Abstract:
PURPOSE:To automatically detect and isolate areas of low and high stiffness temporal stability in shear wave elastography (SWE) image sequences and define their impact in chronic liver disease (CLD) diagnosis improvement by means of clinical examination study and deep learning algorithm employing convolutional neural networks (CNNs). MATERIALS AND METHODS:Two hundred SWE image sequences from 88 healthy individuals (F0 fibrosis stage) and 112 CLD patients (46 with mild fibrosis (F1), 16 with significant fibrosis (F2), 22 with severe fibrosis (F3), and 28 with cirrhosis (F4)) were analyzed to detect temporal stiffness stability between frames. An inverse Red, Green, Blue (RGB) colormap-to-stiffness process was performed for each image sequence, followed by a wavelet transform and fuzzy c-means clustering algorithm. This resulted in a binary mask depicting areas of high and low stiffness temporal stability. The mask was then applied to the first image of the SWE sequence, and the derived, masked SWE image was used to estimate its impact in standard clinical examination and CNN classification. Regarding the impact of the masked SWE image in clinical examination, one measurement by two radiologists was performed in each SWE image and two in the corresponding masked image measuring areas with high and low stiffness temporal stability. Then, stiffness stability parameters, interobserver variability evaluation and diagnostic performance by means of ROC analysis were assessed. The masked and unmasked sets of SWE images were fed into a CNN scheme for comparison. RESULTS:The clinical impact evaluation study showed that the masked SWE images decreased the interobserver variability of the radiologists' measurements in the high stiffness temporal stability areas (interclass correlation coefficient (ICC) = 0.92) compared to the corresponding unmasked ones (ICC = 0.76). In terms of diagnostic accuracy, measurements in the high-stability areas of the masked SWE images (area-under-the-curve (AUC) ranging from 0.800 to 0.851) performed similarly to those in the unmasked SWE images (AUC ranging from 0.805 to 0.893). Regarding the measurements in the low stiffness temporal stability areas of the masked SWE images, results for interobserver variability (ICC = 0.63) and diagnostic accuracy (AUC ranging from 0.622 to 0.791) were poor. Regarding the CNN classification, the masked SWE images showed improved accuracy (ranging from 82.5% to 95.5%) compared to the unmasked ones (ranging from 79.5% to 93.2%) for various CLD stage combinations. CONCLUSION:Our detection algorithm excludes unreliable areas in SWE images, reduces interobserver variability, and augments CNN's accuracy scores for many combinations of fibrosis stages.
journal_name
Med Physjournal_title
Medical physicsauthors
Gatos I,Tsantis S,Spiliopoulos S,Karnabatidis D,Theotokas I,Zoumpoulis P,Loupas T,Hazle JD,Kagadis GCdoi
10.1002/mp.13521subject
Has Abstractpub_date
2019-05-01 00:00:00pages
2298-2309issue
5eissn
0094-2405issn
2473-4209journal_volume
46pub_type
杂志文章相关文献
MEDICAL PHYSICS文献大全abstract::The relationship between the pixel value and exit dose was investigated for a new commercially available amorphous silicon electronic portal imaging device. The pixel to dose mapping function was established to be linear for detector distances between 116.5 cm to 150 cm from the source, radiation field sizes from 5 x ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1508108
更新日期:2002-10-01 00:00:00
abstract::The variance in the number of x-ray photons absorbed by a detector is derived from theoretical considerations. The distributions in the number of x-ray photons produced by the x-ray tube, transmitted through the patient, and absorbed by the detector are described. These distributions are compounded to yield a distribu...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.595393
更新日期:1983-07-01 00:00:00
abstract:PURPOSE:Both spatial and biological information are necessary in order to perform true optimization of a treatment plan and for predicting clinical outcome. The goal of this work is to develop an enhanced treatment plan evaluation tool which incorporates biological parameters and retains spatial dose information. METH...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3497152
更新日期:2010-11-01 00:00:00
abstract:PURPOSE:4d cone-beam computed tomography (CBCT) scans are usually reconstructed by extracting the motion information from the 2d projections or an external surrogate signal, and binning the individual projections into multiple respiratory phases. In this "after-the-fact" binning approach, however, projections are uneve...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4817479
更新日期:2013-09-01 00:00:00
abstract:PURPOSE:Intraoperative electron radiation therapy (IOERT) involves the delivery of a high radiation dose during tumor resection in a shorter time than other radiation techniques, thus improving local control of tumors. However, a linear accelerator device is needed to produce the beam safely. Mobile linear accelerators...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.12482
更新日期:2017-10-01 00:00:00
