Automated lung segmentation of diseased and artifact-corrupted magnetic resonance sections.

abstract：PURPOSE:Timely identification of systematic changes in radiation delivery of an imaging system can lead to a reduction in risk for the patients involved. However, existing quality assurance programs involving the routine testing of equipment performance using phantoms are limited in their ability to effectively carry o...

journal_title：Medical physics

authors： Stevens NT,Steiner SH,Smith IR,MacKay RJ

更新日期：2011-01-01 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：:An important aspect of the intensity modulated radiotherapy (IMRT) process is that of optimizing the beam intensity profiles. Most such methods use a comparison between the defined dose distribution (including prescription dose and dose limits for critical structures) and the current distribution. The comparison may i...

journal_title：Medical physics

authors： Jones L,Hoban P

更新日期：2002-01-01 00:00:00

abstract：:Quantification of transit time of a remote after-loading high dose rate (HDR) brachytherapy source is important both for accurate treatment planning and for quality assurance checks. In this investigation, an HDR-1000 well ionization chamber and a precision electrometer are used to measure the transit time of the Ir-1...

journal_title：Medical physics

authors： Sahoo N

更新日期：2001-08-01 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：:Hyperthermia, as an adjuvant with radiation and chemotherapy, has shown promise in the treatment of cancer. The relevant biological effects of a hyperthermia treatment are both time and temperature-dependent, creating a need for accurate thermometry. We present a novel noninvasive thermometry modality that combines a ...

journal_title：Medical physics

authors： Dreher MR,Elas M,Ichikawa K,Barth ED,Chilkoti A,Rosen GM,Halpern HJ,Dewhirst M

更新日期：2004-10-01 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：PURPOSE:The combination of nonhuman primates (NHPs) with the state-of-the-art molecular imaging technologies allows for within-subject longitudinal research aiming at gaining new insights into human normal and disease conditions and provides an ideal foundation for future translational studies of new diagnostic tools, ...

journal_title：Medical physics

authors： Xie T,Chen X,Zaidi H

更新日期：2020-09-01 00:00:00

abstract：:This study evaluates the effects of respiratory motion on breast radiotherapy delivered using segmented multileaf collimator (SMLC) intensity modulation. An anthropomorphic breast phantom was constructed of polystyrene plates between which radiographic films were inserted. The phantom was mounted on a moving platform ...

journal_title：Medical physics

authors： Liu Q,McDermott P,Burmeister J

更新日期：2007-01-01 00:00:00

abstract：:Diode sensitivity variations with temperature (SVWT) have been reported to vary from small negative values up to 0.6% per degrees C. Thus it is possible for diode calibration factors established at room temperature (approximately 20 degrees C) to yield errors in the range of -1% to +9% when diodes are placed on a pati...

journal_title：Medical physics

authors： Welsh KT,Reinstein LE

更新日期：2001-05-01 00:00:00

abstract：PURPOSE:To characterize the radiation dose and three-dimensional (3D) imaging performance of a recently developed mobile, isocentric C-arm equipped with a flat-panel detector (FPD) for intraoperative cone-beam computed tomography (CBCT) (Cios Spin 3D, Siemens Healthineers) and to identify potential improvements in 3D i...

journal_title：Medical physics

authors： Sheth NM,De Silva T,Uneri A,Ketcha M,Han R,Vijayan R,Osgood GM,Siewerdsen JH

更新日期：2020-03-01 00:00:00

abstract：PURPOSE:MR thermometry based on the proton resonance frequency shift (PRFS) is the most commonly used method for the monitoring of thermal therapies. As the chemical shift of water protons is temperature dependent, the local temperature variation (relative to an initial baseline) may be calculated from time-dependent p...

journal_title：Medical physics

authors： Viallon M,Terraz S,Roland J,Dumont E,Becker CD,Salomir R

更新日期：2010-04-01 00:00:00

abstract：PURPOSE:Recent recommendations of the International Commission on Radiological Protection state that the use of effective dose (E) for assessing patient exposure has severe limitations, though it can be kept for dose comparisons. In cardiology procedures, the equivalent dose (H(T)) is one of the most appropriate dose q...

journal_title：Medical physics

authors： Compagnone G,Ortolani P,Domenichelli S,Ovi V,Califano G,Dall'Ara G,Marzocchi A

更新日期：2011-04-01 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:In cardiac ablation therapy, accurate anatomic guidance is necessary to create effective tissue lesions for elimination of left atrial fibrillation. While fluoroscopy, ultrasound, and electroanatomic maps are important guidance tools, they lack information regarding detailed patient anatomy which can be obtaine...

journal_title：Medical physics

authors： Rettmann ME,Holmes DR 3rd,Kwartowitz DM,Gunawan M,Johnson SB,Camp JJ,Cameron BM,Dalegrave C,Kolasa MW,Packer DL,Robb RA

更新日期：2014-02-01 00:00:00

abstract：PURPOSE:Theoretical reasoning suggests that direct conversion digital x-ray detectors based upon photoconductive amorphous-selenium (a-Se) could attain very high values of the MTF (modulation transfer function) at spatial frequencies well beyond 20 cycles mm(-1). One of the fundamental factors affecting resolution loss...

journal_title：Medical physics

authors： Hunter DM,Belev G,Kasap S,Yaffe MJ

更新日期：2012-02-01 00:00:00

abstract：:In this paper, a unified framework of iterative algebraic reconstruction for emission computed tomography (ECT) and its application to positron emission tomography (PET) is presented. The unified framework is based on an algebraic image restoration model and contains conventional iterative algebraic reconstruction alg...

