Temporal backward projection of optoacoustic pressure transients using fourier transform methods.

abstract：:Elevated interstitial fluid pressure is one of the barriers of drug delivery in solid tumors. Recent studies have shown that normalization of tumor vasculature by anti-angiogenic factors may improve the delivery of conventional cytotoxic drugs, possibly by increasing blood flow, decreasing interstitial fluid pressure,...

journal_title：Physics in medicine and biology

authors： Ozturk D,Yonucu S,Yilmaz D,Unlu MB

更新日期：2015-02-21 00:00:00

abstract：:For treatments with dynamic intensity modulated radiotherapy (IMRT), the adjustment of multileaf collimator (MLC) parameters affecting both the optimization algorithm and dose distributions is crucial. The main parameters characterizing the MLC are the transmission (T) and the dosimetric leaf separation (DLS). The aim...

journal_title：Physics in medicine and biology

authors： Chauvet I,Petitfils A,Lehobey C,Kristner JY,Brunet Y,Lembrez R,Gaboriaud G,Mazal A,Zefkili S,Rosenwald JC

更新日期：2005-02-21 00:00:00

abstract：:This paper extends the kernel method that was proposed previously for dynamic PET reconstruction, to incorporate anatomical side information into the PET reconstruction model. In contrast to existing methods that incorporate anatomical information using a penalized likelihood framework, the proposed method incorporate...

journal_title：Physics in medicine and biology

authors： Hutchcroft W,Wang G,Chen KT,Catana C,Qi J

更新日期：2016-09-21 00:00:00

abstract：:Few quantitative data are available on the kinetics of polymerization reactions in polymer gel (PAG) dosimeters and their long-term stability. Post-irradiation polymerization reactions have been found to continue for several weeks, posing questions regarding dosimeter stability and its achievement. In this paper we re...

journal_title：Physics in medicine and biology

authors： McJury M,Oldham M,Leach MO,Webb S

更新日期：1999-08-01 00:00:00

abstract：:Quantification in cardiac mouse positron emission tomography (PET) imaging is limited by the imaging spatial resolution. Spillover of left ventricle (LV) myocardial activity into adjacent organs results in partial volume (PV) losses leading to underestimation of myocardial activity. A PV correction method was develope...

journal_title：Physics in medicine and biology

authors： Dumouchel T,Thorn S,Kordos M,DaSilva J,Beanlands RS,deKemp RA

更新日期：2012-07-07 00:00:00

abstract：:The total ionisation produced by ions stopped in nitrogen, methane and carbon dioxide has been measured in the energy range 25-375 keV using a chamber described previously. The chamber was operated alternately as a proportional counter and as an ionisation chamber to measure respectively the particle rate and the tota...

journal_title：Physics in medicine and biology

authors： Nguyen VD,Chemtob M,Chary J,Posny F,Parmentier N

更新日期：1980-05-01 00:00:00

abstract：:This paper reports a theoretical study on the distribution of blood flow in the human cardiovascular system when one or more blood vessels are affected by stenosis. The analysis employs a mathematical model of the entire system based on the finite element method. The arterial-venous network is represented by a large n...

journal_title：Physics in medicine and biology

authors： Sud VK,Srinivasan RS,Charles JB,Bungo MW

更新日期：1993-03-01 00:00:00

abstract：:The current UK code of practice for high-energy photon therapy dosimetry (Lillicrap et al 1990 Phys. Med. Biol. 35 1355-60) gives instructions for measuring absorbed dose to water under reference conditions for megavoltage photons. The reference conditions and the index used to specify beam quality require that a mach...

journal_title：Physics in medicine and biology

authors： Thomas SJ,Aspradakis MM,Byrne JP,Chalmers G,Duane S,Rogers J,Thomas RA,Tudor GS,Twyman N,IPEM Working Party.

