Physical mechanisms of gas and perfluoron retinopexy and sub-retinal fluid displacement.


:Injection of gas into the eye, followed by face-down positioning, is a common protocol for the reseating of the retina in posterior and superior retinal tears and breaks. The physical mechanism by which injected gas helps reattach retinal flaps is often ascribed to the 'buoyancy' force of the injected gas bubble. The various forces at play in this system (surface tension and buoyancy) were calculated and compared. The results are extended to the case in which the retina is intact (pneumatic displacement of blood) and to the use of intraocular perfluoron (n-perfluorooctane). We show that buoyancy forces are applicable only for gas or n-perfluorooctane bubbles that are smaller than the detached retina and that do not invade underneath the retina. For larger bubbles, as is normally used in reattachment protocols, we show that it is the interfacial tension that reattaches the retina. The range of angles within which patients can position, and still maintain a gas-vitreous interface along a tear is calculated as a function of the volume of injected gas and size of the tear. The maximum retinal flap size that can be reattached using surface tension forces is also estimated.


Phys Med Biol


Foster WJ,Chou T




Has Abstract


2004-07-07 00:00:00












  • The use of customized spreadsheets in radiation therapy.

    abstract::A number of radiation-therapy-related uses based on a commercially available spreadsheet program have been developed at our facility. The graphics and display capabilities inherent in these spreadsheet programs allow for concise visual results. The spreadsheets are used as an independent check for several types of rad...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Balog JP,Sibata CH,Podgorsak MB,Shin KH

    更新日期:1995-06-01 00:00:00

  • Automatic system for measuring dose-area product (DAP) in ROI fluoroscopy.

    abstract::A computerized system for monitoring dose-area product (DAP) has been developed for region of interest (ROI) fluoroscopy in which patient exposure is reduced using an x-ray attenuating filter with an aperture. The system includes an IBM compatible computer which is connected through an IEEE-488 interface to an electro...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Kezerashvili M,Bednarek DR,Rudin S

    更新日期:1997-04-01 00:00:00

  • Assessment of the effects of pixel loss on image quality in direct digital radiography.

    abstract::Modern digital radiographic 'flat panel' detectors can exhibit a progressive form of image degradation arising from non-functioning pixels. The effect of these 'dead pixels' on the quantitive image quality measures of modulation transfer function (MTF), noise power spectrum (NPS) and detective quantum efficiency (DQE)...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Padgett R,Kotre CJ

    更新日期:2004-03-21 00:00:00

  • Accurate Monte Carlo calculations of the combined attenuation and build-up factors, for energies (20-1500 keV) and distances (0-10 cm) relevant in brachytherapy.

    abstract::The combined build-up and attenuation factor, B exp (-mu r), of point isotropic photon sources in a water medium has been calculated using the Monte Carlo method, for energies (20-1500 keV) and distances (1-10 cm) relevant in brachytherapy. For the transport of photons and electrons, up-to-date and self-consistent tot...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Angelopoulos A,Perris A,Sakellariou K,Sakelliou L,Sarigiannis K,Zarris G

    更新日期:1991-06-01 00:00:00

  • An extended diffraction-enhanced imaging method for implementing multiple-image radiography.

    abstract::Diffraction-enhanced imaging (DEI) is an analyser-based x-ray imaging method that produces separate images depicting the projected x-ray absorption and refractive properties of an object. Because the imaging model of DEI does not account for ultra-small-angle x-ray scattering (USAXS), the images produced in DEI can co...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Chou CY,Anastasio MA,Brankov JG,Wernick MN,Brey EM,Connor DM,Zhong Z

    更新日期:2007-04-07 00:00:00

  • NEMA NU 4-2008 validation and applications of the PET-SORTEO Monte Carlo simulations platform for the geometry of the Inveon PET preclinical scanner.

