Image quality analysis of digital mammographic equipments

International Nuclear Information System (INIS)

Mayo, P.; Pascual, A.; Verdu, G.; Rodenas, F.; Campayo, J.M.; Villaescusa, J.I.

2006-01-01

The image quality assessment of a radiographic phantom image is one of the fundamental points in a complete quality control programme. The good functioning result of all the process must be an image with an appropriate quality to carry out a suitable diagnostic. Nowadays, the digital radiographic equipments are replacing the traditional film-screen equipments and it is necessary to update the parameters to guarantee the quality of the process. Contrast-detail phantoms are applied to digital radiography to study the threshold contrast detail sensitivity at operation conditions of the equipment. The phantom that is studied in this work is C.D.M.A.M. 3.4, which facilitates the evaluation of image contrast and detail resolution. One of the most extended indexes to measure the image quality in an objective way is the Image Quality Figure (I.Q.F.). This parameter is useful to calculate the image quality taking into account the contrast and detail resolution of the image analysed. The contrast-detail curve is useful as a measure of the image quality too, because it is a graphical representation in which the hole thickness and diameter are plotted for each contrast-detail combination detected in the radiographic image of the phantom. It is useful for the comparison of the functioning of different radiographic image systems, for phantom images under the same exposition conditions. The aim of this work is to study the image quality of different images contrast-detail phantom C.D.M.A.M. 3.4, carrying out the automatic detection of the contrast-detail combination and to establish a parameter which characterize in an objective way the mammographic image quality. This is useful to compare images obtained at different digital mammographic equipments to study the functioning of the equipments. (authors)

Assessing product image quality for online shopping

Science.gov (United States)

Goswami, Anjan; Chung, Sung H.; Chittar, Naren; Islam, Atiq

2012-01-01

Assessing product-image quality is important in the context of online shopping. A high quality image that conveys more information about a product can boost the buyer's confidence and can get more attention. However, the notion of image quality for product-images is not the same as that in other domains. The perception of quality of product-images depends not only on various photographic quality features but also on various high level features such as clarity of the foreground or goodness of the background etc. In this paper, we define a notion of product-image quality based on various such features. We conduct a crowd-sourced experiment to collect user judgments on thousands of eBay's images. We formulate a multi-class classification problem for modeling image quality by classifying images into good, fair and poor quality based on the guided perceptual notions from the judges. We also conduct experiments with regression using average crowd-sourced human judgments as target. We compute a pseudo-regression score with expected average of predicted classes and also compute a score from the regression technique. We design many experiments with various sampling and voting schemes with crowd-sourced data and construct various experimental image quality models. Most of our models have reasonable accuracies (greater or equal to 70%) on test data set. We observe that our computed image quality score has a high (0.66) rank correlation with average votes from the crowd sourced human judgments.

Improving image quality in portal venography with spectral CT imaging

International Nuclear Information System (INIS)

Zhao, Li-qin; He, Wen; Li, Jian-ying; Chen, Jiang-hong; Wang, Ke-yang; Tan, Li

2012-01-01

Objective: To investigate the effect of energy spectral CT on the image quality of CT portal venography in cirrhosis patients. Materials and methods: 30 portal hypertension patients underwent spectral CT examination using a single-tube, fast dual tube voltage switching technique. 101 sets of monochromatic images were generated from 40 keV to 140 keV. Image noise and contrast-to-noise ratio (CNR) for portal veins from the monochromatic images were measured. An optimal monochromatic image set was selected for obtaining the best CNR for portal veins. The image noise and CNR of the intra-hepatic portal vein and extra-hepatic main stem at the selected monochromatic level were compared with those from the conventional polychromatic images. Image quality was also assessed and compared. Results: The monochromatic images at 51 keV were found to provide the best CNR for both the intra-hepatic and extra-hepatic portal veins. At this energy level, the monochromatic images had about 100% higher CNR than the polychromatic images with a moderate 30% noise increase. The qualitative image quality assessment was also statistically higher with monochromatic images at 51 keV. Conclusion: Monochromatic images at 51 keV for CT portal venography could improve CNR for displaying hepatic portal veins and improve the overall image quality.

Improving image quality in portal venography with spectral CT imaging

Energy Technology Data Exchange (ETDEWEB)

Zhao, Li-qin, E-mail: zhaolqzr@sohu.com [Department of Radiology, Beijing Friendship Hospital Affiliated to Capital Medical University, Beijing,100050 (China); He, Wen, E-mail: hewen1724@sina.com [Department of Radiology, Beijing Friendship Hospital Affiliated to Capital Medical University, Beijing,100050 (China); Li, Jian-ying, E-mail: jianying.li@med.ge.com [CT Advanced Application and Research, GE Healthcare, 100176 China (China); Chen, Jiang-hong, E-mail: chenjianghong1973@hotmail.com [Department of Radiology, Beijing Friendship Hospital Affiliated to Capital Medical University, Beijing,100050 (China); Wang, Ke-yang, E-mail: ke7ke@sina.com [Department of Radiology, Beijing Friendship Hospital Affiliated to Capital Medical University, Beijing,100050 (China); Tan, Li, E-mail: Litan@ge.com [CT product, GE Healthcare, 100176 China (China)

2012-08-15

Objective: To investigate the effect of energy spectral CT on the image quality of CT portal venography in cirrhosis patients. Materials and methods: 30 portal hypertension patients underwent spectral CT examination using a single-tube, fast dual tube voltage switching technique. 101 sets of monochromatic images were generated from 40 keV to 140 keV. Image noise and contrast-to-noise ratio (CNR) for portal veins from the monochromatic images were measured. An optimal monochromatic image set was selected for obtaining the best CNR for portal veins. The image noise and CNR of the intra-hepatic portal vein and extra-hepatic main stem at the selected monochromatic level were compared with those from the conventional polychromatic images. Image quality was also assessed and compared. Results: The monochromatic images at 51 keV were found to provide the best CNR for both the intra-hepatic and extra-hepatic portal veins. At this energy level, the monochromatic images had about 100% higher CNR than the polychromatic images with a moderate 30% noise increase. The qualitative image quality assessment was also statistically higher with monochromatic images at 51 keV. Conclusion: Monochromatic images at 51 keV for CT portal venography could improve CNR for displaying hepatic portal veins and improve the overall image quality.

Hyperspectral Image Analysis of Food Quality

DEFF Research Database (Denmark)

Arngren, Morten

inspection.Near-infrared spectroscopy can address these issues by offering a fast and objectiveanalysis of the food quality. A natural extension to these single spectrumNIR systems is to include image information such that each pixel holds a NIRspectrum. This augmented image information offers several......Assessing the quality of food is a vital step in any food processing line to ensurethe best food quality and maximum profit for the farmer and food manufacturer.Traditional quality evaluation methods are often destructive and labourintensive procedures relying on wet chemistry or subjective human...... extensions to the analysis offood quality. This dissertation is concerned with hyperspectral image analysisused to assess the quality of single grain kernels. The focus is to highlight thebenefits and challenges of using hyperspectral imaging for food quality presentedin two research directions. Initially...

Image quality and dose differences caused by vendor-specific image processing of neonatal radiographs

International Nuclear Information System (INIS)

Sensakovic, William F.; O'Dell, M.C.; Letter, Haley; Kohler, Nathan; Rop, Baiywo; Cook, Jane; Logsdon, Gregory; Varich, Laura

2016-01-01

Image processing plays an important role in optimizing image quality and radiation dose in projection radiography. Unfortunately commercial algorithms are black boxes that are often left at or near vendor default settings rather than being optimized. We hypothesize that different commercial image-processing systems, when left at or near default settings, create significant differences in image quality. We further hypothesize that image-quality differences can be exploited to produce images of equivalent quality but lower radiation dose. We used a portable radiography system to acquire images on a neonatal chest phantom and recorded the entrance surface air kerma (ESAK). We applied two image-processing systems (Optima XR220amx, by GE Healthcare, Waukesha, WI; and MUSICA"2 by Agfa HealthCare, Mortsel, Belgium) to the images. Seven observers (attending pediatric radiologists and radiology residents) independently assessed image quality using two methods: rating and matching. Image-quality ratings were independently assessed by each observer on a 10-point scale. Matching consisted of each observer matching GE-processed images and Agfa-processed images with equivalent image quality. A total of 210 rating tasks and 42 matching tasks were performed and effective dose was estimated. Median Agfa-processed image-quality ratings were higher than GE-processed ratings. Non-diagnostic ratings were seen over a wider range of doses for GE-processed images than for Agfa-processed images. During matching tasks, observers matched image quality between GE-processed images and Agfa-processed images acquired at a lower effective dose (11 ± 9 μSv; P < 0.0001). Image-processing methods significantly impact perceived image quality. These image-quality differences can be exploited to alter protocols and produce images of equivalent image quality but lower doses. Those purchasing projection radiography systems or third-party image-processing software should be aware that image processing

Image quality dependence on image processing software in ...

African Journals Online (AJOL)

Image quality dependence on image processing software in computed radiography. ... Agfa CR readers use MUSICA software, and an upgrade with significantly different image ... Full Text: EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT

Image quality at synthetic brain magnetic resonance imaging in children

Energy Technology Data Exchange (ETDEWEB)

Lee, So Mi; Cho, Seung Hyun; Kim, Won Hwa; Kim, Hye Jung [Kyungpook National University Hospital, Department of Radiology, Daegu (Korea, Republic of); Choi, Young Hun; Cheon, Jung-Eun; Kim, In-One [Seoul National University College of Medicine, Department of Radiology and Institute of Radiation Medicine, Seoul (Korea, Republic of); Cho, Hyun-Hae [Ewha Womans University Mokdong Hospital, Department of Radiology, Seoul (Korea, Republic of); You, Sun-Kyoung [Chungnam National University Hospital, Department of Radiology, Daejeon (Korea, Republic of); Park, Sook-Hyun [Kyungpook National University Hospital, Department of Pediatrics, Daegu (Korea, Republic of); Hwang, Moon Jung [GE Healthcare, MR Applications and Workflow, Seoul (Korea, Republic of)

2017-11-15

The clinical application of the multi-echo, multi-delay technique of synthetic magnetic resonance imaging (MRI) generates multiple sequences in a single acquisition but has mainly been used in adults. To evaluate the image quality of synthetic brain MR in children compared with that of conventional images. Twenty-nine children (median age: 6 years, range: 0-16 years) underwent synthetic and conventional imaging. Synthetic (T2-weighted, T1-weighted and fluid-attenuated inversion recovery [FLAIR]) images with settings matching those of the conventional images were generated. The overall image quality, gray/white matter differentiation, lesion conspicuity and image degradations were rated on a 5-point scale. The relative contrasts were assessed quantitatively and acquisition times for the two imaging techniques were compared. Synthetic images were inferior due to more pronounced image degradations; however, there were no significant differences for T1- and T2-weighted images in children <2 years old. The quality of T1- and T2-weighted images were within the diagnostically acceptable range. FLAIR images showed greatly reduced quality. Gray/white matter differentiation was comparable or better in synthetic T1- and T2-weighted images, but poorer in FLAIR images. There was no effect on lesion conspicuity. Synthetic images had equal or greater relative contrast. Acquisition time was approximately two-thirds of that for conventional sequences. Synthetic T1- and T2-weighted images were diagnostically acceptable, but synthetic FLAIR images were not. Lesion conspicuity and gray/white matter differentiation were comparable to conventional MRI. (orig.)

Balancing patient dose and image quality

International Nuclear Information System (INIS)

Martin, C.J.; Sutton, D.G.; Sharp, P.F.

