Evaluations of two solid water parallel-plate chambers in high-energy photon and electron beams.

abstract：PURPOSE:Target localization accuracy of cone-beam CT (CBCT) images used in radiation treatment of respiratory disease sites is affected by motion artifacts (blurring and streaking). The authors have previously reported on a method of respiratory motion correction in thoracic CBCT at end expiration (EE). The previous re...

journal_title：Medical physics

authors： Dzyubak O,Kincaid R,Hertanto A,Hu YC,Pham H,Rimner A,Yorke E,Zhang Q,Mageras GS

更新日期：2014-10-01 00:00:00

abstract：PURPOSE:To evaluate the image quality of virtual monochromatic images synthesized from dual-source dual-energy computed tomography (CT) in comparison with conventional polychromatic single-energy CT for the same radiation dose. METHODS:In dual-energy CT, besides the material-specific information, one may also synthesi...

journal_title：Medical physics

authors： Yu L,Christner JA,Leng S,Wang J,Fletcher JG,McCollough CH

更新日期：2011-12-01 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: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：PURPOSE:For cone-beam computed tomography (CBCT) systems, we propose a sphere phantom based method to estimate the full three-dimensional (3D) modulation transfer function (MTF). METHODS:The FDK reconstruction of CBCT system in a local region was modeled by a triple convolution operator. Afterward, we calculated the d...

journal_title：Medical physics

authors： Lee C,Song HD,Baek J

更新日期：2020-07-01 00:00:00

abstract：PURPOSE:To perform radiomic analysis of primary tumors extracted from pretreatment contrast-enhanced computed tomography (CE-CT) images for patients with oropharyngeal cancers to identify discriminant features and construct an optimal classifier for the characterization and prediction of human papilloma virus (HPV) sta...

journal_title：Medical physics

authors： Bagher-Ebadian H,Lu M,Siddiqui F,Ghanem AI,Wen N,Wu Q,Liu C,Movsas B,Chetty IJ

更新日期：2020-02-01 00:00:00

abstract：:The use of magnetic resonance imaging as a readout method for polymer gel dosimetry commonly involves long imaging sessions, particularly when high spatial resolution is required in all three dimensions, for the investigation of dose distributions with steep dose gradients and stringent dose delivery specifications. I...

journal_title：Medical physics

authors： Baras P,Seimenis I,Sandilos P,Vlahos L,Bieganski T,Georgiou E,Pantelis E,Papagiannis P,Sakelliou L

更新日期：2005-11-01 00:00:00

abstract：:One of the key components in modern LINAC room shielding design is the amount of 90 degrees head leakage radiation levels. With the general clinical acceptance of intensity-modulated radiation therapy (IMRT) technique, accurate knowledge of this quantity has become even more important. Measurement of 90 degrees head l...

journal_title：Medical physics

authors： Li Z,Mutic S,Low D

更新日期：2006-09-01 00:00:00

abstract：PURPOSE:Brachytherapy with 106 Ru/106 Rh plaques offers good outcomes for small-to-medium choroidal melanomas and retinoblastomas. The dose measurement of the plaques is challenging, due to the small range of the emitted beta particles and steep dose gradients involved. The scarce publications on film dosimetry of 106 ...

journal_title：Medical physics

authors： Hermida-López M,Brualla L

更新日期：2018-04-01 00:00:00

abstract：PURPOSE:This work describes the performance characterization of a cone-beam CT-guided radiosurgery device, the Gamma Knife® Icon™. METHODS:The performance tests have been categorized into: (a) image quality and mechanical integrity; (b) image coregistration fidelity; (c) adaptive treatment delivery quality; (d) high d...

journal_title：Medical physics

authors： Sarfehnia A,Ruschin M,Chugh B,Yeboah C,Becker N,Cho YB,Lee Y

更新日期：2018-06-29 00:00:00

abstract：PURPOSE:In radiotherapy (RT) based on magnetic resonance imaging (MRI) as the only modality, the information on electron density must be derived from the MRI scan by creating a so-called pseudo computed tomography (pCT). This is a nontrivial task, since the voxel-intensities in an MRI scan are not uniquely related to e...

