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"anatomical noise"

Minah Han, Subok Park, Jongduk Baek
We investigate the effect of anatomical noise on the detectability of cone beam CT (CBCT) images with different slice directions, slice thicknesses, and volume glandular fractions (VGFs). Anatomical noise is generated using a power law spectrum of breast anatomy, and spherical objects with diameters from 1mm to 11mm are used as breast masses. CBCT projection images are simulated and reconstructed using the FDK algorithm. A channelized Hotelling observer (CHO) with Laguerre-Gauss (LG) channels is used to evaluate detectability for the signal-known-exactly (SKE) binary detection task...
August 22, 2016: Optics Express
Georg Pelzer, Gisela Anton, Florian Horn, Jens Rieger, André Ritter, Johannes Wandner, Thomas Weber, Thilo Michel
PURPOSE: X-ray dark-field imaging promises information on the small angle scattering properties even of large samples. However, the dark-field image is correlated with the object's attenuation and phase-shift if a polychromatic x-ray spectrum is used. A method to remove part of these correlations is proposed. METHODS: The experimental setup for image acquisition was modeled in a wave-field simulation to quantify the dark-field signals originating solely from a material's attenuation and phase-shift...
June 2016: Medical Physics
James G Mainprize, Olivier Alonzo-Proulx, Roberta A Jong, Martin J Yaffe
PURPOSE: High mammographic density is known to be associated with decreased sensitivity of mammography. Recent changes in the BI-RADS density assessment address the effect of masking by densities, but the BI-RADS assessment remains qualitative and achieves only moderate agreement between radiologists. An automated, quantitative algorithm that estimates the likelihood of masking of simulated masses in a mammogram by dense tissue has been developed. The algorithm considers both the effects of loss of contrast due to density and the distracting texture or appearance of dense tissue...
March 2016: Medical Physics
Lars Olsson, Mats Nilsson, Björn Svenson, Kristina Hellén-Halme
OBJECTIVES: Radiographic images suffer from varying amounts of noise. The most studied and discussed of these is random noise. However, recent research has shown that the projected anatomy contributes substantially to noise, especially when detecting low-contrast objects in the images. Our aim, therefore, was to evaluate the extent to which overprojected anatomical noise affects the detection of low-contrast objects in intra-oral images. METHODS: Our study used four common sensor models...
2016: Dento Maxillo Facial Radiology
Anando Sen, Howard C Gifford
Model observers intended to predict the diagnostic performance of human observers should account for the effects of both quantum and anatomical noise. We compared the abilities of several visual-search (VS) and scanning Hotelling-type models to account for anatomical noise in a localization receiver operating characteristic (LROC) study involving simulated nuclear medicine images. Our VS observer invoked a two-stage process of search and analysis. The images featured lesions in the prostate and pelvic lymph nodes...
January 2016: Journal of Medical Imaging
Polad M Shikhaliev
The purpose of this work was experimental investigation of photon counting spectroscopic CT (PCS-CT) imaging of anatomical soft tissue with clinically relevant size. The imaging experiments were performed using a spectroscopic CT system based on CdZnTe photon counting detector with two rows of pixels, 256 pixels in each row, 1  ×  1 mm(2) pixel size, and 25.6 cm detector length. The detector could split the x-ray energy spectrum to 5 regions (energy bins), and acquire 5 multi-energy (spectroscopic) CT images in a single CT scan...
March 21, 2015: Physics in Medicine and Biology
C S Moore, T J Wood, G Avery, S Balcam, L Needler, A Smith, J R Saunderson, A W Beavis
OBJECTIVE: The aim of this study was to investigate via simulation a proposed change to clinical practice for chest radiography. The validity of using a scatter rejection grid across the diagnostic energy range (60-125 kVp), in conjunction with appropriate tube current-time product (mAs) for imaging with a computed radiography (CR) system was investigated. METHODS: A digitally reconstructed radiograph algorithm was used, which was capable of simulating CR chest radiographs with various tube voltages, receptor doses and scatter rejection methods...
