A computer simulation of wavelet noise reduction in computed tomography.

abstract：:The dose distribution for an ovoid with a new tungsten shielding design was determined using Monte Carlo simulation. Standard Cesium-137 tube sources, tungsten shielding, and aluminum ovoid applicator were each modeled as a collection of solid objects. Dose was calculated in planes above, below, in front of, and on th...

journal_title：Medical physics

authors： Weeks KJ

更新日期：1998-12-01 00:00:00

abstract：:Age-related macular degeneration (AMD) is a leading cause for vision loss for people over the age of 65 in the United States and a major health problem worldwide. Research for new treatments of the wet form of the disease using kilovoltage stereotactic radiosurgery is currently underway at Oraya Therapeutics, Inc. In ...

journal_title：Medical physics

authors： Hanlon J,Lee C,Chell E,Gertner M,Hansen S,Howell RW,Bolch WE

更新日期：2009-08-01 00:00:00

abstract：PURPOSE:Developed herein is a three-dimensional (3D) flow contrast imaging system leveraging advancements in the extension of laser speckle contrast imaging theories to deep tissues along with our recently developed finite-element diffuse correlation tomography (DCT) reconstruction scheme. This technique, termed speckl...

journal_title：Medical physics

authors： Huang C,Irwin D,Lin Y,Shang Y,He L,Kong W,Luo J,Yu G

更新日期：2015-07-01 00:00:00

abstract：PURPOSE:TransitQA is an innovative method for Tomotherapy transit dosimetry using the on-board detector (OBD). Our previously published model for Tomotherapy treatment plan verification (AirQA) has been enhanced to take into account patient and couch transmission. AirQA estimates the OBD signal during irradiation with ...

journal_title：Medical physics

authors： Pisaturo O,Miéville F,Tercier PA,Allal AS

更新日期：2018-01-01 00:00:00

abstract：PURPOSE:State of the art to access radiofrequency (RF) heating near implants is computer modeling of the devices and solving Maxwell's equations for the specific setup. For a set of input parameters, a fixed result is obtained. This work presents a theoretical approach in the alternating current (ac) limit, which can p...

journal_title：Medical physics

authors： Ballweg V,Eibofner F,Graf H

更新日期：2011-10-01 00:00:00

abstract：PURPOSE:This work is to evaluate the effects of Compton current generation in three small-volume ionization chambers on measured beam characteristics for electron fields. METHODS:Beam scans were performed using Exradin A16, A26, and PTW 31014 microchambers. Scans with varying chamber components shielded were performed...

journal_title：Medical physics

authors： Tanny S,Holmes S,Sperling N,Parsai EI

更新日期：2015-10-01 00:00:00

abstract：PURPOSE:Four-dimensional volumetric modulated arc therapy (4D VMAT) and four-dimensional intensity-modulated radiotherapy (4D IMRT) are developing radiation therapy treatment strategies designed to maximize dose conformality, minimize normal tissue dose, and deliver the treatment as efficiently as possible. The patient...

journal_title：Medical physics

authors： Klawikowski S,Tai A,Ates O,Ahunbay E,Li XA

更新日期：2018-04-01 00:00:00

abstract：:Estimated photon energy spectra are derived from transmission measurements using aluminium, copper, and sodium iodide absorbers. Two spectral models are proposed. One is based on a previously published model that analyzes the electron's penetration into the anode, and the production and attenuation of bremsstrahlung p...

journal_title：Medical physics

authors： Ruth C,Joseph PM

更新日期：1997-05-01 00:00:00

abstract：PURPOSE:Dose verification in highly conformal radiation therapy such as IMRT or proton therapy can benefit from the high spatial resolution offered by radio-chromic films such as Gafchromic EBT or EBT2. Recently, a new generation of these films, EBT3, has become available. The composition and thickness of the sensitive...

journal_title：Medical physics

authors： Reinhardt S,Hillbrand M,Wilkens JJ,Assmann W

更新日期：2012-08-01 00:00:00

abstract：PURPOSE:Colitis refers to inflammation of the inner lining of the colon that is frequently associated with infection and allergic reactions. In this paper, we propose deep convolutional neural networks methods for lesion-level colitis detection and a support vector machine (SVM) classifier for patient-level colitis dia...

journal_title：Medical physics

authors： Liu J,Wang D,Lu L,Wei Z,Kim L,Turkbey EB,Sahiner B,Petrick NA,Summers RM

更新日期：2017-09-01 00:00:00

abstract：:Model-based deformable organ registration techniques using the finite element method (FEM) have recently been investigated intensively and applied to image-guided adaptive radiotherapy (IGART). These techniques assume that human organs are linearly elastic material, and their mechanical properties are predetermined. U...

journal_title：Medical physics

authors： Chi Y,Liang J,Yan D

更新日期：2006-02-01 00:00:00

abstract：PURPOSE:Currently applied calibration approaches lead to satisfying 3D roadmapping overlay and 3D reconstruction accuracies; however, the required calibration times are extensive. The aim of this paper is the introduction of a novel model-based approach for geometric system calibrations, leading to a significant reduct...

journal_title：Medical physics

authors： van der Maas R,de Jager B,Steinbuch M,Dries J

更新日期：2015-11-01 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

authors： Lagerlöf JH,Kindblom J,Bernhardt P

更新日期：2014-09-01 00:00:00

abstract：PURPOSE:Planning for the delivery of intensity-modulated radiation therapy (IMRT) to a moving target, referred to as four-dimensional (4D) IMRT planning, is a crucial step for achieving the treatment objectives for sites that move during treatment delivery. The authors proposed a simplistic method that accounts for bot...