更新日期：2014-03-21 00:00:00

abstract：:The goal of this study is to demonstrate the feasibility of a novel non-coplanar-arc optimization algorithm (CyberArc). This method aims to reduce the delivery time of conventional CyberKnife treatments by allowing for continuous beam delivery. CyberArc uses a 4 step optimization strategy, in which nodes, beams, and c...

journal_title：Physics in medicine and biology

authors： Kearney V,Cheung JP,McGuinness C,Solberg TD

更新日期：2017-06-26 00:00:00

abstract：:This work investigated the differences between multileaf collimator (MLC) positioning accuracy determined using either log files or electronic portal imaging devices (EPID) and then assessed the possibility of reducing patient specific quality control (QC) via phantom-less methodologies. In-house software was develope...

journal_title：Physics in medicine and biology

authors： Agnew A,Agnew CE,Grattan MW,Hounsell AR,McGarry CK

更新日期：2014-05-07 00:00:00

abstract：:Dose reconstruction is a process that re-creates the treatment-time dose deposited in a patient provided there is knowledge of the delivered energy fluence and the patient's anatomy at the time of treatment. A method for reconstructing dose is presented. The process starts with delivery verification, in which the inci...

journal_title：Physics in medicine and biology

authors： Kapatoes JM,Olivera GH,Balog JP,Keller H,Reckwerdt PJ,Mackie TR

更新日期：2001-04-01 00:00:00

abstract：:Although field area and object thickness are important parameters in comparisons of techniques for optimal reduction of scattered radiation to the image, they are in practice seldom varied. For this reason, we suggest that contrast degradation (CDF) and contrast improvement (CIF) factors be more frequently used and ap...

journal_title：Physics in medicine and biology

authors： Carlsson GA,Carlsson CA,Nielsen B,Persliden J

更新日期：1986-07-01 00:00:00

abstract：:Andreo and Benmakhlouf (2017 Phys. Med. Biol. 62 1518-32) have disputed a finding of Scott et al (2012 Phys. Med. Biol. 57 4461-76) that the variation with field-size of the response of small ion chambers and solid-state dosimeters in small megavoltage photon radiation fields can largely be attributed to density. Furt...

journal_title：Physics in medicine and biology

authors： Fenwick JD,Georgiou G,Rowbottom CG,Underwood TSA,Kumar S

更新日期：2018-10-03 00:00:00

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

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

更新日期：2006-08-21 00:00:00

abstract：:The University of Washington (UW) Clinical Neutron Therapy System (CNTS) has been used to treat over 3300 patients. Treatment planning for these patients is currently performed using an MV x-ray model in Pinnacle® adapted to fit measurements of fast neutron output factors, wedge factors, depth-dose and lateral profile...

journal_title：Physics in medicine and biology

authors： Moffitt GB,Wootton LS,Hårdemark B,Sandison GA,Laramore GE,Parvathaneni U,Stewart RD

更新日期：2020-08-31 00:00:00

abstract：:This paper discusses the effect of blood perfusion on the ablation of rat liver tissue with high-intensity focused ultrasound (HIFU). For this study a practical method has been developed, in which the liver blood flow can be reduced by ligation of the hepatic artery and portal vein. During the treatment the rat liver ...

journal_title：Physics in medicine and biology

authors： Chen L,ter Haar G,Hill CR,Dworkin M,Carnochan P,Young H,Bensted JP

更新日期：1993-11-01 00:00:00

abstract：:We compare two different implementations of a 3D SPECT system model for iterative reconstruction, both of which compensate for non-uniform photon attenuation and depth-dependent system response. One implementation performs fast rotation of images represented using a basis of rectangular voxels, whereas the other repre...

journal_title：Physics in medicine and biology

authors： Yendiki A,Fessler JA

更新日期：2004-06-07 00:00:00

abstract：:The sulphuric acid used for the preparation of the Fricke dosimeter solution may contain trace impurities that can affect the yield of ferric ions. Two methods, pre-irradiation or oxidation with hydrogen peroxide, have been proposed to reduce the influence of these impurities. Fricke users sometimes omit this treatmen...

journal_title：Physics in medicine and biology

authors： Palm A,Mattsson O

更新日期：2000-09-01 00:00:00

abstract：:Rotational coronary angiography provides a multitude of x-ray projections of the contrast agent enhanced coronary arteries along a given trajectory with parallel ECG recording. These data can be used to derive motion information of the coronary arteries including vessel displacement and pulsation. In this paper, a ful...

