Abstract：
:In order to measure in vivo resistivity of tissues in the thorax, the possibility of combining anatomical data extracted from high-resolution images with multiple-electrode impedance measurements, a priori knowledge of the range of tissue resistivities, and a priori data on the instrumentation noise is assessed in this study. A statistically constrained minimum-mean-square error estimator (MIMSEE) that minimizes the effects of linearization errors and instrumentation noise is developed and compared to the conventional least-squares error estimator (LSEE). The MIMSEE requires a priori signal and noise information. The statistical constraint signal information was obtained from a priori knowledge of the physiologically allowed range of regional resistivities. The noise constraint information was obtained from a priori knowledge of the linearization error and the instrumentation noise. The torso potentials were simulated by employing a three-dimensional canine torso model. The model consists of four different conductivity regions: heart, right lung, left lung, and body. It is demonstrated that the statistically constrained MIMSEE performs significantly better than the LSEE in determining resistivities. The results based on the torso model indicate that regional resistivities can be estimated to within 40% accuracy of their true values by utilizing a statistically constrained MIMSEE, even if the instrumentation noise is comparable to the measured torso potentials. The errors obtained using the LSEE with the same linearized transfer function and level of instrumentation noise were about five times larger than those obtained using the MIMSEE. For larger measurement errors the MIMSEE performs even better when compared to the LSEE.
journal_name
Phys Med Bioljournal_title
Physics in medicine and biologyauthors
Eyüboğlu BM,Pilkington TC,Wolf PDdoi
10.1088/0031-9155/39/1/001subject
Has Abstractpub_date
1994-01-01 00:00:00pages
1-17issue
1eissn
0031-9155issn
1361-6560journal_volume
39pub_type
杂志文章abstract：:A pencil beam model for the calculation of the lateral scattering in water of protons for any therapeutic energy and depth is presented. It is based on the full Molière theory, taking into account the energy loss and the effects of mixtures and compounds. Concerning the electromagnetic part, the model has no free para...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/61/4/N102
更新日期：2016-02-21 00:00:00
abstract：:Cardiac and respiratory motion artefacts in PET imaging have been traditionally resolved by acquiring the data in gated mode. However, gated PET images are usually characterized by high noise content due to their low photon statistics. In this paper, we present a novel 4D model for the PET imaging system, which can in...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/51/15/012
更新日期：2006-08-07 00:00:00
abstract：:Lymphedema is a common condition involving an abnormal accumulation of lymphatic fluid in the interstitial space that causes swelling, most often in the arm(s) and leg(s). Lymphedema is a significant lifelong concern that can be congenital or develop following cancer treatment or cancer metastasis. Common methods of e...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/52/21/013
更新日期：2007-11-07 00:00:00
abstract：:In this paper we present a novel method of reducing the dosimetric effects of the finite leaf width of a multileaf collimator (MLC) in conformal and intensity modulated radiotherapy (IMRT). This is achieved by decomposing the required high-resolution fluence distribution into two orthogonal components, which are deliv...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/45/3/304
更新日期：2000-03-01 00:00:00
abstract：:A silicon semiconductor photodiode was used to measure the TL-signal of TLD-300 (CaF2:Tm) detectors irradiated with 60Co gamma rays and 226Ra alpha particles. The applied dose values varied from 0.12 to 14.3 Gy for gamma rays and from about 50 to 300 Gy for alpha particles. Because of the infrared sensitivity of the p...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/33/12/006
更新日期：1988-12-01 00:00:00
abstract：:Until now, no matrix transducer has been realized for 3D transesophageal echocardiography (TEE) in pediatric patients. In 3D TEE with a matrix transducer, the biggest challenges are to connect a large number of elements to a standard ultrasound system, and to achieve a high volume rate (>200 Hz). To address these issu...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/1361-6560/aab45e
更新日期：2018-03-29 00:00:00
abstract：:Microcalcification is one of the earliest and main indicators of breast cancer. Because dual-energy digital mammography could suppress the contrast between the adipose and glandular tissues of the breast, it is considered a promising technique that will improve the detection of microcalcification. In dual-energy digit...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/53/22/004
更新日期：2008-11-21 00:00:00
abstract：:The performance of a light sharing and recirculation mechanism that allows the extraction of depth of interaction (DOI) are investigated in this paper, with a particular focus on timing. In parallel, a method to optimize the coincidence time resolution (CTR) of PET detectors by use of the DOI information is proposed a...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/1361-6560/ab2cb0
更新日期：2019-08-07 00:00:00
abstract：:A motorized electron multileaf collimator (eMLC) was developed as an add-on device to the Varian linac for delivery of advanced electron beam therapy. It has previously been shown that electron beams collimated by an eMLC have very similar penumbra to those collimated by applicators and cutouts. Thus, manufacturing pa...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/58/16/5653
更新日期：2013-08-21 00:00:00
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
doi：10.1088/0031-9155/61/12/4346
更新日期：2016-06-21 00:00:00
abstract：:Magnetic resonance imaging is effective for non-invasive detection of myocardial diseases by extracellular volume fraction (ECV) estimation. A new methodology for T1 and ECV mapping is tested in this work, comparing results with other well-consolidated methods. The associated level of uncertainty for data was also est...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/1361-6560/aafcca
更新日期：2019-02-11 00:00:00
abstract：:Radionuclides which decay by electron capture accompanied by Auger electron cascades, or by beta emission are thought to be excessively damaging when incorporated into the molecular structure of mammalian cell nuclei and thereby pose a radiation hazard which is not assessable by conventional dosimetry. Survival data, ...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/34/7/003
