A method to estimate transmission profiles of bow-tie filters using rotating tube measurements.

abstract：PURPOSE:The image registration literature comprises many methods for 2D-3D registration for which accuracy has been established in a variety of applications. However, clinical application is limited by a small capture range. Initial offsets outside the capture range of a registration method will not converge to a succe...

journal_title：Medical physics

authors： van der Bom MJ,Bartels LW,Gounis MJ,Homan R,Timmer J,Viergever MA,Pluim JP

更新日期：2010-04-01 00:00:00

abstract：:Stereo x-ray radiography attracts increasing attention in major clinical applications. The purpose of this paper is to analyze the 3D localization error for breast biopsy procedures and provide guidelines for improving its accuracy. Our prototype is a CCD based digital stereo x-ray imaging system. The mathematical mod...

journal_title：Medical physics

authors： Jiang H,Liu H,Wang G,Chen W,Fajardo LL

更新日期：2000-05-01 00:00:00

abstract：PURPOSE:To determine the accuracy of VMAT treatment planning and delivery for patients undergoing radiotherapy in the head and neck. METHOD AND MATERIALS:A dosimetric study of a typical head and neck treatment plan has been carried out using Chamber, film and TLD's placed inside an anthropomorphic phantom. Lateral and...

journal_title：Medical physics

authors： Aldaais E,Tedeschi D,Gebreamlak W,Shieder T,Alkhatib H

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:The study aims to investigate whether Nakagami parameters--estimated from the statistical distribution of the backscattered ultrasound radio-frequency (RF) signals--could provide a means for quantitative characterization of parotid-gland injury resulting from head-and-neck radiotherapy. METHODS:A preliminary c...

journal_title：Medical physics

authors： Yang X,Tridandapani S,Beitler JJ,Yu DS,Wu N,Wang Y,Bruner DW,Curran WJ,Liu T

更新日期：2014-02-01 00:00:00

abstract：PURPOSE:Radiopharmaceutical applications in nuclear medicine require a detailed dosimetry estimate of the radiation energy delivered to the human tissues. Over the past years, several publications addressed the problem of internal dose estimate in volumes of several sizes considering photon and electron sources. Most o...

journal_title：Medical physics

authors： Yoriyaz H,Moralles M,Siqueira Pde T,Guimarães Cda C,Cintra FB,dos Santos A

更新日期：2009-11-01 00:00:00

abstract：PURPOSE:To use Cone Beam CT scans obtained just prior to treatments of head and neck cancer patients to measure the setup error and cumulative dose uncertainty of the cochlea. METHODS:Data from 10 head and neck patients with 10 planning CTs and 52 Cone Beam CTs taken at time of treatment were used in this study. Patie...

journal_title：Medical physics

authors： Yan M,Lovelock D,Hunt M,Mechalakos J,Hu Y,Pham H,Jackson A

更新日期：2013-12-01 00:00:00

abstract：:A clamp-on current probe utilizing the Hall effect was used to determine x-ray tube current. This noninvasive technique was compared to two other methods of mA measurement: the Machlett Dynalyzer and the mR/mAs linearity method. Three diagnostic x-ray units were used in the comparison; two modern three-phase rooms and...

journal_title：Medical physics

authors： Atherton JV,Nickoloff EL

更新日期：1987-03-01 00:00:00

abstract：PURPOSE:The authors describe the integration of optical imaging with a targeted small animal irradiator device, focusing on design, instrumentation, 2D to 3D image registration, 2D targeting, and the accuracy of recovering and mapping the optical signal to a 3D surface generated from the cone-beam computed tomography (...

journal_title：Medical physics

authors： Weersink RA,Ansell S,Wang A,Wilson G,Shah D,Lindsay PE,Jaffray DA

更新日期：2014-10-01 00:00:00

abstract：PURPOSE:The authors investigate the extent to which Response Evaluation Criteria in Solid Tumors (RECIST) can predict tumor volumes in ideal geometric settings and using clinical data. METHODS:The authors consider a hierarchy of models including uniaxial ellipsoids, general ellipsoids, and composites of ellipsoids, us...

journal_title：Medical physics

authors： Levine ZH,Galloway BR,Peskin AP,Heussel CP,Chen JJ

更新日期：2011-05-01 00:00:00

abstract：:Many problems in physics involve imaging objects with high spatial frequency content in a limited amount of time. The limitation of available experimental data leads to the infamous problem of diffraction limited data which manifests itself by causing ringing in the image. This ringing is due to the interference pheno...

