The Experts below are selected from a list of 270 Experts worldwide ranked by ideXlab platform
Heber Macmahon - One of the best experts on this subject based on the ideXlab platform.
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Dual energy Subtraction and temporal Subtraction chest radiography.
Journal of thoracic imaging, 2008Co-Authors: Heber Macmahon, Roger Engelmann, Rachael Y. Roberts, Samuel G. ArmatoAbstract:Digital radiography and display systems have revolutionized radiologic practice in recent years and have enabled clinical application of advanced image processing techniques. These include dual energy Subtraction and temporal Subtraction, both of which can improve diagnostic accuracy for abnormal findings in chest radiographs, especially for subtle lesions such as early lung cancer or focal pneumonia. Dual energy radiography exploits the differential attenuation of low-energy x-ray photons by calcium to produce separate images on the bones and soft tissues, which provides improved detection and characterization of both calcified and noncalcified lung lesions. Dual energy Subtraction radiography is currently available from 2 of the major vendors and is in clinical use at many institutions in the United States. Temporal Subtraction is a complementary technique that enhances interval change, by using a previous radiograph as a Subtraction mask, so that unchanged normal anatomy is suppressed, whereas new abnormalities are enhanced. Though it is not yet a product in the United States, temporal Subtraction is available for clinical use in Japan. Temporal Subtraction can be combined with energy Subtraction to reduce misregistration artifacts, and also has potential to improve computer-aided detection of nodules and other types of lung disease.
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Temporal Subtraction of dual‐energy chest radiographs
Medical physics, 2006Co-Authors: Samuel G. Armato, Roger Engelmann, Devang J. Doshi, Philip Caligiuri, Heber MacmahonAbstract:Temporal Subtraction and dual-energy imaging are two enhanced radiography techniques that are receiving increased attention in chest radiography. Temporal Subtraction is an image processing technique that facilitates the visualization of pathologic change across serial chest radiographic images acquired from the same patient; dual-energy imaging exploits the differential relative attenuation of x-ray photons exhibited by soft-tissue and bony structures at different x-ray energies to generate a pair of images that accentuate those structures. Although temporal Subtraction images provide a powerful mechanism for enhancing visualization of subtle change, misregistration artifacts in these images can mimic or obscure abnormalities. The purpose of this study was to evaluate whether dual-energy imaging could improve the quality of temporal Subtraction images. Temporal Subtraction images were generated from 100 pairs of temporally sequential standard radiographic chest images and from the corresponding 100 pairs of dual-energy, soft-tissue radiographic images. The registration accuracy demonstrated in the resulting temporal Subtraction images was evaluated subjectively by two radiologists. The registration accuracy of the soft-tissue-based temporal Subtraction images was rated superior to that of the conventional temporal Subtraction images. Registration accuracy also was evaluated objectively through an automated method, which achieved an area-under-the-ROC-curve value of 0.92 in the distinction between temporal Subtraction images that demonstrated clinically acceptable and clinically unacceptable registration accuracy. By combining dual-energy soft-tissue images with temporal Subtraction, misregistration artifacts can be reduced and superior image quality can be obtained.
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application of temporal Subtraction for detection of interval changes on chest radiographs improvement of Subtraction images using automated initial image matching
Journal of Digital Imaging, 1999Co-Authors: Takayuki Ishida, Roger Engelmann, Shigehiko Katsuragawa, Kazuto Ashizawa, Heber MacmahonAbstract:The authors developed a temporal Subtraction scheme based on a nonlinear geometric warping technique to assist radiologists in the detection of interval changes in chest radiographs obtained on different occasions. The performance of the current temporal Subtraction scheme is reasonably good; however, severe misregistration can occur in some cases. The authors evaluated the quality of 100 chest temporal Subtraction images selected from their clinical image database. Severe misregistration was mainly attributable to initial incorrect global matching. Therefore, they attempted to improve the quality of the Subtraction images by applying a new initial image matching technique to determine the global shift value between the current and the previous chest images. A cross-correlation method was employed for the initial image matching by use of blurred low-resolution chest images. Nineteen cases (40.4%) among 47 poor registered Subtraction images were improved. These results show that the new initial image matching technique is very effective for improving the quality of chest temporal Subtraction images, which can greatly enhance subtle changes in chest radiographs.
D. Maître - One of the best experts on this subject based on the ideXlab platform.
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Antenna Subtraction with hadronic initial states
Journal of High Energy Physics, 2007Co-Authors: Alejandro Daleo, Thomas Gehrmann, D. MaîtreAbstract:The antenna Subtraction method for the computation of higher order corrections to jet observables and exclusive cross sections at collider experiments is extended to include hadronic initial states. In addition to the already known antenna Subtraction with both radiators in the final state (final-final antennae), we introduce antenna Subtractions with one or two radiators in the initial state (initial-final or initial-initial antennae). For those, we derive the phase space factorization and discuss the allowed phase space mappings at NLO and NNLO. We present integrated forms for all antenna functions relevant to NLO calculations, and describe the construction of the full antenna Subtraction terms at NLO on two examples. The extension of the formalism to NNLO is outlined.
