Calibration of a scintillation dosemeter for beta rays using an extrapolation ionization chamber.

abstract：PURPOSE:To demonstrate, via Monte Carlo simulation, that an image obtained from the patient-generated scattered radiation forced to impinge on the detector from a known direction by means of parallel-focused grids, can be used to complement the information conveyed by the primary image, such that accurate stereoscopic ...

journal_title：Medical physics

authors： Garnica-Garza HM

更新日期：2018-02-01 00:00:00

abstract：:Computer algorithms for rotational therapy beams, in most cases, perform dose calculations by summing stored fixed beam data at finite angular steps. Such an algorithm, based on the Bentley beam model, was evaluated by comparing calculations with measured data for an 18-MV x-ray beam. Measurements were made in a speci...

journal_title：Medical physics

authors： Kurup RG,Hogstrom KR,Hwang CC

更新日期：1987-11-01 00:00:00

abstract：PURPOSE:Prostate biopsy, performed using two-dimensional (2D) transrectal ultrasound (TRUS) guidance, is the clinical standard for a definitive diagnosis of prostate cancer. Histological analysis of the biopsies can reveal cancerous, noncancerous, or suspicious, possibly precancerous, tissue. During subsequent biopsy s...

journal_title：Medical physics

authors： Karnik VV,Fenster A,Bax J,Cool DW,Gardi L,Gyacskov I,Romagnoli C,Ward AD

更新日期：2010-02-01 00:00:00

abstract：:A single-field rotational total skin electron irradiation technique has recently been developed at the McGill University for treatment of skin malignancies. The dose received by a given surface point during rotation in a uniform large electron field depends on the radius of rotation of the surface point, on the local ...

journal_title：Medical physics

authors： Pla C,Heese R,Pla M,Podgorsak EB

更新日期：1984-07-01 00:00:00

abstract：:Current dosimetry protocols for clinical protons do not take into account any secondary electron fluence perturbation in ion chambers. In this work, we performed a systematic study of secondary electron fluence perturbation factors for spherical and cylindrical ion chambers in proton beams (70-250 MeV). The electron f...

journal_title：Medical physics

authors： Verhaegen F,Palmans H

更新日期：2001-10-01 00:00:00

abstract：PURPOSE:To investigate the difference of MR percent breast density measured from fat-suppressed versus nonfat-suppressed imaging sequences. METHODS:Breast magnetic resonance imaging (MRI) with and without fat suppression was acquired from 38 subjects. Breasts were divided into subgroups of different morphological patt...

journal_title：Medical physics

authors： Chang DH,Chen JH,Lin M,Bahri S,Yu HJ,Mehta RS,Nie K,Hsiang DJ,Nalcioglu O,Su MY

更新日期：2011-11-01 00:00:00

abstract：PURPOSE:A dosimetry evaluation model for treatment planning of esophageal radiation therapy is developed using a deep learning model. The model predicts dose volume histogram (DVH) from distance to target histogram (DTH) based on stacked de-noise auto-encoder (SDAE) and one-dimensional convolutional network (1D-CN). M...

journal_title：Medical physics

authors： Jiang D,Yan H,Chang N,Li T,Mao R,Du C,Guo B,Liu J

更新日期：2020-10-01 00:00:00

abstract：:The measurement of output factors for small fields is challenging and can lead to large dose errors in patient treatments if corrections for detector size and scatter from high-Z material are not applied. Due to its high spatial resolution and near tissue equivalence, GAFCHROMIC® film potentially provides a correction...

journal_title：Medical physics

authors： Vandervoort E,La Russa D,Ploquin N,Kadir IAE,Szanto J

更新日期：2012-07-01 00:00:00

abstract：:The measurement of the radioactivity administered to the patient is one of the major components of 90Y microsphere liver brachytherapy. The activity of 90Y microspheres in a glass delivery vial was measured in a dose calibrator. The calibration value to use for 90Y in the dose calibrator was verified using an activity...

journal_title：Medical physics

authors： Dezarn WA,Kennedy AS

更新日期：2007-06-01 00:00:00

abstract：:The objective of this study was to compare the contrast-detail performance of five different commercial liquid crystal displays (LCDs) to other LCD and cathode-ray tube (CRT) displays for medical applications. A contrast-detail phantom, supplemented with 5 in. of acrylic, was imaged on a commercial digital radiographi...

journal_title：Medical physics

authors： Samei E,Ranger NT,Delong DM

更新日期：2008-04-01 00:00:00

abstract：PURPOSE:The biologically effective dose (BED) of temporary brachytherapy treatments is a function of both chosen radionuclide (R) and implant duration (T). This study endeavored to evaluate BED delivered to the tumor volume and surrounding ocular structures as a function of plaque position (P), prescription dose, R, an...

