Abstract:
:The dielectric properties of glycerol, propylene glycol, ethylene glycol and dimethyl sulphoxide have been measured in various aqueous concentrations generally sufficient to allow supercooling rather than freezing. The temperature range investigated is from -80 degrees C to +20 degrees C and the frequency range is 100 MHz to 2 GHz. The aim is to find the materials and conditions most favorable for very rapid re-warming of perfused biological tissue by electromagnetic fields, avoiding thermal runaway in the bulk and local non-uniformity of temperature. Frequencies below 500 MHz are generally indicated.
journal_name
Phys Med Bioljournal_title
Physics in medicine and biologyauthors
Michelson SC,Evans Sdoi
10.1088/0031-9155/41/10/014subject
Has Abstractpub_date
1996-10-01 00:00:00pages
2053-66issue
10eissn
0031-9155issn
1361-6560journal_volume
41pub_type
杂志文章abstract::We tested the ability of a single Compton camera (CC) to produce 3-dimensional (3D) images of prompt gammas (PGs) emitted during the irradiation of a tissue-equivalent plastic phantom with proton pencil beams for clinical doses delivered at clinical dose rates. PG measurements were made with a small prototype CC place...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/aaa203
更新日期:2018-01-30 00:00:00
abstract::An optimized configuration of multi-pinhole aperture can improve the spatial resolution and the sensitivity of pinhole SPECT simultaneously. In this study, an optimization strategy of the multi-pinhole configuration with a small detector is proposed for mouse cardiac imaging. A 14 mm-diameter spherical field-of-view (...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/60/2/473
更新日期:2015-01-21 00:00:00
abstract::We have compared two methods of estimating the cellular radiosensitivity of a heterogeneous tumour, namely, via cell-survival and via tumour control probability (TCP) pseudo-experiments. It is assumed that there exists intra-tumour variability in radiosensitivity and that the tumour consists predominantly of radiosens...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/60/15/N293
更新日期:2015-08-07 00:00:00
abstract::As a new method, x-ray diffraction enhanced imaging (DEI) has extremely high sensitivity for weakly absorbing low-Z samples in medical and biological fields. Conventional performance parameters, such as spatial resolution and low-contrast resolution, are not enough to describe the characteristics of a DEI system. This...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/51/12/002
更新日期:2006-06-21 00:00:00
abstract::The electron pencil-beam redefinition algorithm (PBRA), which is used to calculate electron beam dose distributions, assumes that the virtual source of each pencil beam is identical to that of the broad beam incident on the patient. In the present work, a virtual source specific for each pencil beam is modelled by inc...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/46/11/306
更新日期:2001-11-01 00:00:00
abstract::The design and performance of a dosimetric system for the irradiation of thin biological samples with therapeutic proton beams is reported. Protons with initial energies between 40 MeV and 250 MeV are degraded with polystyrene blocks of variable thickness in order to place the sample, an aqueous layer of 10 microm thi...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/47/3/304
更新日期:2002-02-07 00:00:00
abstract::In a previous paper, we described quality assurance procedures for Hi-Art helical tomotherapy machines. Here, we develop further some ideas discussed briefly in that paper. Simple helically generated dose distributions are modelled, and relationships between these dose distributions and underlying characteristics of H...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/50/7/013
更新日期:2005-04-07 00:00:00
abstract::Micro-CT is widely used in preclinical studies, generating substantial interest in extending its capabilities in functional imaging applications such as blood perfusion and cardiac function. However, imaging cardiac structure and function in mice is challenging due to their small size and rapid heart rate. To overcome...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/aa9b45
更新日期:2018-01-09 00:00:00
abstract::Fluorescence diffuse optical tomography (fDOT) provides 3D images of fluorescence distributions in biological tissue, which represent molecular and cellular processes. The image reconstruction problem is highly ill-posed and requires regularisation techniques to stabilise and find meaningful solutions. Quadratic regul...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/61/4/1452
更新日期:2016-02-21 00:00:00
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journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/60/13/5007
更新日期:2015-07-07 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
pub_type: 杂志文章
doi:10.1088/0031-9155/47/19/307
更新日期:2002-10-07 00:00:00
abstract::The rationale for multi-modality imaging is to integrate the strengths of different imaging technologies while reducing the shortcomings of an individual modality. The work presented here proposes a limited-field-of-view (LFOV) SPECT reconstruction technique that can be implemented on a multi-modality MR/SPECT system ...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/56/3/010
更新日期:2011-02-07 00:00:00
abstract::The treatment delivery time of intensity-modulated radiation therapy (IMRT) with a multileaf collimator (MLC) is generally longer than that of conventional radiotherapy. In theory, removing the flattening filter from the treatment head may reduce the beam-on time by enhancing the output dose rate, and then reduce the ...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/49/8/011
更新日期:2004-04-21 00:00:00
abstract::This study evaluates the performance of the Bruker positron emission tomograph (PET) insert combined with a BioSpec 70/30 USR magnetic resonance imaging (MRI) scanner using the manufacturer acceptance protocol and the NEMA NU 4-2008 for small animal PET. The PET insert is made of 3 rings of 8 monolithic LYSO crystals ...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/aba08c
更新日期:2020-06-26 00:00:00
abstract::A new class of dose calibrator called a micro-dose calibrator, designed to measure radioactivity rates in the range between 1 kBq up to 370 kBq, has been designed and an 8 NaI(Tl)/photo multiplier tube (PMT) module prototype built to evaluate its performance. The design of the micro-dose calibrator is based on the con...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/aadb3b