1999-01-01

The formation of images in diagnostic radiology involves a complex interdependence of many factors. The ideal balance is to obtain an image which is adequate for the clinical purpose with the minimum radiation dose. Factors which affect radiation dose and image quality can be grouped under three headings; radiation quality, photon fluence and removal of scattered radiation. If optimal performance is to be achieved, it is necessary to understand how these factors influence image formation and affect radiation dose, and apply methodology for image quality and dose analysis at each stage in the development and use of X-ray equipment

Quality assurance: image production and film quality

International Nuclear Information System (INIS)

Abd Aziz Mhd Ramli

2004-01-01

The contents of this chapter are follows - Factors Affecting Image Quality and Patient Dose: Quality Control in Diagnostic Radiology, Mechanical Safety, Electrical Safety, Radiation Protection, Performance and Safety Standard, Calibration of QC Test Tools

Blind image quality assessment based on aesthetic and statistical quality-aware features

Science.gov (United States)

Jenadeleh, Mohsen; Masaeli, Mohammad Masood; Moghaddam, Mohsen Ebrahimi

2017-07-01

The main goal of image quality assessment (IQA) methods is the emulation of human perceptual image quality judgments. Therefore, the correlation between objective scores of these methods with human perceptual scores is considered as their performance metric. Human judgment of the image quality implicitly includes many factors when assessing perceptual image qualities such as aesthetics, semantics, context, and various types of visual distortions. The main idea of this paper is to use a host of features that are commonly employed in image aesthetics assessment in order to improve blind image quality assessment (BIQA) methods accuracy. We propose an approach that enriches the features of BIQA methods by integrating a host of aesthetics image features with the features of natural image statistics derived from multiple domains. The proposed features have been used for augmenting five different state-of-the-art BIQA methods, which use statistical natural scene statistics features. Experiments were performed on seven benchmark image quality databases. The experimental results showed significant improvement of the accuracy of the methods.

Image quality and dose differences caused by vendor-specific image processing of neonatal radiographs

Energy Technology Data Exchange (ETDEWEB)

Sensakovic, William F.; O' Dell, M.C.; Letter, Haley; Kohler, Nathan; Rop, Baiywo; Cook, Jane; Logsdon, Gregory; Varich, Laura [Florida Hospital, Imaging Administration, Orlando, FL (United States)

2016-10-15

Image processing plays an important role in optimizing image quality and radiation dose in projection radiography. Unfortunately commercial algorithms are black boxes that are often left at or near vendor default settings rather than being optimized. We hypothesize that different commercial image-processing systems, when left at or near default settings, create significant differences in image quality. We further hypothesize that image-quality differences can be exploited to produce images of equivalent quality but lower radiation dose. We used a portable radiography system to acquire images on a neonatal chest phantom and recorded the entrance surface air kerma (ESAK). We applied two image-processing systems (Optima XR220amx, by GE Healthcare, Waukesha, WI; and MUSICA{sup 2} by Agfa HealthCare, Mortsel, Belgium) to the images. Seven observers (attending pediatric radiologists and radiology residents) independently assessed image quality using two methods: rating and matching. Image-quality ratings were independently assessed by each observer on a 10-point scale. Matching consisted of each observer matching GE-processed images and Agfa-processed images with equivalent image quality. A total of 210 rating tasks and 42 matching tasks were performed and effective dose was estimated. Median Agfa-processed image-quality ratings were higher than GE-processed ratings. Non-diagnostic ratings were seen over a wider range of doses for GE-processed images than for Agfa-processed images. During matching tasks, observers matched image quality between GE-processed images and Agfa-processed images acquired at a lower effective dose (11 ± 9 μSv; P < 0.0001). Image-processing methods significantly impact perceived image quality. These image-quality differences can be exploited to alter protocols and produce images of equivalent image quality but lower doses. Those purchasing projection radiography systems or third-party image-processing software should be aware that image

Image quality and dose differences caused by vendor-specific image processing of neonatal radiographs.

Science.gov (United States)

Sensakovic, William F; O'Dell, M Cody; Letter, Haley; Kohler, Nathan; Rop, Baiywo; Cook, Jane; Logsdon, Gregory; Varich, Laura

2016-10-01

Image processing plays an important role in optimizing image quality and radiation dose in projection radiography. Unfortunately commercial algorithms are black boxes that are often left at or near vendor default settings rather than being optimized. We hypothesize that different commercial image-processing systems, when left at or near default settings, create significant differences in image quality. We further hypothesize that image-quality differences can be exploited to produce images of equivalent quality but lower radiation dose. We used a portable radiography system to acquire images on a neonatal chest phantom and recorded the entrance surface air kerma (ESAK). We applied two image-processing systems (Optima XR220amx, by GE Healthcare, Waukesha, WI; and MUSICA(2) by Agfa HealthCare, Mortsel, Belgium) to the images. Seven observers (attending pediatric radiologists and radiology residents) independently assessed image quality using two methods: rating and matching. Image-quality ratings were independently assessed by each observer on a 10-point scale. Matching consisted of each observer matching GE-processed images and Agfa-processed images with equivalent image quality. A total of 210 rating tasks and 42 matching tasks were performed and effective dose was estimated. Median Agfa-processed image-quality ratings were higher than GE-processed ratings. Non-diagnostic ratings were seen over a wider range of doses for GE-processed images than for Agfa-processed images. During matching tasks, observers matched image quality between GE-processed images and Agfa-processed images acquired at a lower effective dose (11 ± 9 μSv; P < 0.0001). Image-processing methods significantly impact perceived image quality. These image-quality differences can be exploited to alter protocols and produce images of equivalent image quality but lower doses. Those purchasing projection radiography systems or third-party image-processing software should be aware that image

Tradeoffs between image quality and dose

International Nuclear Information System (INIS)

Seibert, J.A.

2004-01-01

Image quality takes on different perspectives and meanings when associated with the concept of as low as reasonably achievable (ALARA), which is chiefly focused on radiation dose delivered as a result of a medical imaging procedure. ALARA is important because of the increased radiosensitivity of children to ionizing radiation and the desire to keep the radiation dose low. By the same token, however, image quality is also important because of the need to provide the necessary information in a radiograph in order to make an accurate diagnosis. Thus, there are tradeoffs to be considered between image quality and radiation dose, which is the main topic of this article. ALARA does not necessarily mean the lowest radiation dose, nor, when implemented, does it result in the least desirable radiographic images. With the recent widespread implementation of digital radiographic detectors and displays, a new level of flexibility and complexity confronts the technologist, physicist, and radiologist in optimizing the pediatric radiography exam. This is due to the separation of the acquisition, display, and archiving events that were previously combined by the screen-film detector, which allows for compensation for under- and overexposures, image processing, and on-line image manipulation. As explained in the article, different concepts must be introduced for a better understanding of the tradeoffs encountered when dealing with digital radiography and ALARA. In addition, there are many instances during the image acquisition/display/interpretation process in which image quality and associated dose can be compromised. This requires continuous diligence to quality control and feedback mechanisms to verify that the goals of image quality, dose and ALARA are achieved. (orig.)

Optimization of Synthetic Aperture Image Quality

DEFF Research Database (Denmark)

Moshavegh, Ramin; Jensen, Jonas; Villagómez Hoyos, Carlos Armando

2016-01-01

Synthetic Aperture (SA) imaging produces high-quality images and velocity estimates of both slow and fast flow at high frame rates. However, grating lobe artifacts can appear both in transmission and reception. These affect the image quality and the frame rate. Therefore optimization of parameter...

Image quality assessment using deep convolutional networks

Science.gov (United States)

Li, Yezhou; Ye, Xiang; Li, Yong

2017-12-01

This paper proposes a method of accurately assessing image quality without a reference image by using a deep convolutional neural network. Existing training based methods usually utilize a compact set of linear filters for learning features of images captured by different sensors to assess their quality. These methods may not be able to learn the semantic features that are intimately related with the features used in human subject assessment. Observing this drawback, this work proposes training a deep convolutional neural network (CNN) with labelled images for image quality assessment. The ReLU in the CNN allows non-linear transformations for extracting high-level image features, providing a more reliable assessment of image quality than linear filters. To enable the neural network to take images of any arbitrary size as input, the spatial pyramid pooling (SPP) is introduced connecting the top convolutional layer and the fully-connected layer. In addition, the SPP makes the CNN robust to object deformations to a certain extent. The proposed method taking an image as input carries out an end-to-end learning process, and outputs the quality of the image. It is tested on public datasets. Experimental results show that it outperforms existing methods by a large margin and can accurately assess the image quality on images taken by different sensors of varying sizes.

The study of surgical image quality evaluation system by subjective quality factor method

Science.gov (United States)

Zhang, Jian J.; Xuan, Jason R.; Yang, Xirong; Yu, Honggang; Koullick, Edouard

2016-03-01

GreenLightTM procedure is an effective and economical way of treatment of benign prostate hyperplasia (BPH); there are almost a million of patients treated with GreenLightTM worldwide. During the surgical procedure, the surgeon or physician will rely on the monitoring video system to survey and confirm the surgical progress. There are a few obstructions that could greatly affect the image quality of the monitoring video, like laser glare by the tissue and body fluid, air bubbles and debris generated by tissue evaporation, and bleeding, just to name a few. In order to improve the physician's visual experience of a laser surgical procedure, the system performance parameter related to image quality needs to be well defined. However, since image quality is the integrated set of perceptions of the overall degree of excellence of an image, or in other words, image quality is the perceptually weighted combination of significant attributes (contrast, graininess …) of an image when considered in its marketplace or application, there is no standard definition on overall image or video quality especially for the no-reference case (without a standard chart as reference). In this study, Subjective Quality Factor (SQF) and acutance are used for no-reference image quality evaluation. Basic image quality parameters, like sharpness, color accuracy, size of obstruction and transmission of obstruction, are used as subparameter to define the rating scale for image quality evaluation or comparison. Sample image groups were evaluated by human observers according to the rating scale. Surveys of physician groups were also conducted with lab generated sample videos. The study shows that human subjective perception is a trustworthy way of image quality evaluation. More systematic investigation on the relationship between video quality and image quality of each frame will be conducted as a future study.

Modified-BRISQUE as no reference image quality assessment for structural MR images.

Science.gov (United States)

Chow, Li Sze; Rajagopal, Heshalini

2017-11-01

An effective and practical Image Quality Assessment (IQA) model is needed to assess the image quality produced from any new hardware or software in MRI. A highly competitive No Reference - IQA (NR - IQA) model called Blind/Referenceless Image Spatial Quality Evaluator (BRISQUE) initially designed for natural images were modified to evaluate structural MR images. The BRISQUE model measures the image quality by using the locally normalized luminance coefficients, which were used to calculate the image features. The modified-BRISQUE model trained a new regression model using MR image features and Difference Mean Opinion Score (DMOS) from 775 MR images. Two types of benchmarks: objective and subjective assessments were used as performance evaluators for both original and modified-BRISQUE models. There was a high correlation between the modified-BRISQUE with both benchmarks, and they were higher than those for the original BRISQUE. There was a significant percentage improvement in their correlation values. The modified-BRISQUE was statistically better than the original BRISQUE. The modified-BRISQUE model can accurately measure the image quality of MR images. It is a practical NR-IQA model for MR images without using reference images. Copyright © 2017 Elsevier Inc. All rights reserved.

Quality assurance for image-guided radiotherapy

International Nuclear Information System (INIS)

Marinello, Ginette

2008-01-01

The topics discussed include, among others, the following: Quality assurance program; Image guided radiotherapy; Commissioning and quality assurance; Check of agreement between visual and displayed scales; quality controls: electronic portal imaging device (EPID), MV-kV and kV-kV, cone-beam CT (CBCT), patient doses. (P.A.)

Image quality and dose in computed tomography

International Nuclear Information System (INIS)

Jurik, A.G.; Jessen, K.A.; Hansen, J.