journal_title：Medical physics

authors： Xu XL,Liow JS,Strother SC

更新日期：1993-11-01 00:00:00

abstract：PURPOSE:Over the last ten years, there has been an extensive growth in the development of microSPECT imagers. Most of the systems are based on the combination of conventional, relatively large gamma cameras with poor intrinsic spatial resolution and multipinhole collimators working in large magnification mode. Spatial ...

journal_title：Medical physics

authors： Van Holen R,Vandeghinste B,Deprez K,Vandenberghe S

更新日期：2013-11-01 00:00:00

abstract：:Seeds containing radioactive Ytterbium-169 (169Yb) have recently been manufactured for possible application to brachytherapy. Ytterbium-169 emits photons with an average energy of 93 keV (excluding energies less than 10 keV), and decays with a half-life of 32 days. Analytic and Monte Carlo computations have been used ...

journal_title：Medical physics

authors： Mason DL,Battista JJ,Barnett RB,Porter AT

更新日期：1992-05-01 00:00:00

abstract：PURPOSE:This study aims to investigate the prompt secondary gamma spectrum and thedepth-dose distributions of incident 40 MeV protons onto various phantom materials.The goal is to find a relationship between the secondary prompt gamma emissions andthe range of the incident particles. METHODS:An application was constru...

journal_title：Medical physics

authors： Lau A,Chen Y,Ahmad S

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:The spatial and temporal tracking performance of a commercially available 3D optical surface imaging system is evaluated for its potential use in frameless stereotactic radiosurgery head tracking applications. METHODS:Both 3D surface and infrared (IR) marker tracking were performed simultaneously on a head pha...

journal_title：Medical physics

authors： Wiersma RD,Tomarken SL,Grelewicz Z,Belcher AH,Kang H

更新日期：2013-11-01 00:00:00

abstract：PURPOSE:To investigate how the setting of optimization parameters, fractional dose and tuning structure in tomotherapy treatment planning affects plan dosimetric quality and treatment efficiency. METHODS:A digital phantom to simulate head and neck radiotherapy was constructed for this study. Tumor was 10cm long C-shap...

journal_title：Medical physics

authors： Lian J,Burkhardt K,Chera B,Chang S

更新日期：2012-06-01 00:00:00

abstract：:New in vivo dosimetry methods would be useful for clinical HDR brachytherapy. An implantable MOSFET Dose Verification System designed by Sicel Technologies, Inc. was examined for use with 192Ir HDR applications. This investigation demonstrated that varying the dose rate from 22 to 84 cGy/min did not change detector re...

journal_title：Medical physics

authors： Fagerstrom JM,Micka JA,DeWerd LA

更新日期：2008-12-01 00:00:00

abstract：PURPOSE:Accurate segmentation of lung and infection in COVID-19 computed tomography (CT) scans plays an important role in the quantitative management of patients. Most of the existing studies are based on large and private annotated datasets that are impractical to obtain from a single institution, especially when radi...

journal_title：Medical physics

authors： Ma J,Wang Y,An X,Ge C,Yu Z,Chen J,Zhu Q,Dong G,He J,He Z,Cao T,Zhu Y,Nie Z,Yang X

更新日期：2020-12-23 00:00:00

abstract：:Machine outputs, peak scatter factors, and central axis percentage depth dose distributions were measured for various phantom sizes in large radiation fields produced at extended distances by cobalt, 6-MV, and 10-MV photon beams. The results can be applied to practical total body irradiation procedures which usually i...

journal_title：Medical physics

authors： Podgorsak EB,Pla C,Evans MD,Pla M

更新日期：1985-09-01 00:00:00

abstract：PURPOSE:To investigate whether building a knowledge-based planning (KBP) model with prostate bed plans constructed from constrained hierarchical optimization (CHO) would result in more efficient model construction with more consistent output than a model built using plans from a traditional, trial-and-error-based optim...

journal_title：Medical physics

authors： Lin YH,Hong LX,Hunt MA,Berry SL

更新日期：2018-10-01 00:00:00

abstract：:The data from Meisberger et al. [Radiology 90, 953-957 (1968)] are often used as a basis for dose calculations in brachytherapy. In order to describe the absorbed dose in water around a brachytherapy point source, Meisberger provided a polynomial fit for different isotopes taking into account the effect of attenuation...

journal_title：Medical physics

authors： Tiourina TB,Dries WJ,van der Linden PM

更新日期：1995-05-01 00:00:00

abstract：:The relationship between the pixel value and exit dose was investigated for a new commercially available amorphous silicon electronic portal imaging device. The pixel to dose mapping function was established to be linear for detector distances between 116.5 cm to 150 cm from the source, radiation field sizes from 5 x ...

journal_title：Medical physics

authors： Grein EE,Lee R,Luchka K

更新日期：2002-10-01 00:00:00

abstract：PURPOSE:There is an increasing interest in calculating linear energy transfer (LET) distributions for proton therapy treatments in order to assess the influence of this quantity in biological terms. Microdosimetric Monte Carlo (MC) simulations are useful tools to calculate dose-averaged LET, as this has been broadly pr...

journal_title：Medical physics

authors： Bertolet A,Baratto-Roldán A,Barbieri S,Baiocco G,Carabe A,Cortés-Giraldo MA

更新日期：2019-09-01 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