A moving slanted-edge method to measure the temporal modulation transfer function of fluoroscopic systems.

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

authors： McLellan J,Sandison GA,Papiez L,Huda W

更新日期：1991-01-01 00:00:00

abstract：PURPOSE:Given its sensitivity to anatomical variations, proton therapy is expected to benefit greatly from integration with magnetic resonance imaging for online anatomy monitoring during irradiation. Such an integration raises several challenges, as both systems mutually interact. The proton beam will experience quasi...

journal_title：Medical physics

authors： Schellhammer SM,Gantz S,Lühr A,Oborn BM,Bussmann M,Hoffmann AL

更新日期：2018-07-01 00:00:00

abstract：PURPOSE:Many clinical applications depend critically on the accurate differentiation and classification of different types of materials in patient anatomy. This work introduces a unified framework for accurate nonlinear material decomposition and applies it, for the first time, in the concept of triple-energy CT (TECT)...

journal_title：Medical physics

authors： Zhao W,Vernekohl D,Han F,Han B,Peng H,Yang Y,Xing L,Min JK

更新日期：2018-07-01 00:00:00

abstract：PURPOSE:The use of X-ray imaging in radiation therapy can give a substantial dose to the patient. A Cobalt machine combined with an magnetic resonance imaging (MRI) was recently introduced to clinical work. One positive aspect of using non-ionizing imaging devices is the reduction of the patient exposure. The purpose o...

journal_title：Medical physics

authors： Hauri P,Hälg RA,Schneider U

更新日期：2017-07-01 00:00:00

abstract：PURPOSE:A 3-year project called LABSYNC has been recently funded by the European Commission, with the aim of designing a radiation facility based on a compact light source, i.e., a laboratory-sized commercial synchrotron, capable of accelerating electrons up to 6 or 20 MeV. An accurate spectral description of hard x ra...

journal_title：Medical physics

authors： Marziani M,Taibi A,Di Domenico G,Gambaccini M

更新日期：2009-10-01 00:00:00

abstract：:The surface radio frequency (rf) power absorption in human head and torso nuclear magnetic resonance (NMR) imaging experiments is estimated. The results are expressed as a function of the NMR frequency, the rf pulse length, and the pulse duty cycle, which are varied over six orders of magnitude for general applicabili...

journal_title：Medical physics

authors： Bottomley PA,Edelstein WA

更新日期：1981-07-01 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

authors： Wang X,Duan J,Du Y,Shen N,He B,Yuan H

更新日期：2013-08-01 00:00:00

abstract：:This study proposes an algorithm for selecting beam weight, wedge angle, and wedge orientation for three-dimensional radiation therapy treatment planning. According to dose gradient analysis, the necessary and sufficient condition for achieving a homogeneous dose over the target volume is that the total vector sum of ...

journal_title：Medical physics

authors： Dai J,Zhu Y

更新日期：2000-08-01 00:00:00

abstract：PURPOSE:Monte Carlo (MC) dose calculation is generally superior to analytical dose calculation (ADC) used in commercial TPS to model the dose distribution especially for heterogeneous sites, such as lung and head/neck patients. The purpose of this study was to provide a validated, fast, and open-source MC code, MCsquar...

journal_title：Medical physics

authors： Huang S,Souris K,Li S,Kang M,Barragan Montero AM,Janssens G,Lin A,Garver E,Ainsley C,Taylor P,Xiao Y,Lin L

更新日期：2018-12-01 00:00:00

abstract：:A simple noninvasive method is described for determining the backscatter to a monitor chamber of a medical accelerator based on the measurement of charge deposited in the target. This method is compared quantitatively to the more elaborate telescopic method for photon beams of 6 MV and 15 MV on linear accelerators hav...

journal_title：Medical physics

authors： Lam KL,Muthuswamy MS,Ten Haken RK

更新日期：1998-03-01 00:00:00

abstract：:Fluoroscopy is a low dose imaging technique. As such, a very sensitive detector is required to create images of good quality. Present day flat panel active matrix read out systems introduce an amount of noise that inhibits present direct and indirect methods from producing optimal quality images at fluoroscopic exposu...

