High-speed photography during ultrasound illustrates potential therapeutic applications of microbubbles.

abstract：:The minimum margins required to compensate for random geometric uncertainties in the delivery of radiotherapy treatment were determined for a spherical Clinical Target Volume, using an analytic model for the cumulative dose. Margins were calculated such that the minimum dose in the target would be no less than 95% of ...

journal_title：Medical physics

authors： Witte MG,van der Geer J,Schneider C,Lebesque JV,van Herk M

更新日期：2004-11-01 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：:The Los Alamos code MCNP4A (Monte Carlo N-Particle version 4A) is currently used to simulate a variety of problems ranging from nuclear reactor analysis to boron neutron capture therapy. A graphical user interface has been developed that automatically sets up the MCNP4A geometry and radiation source requirements for a...

journal_title：Medical physics

authors： DeMarco JJ,Solberg TD,Smathers JB

更新日期：1998-01-01 00:00:00

abstract：PURPOSE:To design an efficient method for utilizing phase-space source models in the GPU-based Monte Carlo (MC) dose calculation engine gDPM. METHODS:In GPU-based MC algorithms, particles are transported in parallel on different threads. Particles of different types and energies can require significantly different exe...

journal_title：Medical physics

authors： Townson R,Jia X,Zavgorodni S,Jiang S

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:To present EBT2 film verification of treatment planning with the eXtend System, a relocatable frame system for multiple-fraction or serial multiple-session radiosurgery. METHODS:A human head shaped phantom simulated the verification process for fractionated Gamma Knife (GK) treatment. Phantom preparation for e...

journal_title：Medical physics

authors： Gopishankar N,Bisht RK

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:To perform a comprehensive and systematic comparison of fixed-beam IMRT and volumetric modulated arc therapy (VMAT) patient-specific QA measurements for a common set of geometries using typical measurement methods. METHODS:Fixed-beam IMRT and VMAT plans were constructed for structure set geometries provided by...

journal_title：Medical physics

authors： Mancuso GM,Fontenot JD,Gibbons JP,Parker BC

更新日期：2012-07-01 00:00:00

abstract：PURPOSE:Most radiation therapy optimization problems can be formulated as an unconstrained problem and solved efficiently by quasi-Newton methods such as the Limited-memory Broyden-Fletcher-Goldfarb-Shanno (L-BFGS) algorithm. However, several next generation planning techniques such as total variation regularization- b...

journal_title：Medical physics

authors： Liu X,Pelizzari C,Belcher AH,Grelewicz Z,Wiersma RD

更新日期：2017-04-01 00:00:00

abstract：PURPOSE:Anatomical variations occur during head and neck (H&N) radiotherapy treatment. kV cone-beam computed tomography (CBCT) images can be used for daily dose monitoring to assess dose variations owing to anatomic changes. Deep learning methods (DLMs) have recently been proposed to generate pseudo-CT (pCT) from CBCT ...

journal_title：Medical physics

authors： Barateau A,De Crevoisier R,Largent A,Mylona E,Perichon N,Castelli J,Chajon E,Acosta O,Simon A,Nunes JC,Lafond C

更新日期：2020-10-01 00:00:00

abstract：:In conventional dose optimization algorithms, in brachytherapy, multiple objectives are expressed in terms of an aggregating function which combines individual objective values into a single utility value, making the problem single objective, prior to optimization. A multiobjective genetic algorithm (MOGA) was develop...

journal_title：Medical physics

authors： Lahanas M,Baltas D,Zamboglou N

更新日期：1999-09-01 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: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：:A simple approach was developed that calculates the output factors and tissue maximum ratio of an asymmetric field at any point within the open field, and specifically both at the central axis (when the jaws do not shadow it) and at the effective center of the open field, using the existing tables for symmetric fields...

journal_title：Medical physics

authors： Rosenberg I,Chu JC,Saxena V

更新日期：1995-01-01 00:00:00

abstract：PURPOSE:In this study, we evaluated the degree of consistency between size metrics obtained from PEM and MRI to determine the intrinsic effectiveness of a multimodality approach using these two systems for breast imaging. METHODS:Under an IRB-approved protocol, 42 cases were considered (16 patients with 28 lesions), e...

journal_title：Medical physics

authors： Sadinski M,Giger M,Drukker K,Yamaguchi K,Lan L,Li H

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:A major challenge of four dimensional computed tomography (4DCT) in treatment planning and delivery has been the lack of respiration amplitude and phase reproducibility during image acquisition. The implementation of a prospective gating algorithm would ensure that images would be acquired only during user-spec...

journal_title：Medical physics

authors： White BM,Low DA,Zhao T,Wuenschel S,Lu W,Lamb JM,Mutic S,Bradley JD,El Naqa I

更新日期：2011-03-01 00:00:00

abstract：PURPOSE:Proton computed tomography (pCT) will enable accurate prediction of proton and ion range in a patient while providing the benefit of lower radiation exposure than in x-ray CT. The accuracy of the range prediction is essential for treatment planning in proton or ion therapy and depends upon the detector used to ...

journal_title：Medical physics

authors： Bashkirov VA,Schulte RW,Hurley RF,Johnson RP,Sadrozinski HF,Zatserklyaniy A,Plautz T,Giacometti V

更新日期：2016-02-01 00:00:00

abstract：:For diagnostic ultrasound imaging, as in computed tomography, a feature of prime importance is the detection of focal lesions of varying size and contrast (echo amplitude) from surrounding tissue. This study describes a new tissue-stimulating phantom which has been used to measure the threshold detection of varying co...

