Two-dimensional antiscatter grid: A novel scatter rejection device for Cone-beam computed tomography.

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：:An improved reconstructed stereoscopic x-ray image display system, based on the principle of binocular parallax, is described. Pulse-synchronized operation of two triode x-ray tubes and one plumbicon TV camera is employed to separate the left and right images for presentation to the two eyes, respectively. The princip...

journal_title：Medical physics

authors： Zhang S,King PH,Pang XD

更新日期：1983-09-01 00:00:00

abstract：:A new high dose rate 20 mm 32P intravascular brachytherapy (IVB) beta source used with automated stepping has recently been introduced. The AAPM Task Group 60 recommends that beta IVB sources should have well characterized dosimetric parameters in water. In this study, Monte Carlo simulations (MCNPX v 2.4) were used t...

journal_title：Medical physics

authors： Mourtada F,Soares CG,Horton JL

更新日期：2004-03-01 00:00:00

abstract：:We investigated protection strategies of organs at risk (OARs) in intensity modulated radiation therapy (IMRT). These strategies apply to delivery of IMRT to moving body anatomies that show relative displacement of OAR in close proximity to a tumor target. We formulated an efficient genetic algorithm which makes it po...

journal_title：Medical physics

authors： Abolfath RM,Papiez L

更新日期：2009-07-01 00:00:00

abstract：PURPOSE:In current clinical practice, there is no integrated 3D ultrasound (3DUS) guidance system clinically available for breast brachytherapy. In this study, the authors present a novel robot-assisted 3DUS system for real-time planning and guidance of breast interstitial high dose rate (HDR) brachytherapy treatment. ...

journal_title：Medical physics

authors： Poulin E,Gardi L,Barker K,Montreuil J,Fenster A,Beaulieu L

更新日期：2015-12-01 00:00:00

abstract：:Two recently developed A 150 plastic-equivalent gas mixtures have been tested for suitability in proportional counter applications. Methane- and propane-based "tissue-equivalent" gases were also included for comparison purposes. Event-size weighted dose distributions were measured in a 14.8-MeV neutron beam. Resolutio...

journal_title：Medical physics

authors： DeLuca PM Jr,Schell MC,Pearson DW,Higgins PD,Attix FH

更新日期：1984-07-01 00:00:00

abstract：:In computer simulations of x-ray CT systems one can either use continuous geometrical descriptions for phantoms or a voxelized representation. The voxelized approach allows arbitrary phantoms to be defined without being confined to geometrical shapes. The disadvantage of the voxelized approach is that inherent errors ...

journal_title：Medical physics

authors： Goertzen AL,Beekman FJ,Cherry SR

更新日期：2002-04-01 00:00:00

abstract：PURPOSE:It is estimated that 7% of women in the western world will develop palpable breast cysts in their lifetime. Even though cysts have been correlated with risk of developing breast cancer, many of them are benign and do not require follow-up. We develop a method to discriminate benign solitary cysts from malignant...

journal_title：Medical physics

authors： Kooi T,van Ginneken B,Karssemeijer N,den Heeten A

更新日期：2017-03-01 00:00:00

abstract：PURPOSE:Task Group 119 (TG-119) has been adopted for evaluating the adequacy of intensity-modulated radiation therapy (IMRT) commissioning and for establishing patient-specific IMRT quality assurance (QA) passing criteria in clinical practice. TG-119 establishes 95% confidence limits (CLs), which help clinics identify ...

journal_title：Medical physics

authors： Kearney V,Solberg T,Jensen S,Cheung J,Chuang C,Valdes G

更新日期：2018-03-01 00:00:00

abstract：PURPOSE:Cone beam computed tomography (CBCT) image quality suffers from contamination from scattered photons in the projection images. Monte Carlo simulations are a powerful tool to investigate the properties of scattered photons.egs_cbct, a recent EGSnrc user code, provides the ability of performing fast scatter calcu...

journal_title：Medical physics

authors： Thing RS,Mainegra-Hing E

更新日期：2014-07-01 00:00:00

abstract：PURPOSE:Theoretical models of the detective quantum efficiency (DQE) of x-ray detectors are an important step in new detector development by providing an understanding of performance limitations and benchmarks. Previous cascaded-systems analysis (CSA) models accounted for photoelectric interactions only. This paper des...