journal_title：Medical physics

authors： Hunt DC,Kirby SS,Rowlands JA

更新日期：2002-11-01 00:00:00

abstract：PURPOSE:4d cone-beam computed tomography (CBCT) scans are usually reconstructed by extracting the motion information from the 2d projections or an external surrogate signal, and binning the individual projections into multiple respiratory phases. In this "after-the-fact" binning approach, however, projections are uneve...

journal_title：Medical physics

authors： Fast MF,Wisotzky E,Oelfke U,Nill S

更新日期：2013-09-01 00:00:00

abstract：:In a recent paper of Miller et al. (Med. Phys. 43(5), 2141-2152 (2016), the voltage dependence polarity effect of microionization chambers was studied. It was identified that polarity effect arises from the difference in electric potential between the collecting electrode and the guard electrode, which in turn deforms...

journal_title：Medical physics

authors： Brivio D,Sajo E,Zygmanski P

更新日期：2017-03-01 00:00:00

abstract：:Based on direction from AAM Board of Directors, JMPLSC has redefined its scope and name. On November 4, 2011 the subcommittee renamed itself the Medical Physics Licensure and Regulatory Recognition Subcommittee. Its newly defined charge is to promote the protection of the public through the recognition of the professi...

journal_title：Medical physics

authors： Pizzutiello R

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:CT reconstruction algorithms implemented on the GPU are highly sensitive to their implementation details and the hardware they run on. Fine-tuning an implementation for optimal performance can be a time consuming task and require many updates when the hardware changes. There are some techniques that do automati...

journal_title：Medical physics

authors： Papenhausen E,Zheng Z,Mueller K

更新日期：2013-03-01 00:00:00

abstract：PURPOSE:A modular phantom for dosimetry and imaging performance evaluation in cone-beam computed tomography (CBCT) is reported, providing a tool for quantitative technical assessment that can be adapted to a broad variety of CBCT imaging configurations and clinical applications. METHODS:The phantom presents a set of m...

journal_title：Medical physics

authors： Siewerdsen JH,Uneri A,Hernandez AM,Burkett GW,Boone JM

更新日期：2020-02-01 00:00:00

abstract：:In this paper, two new boundary tracing algorithms for segmentation of breast masses are presented. These new algorithms are based on the dynamic programming-based boundary tracing (DPBT) algorithm proposed in Timp and Karssemeijer, [S. Timp and N. Karssemeijer, Med. Phys. 31, 958-971 (2004)] The DPBT algorithm contai...

journal_title：Medical physics

authors： Rojas Domínguez A,Nandi AK

更新日期：2007-11-01 00:00:00

abstract：PURPOSE:To determine the accuracy and reproducibility of the automatic- setup procedure of a 3D water scanner (3D SCANNER, Sun Nuclear Corp). The procedure automatically aligns the scanner's coordinate system to the Linac coordinate system. A unique off-center detector holder extends the scan range to 630 mm, eliminati...

journal_title：Medical physics

authors： Li J,Lu B,Yan G,Huang Y,Liu C

更新日期：2012-06-01 00:00:00

abstract：:Single photon emission computed tomography (SPECT) is an important technology for molecular imaging studies of small animals. In this arena, there is an increasing demand for high performance imaging systems that offer improved spatial resolution and detection efficiency. We have designed a multipinhole small animal i...

journal_title：Medical physics

authors： Funk T,Després P,Barber WC,Shah KS,Hasegawa BH

更新日期：2006-05-01 00:00:00

abstract：PURPOSE:To provide a fast computational method, based on the proximal graph solver (POGS) - A convex optimization solver using the alternating direction method of multipliers (ADMM), for calculating an optimal treatment plan in rotating shield brachytherapy (RSBT). RSBT treatment planning has more degrees of freedom th...

journal_title：Medical physics

authors： Cho M,Wu X,Dadkhah H,Yi J,Flynn RT,Kim Y,Xu W

更新日期：2017-10-01 00:00:00

abstract：PURPOSE:We have investigated the dosimetric errors caused by the interplay between the motions of the LINAC and the tumor during the delivery of a volume modulated arc therapy treatment. This includes the development of an IMRT QA technique, applied here to evaluate RapidArc plans of varying complexity. METHODS:An IMR...

