Dynamics of the upper urinary tract: I. Peristaltic flow through a distensible tube of limited length.

abstract：:Biomedical fibre-optic sensors are attractive for the measurement of physical, chemical and biochemical parameters and for spectral measurements directly performed on the patient. An overview of fibre-optic sensors for in vivo monitoring is given, with particular attention paid to the advantages that these sensors are...

journal_title：Physics in medicine and biology

authors： Mignani AG,Baldini F

更新日期：1997-05-01 00:00:00

abstract：:Fractional flow reserve (FFR) provides an objective physiological evaluation of stenosis severity. A technique that can measure FFR using only angiographic images would be a valuable tool in the cardiac catheterization laboratory. To perform this, the diseased blood flow can be measured with a first pass distribution ...

journal_title：Physics in medicine and biology

authors： Wong JT,Molloi S

更新日期：2008-07-21 00:00:00

abstract：:In CT imaging, a variety of applications exist which are strongly SNR limited. However, in some cases redundant data of the same body region provide additional quanta. Examples in dual energy CT, the spatial resolution has to be compromised to provide good SNR for material decomposition. However, the respective spectr...

journal_title：Physics in medicine and biology

authors： Bruder H,Raupach R,Sunnegardh J,Allmendinger T,Klotz E,Stierstorfer K,Flohr T

更新日期：2015-11-07 00:00:00

abstract：:This work presents an improvement of the VIPARnd ('nd' stands for 'normoxic, double', or VIP) polymer gel dosimeter. The gel composition was altered by increasing the concentration of the monomeric components, N-vinylpyrrolidone (NVP) and N,N'-methylenebisacrylamide (MBA), in co-solvent solutions. The optimal composit...

journal_title：Physics in medicine and biology

authors： Kozicki M,Jaszczak M,Maras P,Dudek M,Cłapa M

更新日期：2017-02-07 00:00:00

abstract：:The potential of the variable-aperture collimator (VAC) in intensity-modulated radiation therapy (IMRT) has been evaluated by comparing its performance with that of the multi-leaf collimator (MLC). This comparison used a decomposition algorithm to find the series of collimator segments that would treat a given intensi...

journal_title：Physics in medicine and biology

authors： Anderson JW,Symonds-Tayler R,Hartmann G,Echner G,Lang C,Schlegel W,Webb S

更新日期：2006-04-07 00:00:00

abstract：:The purpose of this study was to improve the performance of a small gamma camera, utilizing a NaI(Tl) plate and a 5" position sensitive PMT. We attempted to build a NaI(Tl) plate crystal system which retained all its advantages, while at the same time integrating some of the advantages inherent in an array-type scinti...

journal_title：Physics in medicine and biology

authors： Jeong MH,Choi Y,Chung YH,Song TY,Jung JH,Hong KJ,Min BJ,Choe YS,Lee KH,Kim BT

更新日期：2004-11-07 00:00:00

abstract：:Most tissue characterization methods use RF data originating from backscattering processes in the insonified tissue. Characterization of the tissue of a thin layer (e.g., an artery wall) poses problems because of the small amount of data available. The tissue layer may be so thin that there are no RF data that are not...

journal_title：Physics in medicine and biology

authors： Linssen FM,Hoeks AP,Brands PJ

更新日期：1991-10-01 00:00:00

abstract：:Ultrasonic speed of propagation and attenuation were investigated as a function of absorbed radiation dose in PAG and MAGIC polymer gel dosimeters. Both PAG and MAGIC gel dosimeters displayed a dependence of ultrasonic parameters on absorbed dose with attenuation displaying significant changes in the dose range invest...

journal_title：Physics in medicine and biology

authors： Mather ML,De Deene Y,Whittaker AK,Simon GP,Rutgers R,Baldock C

更新日期：2002-12-21 00:00:00

abstract：:In recent codes of practice for reference dosimetry in clinical proton beams using ionization chambers, it is recommended to perform the measurement in a water phantom. However, in situations where the positioning accuracy is very critical, it could be more convenient to perform the measurement in a plastic phantom. I...