journal_title：Medical physics

authors： Andreasen D,Van Leemput K,Hansen RH,Andersen JA,Edmund JM

更新日期：2015-04-01 00:00:00

abstract：PURPOSE:To assess the image quality, scatter, and leakage radiation of an integrated magnetic resonance linear accelerator (MR-LINAC or MRL) system. METHODS:A large American College of Radiology (ACR) magnetic resonance imaging (MRI) accreditation phantom was used to evaluate the MRI capabilities of the integrated MRL...

journal_title：Medical physics

authors： Wang J,Yung J,Kadbi M,Hwang K,Ding Y,Ibbott GS

更新日期：2018-03-01 00:00:00

abstract：PURPOSE:Manual delineation of head and neck (H&N) organ-at-risk (OAR) structures for radiation therapy planning is time consuming and highly variable. Therefore, we developed a dynamic multiatlas selection-based approach for fast and reproducible segmentation. METHODS:Our approach dynamically selects and weights the a...

journal_title：Medical physics

authors： Haq R,Berry SL,Deasy JO,Hunt M,Veeraraghavan H

更新日期：2019-12-01 00:00:00

abstract：:The purpose of this study was to investigate if interfraction and intrafraction motion in free-breathing and gated lung IMRT can lead to systematic dose differences between 3DCT and 4DCT. Dosimetric effects were studied considering the breathing pattern of three patients monitored during the course of their treatment ...

journal_title：Medical physics

authors： Seco J,Sharp GC,Wu Z,Gierga D,Buettner F,Paganetti H

更新日期：2008-01-01 00:00:00

abstract：PURPOSE:The purpose of this study is to investigate some characteristics of the beam delivery system and their effects on the dose distribution of intensity-modulated radiation therapy (IMRT) and the results of patient-specific IMRT quality assurance (QA). These characteristics include the accelerator source distributi...

journal_title：Medical physics

authors： Li JS,Lin T,Chen L,Price RA Jr,Ma CM

更新日期：2010-06-01 00:00:00

abstract：:The ratio between scatter dose and scatter kerma for points on the central axis of 15-MV x-ray beams has been examined by Monte Carlo calculations. This ratio, beta'S, behaves differently from that between the primary dose and kerma, beta'p. Both the primary and scatter components of beta' undergo an initial rapid bui...

journal_title：Medical physics

authors： Hannallah D,Zhu TC,Bjärngard BE

更新日期：1996-11-01 00:00:00

abstract：:This study concerns the accuracy and precision of the IAEA/WHO LiF TLD system used in intercomparison by mail of absorbed doses from 60Co gamma-radiation and 4-25 MV x rays. The system employs 160 mg LiF powder in polystyrene capsules, which are placed at 5 or 7 cm depth in water and irradiated to doses close to 200 r...

journal_title：Medical physics

authors： Bjärngard BE,Kase KR,Rudén BI,Biggs PJ,Boyer AL,Johansson KA

更新日期：1980-09-01 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：PURPOSE:Wide bore CT scanners use extended field-of-view (eFOV) reconstruction algorithms to attempt to recreate tissue truncated due to large patient habitus. Radiation therapy planning systems rely on accurate CT numbers in order to correctly plan and calculate radiation dose. This study looks at the impact of eFOV r...

journal_title：Medical physics

authors： Cheung JP,Shugard E,Mistry N,Pouliot J,Chen J

更新日期：2019-02-01 00:00:00

abstract：:Depth dose characteristics of 24-MV beams from a medical linear accelerator at various SSDs have been measured. The dose buildup, percent depth dose (PDD), and output were measured using ionization chambers and a diode detector under full scatter. Surface dose ranged from 8% to 51% depending upon the collimator settin...