1997-01-01

Radiation exposure to the patient during CT is relatively high, and it is therefore important to optimize the dose so that it is as low as possible but still consistent with required diagnostic image quality. There is no established method for measuring diagnostic image quality; therefore, a set of image quality criteria which must be fulfilled for optimal image quality was defined for the retroperitoneal space and the mediastinum. The use of these criteria for assessment of image quality was tested based on 113 retroperitoneal and 68 mediastinal examinations performed in seven different CT units. All the criteria, except one, were found to be usable for measuring diagnostic image quality. The fulfilment of criteria was related to the radiation dose given in the different departments. By examination of the retroperitoneal space the effective dose varied between 5.1 and 20.0 mSv (milli Sievert), and there was a slight correlation between dose and high percent of ''yes'' score for the image quality criteria. For examination of the mediastinum the dose range was 4.4-26.5 mSv, and there was no significant increment of image quality at high doses. The great variation of dose at different CT units was due partly to differences regarding the examination procedure, especially the number of slices and the mAs (milli ampere second), but inherent dose variation between different scanners also played a part. (orig.). With 6 figs., 6 tabs

Retinal image quality assessment based on image clarity and content

Science.gov (United States)

Abdel-Hamid, Lamiaa; El-Rafei, Ahmed; El-Ramly, Salwa; Michelson, Georg; Hornegger, Joachim

2016-09-01

Retinal image quality assessment (RIQA) is an essential step in automated screening systems to avoid misdiagnosis caused by processing poor quality retinal images. A no-reference transform-based RIQA algorithm is introduced that assesses images based on five clarity and content quality issues: sharpness, illumination, homogeneity, field definition, and content. Transform-based RIQA algorithms have the advantage of considering retinal structures while being computationally inexpensive. Wavelet-based features are proposed to evaluate the sharpness and overall illumination of the images. A retinal saturation channel is designed and used along with wavelet-based features for homogeneity assessment. The presented sharpness and illumination features are utilized to assure adequate field definition, whereas color information is used to exclude nonretinal images. Several publicly available datasets of varying quality grades are utilized to evaluate the feature sets resulting in area under the receiver operating characteristic curve above 0.99 for each of the individual feature sets. The overall quality is assessed by a classifier that uses the collective features as an input vector. The classification results show superior performance of the algorithm in comparison to other methods from literature. Moreover, the algorithm addresses efficiently and comprehensively various quality issues and is suitable for automatic screening systems.

REMOTE SENSING IMAGE QUALITY ASSESSMENT EXPERIMENT WITH POST-PROCESSING

Directory of Open Access Journals (Sweden)

W. Jiang

2018-04-01

Full Text Available This paper briefly describes the post-processing influence assessment experiment, the experiment includes three steps: the physical simulation, image processing, and image quality assessment. The physical simulation models sampled imaging system in laboratory, the imaging system parameters are tested, the digital image serving as image processing input are produced by this imaging system with the same imaging system parameters. The gathered optical sampled images with the tested imaging parameters are processed by 3 digital image processes, including calibration pre-processing, lossy compression with different compression ratio and image post-processing with different core. Image quality assessment method used is just noticeable difference (JND subject assessment based on ISO20462, through subject assessment of the gathered and processing images, the influence of different imaging parameters and post-processing to image quality can be found. The six JND subject assessment experimental data can be validated each other. Main conclusions include: image post-processing can improve image quality; image post-processing can improve image quality even with lossy compression, image quality with higher compression ratio improves less than lower ratio; with our image post-processing method, image quality is better, when camera MTF being within a small range.

Subjective matters: from image quality to image psychology

Science.gov (United States)

Fedorovskaya, Elena A.; De Ridder, Huib

2013-03-01

From the advent of digital imaging through several decades of studies, the human vision research community systematically focused on perceived image quality and digital artifacts due to resolution, compression, gamma, dynamic range, capture and reproduction noise, blur, etc., to help overcome existing technological challenges and shortcomings. Technological advances made digital images and digital multimedia nearly flawless in quality, and ubiquitous and pervasive in usage, provide us with the exciting but at the same time demanding possibility to turn to the domain of human experience including higher psychological functions, such as cognition, emotion, awareness, social interaction, consciousness and Self. In this paper we will outline the evolution of human centered multidisciplinary studies related to imaging and propose steps and potential foci of future research.

Improving the Image Quality of Synthetic Transmit Aperture Ultrasound Images - Achieving Real-Time In-Vivo Imaging

DEFF Research Database (Denmark)

Gammelmark, Kim

in-vivo experiments, showed, that TMS imaging can increase the SNR by as much as 17 dB compared to the traditional imaging techniques, which improves the in-vivo image quality to a highly competitive level. An in-vivo evaluation of convex array TMS imaging for abdominal imaging applications......-vivo imaging, and that the obtained image quality is highly competitive with the techniques applied in current medical ultrasound scanners. Hereby, the goals of the PhD have been successfully achieved.......Synthetic transmit aperture (STA) imaging has the potential to increase the image quality of medical ultrasound images beyond the levels obtained by conventional imaging techniques (linear, phased, and convex array imaging). Currently, however, in-vivo applications of STA imaging is limited...

No-reference image quality assessment for horizontal-path imaging scenarios

Science.gov (United States)

Rios, Carlos; Gladysz, Szymon

2013-05-01

There exist several image-enhancement algorithms and tasks associated with imaging through turbulence that depend on defining the quality of an image. Examples include: "lucky imaging", choosing the width of the inverse filter for image reconstruction, or stopping iterative deconvolution. We collected a number of image quality metrics found in the literature. Particularly interesting are the blind, "no-reference" metrics. We discuss ways of evaluating the usefulness of these metrics, even when a fully objective comparison is impossible because of the lack of a reference image. Metrics are tested on simulated and real data. Field data comes from experiments performed by the NATO SET 165 research group over a 7 km distance in Dayton, Ohio.

The effect of image sharpness on quantitative eye movement data and on image quality evaluation while viewing natural images

Science.gov (United States)

Vuori, Tero; Olkkonen, Maria

2006-01-01

The aim of the study is to test both customer image quality rating (subjective image quality) and physical measurement of user behavior (eye movements tracking) to find customer satisfaction differences in imaging technologies. Methodological aim is to find out whether eye movements could be quantitatively used in image quality preference studies. In general, we want to map objective or physically measurable image quality to subjective evaluations and eye movement data. We conducted a series of image quality tests, in which the test subjects evaluated image quality while we recorded their eye movements. Results show that eye movement parameters consistently change according to the instructions given to the user, and according to physical image quality, e.g. saccade duration increased with increasing blur. Results indicate that eye movement tracking could be used to differentiate image quality evaluation strategies that the users have. Results also show that eye movements would help mapping between technological and subjective image quality. Furthermore, these results give some empirical emphasis to top-down perception processes in image quality perception and evaluation by showing differences between perceptual processes in situations when cognitive task varies.

Quality of radiation field imaging

International Nuclear Information System (INIS)

Petr, I.

1988-01-01

The questions were studied of the quality of imaging the gamma radiation field and of the limits of the quality in directional detector scanning. A resolution angle was introduced to quantify the imaging quality, and its relation was sought with the detection effective half-angle of the directional detector. The resolution angle was defined for the simplest configuration of the radiation field consisting of two monoenergetic gamma beams in one plane. It was shown that the resolution angle decreases, i.e., resolution in imaging the radiation field is better, with the effective half-angle of the directional detector. It was also found that resolution of both gamma beams deteriorated when the beams were surrounded with an isotropic background field. If the beams are surrounded with a background field showing general distribution, the angle size will be affected not only by the properties of the detector but also by the distribution of the ambient radiation field and the method of its scanning. The method described can be applied in designing a directional detector necessary for imaging the presumed radiation field in the required quality. (Z.M.). 4 figs., 3 refs

Quality assessment for online iris images

CSIR Research Space (South Africa)

Makinana, S

2015-01-01

Full Text Available Iris recognition systems have attracted much attention for their uniqueness, stability and reliability. However, performance of this system depends on quality of iris image. Therefore there is a need to select good quality images before features can...

Increased Frame Rate for Plane Wave Imaging Without Loss of Image Quality

DEFF Research Database (Denmark)

Jensen, Jonas; Stuart, Matthias Bo; Jensen, Jørgen Arendt

2015-01-01

Clinical applications of plane wave imaging necessitate the creation of high-quality images with the highest possible frame rate for improved blood flow tracking and anatomical imaging. However, linear array transducers create grating lobe artefacts, which degrade the image quality especially...... in the near field for λ-pitch transducers. Artefacts can only partly be suppressed by increasing the number of emissions, and this paper demonstrates how the frame rate can be increased without loss of image quality by using λ/2-pitch transducers. The number of emissions and steering angles are optimized...

Image quality and dose in mammographic images obtained in Mexico City hospitals

International Nuclear Information System (INIS)

Ruiz-Trejo, C.; Brandan, M.-E.; Verdejo, M.; Flores, A.; Guevara, M.; Martin, J.; Madero-Preciado, L.

2001-01-01

The performance of three mammographic systems in large Mexican hospitals has been evaluated, as well as the image quality and associated dose. Quality control tests include examination of X-ray equipment, darkroom conditions, film processor, and viewboxes. Systems referred to as '1', '2', and '3' passed 50%, 75% and 75% of these tests, respectively. Quality image is assessed using five images obtained under similar nominal conditions in each X-ray equipment. System 1 generates no image of acceptable quality, while equipment 2 and 3 produce one and two, respectively. The mean glandular dose for the best images obtained in each service with an accreditation phantom has been measured, and the values are 1.4 mGy, 1.6 mGy, and 1.0 mGy, respectively. (author)

Objective and Subjective Assessment of Digital Pathology Image Quality

Directory of Open Access Journals (Sweden)

Prarthana Shrestha

2015-03-01

Full Text Available The quality of an image produced by the Whole Slide Imaging (WSI scanners is of critical importance for using the image in clinical diagnosis. Therefore, it is very important to monitor and ensure the quality of images. Since subjective image quality assessments by pathologists are very time-consuming, expensive and difficult to reproduce, we propose a method for objective assessment based on clinically relevant and perceptual image parameters: sharpness, contrast, brightness, uniform illumination and color separation; derived from a survey of pathologists. We developed techniques to quantify the parameters based on content-dependent absolute pixel performance and to manipulate the parameters in a predefined range resulting in images with content-independent relative quality measures. The method does not require a prior reference model. A subjective assessment of the image quality is performed involving 69 pathologists and 372 images (including 12 optimal quality images and their distorted versions per parameter at 6 different levels. To address the inter-reader variability, a representative rating is determined as a one-tailed 95% confidence interval of the mean rating. The results of the subjective assessment support the validity of the proposed objective image quality assessment method to model the readers’ perception of image quality. The subjective assessment also provides thresholds for determining the acceptable level of objective quality per parameter. The images for both the subjective and objective quality assessment are based on the HercepTestTM slides scanned by the Philips Ultra Fast Scanners, developed at Philips Digital Pathology Solutions. However, the method is applicable also to other types of slides and scanners.

STANDARDIZING QUALITY ASSESSMENT OF FUSED REMOTELY SENSED IMAGES

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C. Pohl

2017-09-01

Full Text Available The multitude of available operational remote sensing satellites led to the development of many image fusion techniques to provide high spatial, spectral and temporal resolution images. The comparison of different techniques is necessary to obtain an optimized image for the different applications of remote sensing. There are two approaches in assessing image quality: 1. Quantitatively by visual interpretation and 2. Quantitatively using image quality indices. However an objective comparison is difficult due to the fact that a visual assessment is always subject and a quantitative assessment is done by different criteria. Depending on the criteria and indices the result varies. Therefore it is necessary to standardize both processes (qualitative and quantitative assessment in order to allow an objective image fusion quality evaluation. Various studies have been conducted at the University of Osnabrueck (UOS to establish a standardized process to objectively compare fused image quality. First established image fusion quality assessment protocols, i.e. Quality with No Reference (QNR and Khan's protocol, were compared on varies fusion experiments. Second the process of visual quality assessment was structured and standardized with the aim to provide an evaluation protocol. This manuscript reports on the results of the comparison and provides recommendations for future research.

Standardizing Quality Assessment of Fused Remotely Sensed Images

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Pohl, C.; Moellmann, J.; Fries, K.