journal_title：Medical physics

authors： Court L,Wagar M,Berbeco R,Reisner A,Winey B,Schofield D,Ionascu D,Allen AM,Popple R,Lingos T

更新日期：2010-01-01 00:00:00

abstract：:The availability of digital radiographic imaging on simulators has led to the investigation of a number of new imaging possibilities, including digital linear tomography (tomosynthesis). It has been shown that a single set of projections in this case is sufficient to reconstruct images from multiple planes, including ...

journal_title：Medical physics

authors： Zwicker RD,Atari NA

更新日期：1997-06-01 00:00:00

abstract：PURPOSE:To overcome the problem of organ motion in intensity-modulated radiation therapy (IMRT), gated IMRT is often used for the treatment of lung cancer. In this study, the authors investigated the accuracy of the delivered monitor units (MUs) from each segment during gated IMRT using a two-dimensional detector array...

journal_title：Medical physics

authors： Cheong KH,Kang SK,Lee M,Kim SS,Park S,Hwang TJ,Kim KJ,Oh DH,Bae H,Suh TS

更新日期：2010-03-01 00:00:00

abstract：PURPOSE:The accuracy and precision of computed tomography (CT) pulmonary ventilation imaging with conventional CT scanners are limited by breathing variations. We propose a method to correct for the effect of breathing variations in CT ventilation imaging based on external respiratory signals acquired throughout a scan...

journal_title：Medical physics

authors： Yamamoto T,Kabus S

更新日期：2018-01-01 00:00:00

abstract：:Gd2O2S phosphor screens between 250 and 1000 mg/cm2 thick were evaluated for use in megavoltage imaging systems. The phosphor layers were placed on brass plates ranging from 1 to 5 mm thick, each with and without an optical back reflector (white paint). Light output and spatial resolution were measured at 6- and 23-MV...

journal_title：Medical physics

authors： Wowk B,Shalev S

更新日期：1994-08-01 00:00:00

abstract：:Intrafraction organ motion can limit the advantage of highly conformal dose techniques such as intensity modulated radiation therapy (IMRT) due to target position uncertainty. To ensure high accuracy in beam targeting, real-time knowledge of the target location is highly desired throughout the beam delivery process. T...

journal_title：Medical physics

authors： Mao W,Wiersma RD,Xing L

更新日期：2008-05-01 00:00:00

abstract：:The dissemination of scientific advances has changed little since the first peer-reviewed journal was published in 1665 - that is, until this past decade. The print journal, delivered by mail and stored on office shelves and in library reading rooms around the world, has been transformed by immediate, on-demand access...

journal_title：Medical physics

authors： Armato S,Hendee W,Marshall C,Curran B

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:To provide results of water calorimetry and ion chamber measurements in high-energy electron beams carried out at the National Research Council Canada (NRC). There are three main aspects to this work: (a) investigation of the behavior of ionization chambers in electron beams of different energies with focus on ...

journal_title：Medical physics

authors： Muir BR,Cojocaru CD,McEwen MR,Ross CK

更新日期：2017-10-01 00:00:00

abstract：PURPOSE:To develop an accurate and efficient single-marker-based optical tracking system to enhance patient safety and quality of care in radiotherapy. METHODS:The optical tracking system consists of a Polaris camera as well as in-house software. The camera is mounted inside the treatment room and detects the location...

journal_title：Medical physics

authors： Yan G,Lu B,Mittauer K,Liu C,Li J

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:The quantification of vessel wall morphology and plaque burden requires vessel segmentation, which is generally performed by manual delineations. The purpose of our work is to develop and evaluate a new 3D model-based approach for carotid artery wall segmentation from dual-sequence MRI. METHODS:The proposed me...

journal_title：Medical physics

authors： Gao S,van 't Klooster R,Kitslaar PH,Coolen BF,van den Berg AM,Smits LP,Shahzad R,Shamonin DP,de Koning PJH,Nederveen AJ,van der Geest RJ

更新日期：2017-10-01 00:00:00