更新日期:2018-09-10 00:00:00
abstract::Two dosimetry protocols based on absorbed dose to water have recently been implemented: TG-51 and TRS-398. These protocols use different beam-quality indices: %dd(10)x and TPR20,10. The effect of electron contamination in measurements of %dd(10)x has been proposed as a disadvantage of the TG-51. For actual measurement...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/49/1/002
更新日期:2004-01-07 00:00:00
abstract::This work aims to contribute to the study of the radiation dose distribution delivered to the hands of medical staff members during a general computed tomographic (CT) fluoroscopic guided procedure. In this study, both Monte Carlo simulations and measurements were performed. For free-in-air and computed tomography dos...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/58/16/5433
更新日期:2013-08-21 00:00:00
abstract::During image-guided cancer radiation treatment, three-dimensional (3D) tumor volumetric information is important for treatment success. However, it is typically not feasible to image a patient's 3D tumor continuously in real time during treatment due to concern over excessive patient radiation dose. We present a new i...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/aa56b2
更新日期:2017-02-21 00:00:00
abstract::It has been reported that the dose effects of metallic guidewires are significant in intravascular brachytherapy (IVBT) using a beta source. The purpose of this work is to investigate the dependence of these dose effects on guidewire position. The EGS4 Monte Carlo codes were used to perform the dose calculations for t...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/47/10/309
更新日期:2002-05-21 00:00:00
abstract::Recently, a new family of low-cost x-radiation detectors have been developed, based on semiconducting polymer diodes, which are easy to process, mechanically flexible, relatively inexpensive, and able to cover large areas. To test their potential for radiotherapy applications such as beam monitors or dosimeters, as an...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/58/13/4471
更新日期:2013-07-07 00:00:00
abstract::Lung tumors treated in breath-hold are subject to inter- and intra-breath-hold variations, which makes tumor position monitoring during each breath-hold important. A markerless technique is desirable, but limited tumor visibility on kV images makes this challenging. We evaluated if template matching + triangulation ...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/aac1a9
更新日期:2018-05-29 00:00:00
abstract::Incorrect prediction of skin dose in external beam radiotherapy (EBR) can have normal tissue complication such as acute skin desquamation and skin necrosis. The absorbed dose of skin should be evaluated within basal layer, placed between the epidermis and dermis layers. However, current treatment planning systems (TPS...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/ab2ef5
更新日期:2019-08-14 00:00:00
abstract::Today, new single photon emission computed tomography (SPECT) reconstruction techniques rely on accurate Monte Carlo (MC) simulations to optimize reconstructed images. However, existing MC scintillation camera models which usually include an accurate description of the collimator and crystal, lack correct implementati...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/56/1/006
更新日期:2011-01-07 00:00:00
abstract::For the treatment planning during intensity modulated radiation therapy (IMRT) or volumetric modulated arc therapy (VMAT), beam fluence maps can be first optimized via fluence map optimization (FMO) under the given dose prescriptions and constraints to conformally deliver the radiation dose to the targets while sparin...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/61/7/2838
更新日期:2016-04-07 00:00:00
abstract::Electron depth-dose curves and spectra have been measured from an experimental accelerator on which both energy and spectral shape could be varied independently. The measurements were made at nominal energies of 6 and 12 MeV, with the energy spread (FWHM) varied from 1.7% to over 10% of average energy. Changes in dept...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/28/12/005
更新日期:1983-12-01 00:00:00
abstract::We propose a method to compensate for six degree-of-freedom rigid motion in helical CT of the head. The method is demonstrated in simulations and in helical scans performed on a 16-slice CT scanner. Scans of a Hoffman brain phantom were acquired while an optical motion tracking system recorded the motion of the bed an...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/60/5/2047
更新日期:2015-03-07 00:00:00
abstract::We comment on a previous article by Zhang and Newhauser (2009 Phys. Med. Biol. 54 1383-95) which presents several approximate ways of computing the water equivalent of an arbitrary degrader. First, we present a simple exact method which depends only on the range-energy relation of water and of the degrader material. S...
journal_title:Physics in medicine and biology
pub_type: 评论,信件
doi:10.1088/0031-9155/55/9/L01
更新日期:2010-05-07 00:00:00
abstract::The 'EXACT3D' positron tomograph, which is now in routine clinical research use, was developed with the aim of achieving unprecedented sensitivity, high spatial and temporal resolution and simplicity of design using proven detector technology. It consists of six rings of standard detector blocks (CTI/Siemens EXACT HR+...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/45/9/313
更新日期:2000-09-01 00:00:00
abstract::Intensity-modulated radiation therapy (IMRT) can be delivered by the 'sliding-leaves' dynamic multileaf collimator (DMLC) technique. Intrafraction organ motion can be accommodated by arranging an identical tracking motion for 'breathing leaves'. However, this is only possible for very specific circumstances such as re...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/51/18/005
更新日期:2006-09-21 00:00:00
abstract::This paper presents two methods for absorbed dose determination with ionization chambers at short distance from 60Co and 192Ir brachytherapy sources. The methods are modifications of the Bragg-Gray and large cavity principles given in the IAEA code of practice for high- and medium-energy photon beams. A non-uniformity...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/43/11/002
更新日期:1998-11-01 00:00:00