Electron dose calculation using multiple-scattering theory. A. Gaussian multiple-scattering theory.

abstract：:This paper outlines a method for determining proper removal-diffusion parameters to be used in removal-diffusion theory calculations for the purpose of BNCT treatment planning. Additionally, this paper demonstrates that, given the proper choice of removal-diffusion parameters, removal-diffusion theory may provide an a...

journal_title：Medical physics

authors： Albertson BJ,Blue TE,Niemkiewicz J

更新日期：2001-09-01 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：: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：:Some limitations of conventional two-dimensional computer programs used to plan radiation therapy are presented. These include: a lack of involvement in defining the clinical problem; deficiencies in the algorithms for computing dose; failure to compute dose throughout the volume of interest; an inability to handle tr...

journal_title：Medical physics

authors： Goitein M

更新日期：1982-07-01 00:00:00

abstract：:The accurate calculation of the skeleton of an object is a problem not satisfactorily solved by existing approaches. Most algorithms require a significant amount of user interaction and use a voxel grid to compute discrete and often coarse approximations of this representation of the data. We present a novel, automati...

journal_title：Medical physics

authors： Van Uitert R,Bitter I

更新日期：2007-02-01 00:00:00

abstract：PURPOSE:To develop a pencil beam dose calculation algorithm for scanned proton beams that improves modeling of scatter events. METHODS:Our pencil beam algorithm (PBA) was developed for calculating dose from monoenergetic, parallel proton beams in homogeneous media. Fermi-Eyges theory was implemented for pencil beam tr...

journal_title：Medical physics

authors： Chapman J,Fontenot J,Newhauser W,Hogstrom K

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:The purpose of this study was to provide updated radiation dose from diagnostic exams performed for pregnant patients suspected of pulmonary embolism (PE) using the recently developed BREP phantoms of pregnant woman and the fetus. Also to challenge the validity of current recommendations suggest that ventilatio...

journal_title：Medical physics

authors： Rafat Motavalli L,Hoseinian Azghadi E,Miri Hakimabad H,Akhlaghi P

更新日期：2017-11-01 00:00:00

abstract：:The implementation of an improved model for multiple scattering into the-Voxel Monte Carlo (VMC) algorithm for fast electron dose calculation in radiation therapy is presented. The model takes into account path-length corrections (PLC) and lateral displacement in the individual electron steps. The extraction of the sc...

journal_title：Medical physics

authors： Kawrakow I

更新日期：1997-04-01 00:00:00

abstract：:The purpose of this work is to calculate the dose perturbations due to the presence of iodine contrast media in catheter-based intravascular brachytherapy (IVBT). The EGSnrc Monte Carlo system was used to perform the calculation for the two most commonly used beta and gamma sources (90Sr and 192Ir as well as for a var...

journal_title：Medical physics

authors： Li XA

更新日期：2001-05-01 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：PURPOSE:To demonstrate an objective approach to determining if a negative report from the Radiological Physics Center (RPC) of greater than 10% error is valid or has clinical significance. METHODS:The discrepancy involved the clinical activity (mgRaEq) of Cs-137 sources, some manufactured by 3M and some by Amersham. M...

journal_title：Medical physics

authors： Grant W 3rd,Mcgary J,Rosen I,Nitsch P,Davidson S

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:The Monte Carlo simulation of electron transport in Linac targets using the condensed history technique is known to be problematic owing to a potential dependence of absorbed dose distributions on the electron step length. In the PENELOPE code, the step length is partially determined by the transport parameters...

journal_title：Medical physics

authors： Rodriguez M,Sempau J,Brualla L

更新日期：2015-06-01 00:00:00

abstract：PURPOSE:Linac-magnetic resonance (MR) systems have been proposed in order to achieve realtime image guided radiotherapy. The design of a new linac-MR system with the in-line 6 MV linac generating x-rays along the symmetry axis of an open MR imager is outlined. This new design allows for a greater MR field strength to a...

journal_title：Medical physics

authors： St Aubin J,Santos DM,Steciw S,Fallone BG

更新日期：2010-09-01 00:00:00

abstract：PURPOSE:Efficient and accurate segmentations of 3D end-firing transrectal ultrasound (TRUS) images play an important role in planning of 3D TRUS guided prostate biopsy. However, poor image quality of the input 3D TRUS images, such as strong imaging artifacts and speckles, often makes it a challenging task to extract th...

journal_title：Medical physics

authors： Qiu W,Yuan J,Ukwatta E,Fenster A

更新日期：2015-02-01 00:00:00

abstract：:Calcium concentration may be a useful feature for distinguishing benign from malignant lung nodules in computer-aided diagnosis. The calcium concentration can be estimated from the measured CT number of the nodule and a CT number vs calcium concentration calibration line that is derived from CT scans of two or more ca...

journal_title：Medical physics

authors： Goodsitt MM,Chan HP,Way TW,Schipper MJ,Larson SC,Christodoulou EG

更新日期：2009-07-01 00:00:00

abstract：:Ionization chambers of varying inside diameter have been used to investigate the penumbral region of 60Co, 6-MV, and 31-MV x-ray beams. Measurements were made in water at varying depths up to 25 cm for a square field of side length 10 cm. The dependence of the penumbral widths on both the inside diameter of the ioniza...

journal_title：Medical physics

authors： Dawson DJ,Schroeder NJ,Hoya JD

更新日期：1986-01-01 00:00:00

abstract：:We designed a novel force/torque moment transducer with six degrees of freedom. This new sensor is used for measuring the forces and torque moments exerted by static magnetic resonance imaging (MRI) fields on various medical implants, instruments, and ballistic shell fragments. To determine the location of strongest e...

