The effects of motion on quantitative vessel measurements.

abstract：PURPOSE:Measured values of ultrasound attenuation in bone represent a combination of different loss mechanisms. As a wave is transmitted from a fluid into bone, reflections occur at the interface. In the bone, mode conversion occurs between longitudinal and shear modes and the mechanical wave is scattered by its comple...

journal_title：Medical physics

authors： Pinton G,Aubry JF,Bossy E,Muller M,Pernot M,Tanter M

更新日期：2012-01-01 00:00:00

abstract：PURPOSE:The efficiency of radioembolization procedures could be greatly enhanced if results of the 99m Tc-MAA pretreatment procedure were immediately available in the interventional suite, enabling 1-day procedures as a result of direct estimation of the hepatic radiation dose and lung shunt fraction. This would, howev...

journal_title：Medical physics

authors： van der Velden S,Dietze MMA,Viergever MA,de Jong HWAM

更新日期：2019-01-01 00:00:00

abstract：PURPOSE:Brachytherapy is a treatment modality which delivers large doses of radiation in a reduced number of visits. Since a small number of large dose-per-fraction is administered in high dose rate brachytherapy, ensuring the right dose is delivered is highly critical. In this work, a scintillation detector is coupled...

journal_title：Medical physics

authors： Tho D,Beaulieu L

更新日期：2019-05-01 00:00:00

abstract：:One of the methods currently being used to treat choroidal melanoma employs an episcleral plaque containing I-125 radioactive seeds. However, comprehensive dosimetry studies on the plaque are scarce and controversial. For this work, we use film to study the dosimetry outside the lip of the gold shield of the eye plaqu...

journal_title：Medical physics

authors： Wu A,Krasin F

更新日期：1990-09-01 00:00:00

abstract：:The aim of the current study was to (a) provide normalized dose data for the estimation of the radiation dose from upper gastrointestinal tract contrast (UGIC) studies carried out to infants and (b) estimate the average patient dose and risks associated with radiation from UGIC examinations performed in our institutio...

journal_title：Medical physics

authors： Damilakis J,Stratakis J,Raissaki M,Perisinakis K,Kourbetis N,Gourtsoyiannis N

更新日期：2006-04-01 00:00:00

abstract：PURPOSE:Photoacoustic imaging has proven to be able to detect vascularization-driven optical absorption contrast associated with tumors. In order to detect breast tumors located a few centimeter deep in tissue, a sensitive ultrasound detector is of crucial importance for photoacoustic mammography. Further, because the ...

journal_title：Medical physics

authors： Xia W,Piras D,van Hespen JC,van Veldhoven S,Prins C,van Leeuwen TG,Steenbergen W,Manohar S

更新日期：2013-03-01 00:00:00

abstract：:Coherent scattering of x-ray photons leads to the phenomenon of x-ray diffraction, which is widely used for determining atomic structure in materials science. A technique [x-ray diffraction computed tomography (CT)] is described, analogous to conventional CT, in which the x-ray diffraction properties of a stack of two...

journal_title：Medical physics

authors： Harding G,Kosanetzky J,Neitzel U

更新日期：1987-07-01 00:00:00

abstract：:Cone beam computed tomography (CBCT) is a relatively new patient imaging technique that has proved invaluable for treatment target verification and patient positioning during image-guided radiotherapy (IGRT). It has been shown that CBCT results in additional dose to bone that may amount to 10% of the prescribed dose. ...

journal_title：Medical physics

authors： Walters BR,Ding GX,Kramer R,Kawrakow I

更新日期：2009-07-01 00:00:00

abstract：:A method is developed to smooth intensity-modulated beam delivery while considering hardware constraints. The method uses matrix algebra to model MLC leaf motion and hardware constraints such as interleaf digitization, synchronization requirements, and intersegment field abutment to deliver intensity modulated beam se...

journal_title：Medical physics

authors： Ma L

更新日期：2002-12-01 00:00:00

abstract：:IMRT treatment plans for step-and-shoot delivery have traditionally been produced through the optimization of intensity distributions (or maps) for each beam angle. The optimization step is followed by the application of a leaf-sequencing algorithm that translates each intensity map into a set of deliverable aperture ...