Samuel G. Armato - One of the best experts on this subject based on the ideXlab platform.
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Dual energy Subtraction and temporal Subtraction chest radiography.
Journal of thoracic imaging, 2008Co-Authors: Heber Macmahon, Roger Engelmann, Rachael Y. Roberts, Samuel G. ArmatoAbstract:Digital radiography and display systems have revolutionized radiologic practice in recent years and have enabled clinical application of advanced image processing techniques. These include dual energy Subtraction and temporal Subtraction, both of which can improve diagnostic accuracy for abnormal findings in chest radiographs, especially for subtle lesions such as early lung cancer or focal pneumonia. Dual energy radiography exploits the differential attenuation of low-energy x-ray photons by calcium to produce separate images on the bones and soft tissues, which provides improved detection and characterization of both calcified and noncalcified lung lesions. Dual energy Subtraction radiography is currently available from 2 of the major vendors and is in clinical use at many institutions in the United States. Temporal Subtraction is a complementary technique that enhances interval change, by using a previous radiograph as a Subtraction mask, so that unchanged normal anatomy is suppressed, whereas new abnormalities are enhanced. Though it is not yet a product in the United States, temporal Subtraction is available for clinical use in Japan. Temporal Subtraction can be combined with energy Subtraction to reduce misregistration artifacts, and also has potential to improve computer-aided detection of nodules and other types of lung disease.
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Temporal Subtraction of dual‐energy chest radiographs
Medical physics, 2006Co-Authors: Samuel G. Armato, Roger Engelmann, Devang J. Doshi, Philip Caligiuri, Heber MacmahonAbstract:Temporal Subtraction and dual-energy imaging are two enhanced radiography techniques that are receiving increased attention in chest radiography. Temporal Subtraction is an image processing technique that facilitates the visualization of pathologic change across serial chest radiographic images acquired from the same patient; dual-energy imaging exploits the differential relative attenuation of x-ray photons exhibited by soft-tissue and bony structures at different x-ray energies to generate a pair of images that accentuate those structures. Although temporal Subtraction images provide a powerful mechanism for enhancing visualization of subtle change, misregistration artifacts in these images can mimic or obscure abnormalities. The purpose of this study was to evaluate whether dual-energy imaging could improve the quality of temporal Subtraction images. Temporal Subtraction images were generated from 100 pairs of temporally sequential standard radiographic chest images and from the corresponding 100 pairs of dual-energy, soft-tissue radiographic images. The registration accuracy demonstrated in the resulting temporal Subtraction images was evaluated subjectively by two radiologists. The registration accuracy of the soft-tissue-based temporal Subtraction images was rated superior to that of the conventional temporal Subtraction images. Registration accuracy also was evaluated objectively through an automated method, which achieved an area-under-the-ROC-curve value of 0.92 in the distinction between temporal Subtraction images that demonstrated clinically acceptable and clinically unacceptable registration accuracy. By combining dual-energy soft-tissue images with temporal Subtraction, misregistration artifacts can be reduced and superior image quality can be obtained.
Marjorie K. Jeffcoat - One of the best experts on this subject based on the ideXlab platform.
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Digital Subtraction radiography.
Dental clinics of North America, 1993Co-Authors: Michael S. Reddy, Marjorie K. JeffcoatAbstract:Subtraction radiography offers greater visualization of radiographic changes between a pair of radiographs by subtracting out the unchanging background distractions. Originally, Subtraction was achieved by using positive and negative prints in angiography. The advent of digital imaging devices has led to validation of quantitative measurements from digital Subtraction images. As well, computer software manipulations have allowed for more flexibility in the clinical application of Subtraction imaging. The clinical application of digital Subtraction radiography is discussed along with clinical cases.
Mathias Ritzmann - One of the best experts on this subject based on the ideXlab platform.
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Antenna Subtraction at NNLO with hadronic initial states: double real radiation for initial-initial configurations with two quark flavours
Journal of High Energy Physics, 2011Co-Authors: Radja Boughezal, Aude Gehrmann-de Ridder, Mathias RitzmannAbstract:The antenna Subtraction formalism allows to calculate QCD corrections to jet observables. Within this formalism, the Subtraction terms are constructed using antenna functions describing all unresolved radiation between a pair of hard radiator partons. In this paper, we focus on the Subtraction terms for double real radiation contributions to jet observables in hadron-hadron collisions evaluated at NNLO. An essential ingredient to these Subtraction terms are the four-parton antenna functions with both radiators in the initial state. We outline the construction of the double real Subtraction terms, classify all relevant antenna functions and describe their integration over the relevant antenna phase space. For the initial-initial antenna functions with two quark flavours, we derive the phase space master integrals and obtain the integrated antennae.