2017-09-01

The multitude of available operational remote sensing satellites led to the development of many image fusion techniques to provide high spatial, spectral and temporal resolution images. The comparison of different techniques is necessary to obtain an optimized image for the different applications of remote sensing. There are two approaches in assessing image quality: 1. Quantitatively by visual interpretation and 2. Quantitatively using image quality indices. However an objective comparison is difficult due to the fact that a visual assessment is always subject and a quantitative assessment is done by different criteria. Depending on the criteria and indices the result varies. Therefore it is necessary to standardize both processes (qualitative and quantitative assessment) in order to allow an objective image fusion quality evaluation. Various studies have been conducted at the University of Osnabrueck (UOS) to establish a standardized process to objectively compare fused image quality. First established image fusion quality assessment protocols, i.e. Quality with No Reference (QNR) and Khan's protocol, were compared on varies fusion experiments. Second the process of visual quality assessment was structured and standardized with the aim to provide an evaluation protocol. This manuscript reports on the results of the comparison and provides recommendations for future research.

Objective masurement of image quality in fluoroscopic x-ray equipment FluoroQuality

CERN Document Server

Tapiovaara, M

2003-01-01

The report describes FluoroQuality, a computer program that is developed in STUK and used for measuring the image quality in medical fluoroscopic equipment. The method is based on the statistical decision theory (SDT) and the main measurement result is given in terms of the accumulation rate of the signal-to-noise ratio squared (SNR sup 2 sub r sub a sub t sub e). In addition to this quantity several other quantities are measured. These quantities include the SNR of single image frames, the spatio-temporal noise power spectrum and the temporal lag. The measurement method can be used, for example, for specifying the image quality in fluoroscopic images, for optimising the image quality and dose rate in fluoroscopy and for quality control of fluoroscopic equipment. The theory behind the measurement method is reviewed and the measurement of the various quantities is explained. An example of using the method for optimising a specified fluoroscopic procedure is given. The User's Manual of the program is included a...

Image quality evaluation of full reference algorithm

Science.gov (United States)

He, Nannan; Xie, Kai; Li, Tong; Ye, Yushan

2018-03-01

Image quality evaluation is a classic research topic, the goal is to design the algorithm, given the subjective feelings consistent with the evaluation value. This paper mainly introduces several typical reference methods of Mean Squared Error(MSE), Peak Signal to Noise Rate(PSNR), Structural Similarity Image Metric(SSIM) and feature similarity(FSIM) of objective evaluation methods. The different evaluation methods are tested by Matlab, and the advantages and disadvantages of these methods are obtained by analyzing and comparing them.MSE and PSNR are simple, but they are not considered to introduce HVS characteristics into image quality evaluation. The evaluation result is not ideal. SSIM has a good correlation and simple calculation ,because it is considered to the human visual effect into image quality evaluation,However the SSIM method is based on a hypothesis,The evaluation result is limited. The FSIM method can be used for test of gray image and color image test, and the result is better. Experimental results show that the new image quality evaluation algorithm based on FSIM is more accurate.

No-reference visual quality assessment for image inpainting

Science.gov (United States)

Voronin, V. V.; Frantc, V. A.; Marchuk, V. I.; Sherstobitov, A. I.; Egiazarian, K.

2015-03-01

Inpainting has received a lot of attention in recent years and quality assessment is an important task to evaluate different image reconstruction approaches. In many cases inpainting methods introduce a blur in sharp transitions in image and image contours in the recovery of large areas with missing pixels and often fail to recover curvy boundary edges. Quantitative metrics of inpainting results currently do not exist and researchers use human comparisons to evaluate their methodologies and techniques. Most objective quality assessment methods rely on a reference image, which is often not available in inpainting applications. Usually researchers use subjective quality assessment by human observers. It is difficult and time consuming procedure. This paper focuses on a machine learning approach for no-reference visual quality assessment for image inpainting based on the human visual property. Our method is based on observation that Local Binary Patterns well describe local structural information of the image. We use a support vector regression learned on assessed by human images to predict perceived quality of inpainted images. We demonstrate how our predicted quality value correlates with qualitative opinion in a human observer study. Results are shown on a human-scored dataset for different inpainting methods.

High-quality compressive ghost imaging

Science.gov (United States)

Huang, Heyan; Zhou, Cheng; Tian, Tian; Liu, Dongqi; Song, Lijun

2018-04-01

We propose a high-quality compressive ghost imaging method based on projected Landweber regularization and guided filter, which effectively reduce the undersampling noise and improve the resolution. In our scheme, the original object is reconstructed by decomposing of regularization and denoising steps instead of solving a minimization problem in compressive reconstruction process. The simulation and experimental results show that our method can obtain high ghost imaging quality in terms of PSNR and visual observation.

Developing and validating a psychometric scale for image quality assessment

International Nuclear Information System (INIS)

Mraity, H.; England, A.; Hogg, P.

2014-01-01

Purpose: Using AP pelvis as a catalyst, this paper explains how a psychometric scale for image quality assessment can be created using Bandura's theory for self-efficacy. Background: Establishing an accurate diagnosis is highly dependent upon the quality of the radiographic image. Image quality, as a construct (i.e. set of attributes that makes up the image quality), continues to play an essential role in the field of diagnostic radiography. The process of assessing image quality can be facilitated by using criteria, such as the European Commission (EC) guidelines for quality criteria as published in 1996. However, with the advent of new technology (Computed Radiography and Digital Radiography), some of the EC criteria may no longer be suitable for assessing the visual quality of a digital radiographic image. Moreover, a lack of validated visual image quality scales in the literature can also lead to significant variations in image quality evaluation. Creating and validating visual image quality scales, using a robust methodology, could reduce variability and improve the validity and reliability of perceptual image quality evaluations

Performance evaluation of no-reference image quality metrics for face biometric images

Science.gov (United States)

Liu, Xinwei; Pedersen, Marius; Charrier, Christophe; Bours, Patrick

2018-03-01

The accuracy of face recognition systems is significantly affected by the quality of face sample images. The recent established standardization proposed several important aspects for the assessment of face sample quality. There are many existing no-reference image quality metrics (IQMs) that are able to assess natural image quality by taking into account similar image-based quality attributes as introduced in the standardization. However, whether such metrics can assess face sample quality is rarely considered. We evaluate the performance of 13 selected no-reference IQMs on face biometrics. The experimental results show that several of them can assess face sample quality according to the system performance. We also analyze the strengths and weaknesses of different IQMs as well as why some of them failed to assess face sample quality. Retraining an original IQM by using face database can improve the performance of such a metric. In addition, the contribution of this paper can be used for the evaluation of IQMs on other biometric modalities; furthermore, it can be used for the development of multimodality biometric IQMs.

The influence of environment temperature on SEM image quality

International Nuclear Information System (INIS)

Chen, Li; Liu, Junshan

2015-01-01

As the structure dimension goes down to the nano-scale, it often requires a scanning electron microscope (SEM) to provide image magnification up to 100 000  ×. However, SEM images at such a high magnification usually suffer from high resolution value and low signal-to-noise ratio, which results in low quality of the SEM image. In this paper, the quality of the SEM image is improved by optimizing the environment temperature. The experimental results indicate that at 100 000  ×, the quality of the SEM image is influenced by the environment temperature, whereas at 50 000  × it is not. At 100 000  × the best SEM image quality can be achieved from the environment temperature ranging 292 from 294 K, and the SEM image quality evaluated by the double stimulus continuous quality scale method can increase from grade 1 to grade 5. It is expected that this image quality improving method can be used in routine measurements with ordinary SEMs to get high quality images by optimizing the environment temperature. (paper)

ANALYSIS OF THE EFFECTS OF IMAGE QUALITY ON DIGITAL MAP GENERATION FROM SATELLITE IMAGES

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H. Kim

2012-07-01

Full Text Available High resolution satellite images are widely used to produce and update a digital map since they became widely available. It is well known that the accuracy of digital map produced from satellite images is decided largely by the accuracy of geometric modelling. However digital maps are made by a series of photogrammetric workflow. Therefore the accuracy of digital maps are also affected by the quality of satellite images, such as image interpretability. For satellite images, parameters such as Modulation Transfer Function(MTF, Signal to Noise Ratio(SNR and Ground Sampling Distance(GSD are used to present images quality. Our previous research stressed that such quality parameters may not represent the quality of image products such as digital maps and that parameters for image interpretability such as Ground Resolved Distance(GRD and National Imagery Interpretability Rating Scale(NIIRS need to be considered. In this study, we analyzed the effects of the image quality on accuracy of digital maps produced by satellite images. QuickBird, IKONOS and KOMPSAT-2 imagery were used to analyze as they have similar GSDs. We measured various image quality parameters mentioned above from these images. Then we produced digital maps from the images using a digital photogrammetric workstation. We analyzed the accuracy of the digital maps in terms of their location accuracy and their level of details. Then we compared the correlation between various image quality parameters and the accuracy of digital maps. The results of this study showed that GRD and NIIRS were more critical for map production then GSD, MTF or SNR.

Comparison of applied dose and image quality in staging CT of neuroendocrine tumor patients using standard filtered back projection and adaptive statistical iterative reconstruction.

Science.gov (United States)

Böning, G; Schäfer, M; Grupp, U; Kaul, D; Kahn, J; Pavel, M; Maurer, M; Denecke, T; Hamm, B; Streitparth, F

2015-08-01

To investigate whether dose reduction via adaptive statistical iterative reconstruction (ASIR) affects image quality and diagnostic accuracy in neuroendocrine tumor (NET) staging. A total of 28 NET patients were enrolled in the study. Inclusion criteria were histologically proven NET and visible tumor in abdominal computed tomography (CT). In an intraindividual study design, the patients underwent a baseline CT (filtered back projection, FBP) and follow-up CT (ASIR 40%) using matched scan parameters. Image quality was assessed subjectively using a 5-grade scoring system and objectively by determining signal-to-noise ratio (SNR) and contrast-to-noise ratios (CNRs). Applied volume computed tomography dose index (CTDIvol) of each scan was taken from the dose report. ASIR 40% significantly reduced CTDIvol (10.17±3.06mGy [FBP], 6.34±2.25mGy [ASIR] (pASIR]) (pASIR]) (pASIR]), visibility of suspicious lesion (4.8±0.5 [FBP], 4.8±0.5 [ASIR]) and artifacts (5.0±0 [FBP], 5.0±0 [ASIR]). ASIR 40% significantly decreased scores for noise (4.3±0.6 [FBP], 4.0±0.8 [ASIR]) (pASIR]) (pASIR]) (pASIR can be used to reduce radiation dose without sacrificing image quality and diagnostic confidence in staging CT of NET patients. This may be beneficial for patients with frequent follow-up and significant cumulative radiation exposure. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Improving high resolution retinal image quality using speckle illumination HiLo imaging.

Science.gov (United States)

Zhou, Xiaolin; Bedggood, Phillip; Metha, Andrew

2014-08-01

Retinal image quality from flood illumination adaptive optics (AO) ophthalmoscopes is adversely affected by out-of-focus light scatter due to the lack of confocality. This effect is more pronounced in small eyes, such as that of rodents, because the requisite high optical power confers a large dioptric thickness to the retina. A recently-developed structured illumination microscopy (SIM) technique called HiLo imaging has been shown to reduce the effect of out-of-focus light scatter in flood illumination microscopes and produce pseudo-confocal images with significantly improved image quality. In this work, we adopted the HiLo technique to a flood AO ophthalmoscope and performed AO imaging in both (physical) model and live rat eyes. The improvement in image quality from HiLo imaging is shown both qualitatively and quantitatively by using spatial spectral analysis.

Learning Receptive Fields and Quality Lookups for Blind Quality Assessment of Stereoscopic Images.

Science.gov (United States)

Shao, Feng; Lin, Weisi; Wang, Shanshan; Jiang, Gangyi; Yu, Mei; Dai, Qionghai

2016-03-01

Blind quality assessment of 3D images encounters more new challenges than its 2D counterparts. In this paper, we propose a blind quality assessment for stereoscopic images by learning the characteristics of receptive fields (RFs) from perspective of dictionary learning, and constructing quality lookups to replace human opinion scores without performance loss. The important feature of the proposed method is that we do not need a large set of samples of distorted stereoscopic images and the corresponding human opinion scores to learn a regression model. To be more specific, in the training phase, we learn local RFs (LRFs) and global RFs (GRFs) from the reference and distorted stereoscopic images, respectively, and construct their corresponding local quality lookups (LQLs) and global quality lookups (GQLs). In the testing phase, blind quality pooling can be easily achieved by searching optimal GRF and LRF indexes from the learnt LQLs and GQLs, and the quality score is obtained by combining the LRF and GRF indexes together. Experimental results on three publicly 3D image quality assessment databases demonstrate that in comparison with the existing methods, the devised algorithm achieves high consistent alignment with subjective assessment.