March 2015: British Journal of Radiology
Björn Cederström, Erik Fredenberg
PURPOSE: Beam-quality optimization in digital mammography traditionally considers detection of a target obscured by quantum noise in a homogeneous background. This does not correspond well to the clinical imaging task because real mammographic images contain a complex superposition of anatomical structures, resulting in anatomical noise that may dominate over quantum noise. The purpose of this paper is to assess the influence on optimal beam quality in mammography when anatomical noise is taken into account...
December 2014: Medical Physics
Digna M A Kamalski, Rudolf M Verdaasdonk, Tjeerd de Boorder, Robert Vincent, Huib Versnel, Wilko Grolman
HYPOTHESIS: The mechanical and acoustic effects that occur during laser-assisted stapedotomy differ among KTP, CO2, and thulium lasers. BACKGROUND: Making a fenestration in stapedotomy with a laser minimizes the risk of a floating footplate caused by mechanical forces. Theoretically, the lasers used in stapedotomy could inflict mechanical trauma because of absorption in the perilymph, causing vaporization bubbles. These bubbles can generate a shock wave, when imploding...
August 2014: Otology & Neurotology
C S Moore, T J Wood, G Avery, S Balcam, L Needler, A W Beavis, J R Saunderson
The purpose of this study was to examine the use of three physical image quality metrics in the calibration of an automatic exposure control (AEC) device for chest radiography with a computed radiography (CR) imaging system. The metrics assessed were signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and mean effective noise equivalent quanta (eNEQm), all measured using a uniform chest phantom. Subsequent calibration curves were derived to ensure each metric was held constant across the tube voltage range...
May 7, 2014: Physics in Medicine and Biology
S Schalekamp, B van Ginneken, N Karssemeijer, C M Schaefer-Prokop
Digital chest radiography is still the most common radiological examination. With the upcoming three-dimensional (3D) acquisition techniques the value of radiography seems to diminish. But because radiography is inexpensive, readily available, and requires very little dose, it is still being used for the first-line detection of many cardiothoracic diseases. In the last decades major technical developments of this 2D technique are being achieved. First, hardware developments of digital radiography have improved the contrast to noise, dose efficacy, throughput, and workflow...
February 2014: Seminars in Respiratory and Critical Care Medicine
Ke Li, John Garrett, Guang-Hong Chen
PURPOSE: With the recently expanding interest and developments in x-ray differential phase contrast CT (DPC-CT), the evaluation of its task-specific detection performance and comparison with the corresponding absorption CT under a given radiation dose constraint become increasingly important. Mathematical model observers are often used to quantify the performance of imaging systems, but their correlations with actual human observers need to be confirmed for each new imaging method. This work is an investigation of the effects of stochastic DPC-CT noise on the correlation of detection performance between model and human observers with signal-known-exactly (SKE) detection tasks...
November 2013: Medical Physics
G J Gang, J Lee, J W Stayman, D J Tward, W Zbijewski, J L Prince, J H Siewerdsen
PURPOSE: In the early development of new imaging modalities - such as tomosynthesis and cone-beam CT (CBCT) - an accurate predictive model for imaging performance is particularly valuable in identifying the physical factors that govern image quality and guiding system optimization. In this work, a task-based cascaded systems model for detectability index is proposed that describes not only the signal and noise propagation in the 2D (projection) and 3D (reconstruction) imaging chain but also the influence of background anatomical noise...
March 22, 2010: Proceedings of SPIE
Seokmin Han, Dong-Goo Kang
An easily implementable tissue cancellation method for dual energy mammography is proposed to reduce anatomical noise and enhance lesion visibility. For dual energy calibration, the images of an imaging object are directly mapped onto the images of a customized calibration phantom. Each pixel pair of the low and high energy images of the imaging object was compared to pixel pairs of the low and high energy images of the calibration phantom. The correspondence was measured by absolute difference between the pixel values of imaged object and those of the calibration phantom...
