Diffusion coefficient for photon transport in turbid media.

abstract：:Values of W (the mean energy required to create an ion pair when a charged particle is stopped in a gas) are needed in radiation dosimetry to convert ionisation chamber current readings to absorbed dose. For neutron dosimetry the most important W values are those for protons, and this paper describes absolute measurem...

journal_title：Physics in medicine and biology

authors： Thomas DJ,Burke M

更新日期：1985-11-01 00:00:00

abstract：:An algorithm for dynamic multileaf-collimator (dMLC) tracking of a target performing a known a priori, rigid-body motion during volumetric modulated arc therapy (VMAT), has been experimentally validated and applied to investigate the potential of the Agility (Elekta AB, Stockholm, Sweden) multileaf-collimator (MLC) fo...

journal_title：Physics in medicine and biology

authors： Davies GA,Clowes P,Bedford JL,Evans PM,Webb S,Poludniowski G

更新日期：2013-07-07 00:00:00

abstract：:We have developed an iterative method to correct axial and tangential patient motion occurring during tomographic acquisition. The method uses axial images reconstructed from the uncorrected projection images, which are then forward projected to form a basis for registering the original planar images and, in the proce...

journal_title：Physics in medicine and biology

authors： Lee KJ,Barber DC

更新日期：1998-01-01 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 reproducibility of polyacrylamide gel (PAG) dosimetry has been evaluated when used to verify two radiotherapy treatment plans of increasing complexity. The plans investigated were a three-field coplanar arrangement, using the linac jaws for field shaping, and a four-field, conformal, non-coplanar plan using precis...

journal_title：Physics in medicine and biology

authors： Cosgrove VP,Murphy PS,McJury M,Adams EJ,Warrington AP,Leach MO,Webb S

更新日期：2000-05-01 00:00:00

abstract：:Cardiac resynchronization therapy (CRT) is an effective procedure for patients with heart failure but 30% of patients do not respond. This may be due to sub-optimal placement of the left ventricular (LV) lead. It is hypothesized that the use of cardiac anatomy, myocardial scar distribution and dyssynchrony information...

journal_title：Physics in medicine and biology

authors： Ma YL,Shetty AK,Duckett S,Etyngier P,Gijsbers G,Bullens R,Schaeffter T,Razavi R,Rinaldi CA,Rhode KS

更新日期：2012-05-21 00:00:00

abstract：:Using a statistical (chi-square) test on simulated data and a realistic noise model derived from the system's hardware we study the performance of diffuse optical tomography systems for fluorescence imaging. We compare the predicted smallest size of detectable lesions at various positions in slab and cup geometry and ...

journal_title：Physics in medicine and biology

authors： Ziegler R,Brendel B,Rinneberg H,Nielsen T

更新日期：2009-01-21 00:00:00

abstract：:Using MRI for radiotherapy treatment planning and image guidance is appealing as it provides superior soft tissue information over CT scans and avoids possible systematic errors introduced by aligning MR to CT images. This study presents a method that generates Synthetic CT (MRCT) volumes by performing probabilistic t...

journal_title：Physics in medicine and biology

authors： Liu L,Jolly S,Cao Y,Vineberg K,Fessler JA,Balter JM

更新日期：2017-04-21 00:00:00

abstract：:Three major linear accelerator vendors offer gantry-mounted single (monoscopic) x-ray imagers. The use of monoscopic imaging to estimate three-dimensional (3D) target positions has not been fully explored. The purpose of this work is to develop and investigate a robust monoscopic method for real-time tumour tracking, ...

journal_title：Physics in medicine and biology

authors： Cho B,Suh Y,Dieterich S,Keall PJ

更新日期：2008-06-07 00:00:00

abstract：:There is a need to verify the accuracy of general purpose Monte Carlo codes like EGSnrc, which are commonly employed for investigations of dosimetric problems in radiation therapy. A number of experimental benchmarks have been published to compare calculated values of absorbed dose to experimentally determined values....