journal_title：Physics in medicine and biology

authors： Palmans H,Symons JE,Denis JM,de Kock EA,Jones DT,Vynckier S

更新日期：2002-09-07 00:00:00

abstract：:Avoiding toxicities in radiotherapy requires the knowledge of tolerable organ doses. For new, experimental fractionation schemes (e.g. hypofractionation) these are typically derived from traditional schedules using the biologically effective dose (BED) model. In this report we investigate the difficulties of establish...

journal_title：Physics in medicine and biology

authors： Perkó Z,Bortfeld T,Hong T,Wolfgang J,Unkelbach J

更新日期：2018-02-05 00:00:00

abstract：:Despite over ten years of in vitro investigations of ultrasound contrast agents, the level of understanding of their behaviour in ultrasound fields is limited. Several problems associated with these investigations, particular to the nature of contrast agents, are discussed. Using a commercial scanner the RF normalized...

journal_title：Physics in medicine and biology

authors： Sboros V,Ramnarine KV,Moran CM,Pye SD,McDicken WN

更新日期：2002-12-07 00:00:00

abstract：:Segmented attenuation correction is now a widely accepted technique to reduce noise propagation from transmission scanning in positron emission tomography (PET). In this paper, we present a new method for segmenting transmission images in whole-body scanning. This reduces the noise in the correction maps while still c...

journal_title：Physics in medicine and biology

authors： Zaidi H,Diaz-Gomez M,Boudraa A,Slosman DO

更新日期：2002-04-07 00:00:00

abstract：:Lung 4D computed tomography (4D-CT), which is a time-resolved CT data acquisition, performs an important role in explicitly including respiratory motion in treatment planning and delivery. However, the radiation dose is usually reduced at the expense of inter-slice spatial resolution to minimize radiation-related heal...

journal_title：Physics in medicine and biology

authors： Fang S,Wang H,Liu Y,Zhang M,Yang W,Feng Q,Chen W,Zhang Y

更新日期：2017-10-03 00:00:00

abstract：:It is difficult to test near-infrared spectrophotometry instruments in vivo. Therefore we constructed a liquid phantom which mimics the neonatal head. It consists of a spherical 3.5 mm thick layer of silicone rubber simulating skin and bone and a 0.5 mm thick clear layer of polypropylene imitating cerebrospinal fluid....

journal_title：Physics in medicine and biology

authors： Wolf M,Keel M,Dietz V,von Siebenthal K,Bucher HU,Baenziger O

更新日期：1999-07-01 00:00:00

abstract：:Heavy-ion radiotherapy exploits the high biological effectiveness of localized energy deposition delivered by so-called Bragg-peak particles. Recent publications have challenged the established procedures to calculate biological effective dose distributions in treatment planning. They emphasize the importance of very ...

journal_title：Physics in medicine and biology

authors： Elsässer T,Gemmel A,Scholz M,Schardt D,Krämer M

更新日期：2009-04-07 00:00:00

abstract：:Absorbed dose values were determined under the reference conditions in a phantom irradiated by high-energy photon beams with quality varying between 60Co gamma rays and 25 MV X-rays, using four commonly employed types of ionisation chamber. The ionisation chamber readings were converted to absorbed dose values applyin...

journal_title：Physics in medicine and biology

authors： Mijnheer BJ,Wittkämper FW

更新日期：1986-04-01 00:00:00

abstract：:A phantom study for dosimetry in the urethra using alanine/ESR during (192)Ir HDR brachytherapy of prostate cancer is presented. The measurement method of the secondary standard of the Physikalisch-Technische Bundesanstalt had to be slightly modified in order to be able to measure inside a Foley catheter. The absorbed...

journal_title：Physics in medicine and biology

authors： Anton M,Wagner D,Selbach HJ,Hackel T,Hermann RM,Hess CF,Vorwerk H

更新日期：2009-05-07 00:00:00

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

authors： Reinstein LE,Gluckman GR,Meek AG

更新日期：1998-10-01 00:00:00

abstract：:A 3D anatomical computational model is developed to assess thermal effects due to exposure to the electromagnetic field required to power a new investigational active implantable microvalve for the treatment of glaucoma. Such a device, located in the temporal superior eye quadrant, produces a filtering bleb, which is ...

journal_title：Physics in medicine and biology

authors： Schaumburg F,Guarnieri FA

更新日期：2017-05-07 00:00:00

abstract：:Electrical properties (EP), namely conductivity and permittivity, can provide endogenous contrast for tissue characterization. Using electrical property tomography (EPT), maps of EP can be generated from conventional MRI data. This report investigates the feasibility and accuracy of EPT at 21.1 T for multiple RF coils...

