Pitch dependence of longitudinal sampling and aliasing effects in multi-slice helical computed tomography (CT).

abstract：:A method to determine the spectrum of a clinical photon beam from measured depth-dose data is described. At shallow depths, where the range of Compton-generated electrons increases rapidly with photon energy, the depth dose provides the information to discriminate the spectral contributions. To minimize the influence ...

journal_title：Physics in medicine and biology

authors： Bloch P,Altschuler MD,Bjärngard BE,Kassaee A,McDonough J

更新日期：2000-01-01 00:00:00

abstract：:Input functions required for positron emission tomography (PET) tracer kinetic modeling are often obtained from arterial blood. In some situations, using short-lived radiotracers, e.g. [(15)O]water, rapid sample handling is required. A method used at several facilities is to pump blood through a detector system at a c...

journal_title：Physics in medicine and biology

authors： Laymon CM,Sashin D,Carney JP,Ruszkiewicz J,Altenburger D,Becker CR,Lopresti BJ,Mason NS,Mountz JM,Price JC,Schavey R,Mathis CA

更新日期：2008-01-21 00:00:00

abstract：:Ion beam therapy offers the possibility of a highly conformal tumor-dose distribution; however, this technique is extremely sensitive to inaccuracies in the treatment procedures. Ambiguities in the conversion of Hounsfield units of the treatment planning x-ray CT to relative stopping power (RSP) can cause uncertaintie...

journal_title：Physics in medicine and biology

authors： Meyer S,Gianoli C,Magallanes L,Kopp B,Tessonnier T,Landry G,Dedes G,Voss B,Parodi K

更新日期：2017-02-07 00:00:00

abstract：:Although x-ray mammography is widely developed for breast tumour detection, it suffers from spatial superposition in its two-dimensional (2D) representation of a three-dimensional (3D) breast structure. Accordingly, 3D breast imaging, such as cone-beam computed tomography (CT), arises at the historic moment. In this p...

journal_title：Physics in medicine and biology

authors： Chen Z,Ning R

更新日期：2003-07-21 00:00:00

abstract：:When dosimetric effects in time-dependent geometries are studied, usually either the results of individual three-dimensional (3D) calculations are combined or probability-based approaches are applied. These methods may become cumbersome and time-consuming if high time resolution is required or if the geometry is compl...

journal_title：Physics in medicine and biology

authors： Paganetti H,Jiang H,Trofimov A

更新日期：2005-03-07 00:00:00

abstract：:Optical experiments are described for measuring the attenuation characteristics of breast tissues at visible and near-infrared wavelengths. Total attenuation coefficients post mortem were measured directly in thin tissue sections. They are usually within the range from 10 to 30 mm-1, are rather higher in fat than in f...

journal_title：Physics in medicine and biology

authors： Key H,Davies ER,Jackson PC,Wells PN

更新日期：1991-05-01 00:00:00

abstract：:The aim of this paper is to determine the dosimetric impact of trace elements in human tissues for low-energy photon sources used in brachytherapy. Monte Carlo dose calculations were used to investigate the dosimetric effect of trace elements present in normal or cancerous human tissues. The effect of individual trace...

journal_title：Physics in medicine and biology

authors： White SA,Landry G,van Gils F,Verhaegen F,Reniers B

更新日期：2012-06-07 00:00:00

abstract：:The purpose of this work was to characterize expert variation in segmentation of intracranial structures pertinent to radiation therapy, and to assess a registration-driven atlas-based segmentation algorithm in that context. Eight experts were recruited to segment the brainstem, optic chiasm, optic nerves, and eyes, o...

journal_title：Physics in medicine and biology

authors： Deeley MA,Chen A,Datteri R,Noble JH,Cmelak AJ,Donnelly EF,Malcolm AW,Moretti L,Jaboin J,Niermann K,Yang ES,Yu DS,Yei F,Koyama T,Ding GX,Dawant BM

更新日期：2011-07-21 00:00:00

abstract：:In modern radiotherapy the verification of complex treatments plans is often performed in inhomogeneous or even anthropomorphic phantoms. For dose verification small detectors are necessary and therefore alanine detectors are most suitable. Though the response of alanine for a wide range of clinical photon energies in...

journal_title：Physics in medicine and biology

authors： von Voigts-Rhetz P,Anton M,Vorwerk H,Zink K

更新日期：2016-02-07 00:00:00

abstract：:The purpose of this work was to use Monte Carlo simulations to verify the accuracy of the dose distributions from a commercial treatment planning optimization system (Corvus, Nomos Corp., Sewickley, PA) for intensity-modulated radiotherapy (IMRT). A Monte Carlo treatment planning system has been implemented clinically...