journal_title：Medical physics

authors： Yun S,Tanguay J,Kim HK,Cunningham IA

更新日期：2013-04-01 00:00:00

abstract：:The purposes of this study are: (i) to design field flattening filters for the Leipzig applicators of 2 and 3 cm of inner diameter with the source traveling parallel to the applicator contact surface, which are accessories of the microSelectron-HDR afterloader (Nucletron, Veenendaal, The Netherlands). These filters, m...

journal_title：Medical physics

authors： Granero D,Pérez-Calatayud J,Gimeno J,Ballester F,Casal E,Crispín V,van der Laarse R

更新日期：2008-02-01 00:00:00

abstract：PURPOSE:Automated detection of solitary pulmonary nodules using positron emission tomography (PET) and computed tomography (CT) images shows good sensitivity; however, it is difficult to detect nodules in contact with normal organs, and additional efforts are needed so that the number of false positives (FPs) can be fu...

journal_title：Medical physics

authors： Teramoto A,Fujita H,Yamamuro O,Tamaki T

更新日期：2016-06-01 00:00:00

abstract：:Monte Carlo simulations of x-ray beams typically take parameters of the electron beam in the accelerating waveguide to be free parameters. In this paper, a methodology is proposed and implemented to determine the energy, spectral width, and beam divergence of the electron source. All treatment head components were rem...

journal_title：Medical physics

authors： Sawkey DL,Faddegon BA

更新日期：2009-03-01 00:00:00

abstract：:Performance characteristics sufficient to provide physical data base specific to the Siemen's Stabilipan 2 orthovoltage x-ray therapy machine are presented. Operating conditions covering the working range of the unit from 100 to 300 kVp are selected. Beam quality, output, the central axis depth dose, relative output f...

journal_title：Medical physics

authors： Niroomand-Rad A,Gillin MT,Lopez F,Grimm DF

更新日期：1987-09-01 00:00:00

abstract：PURPOSE:There are currently several commercially available radiotherapy treatment units without a flattening filter in the beam line. Unflattened photon beams have an energy and lateral fluence distribution that is different from conventional beams and, thus, their attenuation properties differ. As a consequence, for f...

journal_title：Medical physics

authors： Dalaryd M,Knöös T,Ceberg C

更新日期：2014-11-01 00:00:00

abstract：PURPOSE:Image guidance is crucial for percutaneous tumor ablations, enabling accurate needle-like applicator placement into target tumors while avoiding tissues that are sensitive to injury and/or correcting needle deflection. Although ultrasound (US) is widely used for image guidance, magnetic resonance (MR) is prefer...

journal_title：Medical physics

authors： Yamada A,Tokuda J,Naka S,Murakami K,Tani T,Morikawa S

更新日期：2020-03-01 00:00:00

abstract：PURPOSE:The authors describe a design for prepatient region of interest attenuators (ROIAs) to reduce dose area product (DAP) for clinical use. The authors describe a model to predict DAP values from x-ray technique parameters recorded during a clinical procedure for image sequences obtained in the presence or absence ...

journal_title：Medical physics

authors： Robert N,Watt KN,Rochette S,Desponds L,Vaillant R,Rowlands JA

更新日期：2015-01-01 00:00:00

abstract：PURPOSE:We have developed a robust tool for performing volumetric and temporal analysis of nodules from respiratory gated four-dimensional (4D) CT. The method could prove useful in IMRT of lung cancer. METHODS:We modified the conventional graph-cuts method by adding an adaptive shape prior as well as motion informatio...

journal_title：Medical physics

authors： Cha J,Farhangi MM,Dunlap N,Amini AA

更新日期：2018-01-01 00:00:00

abstract：PURPOSE:To use the Monte Carlo code PENELOPE to study attenuation and tissue equivalence properties of a-Al2O3:C for OSL dosimetry. METHODS:Mass attenuation coefficients of α-Al2O3 and α-Al2O3:C with carbon percent weight concentrations from 1% to 150% were simulated with PENELOPE Monte Carlo code and compared to mass...