    abstract::Monte Carlo-based simulation of positron emission tomography (PET) data plays a key role in the design and optimization of data correction and processing methods. Our first aim was to adapt and configure the PET-SORTEO Monte Carlo simulation program for the geometry of the widely distributed Inveon PET preclinical sca...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Boisson F,Wimberley CJ,Lehnert W,Zahra D,Pham T,Perkins G,Hamze H,Gregoire MC,Reilhac A

    更新日期:2013-10-07 00:00:00

  • Survey of numerical electrostimulation models.

    abstract::This paper evaluates results of a survey of electrostimulation models of myelinated nerve. Participants were asked to determine thresholds of excitation for 18 cases involving different characteristics of the neuron, the stimulation waveform, and the electrode arrangement. Responses were received from 7 investigators ...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Reilly JP

    更新日期:2016-06-21 00:00:00

  • Changes in lung tumor shape during respiration.

    abstract::Evidence that some lung tumors change shape during respiration is derived from respiratory gated CT data by statistical shape modeling and image manipulation. Some tumors behave as rigid objects while others show systematic shape changes. Two views of lung motion are presented to allow analysis of the results. In the ...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Kyriakou E,McKenzie DR

    更新日期:2012-02-21 00:00:00

  • A beam profile generation algorithm for wedged half-beam blocked asymmetric fields.

    abstract::A method is presented to predict beam profiles and outputs for wedged asymmetric fields defined by independent collimator jaws allowing fast generation of beam profiles whilst requiring very little additional data to that already used by most treatment planning systems in generating symmetric field isodoses. Symmetric...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Millin AE,Smith CW

    更新日期:1994-01-01 00:00:00

  • A numerical study on the influence of vulnerable plaque composition on intravascular thermography measurements.

    abstract::Intracoronary thermography is a technique that measures lumen wall temperatures for vulnerable plaque detection. In this paper the influence of vulnerable plaque composition on lumen wall temperatures was studied numerically. Concerning the vulnerable plaque heat generation, the location of the heat source and its hea...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: ten Have AG,Gijsen FJ,Wentzel JJ,Slager CJ,Serruys PW,van der Steen AF

    更新日期:2006-11-21 00:00:00

  • Radiation binary targeted therapy for HER-2 positive breast cancers: assumptions, theoretical assessment and future directions.

    abstract::A novel radiation targeted therapy is investigated for HER-2 positive breast cancers. The proposed concept combines two known approaches, but never used together for the treatment of advanced, relapsed or metastasized HER-2 positive breast cancers. The proposed radiation binary targeted concept is based on the anti HE...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Mundy DW,Harb W,Jevremovic T

    更新日期:2006-03-21 00:00:00

  • Characterization of the secondary neutron field produced during treatment of an anthropomorphic phantom with x-rays, protons and carbon ions.

    abstract::Short- and long-term side effects following the treatment of cancer with radiation are strongly related to the amount of dose deposited to the healthy tissue surrounding the tumor. The characterization of the radiation field outside the planned target volume is the first step for estimating health risks, such as devel...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Tessa CL,Berger T,Kaderka R,Schardt D,Burmeister S,Labrenz J,Reitz G,Durante M

    更新日期:2014-04-21 00:00:00

  • Development and evaluation of a deep learning based artificial intelligence for automatic identification of gold fiducial markers in an MRI-only prostate radiotherapy workflow.

    abstract::Identification of prostate gold fiducial markers in magnetic resonance imaging (MRI) images is challenging when CT images are not available, due to misclassifications from intra-prostatic calcifications. It is also a time consuming task and automated identification methods have been suggested as an improvement for bot...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Gustafsson CJ,Swärd J,Adalbjörnsson SI,Jakobsson A,Olsson LE

    更新日期:2020-11-12 00:00:00

  • Comparative behaviour of the dynamically penalized likelihood algorithm in inverse radiation therapy planning.