journal_title：Physics in medicine and biology

authors： Ma CM,Pawlicki T,Jiang SB,Li JS,Deng J,Mok E,Kapur A,Xing L,Ma L,Boyer AL

更新日期：2000-09-01 00:00:00

abstract：:The use of deformable image registration methods in the context of adaptive radiotherapy leads to uncertainties in the simulation of the administered dose distributions during the treatment course. Evaluation of these methods is a prerequisite to decide if a plan adaptation will improve the individual treatment. Curre...

journal_title：Physics in medicine and biology

authors： Teske H,Bartelheimer K,Meis J,Bendl R,Stoiber EM,Giske K

更新日期：2017-06-21 00:00:00

abstract：:This work aims at developing a generic virtual source model (VSM) preserving all existing correlations between variables stored in a Monte Carlo pre-computed phase space (PS) file, for dose calculation and high-resolution portal image prediction. The reference PS file was calculated using the PENELOPE code, after the ...

journal_title：Physics in medicine and biology

authors： Chabert I,Barat E,Dautremer T,Montagu T,Agelou M,Croc de Suray A,Garcia-Hernandez JC,Gempp S,Benkreira M,de Carlan L,Lazaro D

更新日期：2016-07-21 00:00:00

abstract：:Diffuse optical tomography is an imaging technique whereby spatial maps of absorption and scattering coefficients are derived from the characteristics of multiply scattered light transmitted through the object. The system described here used four intensity-modulated light sources and measurements of the intensity and ...

journal_title：Physics in medicine and biology

authors： Pogue BW,Patterson MS,Jiang H,Paulsen KD

更新日期：1995-10-01 00:00:00

abstract：:The purpose of this study is to evaluate a new method to improve performance of computer-aided detection (CAD) schemes of screening mammograms with two approaches. In the first approach, we developed a new case based CAD scheme using a set of optimally selected global mammographic density, texture, spiculation, and st...

journal_title：Physics in medicine and biology

authors： Tan M,Aghaei F,Wang Y,Zheng B

更新日期：2017-01-21 00:00:00

abstract：:The first trimester fetal ultrasound scan is important to confirm fetal viability, to estimate the gestational age of the fetus, and to detect fetal anomalies early in pregnancy. First trimester ultrasound images have a different appearance than for the second trimester scan, reflecting the different stage of fetal de...

journal_title：Physics in medicine and biology

authors： Ryou H,Yaqub M,Cavallaro A,Papageorghiou AT,Alison Noble J

更新日期：2019-09-17 00:00:00

abstract：:Accurate scatter correction is especially important for high-resolution 3D positron emission tomographies (PETs) such as high-resolution research tomograph (HRRT) due to large scatter fraction in the data. To address this problem, a fully 3D iterative scatter-corrected ordered subset expectation maximization (OSEM) in...

journal_title：Physics in medicine and biology

authors： Kim KS,Ye JC

更新日期：2011-08-07 00:00:00

abstract：:In this study, an induced electric field in a human body is evaluated for the magnetic field leaked from a wireless power transfer system for charging an electrical vehicle. The magnetic field from the wireless power transfer system is modelled computationally, and its effectiveness is confirmed by comparison with the...

journal_title：Physics in medicine and biology

authors： Laakso I,Hirata A

更新日期：2013-11-07 00:00:00

abstract：:Ion chamber dosimetry requires a high degree of precision, at all steps within the dosimetric process, in order to ensure accurate dose measurements. This work presents a novel technique for ion chamber volume determination and quality assurance, using micro-computed tomography (micro-CT). Four nominally identical Exr...

journal_title：Physics in medicine and biology

authors： McNiven AL,Umoh J,Kron T,Holdsworth DW,Battista JJ

更新日期：2008-09-21 00:00:00

abstract：:In some medical procedures, it is difficult or impossible to maintain a line of sight for a guidance system. For such applications, people have begun to use electromagnetic trackers. Before a localizer can be effectively used for an image-guided procedure, a characterization of the localizer is required. The purpose o...

journal_title：Physics in medicine and biology

authors： Atuegwu NC,Galloway RL

更新日期：2008-08-21 00:00:00

abstract：:Thermal therapy is an experimental treatment to destroy solid tumours by heating them to temperatures ranging from 55 degrees C to 90 degrees C, inducing thermal coagulation and necrosis of the tumour. We are investigating the feasibility of interstitial microwave thermal therapy as a salvage treatment for prostate ca...

