Local hydrogen clearance as a method for the measurement of capillary blood flow.


:A hydrogen clearance technique for the measurement of capillary blood flow in skeletal muscle (both resting and working) and the beating heart in experimental animals is described. Various methods for introducing the hydrogen into the region of measurement are compared, together with the appropriate methods for evaluating the resultant curves. All methods yielded results which were proportional to each other signifying that this is a reliable method for measuring changes in capillary blood flow. Reproducible results were obtained, and physiological changes in flow could be easily detected. An approach towards obtaining absolute flow values is proposed by simultaneous measurement of the arterial input function together with the independent use of other indicators.


Phys Med Biol


Harrison DK,Kessler M




Has Abstract


1989-10-01 00:00:00












  • A rapid colour stabilization technique for radiochromic film dosimetry.

    abstract::Various forms of GAFChromic film have been used for several years as radiographic media for measuring dose distributions of brachytherapy sources and small radiation fields. Upon irradiation the film changes colour and darkens with time post-irradiation. The darkening is most rapid in the first 24 h, and it has been s...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Reinstein LE,Gluckman GR,Meek AG

    更新日期:1998-10-01 00:00:00

  • Beam configurations for 3D tomographic intensity modulated radiation therapy.

    abstract::We extend the theory of three-dimensional (3D) tomographic intensity modulated radiation therapy (IMRT). The geometry consists of two-dimensional modulated beams on a sphere centred in the tumour. The theory provides an efficient algorithm for computing beam modulation patterns that approximately 'reconstruct' the pre...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Levine RY,Braunstein M

    更新日期:2002-03-07 00:00:00

  • Counting losses in multidetector radiation counters.

    abstract::We examined the reasons for the reduction in response of a multidetector radiation counting system when operated at high count-rates and established a convenient method of correction which is accurate to within +/- 1% up to 0-6 X 10(5) counts per second. In its application the method uses the observed count-rates from...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Oxby CB,Oldroyd B,Appleby DB

    更新日期:1976-01-01 00:00:00

  • Simultaneous minimization of leaf travel distance and tongue-and-groove effect for segmental intensity-modulated radiation therapy.

    abstract::This paper introduces a method to simultaneously minimize the leaf travel distance and the tongue-and-groove effect for IMRT leaf sequences to be delivered in segmental mode. The basic idea is to add a large enough number of openings through cutting or splitting existing openings for those leaf pairs with openings few...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Dai J,Que W

    更新日期:2004-12-07 00:00:00

  • Hemodynamics altered by placing helix stents in an aneurysm at a 45 degrees angle to the curved vessel.

    abstract::Flow visualization, particle image velocimetry and numerical computation have been complementarily performed to study the fluid flow inside a stented lateral aneurysm. The curved afferent vessel had an inner diameter of 5 mm. The diameters of the aneurysmal orifice, neck and fundus were 7 mm, 5 mm and 7.5 mm, respecti...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Liou TM,Li YC,Wang TC

    更新日期:2008-07-21 00:00:00

  • Fast and exact Hessian computation for a class of nonlinear functions used in radiation therapy treatment planning.

    abstract::In nonlinear optimisation, using exact Hessian computations (full-Newton) hold superior convergence properties over quasi-Newton methods or gradient-based methods. However, for medium-scale problems, computing the Hessian can be computationally expensive and thus time-consuming. For solvers dedicated to a specific pro...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: van Haveren R,Breedveld S

    更新日期:2019-08-14 00:00:00

  • The recombination correction for an ionisation chamber exposed to pulsed radiation in a 'swept beam' technique. I. Theory.

    abstract::The established theory for the collection efficiency of an ionisation chamber irradiated by a series of uniform short pulses is extended to the more complex case of irradiation in a pulsed and electromagnetically swept electron beam. The radial variation of exposure rate is assumed to be Gaussian with scale constant e...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Boag JW

    更新日期:1982-02-01 00:00:00

  • 4D digital tomosynthesis image reconstruction using brute force-based adaptive total variation (BF-ATV) in a prototype LINAC system.

    abstract::Respiratory-correlated cone-beam CT (CBCT) not only inhibits rapid scanning due to the slow speed of the LINAC head gantry rotation, but its implementation for routine patient imaging is impractical because of the high radiation dose delivered during the process. Digital tomosynthesis (DTS) is a potentially faster tec...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Choi S,Lee S,Kang YN,Hsieh SS,Kim HJ

    更新日期:2019-05-02 00:00:00

  • The effect of energy and source location on gamma camera intrinsic and extrinsic spatial resolution: an experimental and Monte Carlo study.

    abstract::Quantification of nuclear medicine image data is a prerequisite for personalized absorbed dose calculations and quantitative biodistribution studies. The spatial response of a detector is a governing factor affecting the accuracy of image quantification, and the aim of this work was to model this impact. To simulate s...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Holstensson M,Partridge M,Buckley SE,Flux GD