Image Quality in High-resolution and High-cadence Solar Imaging

Science.gov (United States)

Denker, C.; Dineva, E.; Balthasar, H.; Verma, M.; Kuckein, C.; Diercke, A.; González Manrique, S. J.

2018-03-01

Broad-band imaging and even imaging with a moderate bandpass (about 1 nm) provides a photon-rich environment, where frame selection (lucky imaging) becomes a helpful tool in image restoration, allowing us to perform a cost-benefit analysis on how to design observing sequences for imaging with high spatial resolution in combination with real-time correction provided by an adaptive optics (AO) system. This study presents high-cadence (160 Hz) G-band and blue continuum image sequences obtained with the High-resolution Fast Imager (HiFI) at the 1.5-meter GREGOR solar telescope, where the speckle-masking technique is used to restore images with nearly diffraction-limited resolution. The HiFI employs two synchronized large-format and high-cadence sCMOS detectors. The median filter gradient similarity (MFGS) image-quality metric is applied, among others, to AO-corrected image sequences of a pore and a small sunspot observed on 2017 June 4 and 5. A small region of interest, which was selected for fast-imaging performance, covered these contrast-rich features and their neighborhood, which were part of Active Region NOAA 12661. Modifications of the MFGS algorithm uncover the field- and structure-dependency of this image-quality metric. However, MFGS still remains a good choice for determining image quality without a priori knowledge, which is an important characteristic when classifying the huge number of high-resolution images contained in data archives. In addition, this investigation demonstrates that a fast cadence and millisecond exposure times are still insufficient to reach the coherence time of daytime seeing. Nonetheless, the analysis shows that data acquisition rates exceeding 50 Hz are required to capture a substantial fraction of the best seeing moments, significantly boosting the performance of post-facto image restoration.

Automated image quality assessment for chest CT scans.

Science.gov (United States)

Reeves, Anthony P; Xie, Yiting; Liu, Shuang

2018-02-01

Medical image quality needs to be maintained at standards sufficient for effective clinical reading. Automated computer analytic methods may be applied to medical images for quality assessment. For chest CT scans in a lung cancer screening context, an automated quality assessment method is presented that characterizes image noise and image intensity calibration. This is achieved by image measurements in three automatically segmented homogeneous regions of the scan: external air, trachea lumen air, and descending aorta blood. Profiles of CT scanner behavior are also computed. The method has been evaluated on both phantom and real low-dose chest CT scans and results show that repeatable noise and calibration measures may be realized by automated computer algorithms. Noise and calibration profiles show relevant differences between different scanners and protocols. Automated image quality assessment may be useful for quality control for lung cancer screening and may enable performance improvements to automated computer analysis methods. © 2017 American Association of Physicists in Medicine.

IMAGE QUALITY FORECASTING FOR SPACE OBJECTS

Directory of Open Access Journals (Sweden)

A. I. Altukhov

2013-05-01

Full Text Available The article deals with an approach to quality predicting of the space objects images, which can be used to plan optoelectronic systems of remote sensing satellites work programs. The proposed approach is based on evaluation of the optoelectronic equipment transfer properties and calculation of indexes images quality considering the influence of the orbital shooting conditions.

Ultrafast Ultrasound Imaging With Cascaded Dual-Polarity Waves.

Science.gov (United States)

Zhang, Yang; Guo, Yuexin; Lee, Wei-Ning

2018-04-01

Ultrafast ultrasound imaging using plane or diverging waves, instead of focused beams, has advanced greatly the development of novel ultrasound imaging methods for evaluating tissue functions beyond anatomical information. However, the sonographic signal-to-noise ratio (SNR) of ultrafast imaging remains limited due to the lack of transmission focusing, and thus insufficient acoustic energy delivery. We hereby propose a new ultrafast ultrasound imaging methodology with cascaded dual-polarity waves (CDWs), which consists of a pulse train with positive and negative polarities. A new coding scheme and a corresponding linear decoding process were thereby designed to obtain the recovered signals with increased amplitude, thus increasing the SNR without sacrificing the frame rate. The newly designed CDW ultrafast ultrasound imaging technique achieved higher quality B-mode images than coherent plane-wave compounding (CPWC) and multiplane wave (MW) imaging in a calibration phantom, ex vivo pork belly, and in vivo human back muscle. CDW imaging shows a significant improvement in the SNR (10.71 dB versus CPWC and 7.62 dB versus MW), penetration depth (36.94% versus CPWC and 35.14% versus MW), and contrast ratio in deep regions (5.97 dB versus CPWC and 5.05 dB versus MW) without compromising other image quality metrics, such as spatial resolution and frame rate. The enhanced image qualities and ultrafast frame rates offered by CDW imaging beget great potential for various novel imaging applications.

Image quality preferences among radiographers and radiologists. A conjoint analysis

International Nuclear Information System (INIS)

Ween, Borgny; Kristoffersen, Doris Tove; Hamilton, Glenys A.; Olsen, Dag Rune

2005-01-01

Purpose: The aim of this study was to investigate the image quality preferences among radiographers and radiologists. The radiographers' preferences are mainly related to technical parameters, whereas radiologists assess image quality based on diagnostic value. Methods: A conjoint analysis was undertaken to survey image quality preferences; the study included 37 respondents: 19 radiographers and 18 radiologists. Digital urograms were post-processed into 8 images with different properties of image quality for 3 different patients. The respondents were asked to rank the images according to their personally perceived subjective image quality. Results: Nearly half of the radiographers and radiologists were consistent in their ranking of the image characterised as 'very best image quality'. The analysis showed, moreover, that chosen filtration level and image intensity were responsible for 72% and 28% of the preferences, respectively. The corresponding figures for each of the two professions were 76% and 24% for the radiographers, and 68% and 32% for the radiologists. In addition, there were larger variations in image preferences among the radiologists, as compared to the radiographers. Conclusions: Radiographers revealed a more consistent preference than the radiologists with respect to image quality. There is a potential for image quality improvement by developing sets of image property criteria

Noise Estimation and Quality Assessment of Gaussian Noise Corrupted Images

Science.gov (United States)

Kamble, V. M.; Bhurchandi, K.

2018-03-01

Evaluating the exact quantity of noise present in an image and quality of an image in the absence of reference image is a challenging task. We propose a near perfect noise estimation method and a no reference image quality assessment method for images corrupted by Gaussian noise. The proposed methods obtain initial estimate of noise standard deviation present in an image using the median of wavelet transform coefficients and then obtains a near to exact estimate using curve fitting. The proposed noise estimation method provides the estimate of noise within average error of +/-4%. For quality assessment, this noise estimate is mapped to fit the Differential Mean Opinion Score (DMOS) using a nonlinear function. The proposed methods require minimum training and yields the noise estimate and image quality score. Images from Laboratory for image and Video Processing (LIVE) database and Computational Perception and Image Quality (CSIQ) database are used for validation of the proposed quality assessment method. Experimental results show that the performance of proposed quality assessment method is at par with the existing no reference image quality assessment metric for Gaussian noise corrupted images.

Quality assurance in diagnostic radiology - assessing the fluoroscopic image quality

International Nuclear Information System (INIS)

Tabakov, S.

1995-01-01

The X-ray fluoroscopic image has a considerably lower resolution than the radiographic one. This requires a careful quality control aiming at optimal use of the fluoroscopic equipment. The basic procedures for image quality assessment of Image Intensifier/TV image are described. Test objects from Leeds University (UK) are used as prototypes. The results from examining 50 various fluoroscopic devices are shown. Their limiting spatial resolution varies between 0.8 lp/mm (at maximum II field size) and 2.24 lp/mm (at minimum field size). The mean value of the limiting spatial resolution for a 23 cm Image Intensifier is about 1.24 lp/mm. The mean limits of variation of the contrast/detail diagram for various fluoroscopic equipment are graphically expressed. 14 refs., 1 fig. (author)

Image Quality Assessment of High-Resolution Satellite Images with Mtf-Based Fuzzy Comprehensive Evaluation Method

Science.gov (United States)

Wu, Z.; Luo, Z.; Zhang, Y.; Guo, F.; He, L.

2018-04-01

A Modulation Transfer Function (MTF)-based fuzzy comprehensive evaluation method was proposed in this paper for the purpose of evaluating high-resolution satellite image quality. To establish the factor set, two MTF features and seven radiant features were extracted from the knife-edge region of image patch, which included Nyquist, MTF0.5, entropy, peak signal to noise ratio (PSNR), average difference, edge intensity, average gradient, contrast and ground spatial distance (GSD). After analyzing the statistical distribution of above features, a fuzzy evaluation threshold table and fuzzy evaluation membership functions was established. The experiments for comprehensive quality assessment of different natural and artificial objects was done with GF2 image patches. The results showed that the calibration field image has the highest quality scores. The water image has closest image quality to the calibration field, quality of building image is a little poor than water image, but much higher than farmland image. In order to test the influence of different features on quality evaluation, the experiment with different weights were tested on GF2 and SPOT7 images. The results showed that different weights correspond different evaluating effectiveness. In the case of setting up the weights of edge features and GSD, the image quality of GF2 is better than SPOT7. However, when setting MTF and PSNR as main factor, the image quality of SPOT7 is better than GF2.

Quality assurance for electronic portal imaging devices

International Nuclear Information System (INIS)

Shalev, S.; Rajapakshe, R.; Gluhchev, G.; Luchka, K.

1997-01-01

Electronic portal imaging devices (EPIDS) are assuming an ever-increasing role in the verification of radiation treatment accuracy. They are used both in a passive capacity, for the determination of field displacement distributions (''setup errors''), and also in an active role whereby the patient setup is corrected on the basis of electronic portal images. In spite of their potential impact on the precision of patient treatment, there are few quality assurance procedures available, and most of the EPIDS in clinical use are subject, at best, to only perfunctory quality assurance. The goals of this work are (a) to develop an objective and reproducible test for EPID image quality on the factory floor and during installation of the EPID on site; (b) to provide the user with a simple and accurate tool for acceptance, commissioning, and routine quality control; and (c) to initiate regional, national and international collaboration in the implementation of standardized, objective, and automated quality assurance procedures. To this end we have developed an automated test in which a simple test object is imaged daily, and the spatial and contrast resolution of the EPID are automatically evaluated in terms of ''acceptable'', ''warning'' and ''stop'' criteria. Our experience over two years shows the test to be highly sensitive, reproducible, and inexpensive in time and effort. Inter-institutional trials are under way in Canada, US and Europe which indicate large variations in EPID image quality from one EPID to another, and from one center to another. We expect the new standardized quality assurance procedure to lead to improved, and consistent image quality, increased operator acceptance of the technology, and agreement on uniform standards by equipment suppliers and health care agencies. (author)

Psychophysical evaluation of image quality : from judgment to impression

NARCIS (Netherlands)

Ridder, de H.; Rogowitz, B.E.; Pappas, T.N.

1998-01-01

Designs of imaging systems, image processing algorithms etc. usually take for granted that methods for assessing perceived image quality produce unbiased estimates of the viewers' quality impression. Quality judgments, however, are affected by the judgment strategies induced by the experimental

Image quality of digital mammography images produced using wet and dry laser imaging systems

International Nuclear Information System (INIS)

Al Khalifah, K.; Brindhaban, A.; AlArfaj, R.; Jassim, O.