journal_title：Medical physics

authors： Nicolucci P,Schuch F

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:Positron emission tomography (PET) is an important tool for nuclear medical imaging. It has been widely used in clinical diagnosis, scientific research, and drug testing. PET is a kind of emission computed tomography. Its basic imaging principle is to use the positron annihilation radiation generated by radionu...

journal_title：Medical physics

authors： Zhang W,Gao J,Yang Y,Liang D,Liu X,Zheng H,Hu Z

更新日期：2019-11-01 00:00:00

abstract：PURPOSE:The authors have developed a quantitative calibration method for a multileaf collimator (MLC) which measures individual leaf positions relative to the MLC backup jaw on an Elekta Synergy linear accelerator. METHODS:The method utilizes a commercially available two-axis detector array (Profiler 2; Sun Nuclear Co...

journal_title：Medical physics

authors： Simon TA,Kahler D,Simon WE,Fox C,Li J,Palta J,Liu C

更新日期：2009-10-01 00:00:00

abstract：:Reconstruction of electron spectra of medical accelerators from measured depth dose distributions is an attractive tool for commissioning of a Monte Carlo treatment planning system. However, the reconstruction method is an inverse radiation transport problem which is poorly conditioned, in the sense it may become unst...

journal_title：Medical physics

authors： Chvetsov AV,Sandison GA

更新日期：2002-04-01 00:00:00

abstract：:We proposed to use the prostate dose-volume factor (PDVF), derived from the dose-volume dataset of planning target volume (PTV) in prostate radiotherapy to evaluate treatment plans of prostate volumetric modulated arc therapy (VMAT) and intensity modulated radiotherapy (IMRT). To demonstrate plan evaluation using PDVF...

journal_title：Medical physics

authors： Chow J,Jiang R,Markel D

更新日期：2012-07-01 00:00:00

abstract：PURPOSE:Calculations of deoxyribonucleic acid (DNA) damages involve many parameters in the computation process. As these parameters are often subject to uncertainties, it is of central importance to comprehensively quantify their impacts on DNA single-strand break (SSB) and double-strand break (DSB) yields. This has be...

journal_title：Medical physics

authors： Lai Y,Tsai MY,Tian Z,Qin N,Yan C,Hung SH,Chi Y,Jia X

更新日期：2020-04-01 00:00:00

abstract：:We applied Monte Carlo methods for the simulation of x-ray scattering in water phantoms. The phantom thickness was varied from 5 to 20 cm, and the monoenergetic incident x rays were varied from 15 to 100 keV. Eight screen pairs and a total absorption system were used as x-ray receptors. We determined the angular, spec...

journal_title：Medical physics

authors： Chan HP,Doi K

更新日期：1985-03-01 00:00:00

abstract：PURPOSE:Megavoltage grid therapy is currently delivered with step-and-shoot multisegment techniques or using a high attenuation block with divergent holes. However, the commercial availability of grid blocks is limited, their construction is difficult, and step-and-shoot techniques require longer treatment times and ar...

journal_title：Medical physics

authors： Almendral P,Mancha PJ,Roberto D

更新日期：2013-05-01 00:00:00

abstract：:A method for finding optimal primary fluence profiles for multiple field external beam radiation therapy techniques has been developed using a radiobiologically based objective function that quantifies the probability of achieving complication-free tumor control, P+. The objective function P+ has the valuable property...

journal_title：Medical physics

authors： Södertröm S,Brahme A

更新日期：1993-07-01 00:00:00

abstract：PURPOSE:The response of human cells to applied electrical signals depends on the cellular health status, because it is influenced by the composition and structure of the main cellular components. Therefore, electrical impedance-based techniques can be considered as sensitive tools to investigate healthy or disease stat...

journal_title：Medical physics

authors： Ambrico M,Lasalvia M,Ligonzo T,Ambrico PF,Perna G,Capozzi V

更新日期：2020-10-01 00:00:00

abstract：:Motion and deformation of the cardiac wall may be measured by following the positions of implanted radiopaque markers in three dimensions, using two x-ray cameras simultaneously. Regularly, calibration of the position measurement system is obtained by registration of the images of a calibration object, containing 10-2...

journal_title：Medical physics

authors： Muijtjens AM,Roos JM,Arts T,Hasman A

更新日期：1999-02-01 00:00:00