

journal_title：Medical physics

authors： Zilio VO,Joneja OP,Popowski Y,Rosenfeld A,Chawla R

更新日期：2006-06-01 00:00:00

abstract：PURPOSE:Multiple anatomy optimization (MAO) utilizing deformable dose accumulation on entire 4DCT data sets is implemented to overcome ambiguity between optimal dose defined on a single anatomy and optimal accumulated dose resulting from dose delivery to moving and deforming anatomy. METHODS:Six lung cancer patients a...

journal_title：Medical physics

authors： Watkins WT,Moore JA,Sharma M,Dial C,Xu H,Hugo GD,Gordon JJ,Siebers JV

更新日期：2012-06-01 00:00:00

abstract：:Stereotactic Body Radiation Therapy (SBRT) is an important form of cancer therapy with increasingly broad application across a spectrum of tumor types in primary and metastatic settings. In this presentation the radiation biology, clinical experience from various trials, and cautionary updates on normal tissue toleran...

journal_title：Medical physics

authors： Read P

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:The aims of this work were to evaluate the performance of several deformable image registration (DIR) algorithms implemented in our in-house software (NiftyReg) and the uncertainties inherent to using different algorithms for dose warping. METHODS:The authors describe a DIR based adaptive radiotherapy workflow...

journal_title：Medical physics

authors： Veiga C,Lourenço AM,Mouinuddin S,van Herk M,Modat M,Ourselin S,Royle G,McClelland JR

更新日期：2015-02-01 00:00:00

abstract：:We attempt to select an optimal value of regularization parameter in the optimization problems for intensity-modulated radiotherapy which are solved using a variational regularization technique. We apply to inverse treatment planning the L-curve method which was developed to determine the regularization parameter in t...

journal_title：Medical physics

authors： Chvetsov AV

更新日期：2005-08-01 00:00:00

abstract：PURPOSE:There is an increasing interest in calculating linear energy transfer (LET) distributions for proton therapy treatments in order to assess the influence of this quantity in biological terms. Microdosimetric Monte Carlo (MC) simulations are useful tools to calculate dose-averaged LET, as this has been broadly pr...

journal_title：Medical physics

authors： Bertolet A,Baratto-Roldán A,Barbieri S,Baiocco G,Carabe A,Cortés-Giraldo MA

更新日期：2019-09-01 00:00:00

abstract：PURPOSE:To reduce image noise and radiation dose in Digital Breast Tomosynthesis (DBT) reconstructions. METHODS:A retrospective study was performed on clinical data sets acquired at a normal dose with Hologic Selenia Dimensions DBT systems. The Prior Image Constrained Compressed Sensing (PICCS) algorithm was used to r...

journal_title：Medical physics

authors： Garrett J,Tang J,Zhang Y,Ruth C,Jing Z,Chen GH

更新日期：2012-06-01 00:00:00

abstract：:We measured the characteristic curve, modulation transfer function (MTF), and the Wiener spectrum of a commercially available computed radiographic (CR) system with photostimulable phosphor plate (imaging plate, IP). The characteristic curve (system response) obtained by an inverse-square x-ray sensitometry showed a w...

journal_title：Medical physics

authors： Fujita H,Ueda K,Morishita J,Fujikawa T,Ohtsuka A,Sai T

更新日期：1989-01-01 00:00:00

abstract：PURPOSE:The goal of this work is to propose a new multichannel method correcting for systematic thickness disturbances and to evaluate its precision in relevant radiation dosimetry applications. METHODS:The eigencolor ratio technique is introduced and theoretically developed to provide a method correcting for thicknes...

journal_title：Medical physics

authors： Bouchard H,Billas I,Subie A,Duane S

更新日期：2021-02-01 00:00:00

abstract：PURPOSE:Accurate calculation of proton stopping power ratio (SPR) relative to water is crucial to proton therapy treatment planning, since SPR affects prediction of beam range. Current standard practice derives SPR using a single CT scan. Recent studies showed that dual-energy CT (DECT) offers advantages to accurately ...

journal_title：Medical physics

authors： Shen C,Li B,Chen L,Yang M,Lou Y,Jia X

更新日期：2018-04-01 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

authors： Zhang H,Wang J,Zeng D,Tao X,Ma J

更新日期：2018-10-01 00:00:00

abstract：PURPOSE:Distortions in magnetic resonance imaging (MRI) compromise spatial fidelity, potentially impacting delineation and dose calculation. We characterized 2D and 3D large field of view (FOV), sequence-independent distortion at various positions in a 1.0 T high-field open MR simulator (MR-SIM) to implement correction...

journal_title：Medical physics

authors： Price RG,Kadbi M,Kim J,Balter J,Chetty IJ,Glide-Hurst CK

更新日期：2015-10-01 00:00:00

abstract：PURPOSE:We propose a new metric called Distance Discordance (DD), which is defined as the distance between two anatomic points from two moving images, which are co-located on some reference image, when deformed onto another reference image. METHODS:To demonstrate the concept of DD, we created a reference software phan...

journal_title：Medical physics

authors： Berns E

更新日期：2012-06-01 00:00:00

abstract：:A method to significantly reduce the exposure area product in fluoroscopy using a pre-patient region-of-interest (ROI) attenuator is presented. The attenuator has a thin central region and a gradually increasing thickness away from the center. It is shown that the unwanted brightening artifact caused by the attenuator...

journal_title：Medical physics

authors： Robert N,Komljenovic PT,Rowlands JA

更新日期：2002-05-01 00:00:00