2006-01-01

Introduction: A study was carried out to compare the quality of digital mammographic images printed or processed by a wet laser imaging system and a dedicated mammographic dry laser imaging system. Material and methods: Digital images of a tissue equivalent breast phantom were obtained using a GE Senographe 2000D digital mammography system and different target/filter combinations of the X-ray tube. These images were printed on films using the Fuji FL-IM D wet laser imaging system and the Kodak DryView 8600 dry laser imaging system. The quality of images was assessed in terms of detectability of microcalcifications and simulated tumour masses by five radiologists. In addition, the contrast index and speed index of the two systems were measured using the step wedge in the phantom. The unpaired, unequal variance t-test was used to test any statistically significant differences. Results: There were no significant (p < 0.05) differences between the images printed using the two systems in terms of microcalcification and tumour mass detectability. The wet system resulted in slightly higher contrast index while the dry system showed significantly higher speed index. Conclusion: Both wet and dry laser imaging systems can produce mammography images of good quality on which 0.2 mm microcalcifications and 2 mm tumour masses can be detected. Dry systems are preferable due to the absence of wet chemical processing and solid or liquid chemical waste. The wet laser imaging systems, however, still represent a useful alternative to dry laser imaging systems for mammography studies

The Image Quality of a Digital Chest X-Ray Radiography System: Comparison of Quantitative Image Quality Analysis and Radiologists' Visual Scoring

Energy Technology Data Exchange (ETDEWEB)

Nam, Ji Ho [Dept. of Radiology Oncology, Yongsan Hospital, Pusan National University College of Medicine, Yongsan (Korea, Republic of); Chung, Myung Jin [Dept. of Radiology, Samsung Medical Center, Seoul (Korea, Republic of); Park, Darl; Kim, Won Taek; Kim, Yong Ho; Ki, Yong Kan; Kim, DFong Hyun; Lee, Ju Hee; Kim, Dong Won [Dept. of Radiology Oncology, Yongsan Hospital, Pusan National University College of Medicine, Yongsan (Korea, Republic of); Jeon, Ho Sang [Reserach Institue for Convergence of Biomedical Science and Technology, Yongsan Hospital, Pusan National University College of Medicine, Yongsan (Korea, Republic of)

2011-11-15

To evaluate the performance of imaging devices, which should be periodically monitored to maintain high quality images to the radiologists. Additionally, this evaluation may prevent patients from radiation over-exposure. The most suitable engineering standard for imaging performance evaluation of digital X-ray thoracic images was determined. IEC 62220-1 standards were used to evaluate the performance of the images. In succession, the visibilities of overall image, pneumothorax, and humerus head in anthropomorphic thoracic phantom images were used to evaluate the image qualities by radiologists. The rank correlation coefficient (p) of visual scoring by radiologists with system spatial resolution is not meaningful (p-value, p = 0.295), but is significant with image noise (p-value, p -0.9267). Finally, the noise equivalent quanta (NEQ) presents a high rank correlation for visual scoring of radiologists (p-value, p = 0.9320). Image quality evaluation of radiologists were mainly affected by imaging noise. Hence, the engineered standard for evaluating image noise is the most important index to effectively monitor the performance of X-ray images. Additionally, the NEQ can be used to evaluate the performance of radiographic systems, because it theoretically corresponds to the synthetic image quality of systems.

Image quality transfer and applications in diffusion MRI

DEFF Research Database (Denmark)

Alexander, Daniel C.; Zikic, Darko; Ghosh, Aurobrata

2017-01-01

This paper introduces a new computational imaging technique called image quality transfer (IQT). IQT uses machine learning to transfer the rich information available from one-off experimental medical imaging devices to the abundant but lower-quality data from routine acquisitions. The procedure u...

MYTHS vesus reality in computed radiography image quality

International Nuclear Information System (INIS)

Mango, Steve; Castro, Luiz

2009-01-01

As NDE operation - particularly radiographic testing - ransition form analog to digital technologies such as computed radiography (CR), users are learning that there's more to digital image quality than meets the eye. In fact, there are ultiple factors that determine the final perceived image quality of a computed radiograph. Many of these factors are misunderstood, and some are touted as the ''key parameter'' or ''magic bullet'' in producing optiumum image quality, In reality, such claims are oversimplified, and are more marketing hype than reality. The truth?. Perceived image quality results form the cascaded effects of many factor - such as sharpness, system noise, spot size and pixel size, subject contrast, bit depth, radiographic technique, and so on. Many of these factors are within the control of rdiographers or designers of equipment and media. This paper will explain some of these key factors, dispel some of the myths surrounding them, and will show that qualities such as bigger, smaller, more, or less are not always better when it comes to CR image quality. (authors)

Evaluation of image quality of lumbar spine images: A comparison between FFE and VGA

International Nuclear Information System (INIS)

Tingberg, A.; Baath, M.; Haakansson, M.; Medin, J.; Besjakov, J.; Sandborg, M.; Alm-Carlsson, G.; Mattsson, S.; Maansson, L. G.

2005-01-01

Purpose: The aim of the present study is to compare two different methods for evaluation of the quality of clinical X-ray images. Methods: Based on fifteen lumbar spine radiographs, two new sets of images were created. A hybrid image set was created by adding two distributions of artificial lesions to each original image. The image quality parameters spatial resolution and noise were manipulated and a total of 210 hybrid images were created. A set of 105 disease-free images was created by applying the same combinations of spatial resolution and noise to the original images. The hybrid images were evaluated with the free-response forced error experiment (FFE) and the normal images with visual grading analysis (VGA) by nine experienced radiologists. Results: In the VGA study, images with low noise were preferred over images with higher noise levels. The alteration of the MTF had a limited influence on the VGA score. For the FFE study, the visibility of the lesions was independent of the sharpness and the noise level. No correlation was found between the two image quality measures. Conclusions: FFE is a precise method for evaluation of image quality, but the results are only valid for the type of lesion used in the study, whereas VGA is a more general method for clinical image quality assessment. The results of the FFE study indicate that there might be a potential to lower the dose levels in lumbar spine radiography without losing important diagnostic information. (authors)

Producing quality radiographic images

International Nuclear Information System (INIS)

Cullinan, A.M.

1987-01-01

This book gives an overview of physics, equipment, imaging, and quality assurance in the radiology department. The chapters are laid out with generous use of subheads to allow for quick reference, Points are illustrated with clear, uncluttered line diagrams and well-produced images. The accompanying explanations are miniature lessons by themselves. Inserted at various points throughout the text are important notes that highlight key concepts. The chapter ''Image Evaluation and Application of Radiographic Principles'' present a systematic approach to evaluating radiographs and contains several sample radiographs to illustrate the points made

Quality measures in applications of image restoration.

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Kriete, A; Naim, M; Schafer, L

2001-01-01

We describe a new method for the estimation of image quality in image restoration applications. We demonstrate this technique on a simulated data set of fluorescent beads, in comparison with restoration by three different deconvolution methods. Both the number of iterations and a regularisation factor are varied to enforce changes in the resulting image quality. First, the data sets are directly compared by an accuracy measure. These values serve to validate the image quality descriptor, which is developed on the basis of optical information theory. This most general measure takes into account the spectral energies and the noise, weighted in a logarithmic fashion. It is demonstrated that this method is particularly helpful as a user-oriented method to control the output of iterative image restorations and to eliminate the guesswork in choosing a suitable number of iterations.

Exploratory survey of image quality on CR digital mammography imaging systems in Mexico

International Nuclear Information System (INIS)

Gaona, E.; Rivera, T.; Arreola, M.; Franco, J.; Molina, N.; Alvarez, B.; Azorín, C.G.; Casian, G.

2014-01-01

The purpose of this study was to assess the current status of image quality and dose in computed radiographic digital mammography (CRDM) systems. Studies included CRDM systems of various models and manufacturers which dose and image quality comparisons were performed. Due to the recent rise in the use of digital radiographic systems in Mexico, CRDM systems are rapidly replacing conventional film-screen systems without any regard to quality control or image quality standards. Study was conducted in 65 mammography facilities which use CRDM systems in the Mexico City and surrounding States. The systems were tested as used clinically. This means that the dose and beam qualities were selected using the automatic beam selection and photo-timed features. All systems surveyed generate laser film hardcopies for the radiologist to read on a scope or mammographic high luminance light box. It was found that 51 of CRDM systems presented a variety of image artefacts and non-uniformities arising from inadequate acquisition and processing, as well as from the laser printer itself. Undisciplined alteration of image processing settings by the technologist was found to be a serious prevalent problem in 42 facilities. Only four of them showed an image QC program which is periodically monitored by a medical physicist. The Average Glandular Dose (AGD) in the surveyed systems was estimated to have a mean value of 2.4 mGy. To improve image quality in mammography and make more efficient screening mammographic in early detection of breast cancer is required new legislation. - Highlights: • Radiation dose in CR digital mammography (CRDM) systems was determined. • Image quality related with dose in CR digital mammography (CRDM) systems was analysed. • Image processing artefacts were observed and correlated with dose. • Measured entrance dose by TL phosphors could be good parameter for radiation protection optimization in patient

Effects on MR images compression in tissue classification quality

International Nuclear Information System (INIS)

Santalla, H; Meschino, G; Ballarin, V

2007-01-01

It is known that image compression is required to optimize the storage in memory. Moreover, transmission speed can be significantly improved. Lossless compression is used without controversy in medicine, though benefits are limited. If we compress images lossy, where image can not be totally recovered; we can only recover an approximation. In this point definition of 'quality' is essential. What we understand for 'quality'? How can we evaluate a compressed image? Quality in images is an attribute whit several definitions and interpretations, which actually depend on the posterior use we want to give them. This work proposes a quantitative analysis of quality for lossy compressed Magnetic Resonance (MR) images, and their influence in automatic tissue classification, accomplished with these images

Image quality of cone beam CT on respiratory motion

International Nuclear Information System (INIS)

Zhang Ke; Li Minghui; Dai Jianrong; Wang Shi

2011-01-01

In this study,the influence of respiratory motion on Cone Beam CT (CBCT) image quality was investigated by a motion simulating platform, an image quality phantom, and a kV X-ray CBCT. A total of 21 motion states in the superior-inferior direction and the anterior-posterior direction, separately or together, was simulated by considering different respiration amplitudes, periods and hysteresis. The influence of motion on CBCT image quality was evaluated with the quality indexes of low contrast visibility, geometric accuracy, spatial resolution and uniformity of CT values. The results showed that the quality indexes were affected by the motion more prominently in AP direction than in SI direction, and the image quality was affected by the respiration amplitude more prominently than the respiration period and the hysteresis. The CBCT image quality and its characteristics influenced by the respiration motion, and may be exploited in finding solutions. (authors)

Mathematical determination of image quality

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Barrett, H H

1982-01-01

The subjective term ''image quality'' is generally not easy to define and to measure. If, however, we limit ourselves, to determine certain anomalies in blurred images, then the task can be done more easily. The efficiency can in fact be measured and the results can be presented as ROC-characteristics (receiver operating characteristics). One can determine a relation between the characteristic and the noise distance of the imaging system, and this way the efficiency of an hypothetical ideal observer can be predicted. Furthermore one can compute noise distance and other statistical parameters of X-ray images distorted by quantum interference by special techniques that are founded on the so-called ''blur core''. The technique proved to be very successful in nuclear medicine, but is also valid in computerized tomography and X-ray diagnostics. The technique is explained without mathematical details. The question will be answered concerning the role mathematical analysis will play in the determination and optimization of the quality of diagnostic exposures.

Practical evaluation of clinical image quality (4). Determination of image quality in digital radiography system

International Nuclear Information System (INIS)

Katayama, Reiji

2016-01-01

Recently, for medical imaging, digital radiography systems are widely used in clinical practices. However, a study in the past reported that a patient radiation exposure level by digital radiography is in fact not lower than that by analog radiography system. High level of attention needs to be paid for over-exposure when using the conventional analog radiography with a screen and a film, as it results in high density of the film. However, for digital radiography systems, since the automatic adjusting function of image density is equipped with them, no attention for radiation dose need to be paid. Thus technologists tend to be careless and results in higher chance for over-exposure. Current digital radiography systems are high-performance in the image properties and capable of patient dose reduction. Especially, the image quality of the flat panel detector system is recognized, higher than that of the computed radiography system by imaging plates, in both objective and subjective evaluations. Therefore, we technologists are responsible for optimizing the balance between the image quality of the digital radiogram and the radiation dose required for each case. Moreover, it is also required for us as medical technologists to make effective use of such evaluation result of medical images for patients. (author)

The microcirculation image quality score: development and preliminary evaluation of a proposed approach to grading quality of image acquisition for bedside videomicroscopy.

