Abstract:
:In this study, we explore the potential of compressed sensing (CS) accelerated broadband 3D phase-encoded turbo spin-echo (3D-PE-TSE) for the purpose of geometrically undistorted imaging in the presence of field inhomogeneities. To achieve this goal 3D-PE-SE and 3D-PE-TSE sequences with broadband rf pulses and dedicated undersampling patterns were implemented on a clinical scanner. Additionally, a 3D multi-spectral spin-echo (ms3D-SE) sequence was implemented for reference purposes. First, we demonstrated the influence of susceptibility induced off-resonance effects on the spatial encoding of broadband 3D-SE, ms3D-SE, 3D-PE-SE and 3D-PE-TSE using a grid phantom containing a titanium implant (Δχ = 182 ppm) with x-ray CT as a gold standard. These experiments showed that the spatial encoding of 3D-PE-(T)SE was unaffected by susceptibility induced off-resonance effects, which caused geometrical distortions and/or signal hyper-intensities in broadband 3D-SE and, to a lesser extent, in ms3D-SE frequency encoded methods. Additionally, an SNR analysis was performed and the temporally resolved signal of 3D-PE-(T)SE sequences was exploited to retrospectively decrease the acquisition bandwidth and obtain field offset maps. The feasibility of CS acceleration was studied retrospectively and prospectively for the 3D-PE-SE sequence using an existing CS algorithm adapted for the reconstruction of 3D data with undersampling in all three phase encoded dimensions. CS was combined with turbo-acceleration by variable density undersampling and spherical stepwise T2 weighting by randomly sorting consecutive echoes in predefined spherical k-space layers. The CS-TSE combination resulted in an overall acceleration factor of 60, decreasing the original 3D-PE-SE scan time from 7 h to 7 min. Finally, CS accelerated 3D-PE-TSE in vivo images of a titanium screw were obtained within 10 min using a micro-coil demonstrating the feasibility of geometrically undistorted MRI near severe field inhomogeneities.
journal_name
Phys Med Bioljournal_title
Physics in medicine and biologyauthors
van Gorp JS,Bakker CJ,Bouwman JG,Smink J,Zijlstra F,Seevinck PRdoi
10.1088/0031-9155/60/2/615subject
Has Abstractpub_date
2015-01-21 00:00:00pages
615-31issue
2eissn
0031-9155issn
1361-6560journal_volume
60pub_type
杂志文章abstract::Dental tomographic cone-beam x-ray imaging devices record truncated projections and reconstruct a region of interest (ROI) inside the head. Image reconstruction from the resulting local tomography data is an ill-posed inverse problem. A new Bayesian multiresolution method is proposed for local tomography reconstructio...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/52/22/008
更新日期:2007-11-21 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::The University of Washington (UW) Clinical Neutron Therapy System (CNTS) has been used to treat over 3300 patients. Treatment planning for these patients is currently performed using an MV x-ray model in Pinnacle® adapted to fit measurements of fast neutron output factors, wedge factors, depth-dose and lateral profile...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/ab9a85
更新日期:2020-08-31 00:00:00
abstract::The purpose of this work is to model electron contamination in clinical photon beams and to commission the source model using measured data for Monte Carlo treatment planning. In this work, a planar source is used to represent the contaminant electrons at a plane above the upper jaws. The source size depends on the di...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/49/12/013
更新日期:2004-06-21 00:00:00
abstract::Treatment planning for proton tumor therapy requires a fast and accurate dose-calculation method. We have implemented a simplified Monte Carlo (SMC) method in the treatment planning system of the National Cancer Center Hospital East for the double-scattering beam delivery scheme. The SMC method takes into account the ...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/55/12/018
更新日期:2010-06-21 00:00:00
abstract::None of the existing protocols or codes of practice for high-energy electron dosimetry take any account of the accelerator-generated bremsstrahlung always present in electron beams. This results in a systematic error in the derivation of the absorbed dose. The purpose of this study is to draw attention to this omissio...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/39/7/004
更新日期:1994-07-01 00:00:00
abstract::Statistically based iterative image reconstruction methods have been developed for emission tomography. One important component in iterative image reconstruction is the system matrix, which defines the mapping from the image space to the data space. Several groups have demonstrated that an accurate system matrix can i...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/50/14/007
更新日期:2005-07-21 00:00:00
abstract::This paper contains the recommendations of the high dose rate (HDR) brachytherapy working party of the UK Institute of Physics and Engineering in Medicine (IPEM). The recommendations consist of a Code of Practice (COP) for the UK for measuring the reference air kerma rate (RAKR) of HDR (192)Ir brachytherapy sources. I...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/55/11/011
更新日期:2010-06-07 00:00:00
abstract::The design, construction and use of a large-scale field-cycled proton-electron double-resonance imaging (FC-PEDRI) imager is described. The imager is based on a whole-body sized, vertical field, 59 mT permanent magnet. Field cycling is accomplished by the field compensation method, and uses a secondary, resistive magn...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/43/7/008
更新日期:1998-07-01 00:00:00
abstract::Existing studies have suggested some debate on whether the quality of radiation that delivers dose outside of the primary field of a radiotherapy photon beam can be considered the same as that inside the primary field. We used a Monte Carlo approach to simulate the electron fluence differential in energy inside a wate...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/52/12/015
更新日期:2007-06-21 00:00:00
abstract::Distributions of linear pathlength measurements have been utilized in skeletal dosimetry of internally emitted short-range particles for over 30 years. This work reviews the methods for coupling these distributions to range-energy data. A revised methodology is presented for handling the insertion of the additional do...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/56/9/004
更新日期:2011-05-07 00:00:00
abstract::Many applications of electroporation, especially those utilizing electrofusion and in-vivo electroporation, involve cell environments that include close cell-to-cell proximity and a wide range of target cell size. It is important to understand how this kind of environment may alter optimum electroporation electrical p...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/51/12/012