journal_title：Medical physics

authors： Gagne N,Rivard M

更新日期：2012-06-01 00:00:00

abstract：:The objective of this work is to assess the suitability and performance of a new dosimeter system with a novel geometry for the quality assurance (QA) of volumetric modulated arc therapy (VMAT). The new dosimeter system consists of a hollow cylinder (15 and 25 cm inner and outer diameters) with 124 diodes embedded in ...

journal_title：Medical physics

authors： Létourneau D,Publicover J,Kozelka J,Moseley DJ,Jaffray DA

更新日期：2009-05-01 00:00:00

abstract：:Rotational angiography (RA) gantries are used routinely to acquire sequences of projection images of patients from which 3D renderings of vascular structures are generated using Feldkamp cone-beam reconstruction algorithms. However, these systems have limited resolution (<4 lp/mm). Micro-computed tomography (micro-CT)...

journal_title：Medical physics

authors： Patel V,Hoffmann KR,Ionita CN,Keleshis C,Bednarek DR,Rudin S

更新日期：2008-10-01 00:00:00

abstract：:Effects of changes in the physics of EGSnrc compared to EGS4/PRESTA on energy deposition kernels for monoenergetic photons and on dose point kernels for beta sources in water are investigated. In the diagnostic energy range, Compton binding corrections were found to increase the primary energy fraction up to 4.5% at 3...

journal_title：Medical physics

authors： Mainegra-Hing E,Rogers DW,Kawrakow I

更新日期：2005-03-01 00:00:00

abstract：PURPOSE:IAEA TRS-398 notes that cylindrical ionization chambers are preferred for reference proton dosimetry. If a cylindrical ionization chamber is used in a phantom to measure the dose as a function of depth, the effective point of measurement (EPOM) must be taken into account. IAEA TRS-398 recommends a displacement ...

journal_title：Medical physics

authors： Sugama Y,Nishio T,Onishi H

更新日期：2015-07-01 00:00:00

abstract：PURPOSE:To determine the accuracy and test-retest repeatability of fast radiofrequency (RF) transmit measurement approaches used in Dynamic Contrast Enhanced Magnetic Resonance Imaging (DCE-MRI). Spatial variation in the transmitted RF field introduces bias and increased variance in quantitative DCE-MRI metrics includi...

journal_title：Medical physics

authors： Bliesener Y,Zhong X,Guo Y,Boss M,Bosca R,Laue H,Chung C,Sung K,Nayak KS

更新日期：2019-06-01 00:00:00

abstract：PURPOSE:To evaluate a model which can predict patient's Entrance Skin Exposure (ESE) from height and weight and a single kVp mR/mAs measurement for radiographic. METHODS:Patient height, weight and post exposure mAs are obtained to assess ESE based on IAEA model. Patient's thickness is obtained by assuming a cylindrica...

journal_title：Medical physics

authors： Maricle S,Jeutang L,Prasad G

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:We report on the development of the open-source cross-platform radiation treatment planning toolkit matRad and its comparison against validated treatment planning systems. The toolkit enables three-dimensional intensity-modulated radiation therapy treatment planning for photons, scanned protons and scanned carb...

journal_title：Medical physics

authors： Wieser HP,Cisternas E,Wahl N,Ulrich S,Stadler A,Mescher H,Müller LR,Klinge T,Gabrys H,Burigo L,Mairani A,Ecker S,Ackermann B,Ellerbrock M,Parodi K,Jäkel O,Bangert M

更新日期：2017-06-01 00:00:00

abstract：PURPOSE:The purposes of this study is to measure the low frequency drop (LFD) of the modulation transfer function (MTF), associated with the long tails of the detector point spread function (PSF) of an on-board flat panel imager and study its impact on cone-beam CT (CBCT) image quality and scatter measurement accuracy....

journal_title：Medical physics

authors： Lazos D,Williamson JF

更新日期：2012-09-01 00:00:00

abstract：:Recent absorbed-dose-based protocols allow for two methods of calibrating electron beams using plane-parallel chambers, one using the N(Co)D,w for a plane-parallel chamber, and the other relying on cross-calibration of the plane-parallel chamber in a high-energy electron beam against a cylindrical chamber which has an...