Science.gov (United States)

Massey, Michael J; Larochelle, Ethan; Najarro, Gabriel; Karmacharla, Adarsh; Arnold, Ryan; Trzeciak, Stephen; Angus, Derek C; Shapiro, Nathan I

2013-12-01

Side-stream dark-field microscopy is currently used to directly visualize sublingual microcirculation at the bedside. Our experience has found inherent technical challenges in the image acquisition process. This article presents and assesses a quality assurance method to rate image acquisition quality before analysis. We identified 6 common image capture and analysis problem areas in sublingual side-stream dark-field videos: illumination, duration, focus, content, stability, and pressure. We created the "Microcirculation Image Quality Score" by assigning a score of optimal (0 points), suboptimal but acceptable (1 point), or unacceptable (10 points) to each category (for further details, go to http://www.MicroscanAnalysis.blogspot.com). We evaluated 59 videos from a convenience sample of 34 unselected, noncritically ill emergency department patients to create a test set. Two raters, blinded to each other, implemented the score. Any video with a cumulative score of 10 or higher (range, 0-60) was considered unacceptable for further analysis. We created the Microcirculation Image Quality Score and applied it to 59 videos. For this particular set of 59 videos, the mean (SD) passing quality score was 1.68 (0.90), and the mean (SD) failing quality score was 15.74 (6.19), with 27 of 59 passing the quality score less than 10. Highest failure occurred from pressure artifact. The interrater agreement for acceptability was assessed using Cohen κ for each category: illumination (κ = 1.0), duration (κ = 1.0), focus (κ = 0.91), content (κ = 0.76), stability (κ = 0.71), and pressure (κ = 0.82) and overall pass-fail rates (score >10) (κ = 0.66). Our Microcirculation Image Quality Score addresses many of the common areas where video quality can degrade. The criteria introduced are an objective way to assess the quality of image acquisition, with the goal of selecting videos of adequate quality for analysis. The interrater reliability results in our preliminary study suggest

Cross-layer Energy Optimization Under Image Quality Constraints for Wireless Image Transmissions.

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Yang, Na; Demirkol, Ilker; Heinzelman, Wendi

2012-01-01

Wireless image transmission is critical in many applications, such as surveillance and environment monitoring. In order to make the best use of the limited energy of the battery-operated cameras, while satisfying the application-level image quality constraints, cross-layer design is critical. In this paper, we develop an image transmission model that allows the application layer (e.g., the user) to specify an image quality constraint, and optimizes the lower layer parameters of transmit power and packet length, to minimize the energy dissipation in image transmission over a given distance. The effectiveness of this approach is evaluated by applying the proposed energy optimization to a reference ZigBee system and a WiFi system, and also by comparing to an energy optimization study that does not consider any image quality constraint. Evaluations show that our scheme outperforms the default settings of the investigated commercial devices and saves a significant amount of energy at middle-to-large transmission distances.

Effect of quality control implementation on image quality of radiographic films and irradiation doses to patients

International Nuclear Information System (INIS)

Cheng Yuxi; Zhou Qipu; Ge Lijuan; Hou Changsong; Qi Xuesong; Yue Baorong; Wang Zuoling; Wei Kedao

1999-01-01

Objective: To study the changes in the image quality of radiographic films and the irradiation doses to patients after quality control (QC) implementation. Methods: The entrance surface doses (ESD) to patients measured with TLD and the image quality of radiographic films were evaluated on the basis of CEC image quality criteria. Results: The ESD to patients were significantly reduced after QC implementation (P 0.05), but the post-QC image quality was significantly improved in chest PA, lumbar spine AP and pelvis AP(P0.01 or P<0.05). Conclusion: Significantly reduced irradiation dose with improved image quality can be obtained by QC implementation

Toward optimal color image quality of television display

Science.gov (United States)

MacDonald, Lindsay W.; Endrikhovski, Sergej N.; Bech, Soren; Jensen, Kaj

1999-12-01

A general framework and first experimental results are presented for the `OPTimal IMage Appearance' (OPTIMA) project, which aims to develop a computational model for achieving optimal color appearance of natural images on adaptive CRT television displays. To achieve this goal we considered the perceptual constraints determining quality of displayed images and how they could be quantified. The practical value of the notion of optimal image appearance was translated from the high level of the perceptual constraints into a method for setting the display's parameters at the physical level. In general, the whole framework of quality determination includes: (1) evaluation of perceived quality; (2) evaluation of the individual perceptual attributes; and (3) correlation between the physical measurements, psychometric parameters and the subjective responses. We performed a series of psychophysical experiments, with observers viewing a series of color images on a high-end consumer television display, to investigate the relationships between Overall Image Quality and four quality-related attributes: Brightness Rendering, Chromatic Rendering, Visibility of Details and Overall Naturalness. The results of the experiments presented in this paper suggest that these attributes are highly inter-correlated.

Selecting optimal monochromatic level with spectral CT imaging for improving imaging quality in hepatic venography

International Nuclear Information System (INIS)

Sun Jun; Luo Xianfu; Wang Shou'an; Wang Jun; Sun Jiquan; Wang Zhijun; Wu Jingtao

2013-01-01

Objective: To investigate the effect of spectral CT monochromatic images for improving imaging quality in hepatic venography. Methods: Thirty patients underwent spectral CT examination on a GE Discovery CT 750 HD scanner. During portal phase, 1.25 mm slice thickness polychromatic images and optimal monochromatic images were obtained, and volume rendering and maximum intensity projection were created to show the hepatic veins respectively. The overall imaging quality was evaluated on a five-point scale by two radiologists. Inter-observer agreement in subjective image quality grading was assessed by Kappa statistics. Paired-sample t test were used to compare hepatic vein attenuation, hepatic parenchyma attenuation, CT value difference between the hepatic vein and the liver parenchyma, image noise, vein-to-liver contrast-to-noise ratio (CNR), the image quality score of hepatic venography between the two image data sets. Results: The monochromatic images at 50 keV were found to demonstrate the best CNR for hepatic vein.The hepatic vein attenuation [(329 ± 47) HU], hepatic parenchyma attenuation [(178 ± 33) HU], CT value difference between the hepatic vein and the liver parenchyma [(151 ± 33) HU], image noise (17.33 ± 4.18), CNR (9.13 ± 2.65), the image quality score (4.2 ± 0.6) of optimal monochromatic images were significantly higher than those of polychromatic images [(149 ± 18) HU], [(107 ± 14) HU], [(43 ±11) HU], 12.55 ± 3.02, 3.53 ± 1.03, 3.1 ± 0.8 (t values were 24.79, 13.95, 18.85, 9.07, 13.25 and 12.04, respectively, P < 0.01). In the comparison of image quality, Kappa value was 0.81 with optimal monochromatic images and 0.69 with polychromatic images. Conclusion: Monochromatic images of spectral CT could improve CNR for displaying hepatic vein and improve the image quality compared to the conventional polychromatic images. (authors)

Quality Improvement of Liver Ultrasound Images Using Fuzzy Techniques.

Science.gov (United States)

Bayani, Azadeh; Langarizadeh, Mostafa; Radmard, Amir Reza; Nejad, Ahmadreza Farzaneh

2016-12-01

Liver ultrasound images are so common and are applied so often to diagnose diffuse liver diseases like fatty liver. However, the low quality of such images makes it difficult to analyze them and diagnose diseases. The purpose of this study, therefore, is to improve the contrast and quality of liver ultrasound images. In this study, a number of image contrast enhancement algorithms which are based on fuzzy logic were applied to liver ultrasound images - in which the view of kidney is observable - using Matlab2013b to improve the image contrast and quality which has a fuzzy definition; just like image contrast improvement algorithms using a fuzzy intensification operator, contrast improvement algorithms applying fuzzy image histogram hyperbolization, and contrast improvement algorithms by fuzzy IF-THEN rules. With the measurement of Mean Squared Error and Peak Signal to Noise Ratio obtained from different images, fuzzy methods provided better results, and their implementation - compared with histogram equalization method - led both to the improvement of contrast and visual quality of images and to the improvement of liver segmentation algorithms results in images. Comparison of the four algorithms revealed the power of fuzzy logic in improving image contrast compared with traditional image processing algorithms. Moreover, contrast improvement algorithm based on a fuzzy intensification operator was selected as the strongest algorithm considering the measured indicators. This method can also be used in future studies on other ultrasound images for quality improvement and other image processing and analysis applications.

Da religião do sacrifício à religião da fraternidade =From the religion of sacrifice to the religion of fraternity

Directory of Open Access Journals (Sweden)

Susin, Luiz Carlos

2010-01-01

Full Text Available Há uma relação entre religião e violência que consiste basicamente em sacralização da violência através da sublimação da mesma como sacrifício. Ora, o sacrifício está no coração de toda religião, de forma descarada nas religiões arcaicas e de forma metamorfoseada e mascarada na evolução histórica da religião. A Escritura testemunha as ambiguidades do sacrifício e o choque profético entre o sacrifício e a misericórdia. O Cristianismo, em sua fonte, é a superação radical do sacrifício, mas, ao longo da história, novas metamorfoses do sacrifício surgem no Cristianismo. É a volta às fontes e a renovação de sua experiência na confraternização universal, testada pelos excluídos, que legitimam a originalidade do Cristianismo e um sentido realmente cristão para a palavra sacrifício. There is a relation between religion and violence that consists basically in making violence sacred through its sublimation as a sacrifice. Therefore, sacrifice is at the heart of all religion, in a blatant way in archaic religions and in a metamorphosed and masked way in the historical evolution of religion. The Scriptures witness the ambiguities of sacrifice and the prophetic shock between sacrifice and mercy. Christianity, in its origin, is the radical overcoming of sacrifice, but throughout history new ways sacrifice has metamorphosed appear in Christianity. It’s the return to the sources and the renewal of this experience in universal fellowship, tested by those excluded, who legitimate the uniqueness of Christianity and a true Christian meaning to the word sacrifice.

Quality evaluation of no-reference MR images using multidirectional filters and image statistics.

Science.gov (United States)

Jang, Jinseong; Bang, Kihun; Jang, Hanbyol; Hwang, Dosik

2018-09-01

This study aimed to develop a fully automatic, no-reference image-quality assessment (IQA) method for MR images. New quality-aware features were obtained by applying multidirectional filters to MR images and examining the feature statistics. A histogram of these features was then fitted to a generalized Gaussian distribution function for which the shape parameters yielded different values depending on the type of distortion in the MR image. Standard feature statistics were established through a training process based on high-quality MR images without distortion. Subsequently, the feature statistics of a test MR image were calculated and compared with the standards. The quality score was calculated as the difference between the shape parameters of the test image and the undistorted standard images. The proposed IQA method showed a >0.99 correlation with the conventional full-reference assessment methods; accordingly, this proposed method yielded the best performance among no-reference IQA methods for images containing six types of synthetic, MR-specific distortions. In addition, for authentically distorted images, the proposed method yielded the highest correlation with subjective assessments by human observers, thus demonstrating its superior performance over other no-reference IQAs. Our proposed IQA was designed to consider MR-specific features and outperformed other no-reference IQAs designed mainly for photographic images. Magn Reson Med 80:914-924, 2018. © 2018 International Society for Magnetic Resonance in Medicine. © 2018 International Society for Magnetic Resonance in Medicine.

