X-ray quantum limited portal imaging using amorphous silicon flat-panel arrays.

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:The most common metric for comparing measured to calculated dose planes is a pass rate generated using percent difference, distance-to-agreement (DTA), or some combination of the two (e.g. gamma evaluation). The grid of analyzed points often corresponds to a dosimeter array with low areal-density of point detec...

journal_title：Medical physics

authors： Bailey D,Nelms B,Kumaraswamy L,Attwood K,Podgorsak M

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:Range uncertainties limit the potential of charged particle therapy. In vivo and online range verification techniques could increase the confidence in the dose delivery distribution and lead to more conformal treatments. Prompt gamma imaging and prompt gamma spectroscopy (PGS) have been demonstrated for such a ...

journal_title：Medical physics

authors： Dal Bello R,Magalhaes Martins P,Seco J

更新日期：2018-04-01 00:00:00

abstract：PURPOSE:Having been overlooked for many years, research is now starting to take into account the directional distribution of neutron workplace fields. Existing neutron dosimetry instrumentation does not account for this directional distribution, resulting in conservative estimates of dose in neutron workplace fields (b...

journal_title：Medical physics

authors： Balmer MJ,Gamage KA,Taylor GC

更新日期：2016-11-01 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 head-scatter factors H were examined for four different linear accelerators and were found to be similar at field sizes larger than 3 x 3 cm2. Sharply reduced values for small collimator openings were observed for all the accelerators. It is concluded that the head-scatter (or collimator-scatter) factor has two ma...

journal_title：Medical physics

authors： Zhu TC,Bjärngard BE

更新日期：1994-01-01 00:00:00

abstract：PURPOSE:Automated segmentation could improve the efficiency of modeling-based pelvic organ prolapse (POP) evaluations. However, segmentation performance is limited by the blurry soft tissue boundaries. In this study, we aimed to present a hybrid solution for uterus, rectum, bladder, and levator ani muscle segmentation ...

journal_title：Medical physics

authors： Feng F,Ashton-Miller JA,DeLancey JOL,Luo J

更新日期：2020-09-01 00:00:00

abstract：:In order to investigate the relationship between diagnostic accuracy and radiographic image quality, we have developed a dual-film cassette which produces two radiographs simultaneously with a single exposure. One of these radiographs is of standard quality; the second is of lower quality because of degraded spatial r...

journal_title：Medical physics

authors： Higashida Y,Doi K,Lehr JL,MacMahon H

更新日期：1984-09-01 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:The purpose of this study was to investigate the potential of MR-guided pulsed focused ultrasound (pFUS) for the enhancement of drug uptake in prostate tumors in vivo using doxorubicin (Dox). METHODS:An antitumor drug Dox, an orthotopic animal prostate tumor model using human prostate cancer, LNCaP cell line, ...

journal_title：Medical physics

authors： Chen X,Cvetkovic D,Ma CM,Chen L

更新日期：2012-05-01 00:00:00

abstract：PURPOSE:To show that Cherenkov emission is generated by external radiotherapy beam in tissue, and could serve as optical source to excite an oxygen sensitive phosphor, Oxyphor G4, within tissue. The intensity and lifetime of the phosphorescence was measured with a time-gated system and reveals the oxygenation levels in...

journal_title：Medical physics

authors： Zhang R,Kanick S,Vinogradov S,Esipova T,Pogue B

更新日期：2012-06-01 00:00:00

abstract：:Administration of x-ray contrast agents during heart catheterization examination increases the absorbed radiation dose in tissue. To estimate the dose absorbed by the blood of children undergoing diagnostic heart catheterization and angiocardiography, a number of measurements and calculations were conducted. First, en...

journal_title：Medical physics

authors： Callisen HH,Norman A,Adams FH

更新日期：1979-11-01 00:00:00

abstract：PURPOSE:The purpose of this paper was to present a method of determining the dose profile of the beam bow-tie filter (BTF) without the need for fixing the x ray tube in a position or using special instruments or dosimeters other than the ordinary types of ion chambers used for CT dosimetry (e.g., Farmer chamber). METH...

journal_title：Medical physics

authors： Al-Senan R

更新日期：2018-11-01 00:00:00

abstract：PURPOSE:The most common metric for comparing measured to calculated dose, such as for pretreatment quality assurance of intensity-modulated photon fields, is a pass rate (%) generated using percent difference (%Diff), distance-to-agreement (DTA), or some combination of the two (e.g., gamma evaluation). For many dosimet...

journal_title：Medical physics

authors： Bailey DW,Nelms BE,Attwood K,Kumaraswamy L,Podgorsak MB

更新日期：2011-11-01 00:00:00

abstract：PURPOSE:Several works have recently focused on flattening-filter-free (FFF) beams of linear accelerators of various companies (in particular, Varian and Elekta), but no overview as yet exists for the flattening-filter free 7XU beam (Siemens Artiste). METHODS:Dosimetric properties of the 7XU beam were measured in May a...

journal_title：Medical physics

authors： Dzierma Y,Licht N,Nuesken F,Ruebe C

更新日期：2012-05-01 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：:In this work, we present a calcification-detection scheme that automatically localizes calcifications in a previously detected cluster in order to generate the input for a cluster-classification scheme developed in the past. The calcification-detection scheme makes use of three pieces of a priori information: the loca...

journal_title：Medical physics

authors： Salfity MF,Nishikawa RM,Jiang Y,Papaioannou J

更新日期：2003-05-01 00:00:00

abstract：PURPOSE:To reduce the potential of late toxicity (tissue necrosis and cognitive function loss) from brain radiotherapy, we studied a novel planning technique for MLC-equipped linear accelerators (LINACS) that reduces the high doses delivered outside the PTV, enhancing radiation dose conformity. METHODS:The feasibility...

