Beam angle selection incorporation of anatomical heterogeneities for pencil beam scanning charged-particle therapy.

abstract：:Kilovoltage intratreatment monitoring (KIM) is a novel real-time localization modality where the tumor position is continuously measured during intensity modulated radiation therapy (IMRT) or intensity modulated arc therapy (IMAT) by a kilovoltage (kV) x-ray imager. Adding kV imaging during therapy adds radiation dose...

journal_title：Physics in medicine and biology

authors： Ng JA,Booth J,Poulsen P,Kuncic Z,Keall PJ

更新日期：2013-09-07 00:00:00

abstract：:Peripheral neural stimulation is a major problem in current gradient coil designs. Induced current problems in patients relate directly to gradient strength and modulation frequency. Present designs of gradient coil tend to limit ultra-high-speed imaging methods such as echo-planar imaging (EPI) and echo-volumar imagi...

journal_title：Physics in medicine and biology

authors： Mansfield P,Haywood B

更新日期：2008-04-07 00:00:00

abstract：:To replace the conventional pinhole (normal cone-beam) collimator, a novel skew-slit collimator was previously proposed and a Novikov-type algorithm developed to reconstruct images using the skew-slit geometry. The goal of this paper is to develop a reconstruction algorithm that has better noise control than the Novik...

journal_title：Physics in medicine and biology

authors： Tang Q,Zeng GL,Huang Q

更新日期：2006-12-07 00:00:00

abstract：:Random coincidences can contribute substantially to the background in positron emission tomography (PET). Several estimation methods are being used for correcting them. The goal of this study was to investigate the validity of techniques for random coincidence estimation, with various low-energy thresholds (LETs). Sim...

journal_title：Physics in medicine and biology

authors： Torres-Espallardo I,Rafecas M,Spanoudaki V,McElroy DP,Ziegler SI

更新日期：2008-05-07 00:00:00

abstract：:EEG recordings made in combined EEG-fMRI studies are corrupted by gradient artefacts (GAs) resulting from the interaction of the EEG system with the time-varying magnetic field gradients used in MRI. The dominant contribution to the GA arises from interaction with the leads of the EEG cap and the human head, but artef...

journal_title：Physics in medicine and biology

authors： Chowdhury ME,Mullinger KJ,Bowtell R

更新日期：2015-06-21 00:00:00

abstract：:A micro beam synchrotron x-ray fluorescence (muSRXRF) technique has been used to determine the localization of metals in primary invasive ductal carcinoma of breast. Nine samples were examined, all of which were formalin fixed tissues arranged as micro arrays of 1.0 mm diameter and 10 microm thickness. Cu was the part...

journal_title：Physics in medicine and biology

authors： Farquharson MJ,Al-Ebraheem A,Falkenberg G,Leek R,Harris AL,Bradley DA

更新日期：2008-06-07 00:00:00

abstract：:In treatment planning we depend upon accurate knowledge of geometric and range uncertainties. If the uncertainty model is inaccurate then the plan will produce under-dosing of the target and/or overdosing of OAR. We aim to provide a method for which centre and site-specific population range uncertainty due to inter-fr...

journal_title：Physics in medicine and biology

authors： Holloway SM,Holloway MD,Thomas SJ

更新日期：2017-12-19 00:00:00

abstract：:The use of calibrated tissue-equivalent (TE) ionisation chambers is commonly considered to be the most practical method for total absorbed dose determinations in mixed neutron-photon fields for biomedical applications. The total absorbed dose can be derived from the charge produced within the cavity of an ionisation c...

journal_title：Physics in medicine and biology

authors： Zoetelief J,Broerse JJ

更新日期：1983-05-01 00:00:00

abstract：:Scatter correction is an essential technique to improve the image quality of cone-beam CT (CBCT). Although different scatter correction methods have been proposed in the literature, a standard solution is still being studied due to the limitations including accuracy, computation efficiency and generalization. In this ...

journal_title：Physics in medicine and biology

authors： Jiang Y,Yang C,Yang P,Hu X,Luo C,Xue Y,Xu L,Hu X,Zhang L,Wang J,Sheng K,Niu T

更新日期：2019-07-11 00:00:00

abstract：:Two complementary approaches to the noise suppression problem in on-line portal imaging have been analysed. Temporal filtering by image summation can substantially reduce the amount of noise in an image. In many cases, however, movements of the patient or the radiation source limit the time period over which the avera...