journal_title：Medical physics

authors： Smith SW,Lopez H

更新日期：1982-01-01 00:00:00

abstract：PURPOSE:The purpose of this study is to quantify the change in monthly VMAT quality assurance (QA) and determine the tests to maintain consistent delivery with a baseline. METHODS:VMAT monthly QA has been performed for over 14 months on two Elekta Synergy LINACs. A baseline was established at acceptance and the monthl...

journal_title：Medical physics

authors： Stenbeck J,Oves S,Gebreamlak W,Alkhatib H

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:Current on-board imaging systems commonly used by modern linear accelerators (LINACs) have a limited field of view (FOV) for a cone-beam CT (CBCT) scan, which is typically less than 50 cm. Consequently, truncation artifacts often occur for large patients. The goal of this work is to investigate a novel method t...

journal_title：Medical physics

authors： Li T,Li X,Yang Y,Heron DE,Huq MS

更新日期：2010-12-01 00:00:00

abstract：PURPOSE:Periprocedural assessment of tissue perfusion by imaging methods could improve outcome control during treatment of peripheral vascular disease. Currently, endovascular revascularization treatments are assessed by planar angiography which only allows for qualitative inspection of blood flow in vessels. In this p...

journal_title：Medical physics

authors： Giordano M,Vonken EJ,Bertram M,Mali W,Viergever MA,Neukirchen C

更新日期：2012-03-01 00:00:00

abstract：PURPOSE:The dosimetric advantage of particle therapy comes with a much higher infrastructure investment and operation costs. Increasing patient throughput is a key factor to manage operation costs. We investigate the impact of variable beam spot sizes on treatment time and discuss the tradeoffs involved. METHODS:The f...

journal_title：Medical physics

authors： Riofrio D,Sellner S,Cabal G,Keyes R,Holzscheiter M,Jaekel O,Luan S

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:In Stereotactic body radiation therapy (SBRT) higher dose per fraction is delivered to patients and thus the need for an accurate dose computation is further elevated. However under such conditions of small field geometries, the electronic equilibrium can be lost, making it challenging for the dose-calculation ...

journal_title：Medical physics

authors： Shosha M,Deiab N,Eldib A,Tohamy K

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:Periodic MV∕KV radiographs taken during volumetric modulated arc therapy (VMAT) for hypofractionated treatment provide guidance in intrafractional motion management. The choice of imaging frequency and timing are key components in delivering the desired dose while reducing associated overhead such as imaging do...

journal_title：Medical physics

authors： Zhang P,Hunt M,Happersett L,Cox B,Mageras G

更新日期：2012-09-01 00:00:00

abstract：:Modern radiotherapy linacs often use carbon fibre for their couch tops due to its radio translucent properties. Beam attenuation by the couches is often ignored during planning and MU calculation. This work examines beam attenuation and loss of "skin sparing" (dose build up region) when various photon beams transit ei...

journal_title：Medical physics

authors： Niedbala M,Nyiri B,Gerig L

更新日期：2008-07-01 00:00:00

abstract：:We have reexamined the problem of estimating the luminal area of an elliptically shaped coronary artery cross section from two or more radiographic diameter measurements. The expected error is found to be much smaller than the maximum potential error. In the cases of two orthogonal views, closed form expressions have ...

journal_title：Medical physics

authors： Lee PL,Selzer RH

更新日期：1988-07-01 00:00:00

abstract：PURPOSE:Episcleral eye plaque brachytherapy has been utilized in the treatment of intra-ocular malignancies, delivering large prescription doses to the apex of the tumor. Advances in dose calculation and image guidance, via calibrated fundus images, enable localization of the tumor and determination of dose to the macu...

journal_title：Medical physics

authors： Guida K,Niermann K,Malcolm A,Sternberg P,Munn G,Coffey C

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:Megavoltage grid therapy is currently delivered with step-and-shoot multisegment techniques or using a high attenuation block with divergent holes. However, the commercial availability of grid blocks is limited, their construction is difficult, and step-and-shoot techniques require longer treatment times and ar...

journal_title：Medical physics

authors： Almendral P,Mancha PJ,Roberto D

更新日期：2013-05-01 00:00:00

abstract：PURPOSE:Onboard imaging-currently performed primarily by x-ray transmission modalities-is essential in modern radiation therapy. As radiation therapy moves toward personalized medicine, molecular imaging, which views individual gene expression, may also be important onboard. Nuclear medicine methods, such as single pho...

journal_title：Medical physics

authors： Bowsher J,Yan S,Roper J,Giles W,Yin FF

更新日期：2014-01-01 00:00:00

abstract：:A system for measuring two-dimensional (2D) dose distributions in orthogonal anatomical planes in the cranium was developed and used to evaluate the accuracy of coplanar conformal therapy using ExacTrac image guidance. Dose distributions were measured in the axial, sagittal, and coronal planes using a CIRS (Computeriz...

journal_title：Medical physics

authors： Vinci JP,Hogstrom KR,Neck DW

更新日期：2008-08-01 00:00:00

abstract：PURPOSE:The collimator monitoring fill factor (CM-FF) introduced by Stelljes et al. (2017) and the FWHM fill factor (FWHM-FF) introduced by Gago-Arias et al. (2012) were determined using the measured photon fluence response functions of various 2D-arrays. The error detection capabilities of 2D-arrays were studied by co...

journal_title：Medical physics

authors： Stelljes TS,Poppinga D,Kretschmer J,Brodbek L,Looe HK,Poppe B

更新日期：2019-04-01 00:00:00

abstract：:The mixed-field dosimetry for 252Cf Applicator Tube (AT) type medical sources available from Oak Ridge National Laboratory (ORNL) has been characterized using ionization chambers, a GM counter, and Monte Carlo methods. Unlike the AAPM Task Group No. 43 (TG-43), specification of dose to muscle instead of water is recom...

journal_title：Medical physics

authors： Rivard MJ

更新日期：1999-08-01 00:00:00