Abstract:
:The (83)Kr magnetic resonance (MR) relaxation time T(1) of krypton gas in contact with model surfaces was previously found to be highly sensitive to surface composition, surface-to-volume ratio, and surface temperature. The work presented here explored aspects of pulmonary (83)Kr T(1) relaxation measurements in excised lungs from healthy rats using hyperpolarized (hp) (83)Kr with approximately 4.4% spin polarization. MR spectroscopy without spatial resolution was applied to the ex vivo lungs that actively inhale hp (83)Kr through a custom designed ventilation system. Various inhalation schemes were devised to study the influence of anatomical dead space upon the measured (83)Kr T(1) relaxation times. The longitudinal (83)Kr relaxation times in the distal airways and the respiratory zones were independent of the lung inhalation volume, with T(1) = 1.3 s and T(1) = 1.0 s, depending only on the applied inhalation scheme. The obtained data were highly reproducible between different specimens. Further, the (83)Kr T(1) relaxation times in excised lungs were unaffected by the presence of up to 40% oxygen in the hp gas mixture. The results support the possible importance of (83)Kr as a biomarker for evaluating lung function.
journal_name
Phys Med Bioljournal_title
Physics in medicine and biologyauthors
Stupic KF,Elkins ND,Pavlovskaya GE,Repine JE,Meersmann Tdoi
10.1088/0031-9155/56/13/001subject
Has Abstractpub_date
2011-07-07 00:00:00pages
3731-48issue
13eissn
0031-9155issn
1361-6560pii
S0031-9155(11)78419-6journal_volume
56pub_type
杂志文章abstract::We present the results of utilizing aligned anatomical information from CT images to locally adjust image smoothness during the reconstruction of three-dimensional (3D) whole-body positron emission tomography (PET) data. The ability of whole-body PET imaging to detect malignant neoplasms is becoming widely recognized....
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/47/1/301
更新日期:2002-01-07 00:00:00
abstract::In this study, we evaluate the feasibility of designing a beveled fiber-optic probe coupled with a ball lens for improving depth-resolved fluorescence measurements of epithelial tissue using Monte Carlo (MC) simulations. The results show that by using the probe configuration with a beveled tip collection fiber and a f...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/53/4/008
更新日期:2008-02-21 00:00:00
abstract::The electrostimulation excitation threshold of a nerve depends on temporal and frequency parameters of the stimulus. These dependences were investigated in terms of: (1) strength-duration (SD) curve for a single monophasic rectangular pulse, and (2) frequency dependence of the excitation threshold for a continuous sin...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/61/12/4364
更新日期:2016-06-21 00:00:00
abstract::A post-processing noise suppression technique for biomedical MRI images is presented. The described procedure recovers both sharp edges and smooth surfaces from a given noisy MRI image; it does not blur the edges and does not introduce spikes or other artefacts. The fine details of the image are also preserved. The pr...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/48/13/310
更新日期:2003-07-07 00:00:00
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
doi:10.1088/0031-9155/53/6/006
更新日期:2008-03-21 00:00:00
abstract::Modelling of inhaled particle deposition in the lungs potentially offers data relevant to assessing hazards from toxic inhaled particles, to studying mucus clearance or lung permeability by aerosol techniques, and to achieving better utilisation of drugs administered as aerosols. Analysis of published modelling studie...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/29/7/001
更新日期:1984-07-01 00:00:00
abstract::Over the last 50 years, diagnostic imaging has grown from a state of infancy to a high level of maturity. Many new imaging modalities have been developed. However, modern medical imaging includes not only image production but also image processing, computer-aided diagnosis (CAD), image recording and storage, and image...
journal_title:Physics in medicine and biology
pub_type: 杂志文章,评审
doi:10.1088/0031-9155/51/13/R02
更新日期:2006-07-07 00:00:00
abstract::The 'monoenergetic' electron loss model was derived in a previous work to account for pathlength straggling in the Fermi-Eyges pencil beam problem. In this paper, we extend this model to account for energy-loss straggling and secondary knock-on electron transport in order to adequately predict a depth dose curve. To m...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/45/10/313
更新日期:2000-10-01 00:00:00
abstract::In this paper we describe a method for quantitative photoacoustic tomography (qPAT) based on the photon radiative transfer equation (RTE) coupled with the Helmholtz photoacoustic wave equation. Considerable simulations and tissue-like phantom experiments are conducted to evaluate transport-based qPAT in comparison wit...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/55/7/009
更新日期:2010-04-07 00:00:00
abstract::A method using both patient geometric and dosimetric information was proposed to predict dose-volume histograms (DVHs) of organs at risk (OARs) for a nasopharyngeal cancer (NPC) intensity-modulated radiation therapy (IMRT) plan. A total of 106 nine-field IMRT NPC plans were used in this study. Twenty-six plans were ra...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/ab50eb
更新日期:2019-12-05 00:00:00
abstract::Laser interstitial thermotherapy (LITT) is employed to destroy tumors in organs, and its outcome strongly depends on the temperature distribution inside the treated tissue. The recent introduction of computed tomography (CT) scan thermometry, based on the CT number dependence of the tissue with temperature, overcomes ...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/58/16/5705
更新日期:2013-08-21 00:00:00
abstract::In BANG gel dosimetry, the spin-spin relaxation rate, R2 = I/T2, is related to the radiation dose that has been delivered to the gel phantom. R2 is calculated by fitting the pixel intensities of a set of differently T2-weighted base images. In gel dosimetry for radiotherapy, an accuracy of 5% in dose and 3 mm spatiall...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/45/7/307
更新日期:2000-07-01 00:00:00
abstract::Histotripsy is a therapeutic ultrasound modality under development to liquefy tissue mechanically via bubble clouds. Image guidance of histotripsy requires both quantification of the bubble cloud activity and accurate delineation of the treatment zone. In this study, magnetic resonance (MR) and diagnostic ultrasound i...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/ab143f
更新日期:2019-05-02 00:00:00