journal_title：Physics in medicine and biology

authors： Jandt U,Schäfer D,Grass M,Rasche V

更新日期：2009-01-07 00:00:00

abstract：:The stochastic nature of cavitation implies visualization of the cavitation cloud in real-time and in a discriminative manner for the safe use of focused ultrasound therapy. This visualization is sometimes possible with standard echography, but it strongly depends on the quality of the scanner, and is hindered by diff...

journal_title：Physics in medicine and biology

authors： Arnal B,Baranger J,Demene C,Tanter M,Pernot M

更新日期：2017-02-07 00:00:00

abstract：:For conventional irradiation devices, the radiation isocenter accuracy is determined by star shot measurements on films. In magnetic resonance (MR)-guided radiotherapy devices, the results of this test may be altered by the magnetic field and the need to align the radiation and imaging isocenter may require a modifica...

journal_title：Physics in medicine and biology

authors： Dorsch S,Mann P,Lang C,Haering P,Runz A,Karger CP

更新日期：2018-05-29 00:00:00

abstract：:The measurement of beam data for dynamic wedge dosimetry requires the integration of radiation dose at points across the radiation field during the dose delivery. The different measurement techniques required when using a linear diode array to measure beam profiles and when using ionization chambers to measure depth d...

journal_title：Physics in medicine and biology

authors： Bidmead AM,Garton AJ,Childs PJ

更新日期：1995-03-01 00:00:00

abstract：:Radiation dose calculation using models of the human anatomy has been a subject of great interest to radiation protection, medical imaging, and radiotherapy. However, early pioneers of this field did not foresee the exponential growth of research activity as observed today. This review article walks the reader through...

journal_title：Physics in medicine and biology

authors： Xu XG

更新日期：2014-09-21 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：:Technical advances towards high resolution PET imaging try to overcome the inherent physical limitations to spatial resolution. Positrons travel in tissue until they annihilate into the two gamma photons detected. This range is the main detector-independent contribution to PET imaging blurring. To a large extent, it c...

journal_title：Physics in medicine and biology

authors： Cal-González J,Herraiz JL,España S,Corzo PM,Vaquero JJ,Desco M,Udias JM

更新日期：2013-08-07 00:00:00

abstract：:Although interventional x-ray angiography (XA) procedures involve relatively high radiation doses that can lead to deterministic tissue reactions in addition to stochastic effects, convenient and accurate estimation of absorbed organ doses has traditionally been out of reach. This has mainly been due to the absence of...

journal_title：Physics in medicine and biology

authors： Omar A,Bujila R,Fransson A,Andreo P,Poludniowski G

更新日期：2016-04-21 00:00:00

abstract：:As an x-ray beam goes through the human body, it will collect important information via interaction with tissues. Since this interaction is energy-sensitive, the state-of-the-art spectral CT technologies provide higher quality images of biological tissues with x-ray energy information (or spectral information). With e...

journal_title：Physics in medicine and biology

authors： Shi Z,Yang H,Cong W,Wang G

更新日期：2016-06-07 00:00:00

abstract：:This study presents a combined small animal holding fixture system, termed a 'bridge capsule', which provides for small animal re-fixation with positional reproducibility. This system comprises separate holding fixtures for the head and lower body and a connecting part to a gas anesthesia system. A mouse is fixed in p...

journal_title：Physics in medicine and biology

authors： Kokuryo D,Kimura Y,Obata T,Yamaya T,Kawamura K,Zhang MR,Kanno I,Aoki I

更新日期：2010-07-21 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：:In proton scanning systems that employ active energy variation for depth modulation, a switch of the particle energy might typically require 1-2 s. For plans comprising many energy slices, these seconds could sum up to a non-negligible fraction of the total treatment duration. We have applied the Nyquist-Shannon sampl...

journal_title：Physics in medicine and biology

authors： Kang JH,Wilkens JJ,Oelfke U

更新日期：2008-05-07 00:00:00