journal_title：Medical physics

authors： Jani SK,Pennington EC

更新日期：1991-03-01 00:00:00

abstract：PURPOSE:Intensity-Modulated Radiation Therapy (IMRT), including its variations (including IMRT, Volumetric Arc Therapy (VMAT), and Tomotherapy), is a widely used and critically important technology for cancer treatment. It is a knowledge-intensive technology due not only to its own technical complexity, but also to the...

journal_title：Medical physics

authors： Ge Y,Wu QJ

更新日期：2019-06-01 00:00:00

abstract：:With the increasing complexity of dose patterns external beam radiotherapy, there is a great need for new types of dosimeters. We studied the first prototype of a new dosimeter array consisting of water-equivalent plastic scintillating fibers for dose measurement in external beam radiotherapy. We found that this array...

journal_title：Medical physics

authors： Archambault L,Beddar AS,Gingras L,Lacroix F,Roy R,Beaulieu L

更新日期：2007-05-01 00:00:00

abstract：PURPOSE:The availability of accurate and simple models for the estimation of x-ray spectra is of great importance for system simulation, optimization, or inclusion of photon energy information into data processing. There is a variety of publicly available tools for estimation of x-ray spectra in radiology and mammograp...

journal_title：Medical physics

authors： Sisniega A,Desco M,Vaquero JJ

更新日期：2014-01-01 00:00:00

abstract：:Neutron cross sections for nonelastic and elastic reactions on a range of elements have been evaluated for incident energies up to 150 MeV. These cross sections agree well with experimental cross section data for charged-particle production as well as neutron and photon production. Therefore they can be used to determ...

journal_title：Medical physics

authors： Chadwick MB,Barschall HH,Caswell RS,DeLuca PM,Hale GM,Jones DT,MacFarlane RE,Meulders JP,Schuhmacher H,Schrewe UJ,Wambersie A,Young PG

更新日期：1999-06-01 00:00:00

abstract：PURPOSE:To develop a novel three-dimensional (3D) hybrid-encoding framework using compressed sensing (CS) and Toeplitz encoding with variable phase-scrambled radio-frequency (RF) excitation, which has the following advantages: low power deposition of RF pulses, reduction of the signal dynamic range, no additional hardw...

journal_title：Medical physics

authors： Wang H,Liang D,Su S,King KF,Chang Y,Liu X,Zheng H,Ying L

更新日期：2020-04-01 00:00:00

abstract：:Various techniques have been developed to localize radioactive sources in brachytherapy implants. The most common methods include the orthogonal film method, the stereo-shift film method, and recently, direct localization from a series of contiguous CT transverse images. The major advantage of the CT method is that it...

journal_title：Medical physics

authors： Yue N,Chen Z,Bond JE,Son YH,Nath R

更新日期：1999-04-01 00:00:00

abstract：:A comparison of two methods of scatter compensation in single photon emission computed tomography (SPECT) imaging is made on the basis of improvements in quantification. The methods, scatter-window subtraction and constrained deconvolution of an average point source response function (PSRF), are described; the theoret...

journal_title：Medical physics

authors： Yanch JC,Flower MA,Webb S

更新日期：1990-11-01 00:00:00

abstract：PURPOSE:Deformable image registration (DIR) is often validated based on a distance-to-agreement (DTA) criterion of automatically propagated anatomical landmarks that were manually identified. Due to human observer variability, however, the performance of the registration method is diluted. The purpose of this study was...

journal_title：Medical physics

authors： Mencarelli A,van Beek S,van Kranen S,Rasch C,van Herk M,Sonke JJ

更新日期：2012-11-01 00:00:00

abstract：PURPOSE:Repeated brain MRI scans are performed in many clinical scenarios, such as follow up of patients with tumors and therapy response assessment. In this paper, the authors show an approach to utilize former scans of the patient for the acceleration of repeated MRI scans. METHODS:The proposed approach utilizes the...

journal_title：Medical physics

authors： Weizman L,Eldar YC,Ben Bashat D

更新日期：2015-09-01 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