journal_title：Medical physics

authors： Shepard DM,Earl MA,Li XA,Naqvi S,Yu C

更新日期：2002-06-01 00:00:00

abstract：:The ability to control thermal drifts is essential in operating a calorimeter. We investigated a thermal enclosure, which envelops the calorimeter with temperature-regulated air, thus thermally isolating the calorimeter from the room. The desired temperature in the enclosure is controlled by a control circuit and a th...

journal_title：Medical physics

authors： Kubo H,Brown DE,Russell MD

更新日期：1985-05-01 00:00:00

abstract：:Spectrally resolved bioluminescence optical tomography is an approach to recover images of, for example, Luciferase activity within a volume using multiwavelength emission data from internal bioluminescence sources. The underlying problem of uniqueness associated with nonspectrally resolved intensity-based bioluminesc...

journal_title：Medical physics

authors： Dehghani H,Davis SC,Pogue BW

更新日期：2008-11-01 00:00:00

abstract：:We adapted a small sodium iodide scintillation detector for rapid, in vivo localization of a lost brachytherapy seed. Using the detector, we were able to locate and remove an Ir-192 seed that was not visible to the unaided eye. ...

journal_title：Medical physics

authors： Woolfenden JM,Barber HB,Oleson JR,Wild WJ

更新日期：1984-07-01 00:00:00

abstract：PURPOSE:The primary objective of this work is to measure the secondary neutron field produced by an uncollimated proton pencil beam impinging on different tissue-equivalent phantom materials using organic scintillation detectors. Additionally, the Monte Carlo code mcnpx-PoliMi was used to simulate the detector response...

journal_title：Medical physics

authors： Clarke SD,Pryser E,Wieger BM,Pozzi SA,Haelg RA,Bashkirov VA,Schulte RW

更新日期：2016-11-01 00:00:00

abstract：:Anatomy-based positron emission tomography (PET) image enhancement techniques have been shown to have the potential for improving PET image quality. However, these techniques assume an accurate alignment between the anatomical and the functional images, which is not always valid when imaging the chest due to respirato...

journal_title：Medical physics

authors： Qiao F,Pan T,Clark JW Jr,Mawlawi O

更新日期：2007-12-01 00:00:00

abstract：:The authors are investigating the concept of a direct-conversion flat-panel imager with avalanche gain for low-dose x-ray imaging. It consists of an amorphous selenium (a-Se) photoconductor partitioned into a thick drift region for x-ray-to-charge conversion and a relatively thin region called high-gain avalanche rush...

journal_title：Medical physics

authors： Wronski MM,Rowlands JA

更新日期：2008-12-01 00:00:00

abstract：:MR acoustic radiation force (ARF) imaging was developed for measuring tiSsue elastic properties using focused ultrasound to deliver a localized tissue motion. In this study, an imaging ultrasound transducer was mounted on the focused ultrasound transducer and ultrasound motion tracking was performed simultaneously to ...

journal_title：Medical physics

authors： Huang Y,Curiel L,Kukic A,Plewes DB,Chopra R,Hynynen K

更新日期：2009-06-01 00:00:00

abstract：PURPOSE:An electrically floating radio frequency (RF) shielded PET insert with individual PET detectors shielded by separate Faraday cages enables the MRI built-in body RF coil to be used at least as an RF transmitter, in which the RF field penetrates the imaging region inside the PET ring through the narrow gaps betwe...

journal_title：Medical physics

authors： Akram MSH,Levin CS,Obata T,Hirumi G,Yamaya T

更新日期：2018-10-01 00:00:00

abstract：:The concept of equivalent uniform dose (EUD) has been suggested as a means to quantitatively consider heterogeneous dose distributions within targets. Tumor cell density/function is typically assumed to be uniform. We herein propose to use 18F-labeled 2-deoxyglucose (FDG) positron emission tomography (PET) tumor imagi...

journal_title：Medical physics

authors： Zhou SM,Wong TZ,Marks LB

更新日期：2004-09-01 00:00:00

abstract：PURPOSE:Integrating a linac with a magnetic resonance imager (MRI) will revolutionize the accuracy of external beam radiation treatments. Irradiating in the presence of a strong magnetic field, however, will modify the dose distribution. These dose modifications have been investigated previously, mainly using Monte Car...