更新日期：1989-07-01 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
pub_type： 杂志文章
doi：10.1088/0031-9155/56/2/N02
更新日期：2011-01-21 00:00:00
abstract：:The dose-calculation accuracy of the tomotherapy Hi-Art II(R) (Tomotherapy, Inc., Madison, WI) treatment planning system (TPS) in the presence of low-density lung media was investigated. In this evaluation, a custom-designed heterogeneous phantom mimicking the mediastinum geometry was used. Gammex LN300 and balsa wood...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/54/8/004
更新日期：2009-04-21 00:00:00
abstract：:A method was developed to quantify the intensity of tissue staining using a CCD (charge-coupled device) camera. Reflection spectra of NBT-stained (nitro-blue tetrazolium-stained) and unstained myocardium were recorded via fibre optics coupled to a CCD camera, connected to a microcomputer. The calculation of the intens...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/36/6/007
更新日期：1991-06-01 00:00:00
abstract：:The Jacobian of the deformation field of elastic registration between images taken during radiotherapy is a measure of inter-fraction local deformation. The histogram of the Jacobian values (Jac) within an organ was introduced (JVH-Jacobian-volume-histogram) and first applied in quantifying parotid shrinkage. MVCTs of...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/56/11/008
更新日期：2011-06-07 00:00:00
abstract：:Light propagation in a turbid medium is considered using the linear transport equation. The existence of a diffusion length is proved for the Henyey-Greenstein scattering kernel for all absorption ratios. Numerical methods are given that allow accurate computation of the diffusion coefficient quite easily. ...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/48/23/012
更新日期：2003-12-07 00:00:00
abstract：:Respiratory induced resonance offset (RIRO) is a periodic disturbance of a magnetic field due to breathing. Such disturbance handicaps the accuracy of the proton resonance frequency shift (PRFS) method of MRI temperature mapping in anatomies situated nearby the lungs and chest wall. In this work, we propose a method c...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/51/18/015
更新日期：2006-09-21 00:00:00
abstract：:Our goal was to develop a method for generating high-resolution three-dimensional pulmonary compliance images in rodents from computed tomography (CT) images acquired at a series of constant pressures in ventilated animals. One rat and one mouse were used to demonstrate this technique. A pre-clinical GE flat panel CT ...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/51/5/003
更新日期：2006-03-07 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
pub_type： 杂志文章
doi：10.1088/0031-9155/49/21/008
更新日期：2004-11-07 00:00:00
abstract：:Following the publication of ICRU Report 50, the concepts of GTV (gross tumour volume). CTV (clinical target volume) and PTV (planning target volume) are being used in radiotherapy planning with increasing frequency. In 3D planning, the GTV (or CTV) is normally outlined by the clinician in CT or MRI slices. The PTV is...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/42/4/011
更新日期：1997-04-01 00:00:00
abstract：:The beam quality correction factor k Q for megavoltage photon beams has been calculated for eight PTW (Freiburg, Germany) ionization chambers (Farmer chambers PTW30010, PTW30011, PTW30012, and PTW30013, Semiflex 3D chambers PTW31021, PTW31010, and PTW31013, and the PinPoint 3D chamber PTW31016). Simulations performed ...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/1361-6560/ab9501
更新日期：2020-10-07 00:00:00
abstract：:Positron emission tomography (PET) iterative 3D reconstruction is a very computational demanding task. One of the main issues of the iterative reconstruction concerns the management of the system response matrix (SRM). The SRM models the relationship between the projection and the voxel space and its memory footprint ...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/1361-6560/aae12b
更新日期：2018-09-28 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
pub_type： 杂志文章
doi：10.1088/0031-9155/42/8/011
更新日期：1997-08-01 00:00:00
abstract：:Effective use of the [Formula: see text] decay chain in targeted internal radioimmunotherapy requires the retention of both [Formula: see text] and progeny isotopes at the target site. Imaging-based pharmacokinetic tests of these pharmaceuticals must therefore separately yet simultaneously image multiple isotopes that...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/1361-6560/aa6a99
更新日期：2017-06-07 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
pub_type： 杂志文章
doi：10.1088/1361-6560/aaf098
更新日期：2018-12-10 00:00:00
abstract：:The dynamic collimation system (DCS) can be combined with pencil beam scanning proton therapy to deliver highly conformal treatment plans with unique collimation at each energy layer. This energy layer-specific collimation is accomplished through the synchronized motion of four trimmer blades that intercept the proton...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/1361-6560/ab416d
更新日期：2019-10-21 00:00:00
abstract：:A system is described in which large superficial areas of tissue may be heated using a single plane ultrasonic transducer scanned in a raster fashion. The shape of the heated area is determined by the movement of a microswitch which is activated when it strikes the rigid edge of a hole of the required shape cut in a p...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/30/12/006
更新日期：1985-12-01 00:00:00
abstract：:In addition to being a powerful clinical tool, Positron emission tomography (PET) is also used in small laboratory animal research to visualize and track certain molecular processes associated with diseases such as cancer, heart disease and neurological disorders in living small animal models of disease. However, dosi...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/58/1/169
更新日期：2013-01-07 00:00:00
abstract：:The correlation between radiation quality and cellular RBE of a mixed n-gamma field produced by a collimated fast-neutron beam produced by the bombardment of 14 MeV deuterons on Be in a water phantom is investigated. The microdosimetric parameters yF and YD are used for a physical description of the local distribution...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/26/1/006
更新日期：1981-01-01 00:00:00