journal_title：Physics in medicine and biology

authors： Renner F,Wulff J,Kapsch RP,Zink K

更新日期：2015-10-07 00:00:00

abstract：:There are three ways to determine the spectrum of a clinical photon beam: direct measurement, modelling the source and reconstruction from ion-chamber measurements. We focus on reconstruction because the necessary equipment is readily available and it provides independent confirmation of source models for a given mach...

journal_title：Physics in medicine and biology

authors： Armbruster B,Hamilton RJ,Kuehl AK

更新日期：2004-11-21 00:00:00

abstract：:Many applications of electroporation, especially those utilizing electrofusion and in-vivo electroporation, involve cell environments that include close cell-to-cell proximity and a wide range of target cell size. It is important to understand how this kind of environment may alter optimum electroporation electrical p...

journal_title：Physics in medicine and biology

authors： Gaynor PT,Bodger PS

更新日期：2006-06-21 00:00:00

abstract：:A dynamic-contrast-enhanced magnetic resonance imaging (DCE-MRI) dataset consists of many imaging frames, often acquired both before and after contrast injection. Due to the length of time spent acquiring images, patient motion is likely and image re-alignment or registration is required before further analysis such a...

journal_title：Physics in medicine and biology

authors： Melbourne A,Hipwell J,Modat M,Mertzanidou T,Huisman H,Ourselin S,Hawkes DJ

更新日期：2011-12-21 00:00:00

abstract：:Rheumatoid arthritis is one of the most common epidemic diseases in the world. For some patients, the treatment with steroids or nonsteroidal anti-inflammatory drugs is not effective, thus necessitating physical removal of the inflamed synovium. Alternative approaches other than surgery will provide appropriate diseas...

journal_title：Physics in medicine and biology

authors： Wu J,Chang SJ,Chuang KS,Hsueh YW,Yeh KC,Wang JN,Tsai WP

更新日期：2007-03-21 00:00:00

abstract：:Quantitative assessment of mammographic asymmetry has been investigated for breast cancer risk prediction. A new asymmetry feature extraction method was proposed in this study to enhance the risk prediction accuracy of near-term breast cancer. Breast areas in each pair of bilateral mammographic images were divided int...

journal_title：Physics in medicine and biology

authors： Yan S,Zhang L,Song C

更新日期：2018-10-17 00:00:00

abstract：:Positron emission tomography (PET) has become an important modality in medical and molecular imaging. However, in most PET applications, the resolution is still mainly limited by the physical crystal sizes or the detector's intrinsic spatial resolution. To achieve images with better spatial resolution in a central reg...

journal_title：Physics in medicine and biology

authors： Li Y,Matej S,Karp JS,Metzler SD

更新日期：2015-01-21 00:00:00

abstract：:In a previous paper, we described quality assurance procedures for Hi-Art helical tomotherapy machines. Here, we develop further some ideas discussed briefly in that paper. Simple helically generated dose distributions are modelled, and relationships between these dose distributions and underlying characteristics of H...

journal_title：Physics in medicine and biology

authors： Fenwick JD,Tomé WA,Kissick MW,Mackie TR

更新日期：2005-04-07 00:00:00

abstract：:The geometry of a permanent prostate implant varies over time. Seeds can migrate and edema of the prostate affects the position of seeds. Seed movements directly influence dosimetry which relates to treatment quality. We present a method that tracks all individual seeds over time allowing quantification of seed moveme...

journal_title：Physics in medicine and biology

authors： Westendorp H,Nuver TT,Moerland MA,Minken AW

更新日期：2015-10-21 00:00:00

abstract：:This study evaluated the cavitation activity induced by shock wave (SW) pulses, both in vitro and in vivo, based on the area measurements of echogenic regions observed in B-mode ultrasound images. Residual cavitation bubble clouds induced by SW pulses were detected as echogenic regions in B-mode images. The temporal e...

journal_title：Physics in medicine and biology

authors： Tu J,Matula TJ,Bailey MR,Crum LA

更新日期：2007-10-07 00:00:00

abstract：:At low and intermediate frequencies, the strength of the induced electric field is used as dosimetric quantity for human protection in the International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines. To compute the induced electric field, numerical methods based on anatomically realistic voxel mo...