journal_title：Physics in medicine and biology

authors： Leszczynski KW,Shalev S,Cosby NS

更新日期：1990-03-01 00:00:00

abstract：:Effects of different scatter compensation methods incorporated in fully 3D iterative reconstruction are investigated. The methods are: (i) the inclusion of an 'ideal scatter estimate' (ISE); (ii) like (i) but with a noiseless scatter estimate (ISE-NF); (iii) incorporation of scatter in the point spread function during...

journal_title：Physics in medicine and biology

authors： Beekman FJ,Kamphuis C,Frey EC

更新日期：1997-08-01 00:00:00

abstract：:Commercial TPSs typically model the tongue-and-groove (TG) by extending the projections of the leaf sides by a certain constant width. However, this model may produce discrepancies of as much as 7%-10% in the calculated average doses, especially for the High Definition multi-leaf collimator (MLC) (Hernandez et al 2017...

journal_title：Physics in medicine and biology

authors： Hernandez V,Vera-Sánchez JA,Vieillevigne L,Khamphan C,Saez J

更新日期：2018-12-10 00:00:00

abstract：:Currently, standards for the compliance testing of wireless devices are being extended to cover a wider frequency band and different usage patterns of mobile phones as well as of novel body-worn and handheld devices. As a consequence, not only the head but also strongly varying tissue distributions of the body are exp...

journal_title：Physics in medicine and biology

authors： Christ A,Samaras T,Klingenböck A,Kuster N

更新日期：2006-10-07 00:00:00

abstract：:Deep learning models are highly parameterized, resulting in difficulty in inference and transfer learning for image recognition tasks. In this work, we propose a layered pathway evolution method to compress a deep convolutional neural network (DCNN) for classification of masses in digital breast tomosynthesis (DBT). T...

journal_title：Physics in medicine and biology

authors： Samala RK,Chan HP,Hadjiiski LM,Helvie MA,Richter C,Cha K

更新日期：2018-05-01 00:00:00

abstract：:In order to analyse the respective roles of ion concentration and fractional volume of the interstitial compartment as determinants of the impedance, Z, of renal medullary tissue, a model was needed in which both these factors could be varied independently. An array of blood cell suspensions ions in saline (different ...

journal_title：Physics in medicine and biology

authors： Niewiadomski W,Sadowski J,Badzyńska B,Rasmussen SN

更新日期：1990-11-01 00:00:00

abstract：:Irradiation of moving targets using a scanned ion beam can cause clinically intolerable under- and overdosages within the target volume due to the interplay effect. Several motion mitigation techniques such as gating, beam tracking and rescanning are currently investigated to overcome this restriction. To enable detai...

journal_title：Physics in medicine and biology

authors： Steidl P,Richter D,Schuy C,Schubert E,Haberer T,Durante M,Bert C

更新日期：2012-04-21 00:00:00

abstract：:Statistically based iterative image reconstruction methods have been developed for emission tomography. One important component in iterative image reconstruction is the system matrix, which defines the mapping from the image space to the data space. Several groups have demonstrated that an accurate system matrix can i...

journal_title：Physics in medicine and biology

authors： Qi J,Huesman RH

更新日期：2005-07-21 00:00:00

abstract：:Multileaf collimators (MLCs) have been in clinical use for many years and meanwhile are commonly used to deliver intensity-modulated radiotherapy (IMRT) beams. For this purpose it is important to know their dosimetric properties precisely, one of them being inter- and intraleaf leakage. The Siemens 160 MLC features a ...

journal_title：Physics in medicine and biology

authors： Klüter S,Sroka-Perez G,Schubert K,Debus J

更新日期：2011-01-21 00:00:00

abstract：:The purpose of this paper for four-dimensional (4D) computed tomography (CT) is threefold. (1) A new spatiotemporal model is presented from the matrix perspective with the row dimension in space and the column dimension in time, namely the robust PCA (principal component analysis)-based 4D CT model. That is, instead o...

journal_title：Physics in medicine and biology

authors： Gao H,Cai JF,Shen Z,Zhao H

更新日期：2011-06-07 00:00:00

abstract：:The classical Sievert integral method is a valuable tool for dose rate calculations around brachytherapy sources, combining simplicity with reasonable computational times. However, its accuracy in predicting dose rate anisotropy around 192Ir brachytherapy sources has been repeatedly put into question. In this work, we...