    更新日期:2010-03-21 00:00:00

  • Comparison of blood velocity measurements between ultrasound Doppler and accelerated phase-contrast MR angiography in small arteries with disturbed flow.

    abstract::Ultrasound Doppler (UD) velocity measurements are commonly used to quantify blood flow velocities in vivo. The aim of our work was to investigate the accuracy of in vivo spectral Doppler measurements of velocity waveforms. Waveforms were derived from spectral Doppler signals and corrected for intrinsic spectral broade...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Jiang J,Strother C,Johnson K,Baker S,Consigny D,Wieben O,Zagzebski J

    更新日期:2011-03-21 00:00:00

  • Positron autoradiography for intravascular imaging: feasibility evaluation.

    abstract::Approximately 70% of acute coronary artery disease is caused by unstable (vulnerable) plaques with an inflammation of the overlying cap and high lipid content. A rupturing of the inflamed cap of the plaque results in propagation of the thrombus into the lumen, blockage of the artery and acute ischaemic syndrome or sud...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Shikhaliev PM,Xu T,Ducote JL,Easwaramoorthy B,Mukherjee J,Molloi S

    更新日期:2006-02-21 00:00:00

  • Projection x-ray imaging with photon energy weighting: experimental evaluation with a prototype detector.

    abstract::The signal-to-noise ratio (SNR) in x-ray imaging can be increased using a photon counting detector which could allow for rejecting electronics noise and for weighting x-ray photons according to their energies. This approach, however, was not feasible for a long time because photon counting x-ray detectors with very hi...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Shikhaliev PM

    更新日期:2009-08-21 00:00:00

  • Improved iterative tomographic reconstruction for x-ray imaging with edge-illumination.

    abstract::Iterative tomographic reconstruction has been established as a viable alternative for data analysis in phase-sensitive x-ray imaging based on the edge-illumination principle. However, previously published approaches did not account for drifts of optical elements during a scan, which can lead to artefacts. Up to now, t...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Modregger P,Meganck J,Hagen CK,Massimi L,Olivo A,Endrizzi M

    更新日期:2019-10-10 00:00:00

  • Monte Carlo modelling of electron beams from medical accelerators.

    abstract::Monte Carlo simulation of radiation transport is considered to be one of the most accurate methods of radiation therapy dose calculation. With the rapid development of computer technology, Monte Carlo based treatment planning for radiation therapy is becoming practical. A basic requirement for Monte Carlo treatment pl...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章,评审


    authors: Ma CM,Jiang SB

    更新日期:1999-12-01 00:00:00

  • Modulated photon radiotherapy (XMRT): an algorithm for the simultaneous optimization of photon beamlet energy and intensity in external beam radiotherapy (EBRT) planning.

    abstract::This is a proof of principle study on an algorithm for optimizing external beam radiotherapy in terms of both photon beamlet energy and fluence. This simultaneous beamlet energy and fluence optimization is denoted modulated photon radiotherapy (XMRT). XMRT is compared with single-energy intensity modulated radiotherap...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: McGeachy P,Villarreal-Barajas JE,Zinchenko Y,Khan R

    更新日期:2016-02-21 00:00:00

  • UWB pulse propagation into human tissues.

    abstract::In this paper the propagation of a UWB pulse into a layered model of the human body is studied to characterize absorption and reflection of the UWB signal due to the different body tissues. Several time behaviours for the incident UWB pulse are considered and compared with reference to the feasibility of breath and he...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Cavagnaro M,Pittella E,Pisa S

    更新日期:2013-12-21 00:00:00

  • High-energy x-ray Talbot-Lau radiography of a human knee.

    abstract::We report on a radiographic measurement of an ex vivo human knee using a grating-based phase-contrast imaging setup and a medical x-ray tube at a tube voltage of 70 kV. The measurement has been carried out using a Talbot-Lau setup that is suitable to achieve a high visibility in the energy regime of medical imaging. I...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Horn F,Gelse K,Jabari S,Hauke C,Kaeppler S,Ludwig V,Meyer P,Michel T,Mohr J,Pelzer G,Rieger J,Riess C,Seifert M,Anton G

    更新日期:2017-08-01 00:00:00

  • A mathematical model for predicting the changes of non-small cell lung cancer based on tumor mass during radiotherapy.

    abstract::This study aims to build a feasible mathematical model to analyze the mass evolution of NSCLC during standard fractionated radiotherapy. Seventy-three cases of NSCLC who were received radiotherapy with prescription dose of 2 Gy  ×  30 fx were selected retrospectively and divided into adenocarcinoma (ADC) group and squ...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Chen J,Wang K,Jian J,Zhang W

    更新日期:2019-11-26 00:00:00

  • Inclusion of organ movements in IMRT treatment planning via inverse planning based on probability distributions.

    abstract::In this paper, we investigate an off-line strategy to incorporate inter-fraction organ motion in IMRT treatment planning. It was suggested that inverse planning could be based on a probability distribution of patient geometries instead of a single snap shot. However, this concept is connected to two intrinsic problems...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Unkelbach J,Oelfke U

    更新日期:2004-09-07 00:00:00

  • Quantitative validation of the 3D SAR profile of hyperthermia applicators using the gamma method.

