Application of spherical diodes for megavoltage photon beams dosimetry.

abstract：PURPOSE:To overcome the problem of organ motion in intensity-modulated radiation therapy (IMRT), gated IMRT is often used for the treatment of lung cancer. In this study, the authors investigated the accuracy of the delivered monitor units (MUs) from each segment during gated IMRT using a two-dimensional detector array...

journal_title：Medical physics

authors： Cheong KH,Kang SK,Lee M,Kim SS,Park S,Hwang TJ,Kim KJ,Oh DH,Bae H,Suh TS

更新日期：2010-03-01 00:00:00

abstract：PURPOSE:To develop a hypothesis-generating framework for automatic extraction of dose-outcome relationships from an in-house, analytic oncology database. METHODS:Dose-volume histograms (DVH) and clinical outcomes have been routinely stored to the authors' database for 684 head and neck cancer patients treated from 200...

journal_title：Medical physics

authors： Robertson SP,Quon H,Kiess AP,Moore JA,Yang W,Cheng Z,Afonso S,Allen M,Richardson M,Choflet A,Sharabi A,McNutt TR

更新日期：2015-07-01 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:An improved method of image guidance for lung tumor biopsies could help reduce the high rate of false negatives. The aim of this work is to optimize the geometry of the scanning-beam digital tomography system (SBDX) for providing real-time 3D tomographic reconstructions for target verification. The unique geome...

journal_title：Medical physics

authors： Nelson G,Yoon S,Krishna G,Wilfley B,Fahrig R

更新日期：2013-11-01 00:00:00

abstract：PURPOSE:Cone beam computed tomography (CBCT) image quality suffers from contamination from scattered photons in the projection images. Monte Carlo simulations are a powerful tool to investigate the properties of scattered photons.egs_cbct, a recent EGSnrc user code, provides the ability of performing fast scatter calcu...

journal_title：Medical physics

authors： Thing RS,Mainegra-Hing E

更新日期：2014-07-01 00:00:00

abstract：PURPOSE:Radiation treatments are trending toward delivering higher doses per fraction under stereotactic radiosurgery and hypofractionated treatment regimens. There is a need for accurate 3D in vivo patient dose verification using electronic portal imaging device (EPID) measurements. This work presents a model-based te...

journal_title：Medical physics

authors： Van Uytven E,Van Beek T,McCowan PM,Chytyk-Praznik K,Greer PB,McCurdy BM

更新日期：2015-12-01 00:00:00

abstract：PURPOSE:To evaluate plan quality of a novel MRI-compatible direction modulated brachytherapy (DMBT) tandem applicator using 192 Ir, 60 Co, and 169 Yb HDR brachytherapy sources, for various cervical cancer high-risk clinical target volumes (CTVHR ). MATERIALS AND METHODS:The novel DMBT tandem applicator has six periphe...

journal_title：Medical physics

authors： Safigholi H,Han DY,Mashouf S,Soliman A,Meigooni AS,Owrangi A,Song WY

更新日期：2017-12-01 00:00:00

abstract：:Deformable image registration is an important tool for image-guided radiotherapy. Physics-model-based deformable image registration using finite element analysis is one of the methods currently being investigated. The calculation accuracy of finite element analysis is dependent on given boundary conditions, which are ...

journal_title：Medical physics

authors： Zhang T,Orton NP,Mackie TR,Paliwal BR

更新日期：2004-09-01 00:00:00

abstract：:Measurements of a 670-MeV/amu 20Ne beam at the Lawrence Berkeley Laboratory Bevalac heavy-ion accelerator with various thicknesses of water absorber were obtained with the BERKLET. The BERKLET, a simple three-stage solid-state telescope detector, has been described previously. This instrument measures the linear energ...

journal_title：Medical physics

authors： Llacer J,Schmidt JB,Tobias CA

更新日期：1990-03-01 00:00:00

abstract：PURPOSE:Flattening filter free (FFF) beams generated by medical linear accelerators have recently started to be used in radiotherapy clinical practice. Such beams present fundamental differences with respect to the standard filter flattened (FF) beams, making the generally used dosimetric parameters and definitions not...

journal_title：Medical physics

authors： Fogliata A,Garcia R,Knoos T,Nicolini G,Clivio A,Vanetti E,Khamphan C,Cozzi L