abstract:PURPOSE:The most appropriate method of evaluating the effective atomic number necessitates consideration of energy-dependent behavior. Previously, this required quite laborious calculation, which is why many scientists revert to over-simplistic power-law methods. The purpose of this work is to develop user-friendly sof...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3689810
更新日期:2012-04-01 00:00:00
abstract:PURPOSE:Periodic MV∕KV radiographs taken during volumetric modulated arc therapy (VMAT) for hypofractionated treatment provide guidance in intrafractional motion management. The choice of imaging frequency and timing are key components in delivering the desired dose while reducing associated overhead such as imaging do...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4742846
更新日期:2012-09-01 00:00:00
abstract::Recently, new imaging modalities based on the detection of weak phase perturbations effects, among which are phase contrast and diffraction imaging, have been developed by several researchers. Due to their high sensitivity to weakly absorbing details, these techniques seem to be very promising for applications in the ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1388219
更新日期:2001-08-01 00:00:00
abstract:PURPOSE:High resolution three-dimensional (3D) magnetic resonance (MR) images are well suited for automated cartilage segmentation in the human knee joint. However, volumetric scans such as 3D Double-Echo Steady-State (DESS) images are not routinely acquired in clinical practice which limits opportunities for reliable ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.14421
更新日期:2020-10-01 00:00:00
abstract:PURPOSE:Scattered radiation remains to be a major cause of image quality degradation in Flat Panel Detector (FPD)-based Cone-beam computed tomography (CBCT). We have been investigating a novel two-dimensional antiscatter grid (2D-ASG) concept to reduce scatter intensity, and hence improve CBCT image quality. We present...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.12724
更新日期:2018-02-01 00:00:00
abstract:PURPOSE:Results about the feasibility of a method for quasi real time in vivo dosimetry (IVD) at the isocenter point for volumetric modulated arc therapy (VMAT) are here reported. The method is based on correlations between the EPID signal and the dose on the beam central axis. Moreover, the γ-analysis of EPID images w...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4875685
更新日期:2014-06-01 00:00:00
abstract:PURPOSE:To automatically and efficiently segment the lesion area of the colonoscopy polyp image, a polyp segmentation method has been presented. METHODS:An ensemble model of pretrained convolutional neural networks was proposed, using Unet-VGG, SegNet-VGG, and PSPNet. Firstly, the Unet-VGG is obtained by the first 10 ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.13865
更新日期:2019-12-01 00:00:00
abstract:PURPOSE:Manual delineation of head and neck (H&N) organ-at-risk (OAR) structures for radiation therapy planning is time consuming and highly variable. Therefore, we developed a dynamic multiatlas selection-based approach for fast and reproducible segmentation. METHODS:Our approach dynamically selects and weights the a...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.13854
更新日期:2019-12-01 00:00:00
abstract:PURPOSE:To assess the image quality, scatter, and leakage radiation of an integrated magnetic resonance linear accelerator (MR-LINAC or MRL) system. METHODS:A large American College of Radiology (ACR) magnetic resonance imaging (MRI) accreditation phantom was used to evaluate the MRI capabilities of the integrated MRL...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.12767
更新日期:2018-03-01 00:00:00
abstract::A method for optimizing MR imaging pulse sequence parameters in a statistical framework is presented. Parameters are defined to be optimal when the resulting scalar images yield optimal image segmentations using Bayesian pixel classification. Thus, Bayes risk is used as the objective function to minimize. Approximatio...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.597425
更新日期:1995-10-01 00:00:00
abstract::We studied a recently proposed aggregated CT reconstruction technique which combines the complementary advantages of kilovoltage (kV) and megavoltage (MV) x-ray imaging. Various phantoms were imaged to study the effects of beam orientations and geometry of the imaging object on image quality of reconstructed CT. It wa...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2768862
更新日期:2007-09-01 00:00:00
abstract::Breast density, the percentage of glandular breast tissue, has been identified as an important yet underutilized risk factor in the development of breast cancer. A quantitative method to measure breast density with dual energy imaging was investigated using a computer simulation model. Two configurations to measure br...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3002308
更新日期:2008-12-01 00:00:00
abstract:PURPOSE:Since the introduction of clinical x-ray phase-contrast mammography (PCM), a technique that exploits refractive-index variations to create edge enhancement at tissue boundaries, a number of optimization studies employing physical image-quality metrics have been performed. Ideally, task-based assessment of PCM w...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3676183