journal_title：Medical physics

authors： Planert J,Modler H,Vosshenrich R

更新日期：1996-06-01 00:00:00

abstract：PURPOSE:To propose a method to calculate the tissue phantom ratio (TPR) using the depth dose and to compare the proposed method with two other methods. METHODS:An analytical dose model from Bjärngard was used to describe the depth dose and the TPR. The parameters of the model were derived from depth dose measurements,...

journal_title：Medical physics

authors： Ramos Garcia LI,Almansa JF

更新日期：2011-05-01 00:00:00

abstract：:Like Medical Physics, Imaging Informatics encompasses concepts touching every aspect of the imaging chain from image creation, acquisition, management and archival, to image processing, analysis, display and interpretation. The two disciplines are in fact quite complementary, with similar goals to improve the quality ...

journal_title：Medical physics

authors： Andriole K

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:Removal of the linear accelerator (linac) flattening filter enables a high rate of dose deposition with reduced treatment time. When used for megavoltage imaging, an unflat beam has reduced primary beam scatter resulting in sharper images. In fluoroscopic imaging mode, the unflat beam has higher photon count pe...

journal_title：Medical physics

authors： Christensen JD,Kirichenko A,Gayou O

更新日期：2013-08-01 00:00:00

abstract：PURPOSE:An original radionuclide calibrator method for activity determination is presented. The method could be used for intercomparison surveys for short half-life radioactive sources used in Nuclear Medicine, such as(99m)Tc or most positron emission tomography radiopharmaceuticals. METHODS:By evaluation of the resul...

journal_title：Medical physics

authors： Oliveira PA,Santos JA

更新日期：2014-07-01 00:00:00

abstract：PURPOSE:The presence of respiratory motion during radiation treatment leads to degradation of the expected dose distribution, both for target coverage and healthy tissue sparing, particularly for techniques like pencil beam scanning proton therapy which have dynamic delivery systems. While tools exist to estimate this ...

journal_title：Medical physics

authors： Pepin MD,Tryggestad E,Wan Chan Tseung HS,Johnson JE,Herman MG,Beltran C

更新日期：2018-11-01 00:00:00

abstract：PURPOSE:The impact and the development of aneurysms depend to a significant degree on the exchange of liquid between the regular vessel and the pathological extension. A better understanding of this process will lead to improved prediction capabilities. The aim of the current study was to investigate fluid-exchange in ...

journal_title：Medical physics

authors： Edelhoff D,Walczak L,Frank F,Heil M,Schmitz I,Weichert F,Suter D

更新日期：2015-10-01 00:00:00

abstract：:IMRT treatment plans for step-and-shoot delivery have traditionally been produced through the optimization of intensity distributions (or maps) for each beam angle. The optimization step is followed by the application of a leaf-sequencing algorithm that translates each intensity map into a set of deliverable aperture ...

journal_title：Medical physics

authors： Shepard DM,Earl MA,Li XA,Naqvi S,Yu C

更新日期：2002-06-01 00:00:00

abstract：:The widespread application of positron emission tomography (PET) in clinical oncology has driven this imaging technology into a number of new research and clinical arenas. Increasing numbers of patient scans have led to an urgent need for efficient data handling and the development of new image analysis techniques to ...

journal_title：Medical physics

authors： Montgomery DW,Amira A,Zaidi H

更新日期：2007-02-01 00:00:00

abstract：PURPOSE:The implementation of an accurate beam model is an integral part of the commissioning of any planning system. This process is especially challenging in the case of IMRT beam models owing to the complexity of small field sizes and MLC leaf-end and tongue-and-groove effects. The question of how to judge the quali...

journal_title：Medical physics

authors： Veltchev I,Fourkal E,Price R,Ma C

更新日期：2012-06-01 00:00:00

abstract：:Cone beam computed tomography (CBCT) is a relatively new patient imaging technique that has proved invaluable for treatment target verification and patient positioning during image-guided radiotherapy (IGRT). It has been shown that CBCT results in additional dose to bone that may amount to 10% of the prescribed dose. ...

journal_title：Medical physics

authors： Walters BR,Ding GX,Kramer R,Kawrakow I

更新日期：2009-07-01 00:00:00

abstract：:The MCNP Monte Carlo radiation transport code was modified for diagnostic medical physics applications. In particular, the modified code was thoroughly benchmarked for the production of polychromatic tungsten x-ray spectra in the 30-150 kV range. Validating the modified code for coupled electron-photon transport with ...

journal_title：Medical physics

authors： Mercier JR,Kopp DT,McDavid WD,Dove SB,Lancaster JL,Tucker DM

更新日期：2000-12-01 00:00:00

abstract：:Plaque rupture with superimposed thrombosis is the main cause of the acute coronary syndromes of unstable angina, myocardial infarction, and sudden death. Endothelial disruption leading to plaque rupture may relate to mechanical fatigue associated with cyclic flexion of plaques. A novel method is proposed to assess st...

journal_title：Medical physics

authors： Wu HC,Chen SY,Shroff SG,Carroll JD

更新日期：2003-11-01 00:00:00

abstract：PURPOSE:To develop a deformable mapping technique to match corresponding lesions between digital breast tomosynthesis (DBT) and automated breast ultrasound (ABUS) images. METHODS:External fiducial markers were attached to the surface of two CIRS multi-modality compressible breast phantoms (A and B) containing multiple...

journal_title：Medical physics

authors： Green CA,Goodsitt MM,Brock KK,Davis CL,Larson ED,Lau JH,Carson PL

更新日期：2018-10-01 00:00:00