journal_title：Medical physics

authors： Haacke EM,Liang ZP,Izen SH

更新日期：1989-05-01 00:00:00

abstract：PURPOSE:We investigated the feasibility of proton tomosynthesis as daily positioning of patients and compared the results with photon tomosynthesis as an alternative to conventional portal imaging or on-board cone-beam computed tomography. METHODS:Dedicated photon-like proton beam using the passively scattered proton ...

journal_title：Medical physics

authors： Min B,Kwak J,Lee J,Cho S,Park S,Yoo S,Chung K,Cho S,Lim Y,Shin D,Lee S,Kim J

更新日期：2012-06-01 00:00:00

abstract：:Transmission data for 4-MV bremsstrahlung beams have been measured with a combination of lead and aluminum attenuators. From these data, the original energy spectra have been reconstructed using an iterative least-squares technique, previously evaluated by simulation studies. The spectra on the central axis for three ...

journal_title：Medical physics

authors： Huang PH,Kase KR,Bjärngard BE

更新日期：1983-11-01 00:00:00

abstract：PURPOSE:To investigate using 3D γ analysis for IMRT and VMAT QA. METHODS:We explored and studied 3D γ-analysis by comparing TPS computed and EPID back-projection reconstructed doses in patient's CT images. Two 3D γ quantities, γ(PTV) and γ(10), were proposed and studied for evaluating the QA results, and compared to 2...

journal_title：Medical physics

authors： Wu C,Hosier KE,Beck KE,Radevic MB,Lehmann J,Zhang HH,Kroner A,Dutton SC,Rosenthal SA,Bareng JK,Logsdon MD,Asche DR

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:To compare reconstructed volumes calculated via planimetry and frustum algorithms in the context of stepped transrectal ultrasound (US) imaging, and to estimate the reconstruction error for prostate volumes. METHODS:Prostate contours for 40 permanent implant patients were delineated on magnetic resonance (MR) ...

journal_title：Medical physics

authors： Liu D,Usmani N,Sloboda RS

更新日期：2013-03-01 00:00:00

abstract：:The physical imaging performance of ST-V, ST-VA, and ST-VN computed radiography image plates, read with a Philips AC3 acquisition system, was investigated at 70 kVp with 0.5 mm of copper beam filtration for four different entrance air kerma values: 0.5, 2.6, 26, and 260 micro Gy. Measurements included characteristic r...

journal_title：Medical physics

authors： Kengyelics SM,Davies AG,Cowen AR

更新日期：1998-11-01 00:00:00

abstract：PURPOSE:Secondary particles produced in the collision of protons with beam modifiers are of concern in proton therapy. Nevertheless, secondary radiation can provide information on the dosimetric parameters through its dependency on the modulating accessories (range shifter and range modulating wheel). Relatively little...

journal_title：Medical physics

authors： Carnicer A,Letellier V,Rucka G,Angellier G,Sauerwein W,Herault J

更新日期：2012-12-01 00:00:00

abstract：PURPOSE:To develop a novel aperture-based algorithm for volumetric modulated are therapy (VMAT) treatment plan optimization with high quality and high efficiency. METHODS:The VMAT optimization problem is formulated as a large-scale convex programming problem solved by a column generation approach. The authors consider...

journal_title：Medical physics

authors： Men C,Romeijn HE,Jia X,Jiang SB

更新日期：2010-11-01 00:00:00

abstract：:For Monte Carlo linac simulations and patient dose calculations, it is important to accurately determine the phase space parameters of the initial electron beam incident on the target. These parameters, such as mean energy and radial intensity distribution, have traditionally been determined by matching the calculated...

journal_title：Medical physics

authors： Aljarrah K,Sharp GC,Neicu T,Jiang SB

更新日期：2006-04-01 00:00:00

abstract：PURPOSE:To demonstrate the ultra-high resolution capability of a small field-of-view (FOV) solid state x-ray imaging detector based on an EMCCD sensor. METHODS:A micro-solid state x-ray image intensifier (micro-SSXII) was developed to serve as an ultra-high resolution region-of-interest (ROI) imaging detector. It is b...