journal_title：Medical physics

authors： Ghila A,Steciw S,Fallone BG,Rathee S

更新日期：2017-09-01 00:00:00

abstract：PURPOSE:To develop and validate a multivariate statistical method to optimize scanning parameters for material quantification in spectral x-rayimaging. METHODS:An optimization metric was constructed by extensively sampling the thickness space for the expected number of counts for m (two or three) materials. This resul...

journal_title：Medical physics

authors： Nik SJ,Thing RS,Watts R,Meyer J

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:Real-time tumor position/shape measurement and dynamic beam tracking techniques allow accurate and continuous irradiation to moving tumor, but there can be a delay of several hundred milliseconds between observation and irradiation. A time-variant seasonal autoregressive (TVSAR) model has been proposed for comp...

journal_title：Medical physics

authors： Ichiji K,Homma N,Sakai M,Narita Y,Takai Y,Yoshizawa M

更新日期：2012-06-01 00:00:00

abstract：:A formulation of the single energy photon transport problem is cast in the form of a series of convolutions over the primary fluence distribution with invariant kernels. A method is developed for compensating for the variant intervoxel attenuation in the scattered dose distribution by means of an invariant correction ...

journal_title：Medical physics

authors： Boyer AL,Mok EC

更新日期：1986-07-01 00:00:00

abstract：:Various techniques have been developed to localize radioactive sources in brachytherapy implants. The most common methods include the orthogonal film method, the stereo-shift film method, and recently, direct localization from a series of contiguous CT transverse images. The major advantage of the CT method is that it...

journal_title：Medical physics

authors： Yue N,Chen Z,Bond JE,Son YH,Nath R

更新日期：1999-04-01 00:00:00

abstract：PURPOSE:To measure patient-specific maximum skin dose (MSD) associated with CT fluoroscopy (CTF) lung biopsies and to compare measured MSD with the MSD estimated from phantom measurements, as well as with the CTDIvol of patient examinations. METHODS:Data from 50 patients with lung lesions who underwent a CT fluoroscop...

journal_title：Medical physics

authors： Zanca F,Jacobs A,Crijns W,De Wever W

更新日期：2014-07-01 00:00:00

abstract：PURPOSE:Radiochromic film provides dose measurement at high spatial resolution, but often is not preferred for routine evaluation of patient-specific intensity modulated radiation therapy (IMRT) plans owing to ease-of-use factors. The authors have established an efficient protocol that combines calibration and measurem...

journal_title：Medical physics

authors： Lewis D,Micke A,Yu X,Chan MF

更新日期：2012-10-01 00:00:00

abstract：PURPOSE:We propose a new method for efficient particle transportation in voxelized geometry for Monte Carlo simulations. We describe its use for calculating dose distribution in CT images for radiation therapy. MATERIAL AND METHODS:The proposed approach, based on an implicit volume representation named segmented volum...

journal_title：Medical physics

authors： Sarrut D,Guigues L

更新日期：2008-04-01 00:00:00

abstract：:Variations in the atomic composition, and mass and electron densities of polystyrene and polymethylmethacrylate (PMM) plastics were assessed from experimentally determined mass attenuation coefficients for 125I and 137Cs gamma rays. The means and standard deviations in the mass densities of 16 samples of PMM and 10 sa...

journal_title：Medical physics

authors： Schulz RJ,Nath R

更新日期：1979-03-01 00:00:00

abstract：PURPOSE:Low-dose CT has attracted increasing attention due to growing concerns about radiation exposure in medical scans. However, the frugal use of x-ray radiation inevitably reduces the quality of the CT images, introducing artifacts such as noise and streaks which make the reconstructed images difficult to read in c...

journal_title：Medical physics

authors： Xu W,Mueller K

更新日期：2012-08-01 00:00:00

abstract：PURPOSE:Researchers write many computer programs with unique implementations, usually requiring a great amount of effort for other researchers to learn how to install, configure, and use. Some programs require specialized hardware platforms such as GPU workstation or CPU cluster, which may not readily available for man...

journal_title：Medical physics

authors： Folkerts M,Graves Y,Gautier Q,Kim G,Jia X,Jiang S

更新日期：2012-06-01 00:00:00