Tolerance limits and methodologies for IMRT measurement-based verification QA: Recommendations of AAPM Task Group No. 218.

abstract：PURPOSE:To quickly and automatically propagate organ contours from pretreatment to fraction images in magnetic resonance (MR)-guided prostate external-beam radiotherapy. METHODS:Five prostate cancer patients underwent 20 fractions of image-guided external-beam radiotherapy on a 1.5 T MR-Linac system. For each patient,...

journal_title：Medical physics

authors： Eppenhof KAJ,Maspero M,Savenije MHF,de Boer JCJ,van der Voort van Zyp JRN,Raaymakers BW,Raaijmakers AJE,Veta M,van den Berg CAT,Pluim JPW

更新日期：2020-03-01 00:00:00

abstract：PURPOSE:To evaluate the feasibility of using an objective computer-aided system to assess bladder cancer stage in CT Urography (CTU). MATERIALS AND METHODS:A dataset consisting of 84 bladder cancer lesions from 76 CTU cases was used to develop the computerized system for bladder cancer staging based on machine learnin...

journal_title：Medical physics

authors： Garapati SS,Hadjiiski L,Cha KH,Chan HP,Caoili EM,Cohan RH,Weizer A,Alva A,Paramagul C,Wei J,Zhou C

更新日期：2017-11-01 00:00:00

abstract：:This study compared air exposures during conventional dental and maxillofacial radiography and similar views using free-focus radiography with conventional image receptors. The results show that periapical type surveys on nonscreen film placed extraorally or in the buccal fold may be carried out with an exposure to th...

journal_title：Medical physics

authors： Jensen TW,Randall GJ,Goldberg AJ

更新日期：1980-07-01 00:00:00

abstract：:A Monte Carlo study of dosimetry for eye plaque brachytherapy is performed. BrachyDose, an EGSnrc user code which makes use of Yegin's multi-geometry package, is used to fully model I125 (model 6711) and Pd103 (model 200) brachytherapy seeds and the standardized plaques of the Collaborative Ocular Melanoma Study (COMS...

journal_title：Medical physics

authors： Thomson RM,Taylor REP,Rogers DWO

更新日期：2008-12-01 00:00:00

abstract：:In x-ray spectral measurement using a semiconductor detector system, accurate positioning of the detector in front of the anode is very important. This needs accurate determination of the focal spot position on the target in an x-ray tube. We present a simple technique to determine the focal spot position accurately. ...

journal_title：Medical physics

authors： Kubota H,Ozaki Y,Matsumoto M,Kanamori H

更新日期：1993-07-01 00:00:00

abstract：PURPOSE:To formulate convex planning objectives of treatment plan multicriteria optimization with explicit relationships to the dose-volume histogram (DVH) statistics used in plan quality evaluation. METHODS:Conventional planning objectives are designed to minimize the violation of DVH statistics thresholds using pena...

journal_title：Medical physics

authors： Engberg L,Forsgren A,Eriksson K,Hårdemark B

更新日期：2017-06-01 00:00:00

abstract：:The image display is an important component of the Picture Archiving and Communication System (PACS) and of digital imaging in general. In this paper, we assess the display performance of 32 different flat panel LCD devices, in terms of their reflection, luminance response, luminance uniformity, resolution, noise, vei...

journal_title：Medical physics

authors： Jung H,Kim HJ,Kang WS,Yoo SK,Fujioka K,Hasegawa M,Samei E

更新日期：2004-07-01 00:00:00

abstract：PURPOSE:Positron emission tomography (PET) is considered the gold standard for measuring myocardial blood flow in vivo but it is known that respiratory motion can lead to misalignment of the PET and computed tomography (CT) data sets and introduce artifacts in the CT-based attenuation correction (AC) of images. In addi...

journal_title：Medical physics

authors： Pourmoghaddas A,Klein R,deKemp RA,Wells RG

更新日期：2013-02-01 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：PURPOSE:In the practice code of dosimetry, humidity effect is assumed to be constant as far as the measurements are performed in the relative humidity (RH) range of (20-80)%; thus, the humidity effect can be ignored with a dose uncertainty of 0.15%. This assumption is based on the previous experimental results by Niate...

journal_title：Medical physics

authors： Sato Y,Shimizu M,Morishita Y,Sato M,Hoshina M

更新日期：2019-09-01 00:00:00

abstract：:Magnetic resonance (MR) measurements of relaxation times and diffusion coefficient in tissue have been demonstrated to be sensitive to biological changes induced by radiation therapy. We are currently using mouse models of human glioblastoma multiforme (GBM) to study tumour response to ionizing radiation by MRI at 9.4...

journal_title：Medical physics

authors： Larocque M,Syme A,Fallone BG

更新日期：2008-07-01 00:00:00

abstract：PURPOSE:The authors previously introduced a methodology to generate a realistic three-dimensional (3D), high-resolution, computer-simulated breast phantom based on empirical data. One of the key components of such a phantom is that it provides a means to produce a realistic simulation of clinical breast compression. In...

journal_title：Medical physics

authors： Hsu CM,Palmeri ML,Segars WP,Veress AI,Dobbins JT 3rd

更新日期：2011-10-01 00:00:00

abstract：PURPOSE:With increased use of handheld and tablet display devices for viewing medical images, methods for consistently measuring reflectivity of the devices are needed. In this note, the authors report on the characterization of diffuse reflections for handheld display devices including mobile phones and tablets using ...

journal_title：Medical physics

authors： Liu P,Badano A

更新日期：2014-08-01 00:00:00

abstract：PURPOSE:A modular phantom for dosimetry and imaging performance evaluation in cone-beam computed tomography (CBCT) is reported, providing a tool for quantitative technical assessment that can be adapted to a broad variety of CBCT imaging configurations and clinical applications. METHODS:The phantom presents a set of m...