    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

    pub_type: 杂志文章


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

    更新日期:2007-06-07 00:00:00

  • Verification of absolute dose rates for intravascular brachytherapy beta sources.

    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

    pub_type: 杂志文章


    authors: Piessens M,Reynaert N

    更新日期:2000-08-01 00:00:00

  • Measurement of inter and intra fraction organ motion in radiotherapy using cone beam CT projection images.

    abstract::A method is presented for extraction of intra and inter fraction motion of seeds/markers within the patient from cone beam CT (CBCT) projection images. The position of the marker is determined on each projection image and fitted to a function describing the projection of a fixed point onto the imaging panel at differe...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Marchant TE,Amer AM,Moore CJ

    更新日期:2008-02-21 00:00:00

  • Radiobiological aspects of supralinear photographic emulsions.

    abstract::Nuclear emulsions of the Ilford K series, exposed to X-rays from 15 to 150 kVp and systematically underdeveloped, exhibit supralinear blackness--exposure curves ranging from 1- to 4-hit in character, and whose shape is the same at all excitation voltages. Processing can be so adjusted that the curve shape is well repr...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Katz R,Pennington EC

    更新日期:1978-11-01 00:00:00

  • Alanine dosimetry in strong magnetic fields: use as a transfer standard in MRI-guided radiotherapy.

    abstract::Reference dosimetry in the presence of a strong magnetic field is challenging. Ionisation chambers have shown to be strongly affected by magnetic fields. There is a need for robust and stable detectors in MRI-guided radiotherapy (MRIgRT). This study investigates the behaviour of the alanine dosimeter in magnetic field...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Billas I,Bouchard H,Oelfke U,Shipley D,Gouldstone C,Duane S

    更新日期:2020-06-03 00:00:00

  • Monte Carlo calculations of beam quality correction factors kQ for electron dosimetry with a parallel-plate Roos chamber.

    abstract::Current dosimetry protocols (AAPM, IAEA, DIN) recommend the use of parallel-plate ionization chambers for the measurement of absorbed dose-to-water in clinical electron beams. For well-guarded plane-parallel chambers, it is assumed that the perturbation correction pQ is unity for all electron energies. In this study, ...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Zink K,Wulff J

    更新日期:2008-03-21 00:00:00

  • [A simulation method for studying scintillation camera collimators].

    abstract::This paper presents a computer simulation of photon interaction with collimator septa, which allows the point spread function of scintillation camera collimators to be calculated. The method simulates photon attenuation along their propagation direction in a determinist way. Using this simulation, the spatial resoluti...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Gantet P,Esquerré JP,Danet B,Guiraud R

    更新日期:1990-05-01 00:00:00

  • Conversion factors for the estimation of effective dose in paediatric cardiac angiography.

    abstract::Conversion factors, which relate the kerma-area product to effective dose, have been estimated for paediatric cardiac x-ray angiography. Monte Carlo techniques have been used to calculate the conversion factors for a wide range of projection angles for children of five ages and for adults. Correction factors are provi...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Schmidt PW,Dance DR,Skinner CL,Smith IA,McNeill JG

    更新日期:2000-10-01 00:00:00

  • Adaptive treatment-length optimization in spatiobiologically integrated radiotherapy.

    abstract::Recent theoretical research on spatiobiologically integrated radiotherapy has focused on optimization models that adapt fluence-maps to the evolution of tumor state, for example, cell densities, as observed in quantitative functional images acquired over the treatment course. We propose an optimization model that adap...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Ajdari A,Ghate A,Kim M

    更新日期:2018-03-27 00:00:00

  • Tumour xenograft detection through quantitative analysis of the metabolic profile of urine in mice.

    abstract::The metabolic content of urine from NIH III nude mice (n = 22) was analysed before and after inoculation with human glioblastoma multiforme (GBM) cancer cells. An age- and gender-matched control population (n = 14) was also studied to identify non-tumour-related changes. Urine samples were collected daily for 6 weeks,...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Moroz J,Turner J,Slupsky C,Fallone G,Syme A

    更新日期:2011-02-07 00:00:00

  • In vivo evaluation of a new system for 3D computerized angiography.

    abstract::A new system has been designed and built to validate the concept of 3D computerized angiography (CA). This system can acquire a set of 2D digital subtracted angiography images while rotating around a patient and then, using these images, reconstruct a 3D representation of the opacified vasculature. The design principl...

    journal_title:Physics in medicine and biology

    pub_type: 杂志文章


    authors: Saint-Félix D,Trousset Y,Picard C,Ponchut C,Roméas R,Rougée A

    更新日期:1994-03-01 00:00:00