journal_title：Physics in medicine and biology

authors： Amouzandeh G,Mentink-Vigier F,Helsper S,Bagdasarian FA,Rosenberg JT,Grant SC

更新日期：2020-02-28 00:00:00

abstract：:The dosimetric measurement and modeling of small radiation treatment fields (<2 × 2 cm2) are difficult to perform and prone to error. Measurements of small fields are often adversely influenced by the properties of the detectors used to make them. The dosimetric properties of small fields have been difficult to accura...

journal_title：Physics in medicine and biology

authors： Hundertmark B,Sterpin E,Mackie T

更新日期：2011-06-21 00:00:00

abstract：:The development of new biological imaging technologies offers the opportunity to further individualize radiotherapy. Biologically conformal radiation therapy (BCRT) implies the use of the spatial distribution of one or more radiobiological parameters to guide the IMRT dose prescription. Our aim was to implement BCRT i...

journal_title：Physics in medicine and biology

authors： Vanderstraeten B,De Gersem W,Duthoy W,De Neve W,Thierens H

更新日期：2006-08-21 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：:New definitions of the absorbed dose conversion factors Clambda and CE are proposed. The absorbed dose in water is given by the product of absorbed dose conversion factor, exposure calibration factor, ionisation chamber reading, cap displacement correction factor and perturbation correction factor. At exposure calibra...

journal_title：Physics in medicine and biology

authors： Shiragai A

更新日期：1978-03-01 00:00:00

abstract：:It is a challenging problem to resolve and identify drug (or non-specific fluorophore) distribution throughout the whole body of small animals in vivo. In this article, an algorithm of unmixing multispectral fluorescence tomography (MFT) images based on independent component analysis (ICA) is proposed to solve this pr...

journal_title：Physics in medicine and biology

authors： Pu H,Zhang G,He W,Liu F,Guang H,Zhang Y,Bai J,Luo J

更新日期：2014-09-07 00:00:00

abstract：:We explore how the radioactive background from naturally occurring 176Lu affects single photon transmission imaging for lutetium orthosilicate (LSO) scintillator-based PET cameras by estimating the transmission noise equivalent count rate (NECR) including this background. Assuming a typical PET camera geometry (80 cm ...

journal_title：Physics in medicine and biology

authors： Huber JS,Moses WW,Jones WF,Watson CC

更新日期：2002-10-07 00:00:00

abstract：:Does the posture of a patient have an effect on the organ and tissue absorbed doses caused by x-ray examinations? This study aims to find the answer to this question, based on Monte Carlo (MC) simulations of commonly performed x-ray examinations using adult phantoms modelled to represent humans in standing as well as ...

journal_title：Physics in medicine and biology

authors： Cassola VF,Kramer R,Brayner C,Khoury HJ

更新日期：2010-08-07 00:00:00

abstract：:A common dose-saving technique used in modern CT devices is automatic tube current modulation (TCM), which was originally designed to also reduce the dose in paediatric CT patients. In order to be able to deduce detailed organ doses of paediatric models, dose conversion coefficients normalized to CTDI(vol) for an eigh...

journal_title：Physics in medicine and biology

authors： Schlattl H,Zankl M,Becker J,Hoeschen C

更新日期：2012-10-21 00:00:00

abstract：:This work aims to develop a voxel-level dose prediction framework by integrating distance information between PTV and OARs, as well as image information, into a densely-connected network (DCNN). Firstly, a four-channel feature map, consisting of a PTV image, an OAR image, a CT image, and a distance image, is construct...

journal_title：Physics in medicine and biology

authors： Zhang J,Liu S,Yan H,Li T,Mao R,Liu J

更新日期：2020-10-21 00:00:00

abstract：:The low energy model of the GEANT4 Monte Carlo toolkit was used to simulate the energy response of a T.P.A. Mk-II ionization chamber under a variety of different conditions. The sample position resulting in the maximum response along the axial direction of the chamber was obtained. The parameters of the simulation wer...

journal_title：Physics in medicine and biology

authors： Seneviratne MD,Reinhard MI,Baldock C

更新日期：2007-07-07 00:00:00