更新日期:2012-02-01 00:00:00
abstract:PURPOSE:To establish accurate experimental dosimetry techniques for reference dose measurements in nonstandard composite fields. METHODS:A cylindrical PMMA phantom filled with water was constructed, at the center of which reference absorbed dose to water for a head and neck IMRT delivery was measured. Based on the pro...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3392247
更新日期:2010-06-01 00:00:00
abstract:PURPOSE:In order to build up a reliable dose monitoring system for boron neutron capture therapy (BNCT) applications at the TRIGA reactor in Mainz, a computer model for the entire reactor was established, simulating the radiation field by means of the Monte Carlo method. The impact of different source definition techni...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4897242
更新日期:2014-11-01 00:00:00
abstract:PURPOSE:A novel 3D printing method has been developed, which employs human CT images to construct patient specific phantoms by controlling the filament extrusion rate. METHODS:An in-house software was developed comprising pixel-by-pixel (PbP) reading of the Hounsfield Units (HU) values in the original patient DICOM im...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.13154
更新日期:2018-10-01 00:00:00
abstract:PURPOSE:For accurate tissue inhomogeneity correction in radiotherapy treatment planning, the authors had previously proposed a novel conversion of the energy-subtracted CT number to an electron density (ΔHU-ρe conversion), which provides a single linear relationship between ΔHU and ρe over a wide ρe range. The purpose ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4881327
更新日期:2014-07-01 00:00:00
abstract:PURPOSE:To study the impact of target geometrical and linac operational parameters, such as target material and thickness, electron beam size, repetition rate, and mean current on the ability of the radiotherapy treatment head to deliver high-dose-rate x-ray irradiation in the context of novel linear accelerators capab...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.12615
更新日期:2017-12-01 00:00:00
abstract::This study concerns the accuracy and precision of the IAEA/WHO LiF TLD system used in intercomparison by mail of absorbed doses from 60Co gamma-radiation and 4-25 MV x rays. The system employs 160 mg LiF powder in polystyrene capsules, which are placed at 5 or 7 cm depth in water and irradiated to doses close to 200 r...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.594746
更新日期:1980-09-01 00:00:00
abstract::Convolution/superposition software has been used to produce a library of photon pencil beam dose matrices. This library of pencil beams is designed to serve as a tool for both education and investigation in the field of radiotherapy optimization. The elegance of this pencil beam model stems from its cylindrical symmet...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.598615
更新日期:1999-07-01 00:00:00
abstract::Photoelectric-enhanced radiation therapy is a bimodal therapy, consisting of the administration of highly radiation-absorbing substances into the tumor area and localized regional irradiation with orthovoltage x-rays. Irradiation can be performed by a modified computed tomography (CT) unit equipped with an additional ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3125137
更新日期:2009-06-01 00:00:00
abstract::Ir-192 wires have been used in low-dose-rate brachytherapy for many years. Commercially available treatment planning systems approximate the dose rate distribution of the straight or curved wires applying the superposition principle using one of the following methods: (i) The wire is modeled as a set of point sources,...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2839102
更新日期:2008-03-01 00:00:00
abstract::The dynamic range of the gray level of a digital image is limited by the noise it contains. Two statistical methods called "runs test" and "join-count statistic" are used to measure the noise level in a digital image. A residual image is formed by subtracting an original image from its smoothed version. Theoretically,...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.597058
更新日期:1993-01-01 00:00:00
abstract:PURPOSE:The authors have developed a quantitative calibration method for a multileaf collimator (MLC) which measures individual leaf positions relative to the MLC backup jaw on an Elekta Synergy linear accelerator. METHODS:The method utilizes a commercially available two-axis detector array (Profiler 2; Sun Nuclear Co...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3218767
更新日期:2009-10-01 00:00:00
abstract::Angioplasty balloons inflated with a solution of the beta-emitter Re-188 have been used for intravascular brachytherapy to prevent restenosis. Coronary stents are in extensive clinical use for the treatment of de novo atherosclerotic stenoses. In this study, the effect of an interposed stent on the dose distribution h...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1533749
更新日期:2003-02-01 00:00:00