更新日期：2012-10-01 00:00:00

abstract：PURPOSE:Scatter is a major factor degrading the image quality of cone beam computed tomography (CBCT). Conventional scatter correction strategies require handcrafted analytical models with ad hoc assumptions, which often leads to less accurate scatter removal. This study aims to develop an effective scatter correction ...

journal_title：Medical physics

authors： Nomura Y,Xu Q,Shirato H,Shimizu S,Xing L

更新日期：2019-07-01 00:00:00

abstract：PURPOSE:To design a fast Winston Lutz (fWL) algorithm for accurate analysis of radiation isocenter from images without edge detection or center of mass calculations. METHODS:An algorithm has been developed to implement the Winston Lutz test for mechanical/ radiation isocenter agreement using an electronic portal imagi...

journal_title：Medical physics

authors： Winey B,Sharp G,Bussière M

更新日期：2011-01-01 00:00:00

abstract：:Coherent-scatter computed tomography (CSCT) is a novel imaging method we are developing to produce cross-sectional images based on the low-angle (<10 degrees) scatter properties of tissue. At diagnostic energies, this scatter is primarily coherent with properties dependent upon the molecular structure of the scatterer...

journal_title：Medical physics

authors： Batchelar DL,Cunningham IA

更新日期：2002-08-01 00:00:00

abstract：:Intrafraction organ motion can limit the advantage of highly conformal dose techniques such as intensity modulated radiation therapy (IMRT) due to target position uncertainty. To ensure high accuracy in beam targeting, real-time knowledge of the target location is highly desired throughout the beam delivery process. T...

journal_title：Medical physics

authors： Mao W,Wiersma RD,Xing L

更新日期：2008-05-01 00:00:00

abstract：PURPOSE:In the past decade, phase-contrast imaging (PCI) has been applied to study different kinds of tissues and human body parts, with an increased improvement of the image quality with respect to simple absorption radiography. A technique closely related to PCI is phase-retrieval imaging (PRI). Indeed, PCI is an ima...

journal_title：Medical physics

authors： De Caro L,Scattarella F,Giannini C,Tangaro S,Rigon L,Longo R,Bellotti R

更新日期：2010-07-01 00:00:00

abstract：:Encapsulated, cylindrical sources containing 2, 5, and 8 Ci of 241Am have been designed and fabricated for intracavitary irradiation of uterine cancers. Exposure rates in air and dose rates in water around these sources have been measured using an ionization chamber and a lithium fluoride thermoluminescent dosimetry s...

journal_title：Medical physics

authors： Nath R,Gray L,Park CH

更新日期：1987-09-01 00:00:00

abstract：:Recent absorbed-dose-based protocols allow for two methods of calibrating electron beams using plane-parallel chambers, one using the N(Co)D,w for a plane-parallel chamber, and the other relying on cross-calibration of the plane-parallel chamber in a high-energy electron beam against a cylindrical chamber which has an...

journal_title：Medical physics

authors： Stewart KJ,Seuntjens JP

更新日期：2002-03-01 00:00:00

abstract：PURPOSE:To propose a method to calculate the tissue phantom ratio (TPR) using the depth dose and to compare the proposed method with two other methods. METHODS:An analytical dose model from Bjärngard was used to describe the depth dose and the TPR. The parameters of the model were derived from depth dose measurements,...

journal_title：Medical physics

authors： Ramos Garcia LI,Almansa JF

更新日期：2011-05-01 00:00:00

abstract：PURPOSE:We investigated the feasibility of using simpler methods than manual whole-organ volume-of-interest (VOI) definition to estimate the organ activity concentration in single photon emission computed tomography (SPECT) in cases where the activity in the organ can be assumed to be uniformly distributed on the scale...

journal_title：Medical physics

authors： Vicente EM,Lodge MA,Rowe SP,Wahl RL,Frey EC

更新日期：2017-05-01 00:00:00

abstract：:The output factor for a therapy photon beam is defined as the dose per monitor unit relative to the dose per monitor unit in a reference field. Convolution models for photon dose calculations yield the dose in units normalized to the incident energy fluence with phantom scatter intrinsically modeled. Output factors ca...