journal_title：Physics in medicine and biology

authors： McCann C,Kumaradas JC,Gertner MR,Davidson SR,Dolan AM,Sherar MD

更新日期：2003-04-21 00:00:00

abstract：:A new multiplicative correction factor for tissue heterogeneities based on an exact expression for homogeneous non-unit-density media is proposed. O'Connor's density scaling theorem is invoked to evaluate the medium-specific tissue-maximum ratios used in the exact formulation. Monte Carlo calculations were performed a...

journal_title：Physics in medicine and biology

authors： Petti PL,Siddon RL,Bjärngard BE

更新日期：1986-10-01 00:00:00

abstract：:Energy-resolved attenuation data in spectral x-ray imaging enables material decomposition, in which the different materials inside an object can be identified and separated virtually. Material decomposition has the drawback of increased noise in the resulting material images relative to the measured images. Recently, ...

journal_title：Physics in medicine and biology

authors： Schaff F,Morgan KS,Paganin DM,Kitchen MJ

更新日期：2020-10-07 00:00:00

abstract：:In the IAEA-AAPM dosimetry formalism, detector measurements in general nonstandard conditions are corrected using the factor k(f(clin),f(msr))(Q(clin),Q(msr)). This factor needs to be evaluated on a case-by-case basis which is difficult to accomplish in practice. The present paper aims to provide a method that allows ...

journal_title：Physics in medicine and biology

authors： Kamio Y,Bouchard H

更新日期：2014-09-07 00:00:00

abstract：:Volumetric scintillation dosimetry has the potential to provide fast, high-resolution, three-dimensional radiation dosimetry. However, scintillators exhibit a nonlinear response at the high linear energy transfer (LET) values characteristic of proton Bragg peaks. The purpose of this study was to develop a quenching co...

journal_title：Physics in medicine and biology

authors： Robertson D,Mirkovic D,Sahoo N,Beddar S

更新日期：2013-01-21 00:00:00

abstract：:In this paper, a coupled radiative transfer equation and diffusion approximation model is extended for light propagation in turbid medium with low-scattering and non-scattering regions. The light propagation is modelled with the radiative transfer equation in sub-domains in which the assumptions of the diffusion appro...

journal_title：Physics in medicine and biology

authors： Tarvainen T,Vauhkonen M,Kolehmainen V,Arridge SR,Kaipio JP

更新日期：2005-10-21 00:00:00

abstract：:Lung tumors treated in breath-hold are subject to inter- and intra-breath-hold variations, which makes tumor position monitoring during each breath-hold important. A markerless technique is desirable, but limited tumor visibility on kV images makes this challenging. We evaluated if template matching  +  triangulation ...

journal_title：Physics in medicine and biology

authors： Hazelaar C,Dahele M,Mostafavi H,van der Weide L,Slotman B,Verbakel W

更新日期：2018-05-29 00:00:00

abstract：:Several applications in nuclear medicine require absolute activity quantification of single photon emission computed tomography images. Obtaining a repeatable calibration factor that converts voxel values to activity units is essential for these applications. Because source preparation and measurement of the source ac...

journal_title：Physics in medicine and biology

authors： Anizan N,Wang H,Zhou XC,Wahl RL,Frey EC

更新日期：2015-02-07 00:00:00

abstract：:The class of non-rigid registration methods proposed in the framework of PDE-constrained large deformation diffeomorphic metric mapping is a particularly interesting family of physically meaningful diffeomorphic registration methods. Inexact Gauss-Newton-Krylov optimization has shown an excellent numerical accuracy an...

journal_title：Physics in medicine and biology

authors： Hernandez M

更新日期：2019-01-07 00:00:00

abstract：:For quality assurance of hyperthermia treatment planning systems, quantitative validation of the electromagnetic model of an applicator is essential. The objective of this study was to validate a finite-difference time-domain (FDTD) model implementation of the Lucite cone applicator (LCA) for superficial hyperthermia....

journal_title：Physics in medicine and biology

authors： de Bruijne M,Samaras T,Chavannes N,van Rhoon GC

更新日期：2007-06-07 00:00:00

abstract：:A technique is described for examining the mode of operation of radiation detectors and estimating the losses and gains caused by random summing effects in spectra acquired at high counting rates. The technique is applied to estimating the errors caused by random summing when measuring the amounts of carbon and nitrog...

journal_title：Physics in medicine and biology

authors： Yankuba S,Oldroyd B,Metcalfe SC,Godfrey JE,Oxby CB

更新日期：1989-08-01 00:00:00