journal_title：Medical physics

authors： Siewerdsen JH,Uneri A,Hernandez AM,Burkett GW,Boone JM

更新日期：2020-02-01 00:00:00

abstract：:Using stable materials capable of mimicking any soft tissues of the human body--quantitatively with respect to speed of sound, density, and attenuation coefficient and semiquantitatively with respect to scatter--we have constructed a torso section phantom containing simulated bowel gas, kidney, kidney fat pad, liver, ...

journal_title：Medical physics

authors： Madsen EL,Zagzebski JA,Ghilardi-Netto T

更新日期：1980-01-01 00:00:00

abstract：PURPOSE:Many clinical applications depend critically on the accurate differentiation and classification of different types of materials in patient anatomy. This work introduces a unified framework for accurate nonlinear material decomposition and applies it, for the first time, in the concept of triple-energy CT (TECT)...

journal_title：Medical physics

authors： Zhao W,Vernekohl D,Han F,Han B,Peng H,Yang Y,Xing L,Min JK

更新日期：2018-07-01 00:00:00

abstract：PURPOSE:The appearance of parenchymal∕stromal patterns in mammography have been characterized as having a Wiener power spectrum with an inverse power-law shape described by the exponential parameter, β. The amount of fibroglandular tissue, which can be quantified in terms of volumetric breast density (VBD), influences ...

journal_title：Medical physics

authors： Mainprize JG,Tyson AH,Yaffe MJ

更新日期：2012-08-01 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:We describe the acceptance testing, commissioning, periodic quality assurance, and workflow procedures developed for the first clinically implemented magnetic resonance imaging-guided radiation therapy (MR-IGRT) system for real-time tracking and beam control. METHODS:The system utilizes real-time cine imaging ...

journal_title：Medical physics

authors： Green OL,Rankine LJ,Cai B,Curcuru A,Kashani R,Rodriguez V,Li HH,Parikh PJ,Robinson CG,Olsen JR,Mutic S,Goddu SM,Santanam L

更新日期：2018-05-28 00:00:00

abstract：:We have reported in our previous studies on the methodology, and feasibility of 4D-PET (Gated PET) acquisition, to reduce respiratory motion artifact in PET imaging of the thorax. In this study, we expand our investigation to address the problem of respiration motion in PET/CT imaging. The respiratory motion of four l...

journal_title：Medical physics

authors： Nehmeh SA,Erdi YE,Pan T,Pevsner A,Rosenzweig KE,Yorke E,Mageras GS,Schoder H,Vernon P,Squire O,Mostafavi H,Larson SM,Humm JL

更新日期：2004-12-01 00:00:00

abstract：PURPOSE:The most appropriate method of evaluating the effective atomic number necessitates consideration of energy-dependent behavior. Previously, this required quite laborious calculation, which is why many scientists revert to over-simplistic power-law methods. The purpose of this work is to develop user-friendly sof...

journal_title：Medical physics

authors： Taylor ML,Smith RL,Dossing F,Franich RD

更新日期：2012-04-01 00:00:00

abstract：:The purpose of this work is to investigate algorithms for the delivery of intensity-modulated fields using independent collimators (IC). Two heuristic algorithms are proposed to calculate jaw-setting sequences for arbitrary 2D intensity distributions. The first algorithm is based on searching the whole intensity matri...

journal_title：Medical physics

authors： Dai JR,Hu YM

更新日期：1999-12-01 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: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：PURPOSE:High resolution three-dimensional (3D) magnetic resonance (MR) images are well suited for automated cartilage segmentation in the human knee joint. However, volumetric scans such as 3D Double-Echo Steady-State (DESS) images are not routinely acquired in clinical practice which limits opportunities for reliable ...

journal_title：Medical physics

authors： Neubert A,Bourgeat P,Wood J,Engstrom C,Chandra SS,Crozier S,Fripp J

更新日期：2020-10-01 00:00:00

abstract：PURPOSE:The authors have recently developed a cine-mode T2*/T1-weighted 4D-MRI technique and a sequential-mode T2-weighted 4D-MRI technique for imaging respiratory motion. This study aims at investigating which 4D-MRI image acquisition mode, cine or sequential, provides more accurate measurement of organ motion during ...

journal_title：Medical physics

authors： Liu Y,Yin FF,Rhee D,Cai J

更新日期：2016-01-01 00:00:00

abstract：:Results of a human observer performance study using a new ultrasound contrast-detail (CD) phantom are reported. The new phantom allows estimates of the fundamental statistical uncertainties involved in CD analysis. Results of these experiments show that observers generally considered to be "trained" require experience...

journal_title：Medical physics

authors： Hall TJ,Insana MF,Soller NM,Harrison LA

更新日期：1993-01-01 00:00:00

abstract：:A novel iterative penalized likelihood algorithm with evolutionary components for the optimization of beamlet fluences for intensity modulated radiation therapy (IMRT) is presented. This algorithm is designed to be flexible in terms of the objective function and automatically escalates dose, as long as the objective f...

journal_title：Medical physics

authors： Baydush AH,Marks LB,Das SK

更新日期：2004-08-01 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：:We report our experimental results of measurements of x-ray attenuation coefficients of aqueous solutions of a light absorbing dye, indocyanine green, and an immunoadjuvant, glycated chitosan. In the treatment of metastatic tumors in rats using a novel laser immunotherapy these solutions were administered in situ. The...

journal_title：Medical physics

authors： Xu F,Liu H,Wu X,Jiang H,Nordquist RE,Chen WR

更新日期：1999-07-01 00:00:00