journal_title：Medical physics

authors： Gui M,Feng Y,Yi B,Dhople AA,Yu C

更新日期：2010-05-01 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

authors： Wells RG

更新日期：2008-07-01 00:00:00

abstract：PURPOSE:Proton computed tomography (pCT) will enable accurate prediction of proton and ion range in a patient while providing the benefit of lower radiation exposure than in x-ray CT. The accuracy of the range prediction is essential for treatment planning in proton or ion therapy and depends upon the detector used to ...

journal_title：Medical physics

authors： Bashkirov VA,Schulte RW,Hurley RF,Johnson RP,Sadrozinski HF,Zatserklyaniy A,Plautz T,Giacometti V

更新日期：2016-02-01 00:00:00

abstract：:Current generation electronic portal imaging devices (EPID) contain a 1.0 mm copper conversion plate to increase detection efficiency of a therapeutic megavoltage spectrum. When using these EPIDs for low-Z target imaging, the conversion plate largely attenuates the large populations of diagnostic energy photons, there...

journal_title：Medical physics

authors： Parsons D,Robar JL

更新日期：2012-07-01 00:00:00

abstract：PURPOSE:To show that Cherenkov emission is generated by external radiotherapy beam in tissue, and could serve as optical source to excite an oxygen sensitive phosphor, Oxyphor G4, within tissue. The intensity and lifetime of the phosphorescence was measured with a time-gated system and reveals the oxygenation levels in...

journal_title：Medical physics

authors： Zhang R,Kanick S,Vinogradov S,Esipova T,Pogue B

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:Current on-board imaging systems commonly used by modern linear accelerators (LINACs) have a limited field of view (FOV) for a cone-beam CT (CBCT) scan, which is typically less than 50 cm. Consequently, truncation artifacts often occur for large patients. The goal of this work is to investigate a novel method t...

journal_title：Medical physics

authors： Li T,Li X,Yang Y,Heron DE,Huq MS

更新日期：2010-12-01 00:00:00

abstract：:Limiting spatial resolution is a key metric of the quality of magnetic resonance (MR) images, which can provide an indication of the smallest region that can effectively be imaged. In this paper a novel methodology for measuring the limiting spatial resolution of MR images is mathematically analyzed and successfully i...

journal_title：Medical physics

authors： Delakis I,Xanthis C,Kitney RI

更新日期：2009-05-01 00:00:00

abstract：:The concept of equivalent uniform dose (EUD) has been suggested as a means to quantitatively consider heterogeneous dose distributions within targets. Tumor cell density/function is typically assumed to be uniform. We herein propose to use 18F-labeled 2-deoxyglucose (FDG) positron emission tomography (PET) tumor imagi...

journal_title：Medical physics

authors： Zhou SM,Wong TZ,Marks LB

更新日期：2004-09-01 00:00:00

abstract：PURPOSE:Deformable registration generally relies on the assumption that the sought spatial transformation is smooth. Yet, breathing motion involves sliding of the lung with respect to the chest wall, causing a discontinuity in the motion field, and the smoothness assumption can lead to poor matching accuracy. In respon...

journal_title：Medical physics

authors： Vandemeulebroucke J,Bernard O,Rit S,Kybic J,Clarysse P,Sarrut D

更新日期：2012-02-01 00:00:00

abstract：:Accurate segmentation of microcalcifications in mammography is crucial for the quantification of morphologic properties by features incorporated in computer-aided diagnosis schemes. A novel segmentation method is proposed implementing active rays (polar-transformed active contours) on B-spline wavelet representation t...

journal_title：Medical physics

authors： Arikidis NS,Skiadopoulos S,Karahaliou A,Likaki E,Panayiotakis G,Costaridou L

更新日期：2008-11-01 00:00:00

abstract：:For diagnostic ultrasound imaging, as in computed tomography, a feature of prime importance is the detection of focal lesions of varying size and contrast (echo amplitude) from surrounding tissue. This study describes a new tissue-stimulating phantom which has been used to measure the threshold detection of varying co...

journal_title：Medical physics

authors： Smith SW,Lopez H

更新日期：1982-01-01 00:00:00

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...

journal_title：Medical physics

authors： Blackwell CR,McCullough EC

更新日期：1992-01-01 00:00:00

abstract：PURPOSE:Cardiac motion is typically not accounted for during pretreatment imaging for central lung and mediastinal tumors. However, cardiac induced tumor motion averages 5.8 mm for esophageal tumors and 3-5 mm for some lung tumors, which can result in positioning errors. Our aim is to reduce both cardiac- and respirato...

journal_title：Medical physics

authors： Reynolds T,Shieh CC,Keall PJ,O'Brien RT

更新日期：2019-09-01 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

authors： Schwartz J,Humm JL,Gonen M,Kalaigian H,Schoder H,Larson SM,Nehmeh SA

更新日期：2011-05-01 00:00:00

abstract：:Nuclear Magnetic Resonance (NMR) permits the noninvasive measurement of blood flow signals unimpaired by clothes, bandages, casts, etc. The cylindrical crossed-coil NMR blood flowmeter was used to measure blood flow through a cross-section of the human forearm. Two calibration procedures are described: one for pulsati...

journal_title：Medical physics

authors： Salles-Cunha SX,Halbach RE,Battocletti JH,Sances A Jr

更新日期：1981-07-01 00:00:00

abstract：:An overall practical dosimetric study of a 10-MV photon beam produced by a Varian Clinac-18 linear accelerator is presented. In particular measurements were made to provide data which could be utilized in computerized dosage calculations using the concept of dividing the radiation beam into primary and scatter compone...

journal_title：Medical physics

authors： Van Dyk J

更新日期：1977-03-01 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

authors： Ren L,Wu D,Li Y,Wang G,Wu X,Liu H

更新日期：2014-03-01 00:00:00