更新日期:2006-06-21 00:00:00
abstract::Target motion is one of the major limitations of each high precision radiation therapy. Using advanced active beam delivery techniques, such as the magnetic raster scanning system for particle irradiation, the interplay between time-dependent beam and target position heavily distorts the applied dose distribution. Thi...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/49/14/001
更新日期:2004-07-21 00:00:00
abstract::Inverse treatment planning in intensity modulated particle therapy (IMPT) with scanned carbon-ion beams is currently based on the optimization of RBE-weighted dose to satisfy requirements of target coverage and limited toxicity to organs-at-risk (OARs) and healthy tissues. There are many feasible IMPT plans that meet ...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/aaf400
更新日期:2019-01-04 00:00:00
abstract::This note describes a simple phantom which can be used to check the long term stability and accuracy of relative attenuation measurements made by near infra-red (NIR) spectrometers. The phantom has been calibrated, and the results of the calibration are shown to agree with theoretical predictions of the relative atten...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/39/9/015
更新日期:1994-09-01 00:00:00
abstract::Although interventional x-ray angiography (XA) procedures involve relatively high radiation doses that can lead to deterministic tissue reactions in addition to stochastic effects, convenient and accurate estimation of absorbed organ doses has traditionally been out of reach. This has mainly been due to the absence of...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/61/8/3063
更新日期:2016-04-21 00:00:00
abstract::The purpose of this study is the analysis of the influence of anisotropic conductivity on magnetic fields and electric potentials by means of phantom measurements. An artificial rotating current dipole was placed in the middle of an anisotropic skein arrangement in a torso phantom filled with saline solution. The sign...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/53/1/017
更新日期:2008-01-07 00:00:00
abstract::We implemented a hybrid scatter-correction method for 3D PET that combines two scatter-correction methods in a complementary way. The implemented scheme uses a method based on the discrimination of the energy of events (the estimation of trues method (ETM)) and an auxiliary method (the single scatter simulation method...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/47/9/310
更新日期:2002-05-07 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
pub_type: 杂志文章
doi:10.1088/1361-6560/aba318
更新日期:2020-10-07 00:00:00
abstract::It has been reported that acoustic waves are generated when a high-energy pulsed proton beam is deposited in a small volume within tissue. One possible application of proton-induced acoustics is to get real-time feedback for intra-treatment adjustments by monitoring such acoustic waves. A high spatial resolution in ul...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/aa642c
更新日期:2017-06-21 00:00:00
abstract::For treatments with dynamic intensity modulated radiotherapy (IMRT), the adjustment of multileaf collimator (MLC) parameters affecting both the optimization algorithm and dose distributions is crucial. The main parameters characterizing the MLC are the transmission (T) and the dosimetric leaf separation (DLS). The aim...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/50/4/001
更新日期:2005-02-21 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::Recent research has suggested that endothelialization of vascular stents is crucial to reducing the risk of late stent thrombosis. With a resolution of approximately 10 microm, optical coherence tomography (OCT) may be an appropriate imaging modality for visualizing the vascular response to a stent and measuring the p...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/53/12/001
更新日期:2008-06-21 00:00:00
abstract::Measurements of lung nodule volume with multi-detector computed tomography (MDCT) have been shown to be more accurate and precise compared to conventional lower dimensional measurements. Quantifying the size of lesions is potentially more difficult when the object-to-background contrast is low as with lesions in the l...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/60/2/671
更新日期:2015-01-21 00:00:00
abstract::The layer-stacking method can provide three-dimensional conformal dose distributions to the target based on a passive scattering method using mini-spread-out Bragg peak (SOBP). The purpose of this work is to demonstrate the effectiveness of a new weight optimization algorithm that can enhance the robustness of dose di...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/ab9efd
更新日期:2020-09-28 00:00:00
abstract::The purpose of this investigation is to propose new compensator design strategies for protons and heavier particles which are based on pencil-beam (PB) dose calculations and which significantly reduce the dose to tissues downstream from the target, yet provide acceptable target coverage under conditions of patient mot...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/42/7/005
更新日期:1997-07-01 00:00:00
abstract::Maximum likelihood estimation (MLE) is presented as a statistical tool to evaluate the contribution of measurement error to any measurement series where the same quantity is measured using different independent methods. The technique was tested against artificial data sets; generated for values of underlying variation...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/59/20/6019
更新日期:2014-10-21 00:00:00
abstract::Sparse phased array ultrasound transducers with millimetre length scale elements have previously been proposed for generating hyperthermia but not for imaging. Numerical simulation with a pseudospectral solver was used to investigate: (a) how the position of the maximum pressure in the focal region changed with elemen...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/aace07
更新日期:2018-07-16 00:00:00
abstract::Fluorescence molecular tomography (FMT) is widely used in preclinical oncology research. FMT is the only imaging technique able to provide 3D distribution of fluorescent probes within thick highly scattering media. However, its integration into clinical medicine has been hampered by its low spatial resolution caused b...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/aaf96d
更新日期:2019-01-22 00:00:00
abstract::In the IAEA-AAPM dosimetry formalism, detector measurements in general nonstandard conditions are corrected using the factor k(f(clin),f(msr))(Q(clin),Q(msr)). This factor needs to be evaluated on a case-by-case basis which is difficult to accomplish in practice. The present paper aims to provide a method that allows ...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/59/17/4973
更新日期:2014-09-07 00:00:00