January 2014: IEEE Transactions on Medical Imaging
Sarah J Boyce, Kingshuk Roy Choudhury, Ehsan Samei
PURPOSE: Stereoscopic chest biplane correlation imaging (stereo∕BCI) has been proposed as an alternative modality to single view chest x-ray (CXR). The metrics effective modulation transfer function (eMTF), effective normalized noise power spectrum (eNNPS), and effective detective quantum efficiency (eDQE) have been proposed as clinically relevant metrics for assessing clinical system performance taking into consideration the magnification and scatter effects. This study compared the metrics eMTF, eNNPS, eDQE, and detectability index for stereo∕BCI and single view CXR under isodose conditions at two magnifications for two anthropomorphic phantoms of differing sizes...
September 2013: Medical Physics
Melissa L Hill, James G Mainprize, Ann-Katherine Carton, Sylvie Saab-Puong, Razvan Iordache, Serge Muller, Roberta A Jong, Clarisse Dromain, Martin J Yaffe
PURPOSE: Dual-energy (DE) contrast-enhanced digital mammography (CEDM) uses an iodinated contrast agent in combination with digital mammography (DM) to evaluate lesions on the basis of tumor angiogenesis. In DE imaging, low-energy (LE) and high-energy (HE) images are acquired after contrast administration and their logarithms are subtracted to cancel the appearance of normal breast tissue. Often there is incomplete signal cancellation in the subtracted images, creating a background "clutter" that can impair lesion detection...
August 2013: Medical Physics
Melissa L Hill, James G Mainprize, Ann-Katherine Carton, Serge Muller, Mehran Ebrahimi, Roberta A Jong, Clarisse Dromain, Martin J Yaffe
PURPOSE: The use of an intravenously injected iodinated contrast agent could help increase the sensitivity of digital mammography by adding information on tumor angiogenesis. Two approaches have been made for clinical implementation of contrast-enhanced digital mammography (CEDM), namely, single-energy (SE) and dual-energy (DE) imaging. In each technique, pairs of mammograms are acquired, which are then subtracted with the intent to cancel the appearance of healthy breast tissue to permit sensitive detection and specific characterization of lesions...
May 2013: Medical Physics
Nicholas Allec, Shiva Abbaszadeh, Chris C Scott, Karim S Karim, John M Lewin
PURPOSE: The authors describe modifications to previously developed cascaded systems analysis to include the anatomical noise in evaluation of dual-energy noise reduction techniques. Previous models have ignored the anatomical noise in theoretical analysis of noise reduction techniques. The inclusion of anatomical noise leads to more accurate estimation of potential noise reduction improvements and optimization. METHODS: The model is applied to dual-energy contrast-enhanced mammography...
May 2013: Medical Physics
Lin Chen, Craig K Abbey, John M Boone
Previous research has demonstrated that a parameter extracted from a power function fit to the anatomical noise power spectrum, β, may be predictive of breast mass lesion detectability in x-ray based medical images of the breast. In this investigation, the value of β was compared with a number of other more widely used parameters, in order to determine the relationship between β and these other parameters. This study made use of breast CT data sets, acquired on two breast CT systems developed in our laboratory...
March 21, 2013: Physics in Medicine and Biology
N Allec, S Abbaszadeh, C C Scott, J M Lewin, K S Karim
In contrast-enhanced mammography (CEM), the dual-energy dual-exposure technique, which can leverage existing conventional mammography infrastructure, relies on acquiring the low- and high-energy images using two separate exposures. The finite time between image acquisition leads to motion artifacts in the combined image. Motion artifacts can lead to greater anatomical noise in the combined image due to increased mismatch of the background tissue in the images to be combined, however the impact has not yet been quantified...
December 21, 2012: Physics in Medicine and Biology
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