    abstract::This paper presents a description of tests carried out to compare the behaviour of five algorithms in inverse radiation therapy planning: (1) The Dynamically Penalized Likelihood (DPL), an algorithm based on statistical estimation theory; (2) an accelerated version of the same algorithm: (3) a new fast adaptive simula...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Llacer J,Solberg TD,Promberger C

    更新日期:2001-10-01 00:00:00

  • A novel high-throughput irradiator for in vitro radiation sensitivity bioassays.

    abstract::This paper describes the development and characterization of a fully automated in vitro cell irradiator using an electronic brachytherapy source to perform radiation sensitivity bioassays. This novel irradiator allows complex variable dose and dose rate schemes to be delivered to multiple wells of 96-well culture plat...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Fowler TL,Fulkerson RK,Micka JA,Kimple RJ,Bednarz BP

    更新日期:2014-03-21 00:00:00

  • A Monte Carlo evaluation of RapidArc dose calculations for oropharynx radiotherapy.

    abstract::RapidArc, recently released by Varian Medical Systems, is a novel extension of IMRT in which an optimized 3D dose distribution may be delivered in a single gantry rotation of 360 degrees or less. The purpose of this study was to investigate the accuracy of the analytical anisotropic algorithm (AAA), the sole algorithm...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Gagne IM,Ansbacher W,Zavgorodni S,Popescu C,Beckham WA

    更新日期:2008-12-21 00:00:00

  • On the total system error of a robotic radiosurgery system: phantom measurements, clinical evaluation and long-term analysis.

    abstract::The total system error (TSE) of a CyberKnife® system was measured using two phantom-based methods and one patient-based method. The standard radiochromic film (RCF) end-to-end (E2E) test using an anthropomorphic head and neck phantom and isocentric treatment delivery was used with the 6Dskull, Fiducial and Xsight® spi...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Pantelis E,Moutsatsos A,Antypas C,Zoros E,Pantelakos P,Lekas L,Romanelli P,Zourari K,Hourdakis CJ

    更新日期:2018-08-20 00:00:00

  • Scatter compensation methods in 3D iterative SPECT reconstruction: a simulation study.

    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

    pub_type: 杂志文章


    authors: Beekman FJ,Kamphuis C,Frey EC

    更新日期:1997-08-01 00:00:00

  • A novel linear programming approach to fluence map optimization for intensity modulated radiation therapy treatment planning.

    abstract::We present a novel linear programming (LP) based approach for efficiently solving the intensity modulated radiation therapy (IMRT) fluence-map optimization (FMO) problem to global optimality. Our model overcomes the apparent limitations of a linear-programming approach by approximating any convex objective function by...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Romeijn HE,Ahuja RK,Dempsey JF,Kumar A,Li JG

    更新日期:2003-11-07 00:00:00

  • Accurate helical cone-beam CT reconstruction with redundant data.

    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

    pub_type: 杂志文章


    authors: Schöndube H,Stierstorfer K,Noo F

    更新日期:2009-08-07 00:00:00

  • A feasibility study of the use of fluorescence bronchoscopy for localization of small lung tumours.

    abstract::The possible use of fluorescence bronchoscopy for localization of bronchogenic tumours at the carcinoma in situ stage has been investigated. The target lesion is 80 micrometer thick with a mass of 250 microgram, containing 250 pg of haematoporphyrin derivative. The injected haematoporphyrin-derivative is preferentiall...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Profio AE,Doiron DR

    更新日期:1977-09-01 00:00:00

  • Scatter dose for wedged fields.

    abstract::The behaviour of scatter dose in 4 and 8 MV wedged x-ray beams has been studied by calculating scatter-to-primary dose ratios (SPR) and comparing these with SPR for non-wedged beams. On the central axis the SPR for wedged and non-wedged beams differ only by a few per cent, a difference which increases slightly with we...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Brown LH,Siddon RL,Bjärngard BE

    更新日期:1987-10-01 00:00:00

  • In vitro double-integrating-sphere optical properties of tissues between 630 and 1064 nm.