journal_title：Medical physics

authors： Stewart KJ,Seuntjens JP

更新日期：2002-03-01 00:00:00

abstract：PURPOSE:To evaluate a three-equation three-unknown dual-energy quantitative CT (DEQCT) technique for determining region specific variations in bone spongiosa composition for improved red marrow dose estimation in radionuclide therapy. METHODS:The DEQCT method was applied to 80/140 kVp images of patient-simulating lumb...

journal_title：Medical physics

authors： Goodsitt MM,Shenoy A,Shen J,Howard D,Schipper MJ,Wilderman S,Christodoulou E,Chun SY,Dewaraja YK

更新日期：2014-05-01 00:00:00

abstract：PURPOSE:Photon counting arrays (PCAs), capable of measuring the spectral information of individual x-ray photons and recording that information digitally, provide a number of advantages compared to conventional, energy-integrating active matrix flat-panel imagers - such as reducing the undesirable effects of electronic...

journal_title：Medical physics

authors： Liang AK,Koniczek M,Antonuk LE,El-Mohri Y,Zhao Q

更新日期：2018-10-01 00:00:00

abstract：PURPOSE:The aim of this study was to implement a Dirichlet process mixture (DPM) model for automatic tumor edge identification on (18)F-fluorodeoxyglucose positron emission tomography ((18)F-FDG PET) images by optimizing the parameters on which the algorithm depends, to validate it experimentally, and to test its robus...

journal_title：Medical physics

authors： Giri MG,Cavedon C,Mazzarotto R,Ferdeghini M

更新日期：2016-05-01 00:00:00

abstract：PURPOSE:This article introduces the use of low power continuous wave frequency modulated radar for medical applications, specifically for remote monitoring of vital signs in patients. METHODS:Gigahertz frequency radar measures the electromagnetic wave signal reflected from the surface of a human body and from tissue b...

journal_title：Medical physics

authors： Mostov K,Liptsen E,Boutchko R

更新日期：2010-03-01 00:00:00

abstract：PURPOSE:Transcranial magnetic resonance-guided focused ultrasound surgery is a noninvasive technique for causing selective tissue necrosis. Variations in density, thickness, and shape of the skull cause aberrations in the location and shape of the focal zone. In this paper, the authors propose a hybrid simulation-MR-AR...

journal_title：Medical physics

authors： Vyas U,Kaye E,Pauly KB

更新日期：2014-03-01 00:00:00

abstract：PURPOSE:The purpose of this study was to describe and evaluate methods for calculating a megavoltage computed tomography (MVCT)-derived MR hardware attenuation map (μ-map) and dual-energy CT (DECT) for 511 keV photons. METHODS:Phantom measurements were acquired on a whole-body hybrid PET/MRI system, using a four-chann...

journal_title：Medical physics

authors： Patrick JC,Terry Thompson R,So A,Butler J,Faul D,Stodilka RZ,Yartsev S,Prato FS,Gaede S

更新日期：2017-09-01 00:00:00

abstract：:A formalism for an independent dose verification of the Gamma Knife treatment planning is developed. It is based on the approximation that isodose distribution for a single shot is in the shape of an ellipsoid in three-dimensional space. The dose profiles for a phantom along each of the three major axes are fitted to ...

journal_title：Medical physics

authors： Phaisangittisakul N,Ma L

更新日期：2002-09-01 00:00:00

abstract：:The purpose of this paper is to determine the correlation between dose-volume histogram (DVH) and dose wall-histogram (DWH) in the evaluation of rectal complications for prostate cancer patients treated with three-dimensional conformal radiotherapy (3D-CRT). A retrospective analysis of DVHs and DWHs of a subset of 25 ...

journal_title：Medical physics

authors： García-Vicente F,Zapatero A,Floriano A,Cruz-Conde A,Perez L,Marín A,Mínguez C,Torres JJ

更新日期：2005-08-01 00:00:00

abstract：PURPOSE:To develop a novel system for patient-specific combined optimization of couch, collimator, and gantry angles for use in volumetric modulated arc therapy (VMAT) treatment planning. The system was designed to produce highly compact dose distributions by extensively sampling the 4π space. Automated fixed couch tra...

journal_title：Medical physics

authors： MacDonald RL,Syme A,Little B,Ward L,Thomas CG

更新日期：2020-02-01 00:00:00

abstract：:Compared with slice-by-slice approaches for SPECT reconstruction, three-dimensional iterative methods provide a more accurate physical model and an improved SPECT image. Clinical application of these methods, however, is limited primarily to their computational demands. This paper investigates the methods for approxim...

journal_title：Medical physics

authors： Gilland DR,Jaszczak RJ,Riauka TA,Coleman RE

更新日期：1997-09-01 00:00:00