journal_title：Medical physics

authors： Yang W,Sandler H,Fraass B

更新日期：2012-06-01 00:00:00

abstract：:It has recently been shown that longitudinal aliasing can be a significant and detrimental presence in reconstructed single-slice helical computed tomography (CT) volumes. This aliasing arises because the directly measured data in helical CT are generally undersampled by a factor of at least 2 in the longitudinal dire...

journal_title：Medical physics

authors： La Rivière PJ,Pan X

更新日期：2001-03-01 00:00:00

abstract：PURPOSE:Patient-specific QA of highly conformal radiotherapy treatments are usually conducted using 2D or 3D dosimetry of the incident dose distribution in a water-equivalent phantom. However, dosimeters typically used for this task usually lack in either spatial resolution or dose accuracy. The purpose of this work is...

journal_title：Medical physics

authors： Goulet M,Archambault L,Beaulieu L,Gingras L

更新日期：2012-08-01 00:00:00

abstract：PURPOSE:The aim of this study is to investigate the performance of Sentinel(™), a patient setup verification device based on a laser/camera system, when used on rigid-body phantoms. METHODS:The Sentinel system consists of a scanner unit, containing the laser and the camera, and surface-matching registration software. ...

journal_title：Medical physics

authors： Pallotta S,Marrazzo L,Ceroti M,Silli P,Bucciolini M

更新日期：2012-02-01 00:00:00

abstract：PURPOSE:Scattered radiation remains to be a major cause of image quality degradation in Flat Panel Detector (FPD)-based Cone-beam computed tomography (CBCT). We have been investigating a novel two-dimensional antiscatter grid (2D-ASG) concept to reduce scatter intensity, and hence improve CBCT image quality. We present...

journal_title：Medical physics

authors： Alexeev T,Kavanagh B,Miften M,Altunbas C

更新日期：2018-02-01 00:00:00

abstract：PURPOSE:To objectively characterize the performance of the gemstone spectral imaging (GSI) mode of GE CT750 HD scanner from a user's perspective. METHODS:A regular scan protocol that approximates the adult abdomen scan protocol frequently used in the authors' institute was selected as the baseline, and a GSI protocol ...

journal_title：Medical physics

authors： Zhang D,Li X,Liu B

更新日期：2011-03-01 00:00:00

abstract：PURPOSE:In C-arm computed tomography (CT), the field of view (FOV) is often not sufficient to acquire certain anatomical structures, e.g., a full hip or thorax. Proposed methods to extend the FOV use a fixed detector displacement and a 360° scan range to double the radius of the FOV. These trajectories are designed for...

journal_title：Medical physics

authors： Herbst M,Schebesch F,Berger M,Choi JH,Fahrig R,Hornegger J,Maier A

更新日期：2015-05-01 00:00:00

abstract：:We studied a recently proposed aggregated CT reconstruction technique which combines the complementary advantages of kilovoltage (kV) and megavoltage (MV) x-ray imaging. Various phantoms were imaged to study the effects of beam orientations and geometry of the imaging object on image quality of reconstructed CT. It wa...

journal_title：Medical physics

authors： Zhang J,Yin FF

更新日期：2007-09-01 00:00:00

abstract：PURPOSE:The authors are developing a system for calibrated breast density measurements using full field digital mammography (FFDM). Breast tissue equivalent (BTE) phantom images are used to establish baseline (BL) calibration curves at time zero. For a given FFDM unit, the full BL dataset is comprised of approximately ...

journal_title：Medical physics

authors： Lu B,Smallwood AM,Sellers TA,Drukteinis JS,Heine JJ,Fowler EE

更新日期：2015-02-01 00:00:00

abstract：PURPOSE:To investigate the inconsistency of recent literature on the effect of magnetic field on the response of radiochromic films, we studied the influence of 0.35 T magnetic field on dosimetric response of EBT3 and EBT-XD GafchromicTM films. METHODS:Two different models of radiochromic films, EBT3 and EBT-XD, were ...

journal_title：Medical physics

authors： Darafsheh A,Hao Y,Maraghechi B,Cammin J,Reynoso FJ,Khan R

更新日期：2020-09-01 00:00:00

abstract：PURPOSE:To study the relationships between dose (D), kerma (K), and collision kerma ( K col ) in photon beams and to investigate total radiative yields for electrons and positrons as a functio...

journal_title：Medical physics

authors： Rogers DWO,Townson RW

更新日期：2019-11-01 00:00:00

abstract：PURPOSE:To commission and benchmark a vendor-supplied (Varian Medical Systems) Monte Carlo phase-space data for the 6 MV flattening filter free (FFF) energy mode on a TrueBeam linear accelerator for the purpose of quality assurance of clinical volumetric modulated arc therapy (VMAT) treatment plans. A method for render...

journal_title：Medical physics

authors： Gete E,Duzenli C,Milette MP,Mestrovic A,Hyde D,Bergman AM,Teke T

更新日期：2013-02-01 00:00:00

abstract：PURPOSE:The aim of this study was to evaluate a surrogate-driven motion model based on four-dimensional computed tomography that is able to predict CT volumes corresponding to arbitrary respiratory phases. Furthermore, the comparison of three different driving surrogates is examined and the feasibility of using the mod...

journal_title：Medical physics

authors： Wölfelschneider J,Seregni M,Fassi A,Ziegler M,Baroni G,Fietkau R,Riboldi M,Bert C

更新日期：2017-06-01 00:00:00