journal_title：Medical physics

authors： Singh V,Loughran B,Jain A,Sharma P,Bednarek D,Rudin S

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:Cortical thickness and density are critical components in determining the strength of bony structures. Computed tomography (CT) is one possible modality for analyzing the cortex in 3D. In this paper, a model-based approach for measuring the cortical bone thickness and density from clinical CT images is proposed...

journal_title：Medical physics

authors： Humbert L,Hazrati Marangalou J,Del Río Barquero LM,van Lenthe GH,van Rietbergen B

更新日期：2016-04-01 00:00:00

abstract：PURPOSE:The lateral edge of a proton therapy beam is commonly used to achieve conformality to the treatment volume where critical structures reside close to the target. However, when treating shallow depths, the lateral edge of a pencil beam scanning (PBS) system may be broader than that of a double scattered (DS) syst...

journal_title：Medical physics

authors： Charlwood FC,Aitkenhead AH,Mackay RI

更新日期：2016-03-01 00:00:00

abstract：PURPOSE:The number of pencil beam scanned proton therapy (PBS-PT) facilities equipped with cone-beam computed tomography (CBCT) imaging treating thoracic indications is constantly rising. To enable daily internal motion monitoring during PBS-PT treatments of thoracic tumors, we assess the performance of Motion-Aware Re...

journal_title：Medical physics

authors： den Otter LA,Chen K,Janssens G,Meijers A,Both S,Langendijk JA,Rosen LR,Wu HT,Knopf AC

更新日期：2020-12-01 00:00:00

abstract：PURPOSE:We present a simple, practical framework for truly 4D lung IMRT planning based on a weighted individual-phase optimization paradigm. This strategy is specifically developed for use in real-time tumor tracking delivery systems so as to utilize respiratory motion as an additional degree of freedom rather than a c...

journal_title：Medical physics

authors： Tachibana H,Cheung Y,Jain S,Sawant A

更新日期：2012-06-01 00:00:00

abstract：:In previous work it has been shown that a standard backpropagation neural network can be trained to reconstruct sections of single photon emission computed tomography (SPECT) images based on the planar image projections as inputs. In this study, it is demonstrated that an artificial neural network (ANN) trained on a s...

journal_title：Medical physics

authors： Kerr JP,Bartlett EB

更新日期：1995-05-01 00:00:00

abstract：:The visual observer performance for detecting low-contrast patterns by employing both the receiver operating characteristic (ROC) and the 9-alternative forced choice (9-AFC) method is investigated. For each observer and each experimental technique, the results were reproducible with respect to a repeated observation. ...

journal_title：Medical physics

authors： Herrmann C,Buhr E,Hoeschen D,Fan SY

更新日期：1993-05-01 00:00:00

abstract：PURPOSE:There are currently several commercially available radiotherapy treatment units without a flattening filter in the beam line. Unflattened photon beams have an energy and lateral fluence distribution that is different from conventional beams and, thus, their attenuation properties differ. As a consequence, for f...

journal_title：Medical physics

authors： Dalaryd M,Knöös T,Ceberg C

更新日期：2014-11-01 00:00:00

abstract：PURPOSE:To introduce a pair of accelerated non-Cartesian acquisition principles that when combined, exploit the periodicity of k-space acquisition, and thereby enable acquisition of high-temporal cine Cardiac Magnetic Resonance (CMR). METHODS:The mathematical formulation of a noniterative, undersampled non-Cartesian c...

journal_title：Medical physics

authors： Kawaji K,Patel MB,Cantrell CG,Tanaka A,Marino M,Tamura S,Wang H,Wang Y,Carroll TJ,Ota T,Patel AR

更新日期：2017-07-01 00:00:00

abstract：:Magnetic resonance images can be compromised by constant frequency (CF) noise, such as radio frequency (RF) noise. We investigate the effects of CF noise in four imaging methods with non-uniform k-space sampling: single-shot echo-planar imaging (EPI) with sinusoidal readout gradients, phase-encoded echo-planar spectro...

journal_title：Medical physics

authors： Du W,Karczmar GS,Pan X

更新日期：2002-08-01 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：:Radiation sensitive gels have been used as dosimeters for clinical dose verification of different radiation therapy modalities. However, the use of gels is not widespread, because careful techniques are required to achieve the dose precision and accuracy aimed for in clinical dose verification. Here, the introduction ...

journal_title：Medical physics

authors： Crescenti RA,Scheib SG,Schneider U,Gianolini S

更新日期：2007-04-01 00:00:00