abstract::An algorithm for dynamic multileaf-collimator (dMLC) tracking of a target performing a known a priori, rigid-body motion during volumetric modulated arc therapy (VMAT), has been experimentally validated and applied to investigate the potential of the Agility (Elekta AB, Stockholm, Sweden) multileaf-collimator (MLC) fo...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/58/13/4643
更新日期:2013-07-07 00:00:00
abstract::Modern effort in radiotherapy to address the challenges of tumor localization and motion has led to the development of MRI guided radiotherapy technologies. Accurate dose calculations must properly account for the effects of the MRI magnetic fields. Previous work has investigated the accuracy of a deterministic linear...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/aa959a
更新日期:2017-12-14 00:00:00
abstract::The elastic and hyperelastic properties of biological soft tissues have been of interest to the medical community. There are several biomedical applications where parameters characterizing such properties are critical for a reliable clinical outcome. These applications include surgery planning, needle biopsy and brach...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/54/8/020
更新日期:2009-04-21 00:00:00
abstract::Uncemented prosthetic joint implants used in orthopaedic surgery are usually coated with a porous surface to encourage bone ingrowth. Better contact between the endosteal bone and the porous surface improves ingrowth, and such contact may be increased if the joint further subsides into position in the first weeks foll...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/38/2/009
更新日期:1993-02-01 00:00:00
abstract::The objective of this study was to compare the lesion detection performance of human observers between thin-section computed tomography images of the breast, with thick-section (>40 mm) simulated projection images of the breast. Three radiologists and six physicists each executed a two alterative force choice (2AFC) s...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/60/8/3347
更新日期:2015-04-21 00:00:00
abstract::Novel x-ray medical imaging sensors, such as photon counting detectors (PCDs) and large area CCD and CMOS cameras can involve irregular and/or sparse sampling of the detector plane. Application of such detectors to CT involves undersampling that is markedly different from the commonly considered case of sparse angular...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/61/1/90
更新日期:2016-01-07 00:00:00
abstract::Volumetric scintillation dosimetry has the potential to provide fast, high-resolution, three-dimensional radiation dosimetry. However, scintillators exhibit a nonlinear response at the high linear energy transfer (LET) values characteristic of proton Bragg peaks. The purpose of this study was to develop a quenching co...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/58/2/261
更新日期:2013-01-21 00:00:00
abstract::Time-of-flight (TOF) positron emission tomography (PET) technology has recently regained popularity in clinical PET studies for improving image quality and lesion detectability. Using TOF information, the spatial location of annihilation events is confined to a number of image voxels along each line of response, there...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/61/3/1309
更新日期:2016-02-07 00:00:00
abstract::We investigated the physical characteristics of two complementary metal oxide semiconductor (CMOS) mammography detectors. The detectors featured 14-bit image acquisition, 50 microm detector element (del) size and an active area of 5 cm x 5 cm. One detector was a passive-pixel sensor (PPS) with signal amplification per...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/54/6/022
更新日期:2009-03-21 00:00:00
abstract::An x-ray fluorescence system with a synchrotron radiation source was used to quantify the levels of iron, copper and zinc in breast tissue specimens. Healthy tissue and breast carcinomas were investigated as an aid to understanding the mechanisms of breast cancer and as a possible complementary diagnostic tool. Eighty...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/47/13/310
更新日期:2002-07-07 00:00:00
abstract::We developed an anatomy-guided 4D closed-form algorithm to directly reconstruct parametric images from projection data for (nearly) irreversible tracers. Conventional methods consist of individually reconstructing 2D/3D PET data, followed by graphical analysis on the sequence of reconstructed image frames. The propose...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/55/15/005
更新日期:2010-08-07 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::Two experimental investigations of the electromagnetic method to measure body composition are presented. In the first experiment, the impedance of a single-loop transmitting antenna, located at the centre of a 150 m helical receiving coil, was observed to have a sharp minimum at 2.40 MHz. The impedance of the antenna ...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/40/4/011
更新日期:1995-04-01 00:00:00
abstract::Calibration methods are investigated for the determination of bone density by the Compton scattering method. The scattered radiation from materials of different densities and dimensions is measured for this purpose. A function for the dependence of the intensity on these parameters is derived and compared with the exp...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/25/4/009
更新日期:1980-07-01 00:00:00
abstract::There are a number of gel dosimeter calibration methods in contemporary usage. The present study is a detailed Monte Carlo investigation into the accuracy of several calibration techniques. Results show that for most arrangements the dose to gel accurately reflects the dose to water, with the most accurate method invo...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/52/13/022
更新日期:2007-07-07 00:00:00
abstract::For plane-parallel chambers used in electron dosimetry, modern dosimetry protocols recommend a cross-calibration against a calibrated cylindrical chamber. The rationale for this is the unacceptably large (up to 3-4%) chamber-to-chamber variations of the perturbation factors (pwall)Co, which have been reported for plan...
journal_title:Physics in medicine and biology
pub_type: 杂志文章,多中心研究
doi:10.1088/0031-9155/52/23/026
更新日期:2007-12-07 00:00:00
abstract::In charged particle therapy with pencil beam scanning (PBS), localization of the dose in the Bragg peak makes dose distributions sensitive to lateral tissue heterogeneities. The sensitivity of a PBS plan to lateral tissue heterogeneities can be reduced by selecting appropriate beam angles. The purpose of this study is...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/61/24/8664
更新日期:2016-12-21 00:00:00