journal_title：Physics in medicine and biology

authors： Karaiskos P,Angelopoulos A,Baras P,Rozaki-Mavrouli H,Sandilos P,Vlachos L,Sakelliou L

更新日期：2000-02-01 00:00:00

abstract：:The degradation of low energy electrons in a methane based, tissue equivalent gas was studied experimentally by ionization chamber experiments and theoretically by Monte Carlo electron transport simulation in the energy range between 25 eV and 5 keV. From measured ionization yields and calculated ionization and energy...

journal_title：Physics in medicine and biology

authors： Waibel E,Grosswendt B

更新日期：1992-05-01 00:00:00

abstract：:In order to enable a detailed analysis of radio frequency (RF) absorption in the human middle and inner ear organs, a numerical model of these organs was developed at a spatial resolution of 0.1 mm, based on a real human tissue sample. The dielectric properties of the liquids (perilymph and endolymph) inside the bony ...

journal_title：Physics in medicine and biology

authors： Schmid G,Uberbacher R,Samaras T,Jappel A,Baumgartner WD,Tschabitscher M,Mazal PR

更新日期：2007-04-07 00:00:00

abstract：:A complete characterization of spongiosa (bone marrow plus trabecular bone) is required to calculate the absorbed dose to active bone marrow. Due to the complex microanatomy, it is necessary to apply non-conventional imaging methods in nuclear medicine. The aim of this study is validating a phantomless quantification ...

journal_title：Physics in medicine and biology

authors： Salas-Ramirez M,Tran-Gia J,Gbureck U,Kosmala A,Lassmann M

更新日期：2019-10-16 00:00:00

abstract：:The absolute dose rate around beta sources for intravascular brachytherapy was measured with thin thermoluminescent (TL) dosimeters and radiochromic film. The calibration of these dosimeters was performed at the dose maximum in a 6 MeV electron beam of a linear accelerator. Compared to the values given by the manufact...

journal_title：Physics in medicine and biology

authors： Piessens M,Reynaert N

更新日期：2000-08-01 00:00:00

abstract：:An optimized configuration of multi-pinhole aperture can improve the spatial resolution and the sensitivity of pinhole SPECT simultaneously. In this study, an optimization strategy of the multi-pinhole configuration with a small detector is proposed for mouse cardiac imaging. A 14 mm-diameter spherical field-of-view (...

journal_title：Physics in medicine and biology

authors： Lee MW,Lin WT,Chen YC

更新日期：2015-01-21 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 phantom study was performed in full-field digital mammography to investigate the opportunity and the magnitude of a possible dose reduction that would leave the image quality above the accepted thresholds associated with some classical phantoms. This preliminary work is intended to lay the groundwork for a future cl...

journal_title：Physics in medicine and biology

authors： Gennaro G,Katz L,Souchay H,Alberelli C,di Maggio C

更新日期：2005-04-21 00:00:00

abstract：:Scattered doses, e.g. neutron doses in proton therapy, are of concern in radiation therapy. Although measured data are the gold standard, Monte Carlo simulations allow a more realistic consideration of patient anatomy via whole-body phantoms. When calculating neutron doses with Monte Carlo techniques, the dose can be ...

journal_title：Physics in medicine and biology

authors： Jarlskog CZ,Paganetti H

更新日期：2008-09-07 00:00:00

abstract：:Instead of performing a numerical deconvolution, we propose to use a linear piecewise-continuous model of the renal impulse response function for parametric fitting of renal scintigraphy data, to obtain clinically useful renal parameters. The strengths of the present model are its simplicity and speed of computation, ...

journal_title：Physics in medicine and biology

authors： Zhang JL,Zhang L,Koh TS,Shuter B

更新日期：2003-06-21 00:00:00

abstract：:This paper introduces a novel compartmental model describing the excretion of 18F-fluoro-deoxyglucose (FDG) in the renal system and a numerical method based on the maximum likelihood for its reduction. This approach accounts for variations in FDG concentration due to water re-absorption in renal tubules and the increa...

journal_title：Physics in medicine and biology

authors： Garbarino S,Caviglia G,Sambuceti G,Benvenuto F,Piana M

更新日期：2014-05-21 00:00:00