    abstract::The optical properties (absorption and scattering coefficients and the scattering anisotropy factor) were measured in vitro for cartilage, liver, lung, muscle, myocardium, skin, and tumour (colon adenocarcinoma CC 531) at 630, 632.8, 790, 850 and 1064 nm. Rabbits, rats, piglets, goats, and dogs were used to obtain the...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Beek JF,Blokland P,Posthumus P,Aalders M,Pickering JW,Sterenborg HJ,van Gemert MJ

    更新日期:1997-11-01 00:00:00

  • Modeling late rectal toxicities based on a parameterized representation of the 3D dose distribution.

    abstract::Many models exist for predicting toxicities based on dose-volume histograms (DVHs) or dose-surface histograms (DSHs). This approach has several drawbacks as firstly the reduction of the dose distribution to a histogram results in the loss of spatial information and secondly the bins of the histograms are highly correl...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Buettner F,Gulliford SL,Webb S,Partridge M

    更新日期:2011-04-07 00:00:00

  • Evaluation of transmission methodology and attenuation correction for the microPET Focus 220 animal scanner.

    abstract::An accurate, low noise estimate of photon attenuation in the subject is required for quantitative microPET studies of molecular tracer distributions in vivo. In this work, several transmission-based measurement techniques were compared, including coincidence mode with and without rod windowing, singles mode with two d...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Lehnert W,Meikle SR,Siegel S,Newport D,Banati RB,Rosenfeld AB

    更新日期:2006-08-21 00:00:00

  • The Akaike information criterion in DCE-MRI: does it improve the haemodynamic parameter estimates?

    abstract::The Akaike information criterion and the associated Akaike weights (AW) rank pharmacokinetic models on the basis of goodness-of-fit and number of parameters. The usefulness of this information for improving the haemodynamic parameter estimates from DCE-MRI was investigated through two examples. In each of these, the e...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Luypaert R,Ingrisch M,Sourbron S,de Mey J

    更新日期:2012-06-07 00:00:00

  • Fast laser scanning optical-CT apparatus for 3D radiation dosimetry.

    abstract::Optical computed tomography (optical-CT) of 3D radiation dosimeters is a promising avenue for delivering an economic and reliable quality control of radiotherapy treatments such as intensity modulated radiotherapy, brachytherapy and stereotactic radiosurgery. The main problems in transferring 3D dosimeters to clinical...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Krstajić N,Doran SJ

    更新日期:2007-06-07 00:00:00

  • The transformation method for the MIRD absorbed fraction as applied to various physiques.

    abstract::A transformation method was investigated for applying the MIRD absorbed fraction to internal dose calculations for an individual. The transformation method consists of two parts, transformation of the target organ mass, and of the distance between source and target organs. The variation of the specific absorbed fracti...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Yamaguchi H,Kato Y,Shiragai A

    更新日期:1975-07-01 00:00:00

  • Development of 4D mathematical observer models for the task-based evaluation of gated myocardial perfusion SPECT.

    abstract::This paper presents two 4D mathematical observer models for the detection of motion defects in 4D gated medical images. Their performance was compared with results from human observers in detecting a regional motion abnormality in simulated 4D gated myocardial perfusion (MP) SPECT images. The first 4D mathematical obs...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Lee TS,Frey EC,Tsui BM

    更新日期:2015-04-07 00:00:00

  • DAVID--a translucent multi-wire transmission ionization chamber for in vivo verification of IMRT and conformal irradiation techniques.

    abstract::Permanent in vivo verification of IMRT photon beam profiles by a radiation detector with spatial resolution, positioned on the radiation entrance side of the patient, has not been clinically available so far. In this work we present the DAVID system, which is able to perform this quality assurance measurement while th...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Poppe B,Thieke C,Beyer D,Kollhoff R,Djouguela A,Rühmann A,Willborn KC,Harder D

    更新日期:2006-03-07 00:00:00