journal_title：Physics in medicine and biology

authors： Soldati M,Laakso I

更新日期：2020-01-10 00:00:00

abstract：:Precision image-guided small animal radiotherapy is rapidly advancing through the use of dedicated micro-irradiation devices. However, precise modeling of these devices in model-based dose-calculation algorithms such as Monte Carlo (MC) simulations continue to present challenges due to a combination of very small beam...

journal_title：Physics in medicine and biology

authors： Granton PV,Verhaegen F

更新日期：2013-05-21 00:00:00

abstract：:Knowledge of what dose-volume histograms can be expected for a previously unseen patient could increase consistency and quality in radiotherapy treatment planning. We propose a machine learning method that uses previous treatment plans to predict such dose-volume histograms. The key to the approach is the framing of d...

journal_title：Physics in medicine and biology

authors： Skarpman Munter J,Sjölund J

更新日期：2015-09-07 00:00:00

abstract：:We present a new image reconstruction algorithm for helical cone-beam computed tomography (CT). This algorithm is designed for data collected at or near maximum pitch, and provides a theoretically exact and stable reconstruction while beneficially using all measured data. The main operations involved are a differentia...

journal_title：Physics in medicine and biology

authors： Schöndube H,Stierstorfer K,Noo F

更新日期：2009-08-07 00:00:00

abstract：:Sparse phased array ultrasound transducers with millimetre length scale elements have previously been proposed for generating hyperthermia but not for imaging. Numerical simulation with a pseudospectral solver was used to investigate: (a) how the position of the maximum pressure in the focal region changed with elemen...

journal_title：Physics in medicine and biology

authors： Wilson AJ

更新日期：2018-07-16 00:00:00

abstract：:The intra- and inter-batch accuracy and precision of MRI (polyacrylamide gelatin gel fabricated at atmospheric conditions) polymer gel dosimeters are assessed in full 3D. In the intra-batch study, eight spherical flasks were filled with the same polymer gel along with a set of test tubes that served as calibration pha...

journal_title：Physics in medicine and biology

authors： Vandecasteele J,De Deene Y

更新日期：2013-01-07 00:00:00

abstract：:In external beam radiation therapy, radioactive beams offer the best clinical solution to simultaneously treat and in vivo monitor the dose delivery and tumor response using PET or PET-CT imaging. However, difficulties mainly linked to the low production efficiency have so far limited their use. This study is devoted ...

journal_title：Physics in medicine and biology

authors： Lazzeroni M,Brahme A

更新日期：2011-03-21 00:00:00

abstract：:To investigate the profile measurement capabilities of an IBA-Dosimetry scintillation detector and to assess its feasibility for determining the low-intensity tails of pencil-beam scanning spots, the responses of the scintillation detector and Gafchromic EBT2 film to a 115 MeV proton spot were measured in-air at the i...

journal_title：Physics in medicine and biology

authors： Lin L,Ainsley CG,Mertens T,De Wilde O,Talla PT,McDonough JE

更新日期：2013-06-21 00:00:00

abstract：:We experimentally investigated the SPECT recovery of I-131 activity in multiple spheres located simultaneously at different locations within a cylindrical phantom that had an elliptical cross section. The sphere volumes ranged from 209 cc down to 4.2 cc. A Prism 3000 camera and two types of parallel-hexagonal-hole col...

journal_title：Physics in medicine and biology

authors： Koral KF,Yendiki A,Dewaraja YK

更新日期：2007-02-07 00:00:00

abstract：:The interest in positron emission tomography (PET) and particularly in hybrid integrated PET/CT systems has significantly increased in the last few years due to the improved quality of the obtained images. Nevertheless, one of the most important limits of the PET imaging technique is still its poor spatial resolution ...

journal_title：Physics in medicine and biology

authors： Rapisarda E,Bettinardi V,Thielemans K,Gilardi MC

更新日期：2010-07-21 00:00:00

abstract：:Due to high levels of noise in pixel-wise time-activity curves, the indirect method that generates kinetic parametric images from dynamic positron emission tomography (PET) images often results in poor parametric image quality. We have demonstrated that the quality of parametric images can be improved by denoising dyn...

journal_title：Physics in medicine and biology

authors： Huang HM

更新日期：2020-11-17 00:00:00