journal_title：Medical physics

authors： Ahnesjö A,Knöös T,Montelius A

更新日期：1992-03-01 00:00:00

abstract：PURPOSE:Mega-voltage cone-beam CT (MVCBCT) imaging can be used to monitor changes in neck flexion and calculate the true spinal cord dose during radiotherapy. To sum the dose over multiple fractions and compare with the planned dose requires deformable image registration. This study investigates the accuracy of deforma...

journal_title：Medical physics

authors： Ueda U,Chen J,Kirby N,Quivey J,Yom S,Pouliot J

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:In photon radiotherapy, respiratory-induced target motion can be accounted for by internal target volumes (ITV) or mid-ventilation target volumes (midV) defined on the basis of four-dimensional computed tomography (4D-CT). Intrinsic limitations of these approaches can result in target volumes that are not repre...

journal_title：Medical physics

authors： Rabe M,Thieke C,Düsberg M,Neppl S,Gerum S,Reiner M,Nicolay NH,Schlemmer HP,Debus J,Dinkel J,Landry G,Parodi K,Belka C,Kurz C,Kamp F

更新日期：2020-04-01 00:00:00

abstract：PURPOSE:Currently, only iodine- and barium-based contrast media (CM) are used in clinical contrast-enhanced computed tomography (CE-CT). High-Z metals would produce a higher contrast at equal mass density for the x-ray spectra used in clinical CT. Using such materials might allow for significant dose reductions in CE-C...

journal_title：Medical physics

authors： Nowak T,Hupfer M,Brauweiler R,Eisa F,Kalender WA

更新日期：2011-12-01 00:00:00

abstract：:Transthoracic electrical impedance Z consists of a constant baseline component Z0 and the time variable component delta Z such that Z = Z0 + delta Z. The first time derivative of Z has a negative peak, the magnitude of which is (dZ/dt)min. Measurements of 170 volunteers show that (dZ/dt)min is a function of the consta...

journal_title：Medical physics

authors： Djordjevich L,Sadove MS

更新日期：1981-01-01 00:00:00

abstract：PURPOSE:High-Z material in computed tomography (CT) yields metal artifacts that degrade image quality and may cause substantial errors in dose calculation. This study couples a metal artifact reduction (MAR) algorithm with enhanced 16-bit depth (vs standard 12-bit) to quantify potential gains in image quality and dosim...

journal_title：Medical physics

authors： Glide-Hurst C,Chen D,Zhong H,Chetty IJ

更新日期：2013-06-01 00:00:00

abstract：PURPOSE:Coronary x-ray computed tomography angiography (CCTA) is used to non-invasively assess coronary artery geometry and has, combined with computational modeling, demonstrated the potential to identify physiologically significant lesions. These measurements require robust and accurate coronary imaging and delineati...

journal_title：Medical physics

authors： Contijoch F,Stayman JW,McVeigh ER

更新日期：2017-07-01 00:00:00

abstract：PURPOSE:To quantitatively characterize the interfractional anatomic variations in post-operative radiation therapy (RT) for prostate bed, so that appropriate strategy that can fully address these variations can be developed. METHODS:A total of 102 daily pre-treatment CT acquired using an in-room CT (CTVision, Siemens)...

journal_title：Medical physics

authors： Liu F,Ahunbay E,Christian R,Lawton C,Wang D,Li X

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:The authors investigated the performance of a recently introduced 160-mm/256-row CT system for low dose quantitative myocardial perfusion (MP) imaging of the whole heart. This platform is equipped with a gantry capable of rotating at 280 ms per full cycle, a second generation of adaptive statistical iterative r...

journal_title：Medical physics

authors： So A,Imai Y,Nett B,Jackson J,Nett L,Hsieh J,Wisenberg G,Teefy P,Yadegari A,Islam A,Lee TY

更新日期：2016-08-01 00:00:00

abstract：PURPOSE:Consistency verification between the data from treatment planning system (TPS), record and verification system (R&V), and delivered recorder with visual inspection is time consuming and subject to human error. The purpose of this work is to develop a software tool to automatically perform such verifications. M...

journal_title：Medical physics

authors： Chen G,Li X

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:This paper describes the low-kV spectral optimization of dual-energy CT (DECT) equipped with high-kV tin filtration for the quantitative acquisition of electron density information, which is essential for treatment planning in radiotherapy. In addition, an analytical DECT image simulation was preliminarily perf...

journal_title：Medical physics

authors： Saito M

更新日期：2011-06-01 00:00:00