Clinical image quality evaluation for panoramic radiography in Korean dental clinics

International Nuclear Information System (INIS)

Choi, Bo Ram; Choi, Da Hye; Huh, Kyung Hoe; Yi, Won Jin; Heo, Min Suk; Choi, Soon Chul; Bae, Kwang Hak; Lee, Sam Sun

2012-01-01

The purpose of this study was to investigate the level of clinical image quality of panoramic radiographs and to analyze the parameters that influence the overall image quality. Korean dental clinics were asked to provide three randomly selected panoramic radiographs. An oral and maxillofacial radiology specialist evaluated those images using our self-developed Clinical Image Quality Evaluation Chart. Three evaluators classified the overall image quality of the panoramic radiographs and evaluated the causes of imaging errors. A total of 297 panoramic radiographs were collected from 99 dental hospitals and clinics. The mean of the scores according to the Clinical Image Quality Evaluation Chart was 79.9. In the classification of the overall image quality, 17 images were deemed 'optimal for obtaining diagnostic information,' 153 were 'adequate for diagnosis,' 109 were 'poor but diagnosable,' and nine were 'unrecognizable and too poor for diagnosis'. The results of the analysis of the causes of the errors in all the images are as follows: 139 errors in the positioning, 135 in the processing, 50 from the radiographic unit, and 13 due to anatomic abnormality. Panoramic radiographs taken at local dental clinics generally have a normal or higher-level image quality. Principal factors affecting image quality were positioning of the patient and image density, sharpness, and contrast. Therefore, when images are taken, the patient position should be adjusted with great care. Also, standardizing objective criteria of image density, sharpness, and contrast is required to evaluate image quality effectively.

Quality assurance in digital dental imaging: a systematic review.

Science.gov (United States)

Metsälä, Eija; Henner, Anja; Ekholm, Marja

2014-07-01

Doses induced by individual dental examinations are low. However, dental radiography accounts for nearly one third of the total number of radiological examinations in the European Union. Therefore, special attention is needed with regard to radiation protection. In order to lower patient doses, the staff performing dental examinations must have competence in imaging as well as in radiation protection issues. This paper presents a systematic review about the core competencies needed by the healthcare staff in performing digital dental radiological imaging quality assurance. The following databases were searched: Pubmed, Cinahl, Pro Quest and IEEXplore digital library. Also volumes of some dental imaging journals and doctoral theses of the Finnish universities educating dentists were searched. The search was performed using both MeSH terms and keywords using the option 'search all text'. The original keywords were: dental imaging, digital, x-ray, panoramic, quality, assurance, competence, competency, skills, knowledge, radiographer, radiologist technician, dentist, oral hygienist, radiation protection and their Finnish synonyms. Core competencies needed by the healthcare staff performing digital dental radiological imaging quality assurance described in the selected studies were: management of dental imaging equipment, competence in image quality and factors associated with it, dose optimization and quality assurance. In the future there will be higher doses in dental imaging due to increasing use of CBCT and digital imaging. The staff performing dental imaging must have competence in dental imaging quality assurance issues found in this review. They also have to practice ethical radiation safety culture in clinical practice.

Dose and diagnostic image quality in digital tomosynthesis imaging of facial bones in pediatrics

Science.gov (United States)

King, J. M.; Hickling, S.; Elbakri, I. A.; Reed, M.; Wrogemann, J.

2011-03-01

The purpose of this study was to evaluate the use of digital tomosynthesis (DT) for pediatric facial bone imaging. We compared the eye lens dose and diagnostic image quality of DT facial bone exams relative to digital radiography (DR) and computed tomography (CT), and investigated whether we could modify our current DT imaging protocol to reduce patient dose while maintaining sufficient diagnostic image quality. We measured the dose to the eye lens for all three modalities using high-sensitivity thermoluminescent dosimeters (TLDs) and an anthropomorphic skull phantom. To assess the diagnostic image quality of DT compared to the corresponding DR and CT images, we performed an observer study where the visibility of anatomical structures in the DT phantom images were rated on a four-point scale. We then acquired DT images at lower doses and had radiologists indicate whether the visibility of each structure was adequate for diagnostic purposes. For typical facial bone exams, we measured eye lens doses of 0.1-0.4 mGy for DR, 0.3-3.7 mGy for DT, and 26 mGy for CT. In general, facial bone structures were visualized better with DT then DR, and the majority of structures were visualized well enough to avoid the need for CT. DT imaging provides high quality diagnostic images of the facial bones while delivering significantly lower doses to the lens of the eye compared to CT. In addition, we found that by adjusting the imaging parameters, the DT effective dose can be reduced by up to 50% while maintaining sufficient image quality.

Imaging quality evaluation method of pixel coupled electro-optical imaging system

Science.gov (United States)

He, Xu; Yuan, Li; Jin, Chunqi; Zhang, Xiaohui

2017-09-01

With advancements in high-resolution imaging optical fiber bundle fabrication technology, traditional photoelectric imaging system have become ;flexible; with greatly reduced volume and weight. However, traditional image quality evaluation models are limited by the coupling discrete sampling effect of fiber-optic image bundles and charge-coupled device (CCD) pixels. This limitation substantially complicates the design, optimization, assembly, and evaluation image quality of the coupled discrete sampling imaging system. Based on the transfer process of grayscale cosine distribution optical signal in the fiber-optic image bundle and CCD, a mathematical model of coupled modulation transfer function (coupled-MTF) is established. This model can be used as a basis for following studies on the convergence and periodically oscillating characteristics of the function. We also propose the concept of the average coupled-MTF, which is consistent with the definition of traditional MTF. Based on this concept, the relationships among core distance, core layer radius, and average coupled-MTF are investigated.

Medical Imaging Image Quality Assessment with Monte Carlo Methods

International Nuclear Information System (INIS)

Michail, C M; Fountos, G P; Kalyvas, N I; Valais, I G; Kandarakis, I S; Karpetas, G E; Martini, Niki; Koukou, Vaia

2015-01-01

The aim of the present study was to assess image quality of PET scanners through a thin layer chromatography (TLC) plane source. The source was simulated using a previously validated Monte Carlo model. The model was developed by using the GATE MC package and reconstructed images obtained with the STIR software for tomographic image reconstruction, with cluster computing. The PET scanner simulated in this study was the GE DiscoveryST. A plane source consisted of a TLC plate, was simulated by a layer of silica gel on aluminum (Al) foil substrates, immersed in 18F-FDG bath solution (1MBq). Image quality was assessed in terms of the Modulation Transfer Function (MTF). MTF curves were estimated from transverse reconstructed images of the plane source. Images were reconstructed by the maximum likelihood estimation (MLE)-OSMAPOSL algorithm. OSMAPOSL reconstruction was assessed by using various subsets (3 to 21) and iterations (1 to 20), as well as by using various beta (hyper) parameter values. MTF values were found to increase up to the 12th iteration whereas remain almost constant thereafter. MTF improves by using lower beta values. The simulated PET evaluation method based on the TLC plane source can be also useful in research for the further development of PET and SPECT scanners though GATE simulations. (paper)

Quantifying the impact of respiratory-gated 4D CT acquisition on thoracic image quality: A digital phantom study

International Nuclear Information System (INIS)

Bernatowicz, K.; Knopf, A.; Lomax, A.; Keall, P.; Kipritidis, J.; Mishra, P.

2015-01-01

across all simulations and phase bins, respiratory-gating reduced overall thoracic MSE by 46% compared to conventional 4D CT (p ∼ 10 −19 ). Gating leads to small but significant (p < 0.02) reductions in lung volume errors (1.8%–1.4%), false positives (4.0%–2.6%), and false negatives (2.7%–1.3%). These percentage reductions correspond to gating reducing image artifacts by 24–90 cm 3 of lung tissue. Similar to earlier studies, gating reduced patient image dose by up to 22%, but with scan time increased by up to 135%. Beam paused 4D CT did not significantly impact normal lung tissue image quality, but did yield similar dose reductions as for respiratory-gating, without the added cost in scanning time. Conclusions: For a typical 6 L lung, respiratory-gated 4D CT can reduce image artifacts affecting up to 90 cm 3 of normal lung tissue compared to conventional acquisition. This image improvement could have important implications for dose calculations based on 4D CT. Where image quality is less critical, beam paused 4D CT is a simple strategy to reduce imaging dose without sacrificing acquisition time

Quantifying the impact of respiratory-gated 4D CT acquisition on thoracic image quality: A digital phantom study

Energy Technology Data Exchange (ETDEWEB)

Bernatowicz, K., E-mail: kingab@student.ethz.ch; Knopf, A.; Lomax, A. [Center for Proton Therapy, Paul Scherrer Institute, Villigen PSI 5232, Switzerland and Department of Physics, ETH Zürich, Zürich 8092 (Switzerland); Keall, P.; Kipritidis, J., E-mail: john.kipritidis@sydney.edu.au [Radiation Physics Laboratory, Sydney Medical School, University of Sydney, Sydney, NSW 2006 (Australia); Mishra, P. [Brigham and Womens Hospital, Dana-Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts 02115 (United States)

2015-01-15

: Averaged across all simulations and phase bins, respiratory-gating reduced overall thoracic MSE by 46% compared to conventional 4D CT (p ∼ 10{sup −19}). Gating leads to small but significant (p < 0.02) reductions in lung volume errors (1.8%–1.4%), false positives (4.0%–2.6%), and false negatives (2.7%–1.3%). These percentage reductions correspond to gating reducing image artifacts by 24–90 cm{sup 3} of lung tissue. Similar to earlier studies, gating reduced patient image dose by up to 22%, but with scan time increased by up to 135%. Beam paused 4D CT did not significantly impact normal lung tissue image quality, but did yield similar dose reductions as for respiratory-gating, without the added cost in scanning time. Conclusions: For a typical 6 L lung, respiratory-gated 4D CT can reduce image artifacts affecting up to 90 cm{sup 3} of normal lung tissue compared to conventional acquisition. This image improvement could have important implications for dose calculations based on 4D CT. Where image quality is less critical, beam paused 4D CT is a simple strategy to reduce imaging dose without sacrificing acquisition time.

The art of assessing quality for images and video

International Nuclear Information System (INIS)

Deriche, M.

2011-01-01

The early years of this century have witnessed a tremendous growth in the use of digital multimedia data for di?erent communication applications. Researchers from around the world are spending substantial research efforts in developing techniques for improving the appearance of images/video. However, as we know, preserving high quality is a challenging task. Images are subject to distortions during acquisition, compression, transmission, analysis, and reconstruction. For this reason, the research area focusing on image and video quality assessment has attracted a lot of attention in recent years. In particular, compression applications and other multimedia applications need powerful techniques for evaluating quality objectively without human interference. This tutorial will cover the di?erent faces of image quality assessment. We will motivate the need for robust image quality assessment techniques, then discuss the main algorithms found in the literature with a critical perspective. We will present the di?erent metrics used for full reference, reduced reference and no reference applications. We will then discuss the difference between image and video quality assessment. In all of the above, we will take a critical approach to explain which metric can be used for which application. Finally we will discuss the different approaches to analyze the performance of image/video quality metrics, and end the tutorial with some perspectives on newly introduced metrics and their potential applications.

Image quality in digital radiography

International Nuclear Information System (INIS)

Kuhn, H.

1986-01-01

The contribution deals with the potentials of digital radiography and critically evaluates the advantages of drawbacks of the image intensifier-tv-digital system; digitalisation of the X-ray film and scanning of luminescent storage foils. The evaluation is done in comparison with the image quality of the traditional, large-size X-ray picture. (orig.) [de

Dual-source CT coronary imaging in heart transplant recipients: image quality and optimal reconstruction interval

International Nuclear Information System (INIS)

Bastarrika, Gorka; Arraiza, Maria; Pueyo, Jesus C.; Cecco, Carlo N. de; Ubilla, Matias; Mastrobuoni, Stefano; Rabago, Gregorio

2008-01-01

The image quality and optimal reconstruction interval for coronary arteries in heart transplant recipients undergoing non-invasive dual-source computed tomography (DSCT) coronary angiography was evaluated. Twenty consecutive heart transplant recipients who underwent DSCT coronary angiography were included (19 male, one female; mean age 63.1±10.7 years). Data sets were reconstructed in 5% steps from 30% to 80% of the R-R interval. Two blinded independent observers assessed the image quality of each coronary segments using a five-point scale (from 0 = not evaluative to 4=excellent quality). A total of 289 coronary segments in 20 heart transplant recipients were evaluated. Mean heart rate during the scan was 89.1±10.4 bpm. At the best reconstruction interval, diagnostic image quality (score ≥2) was obtained in 93.4% of the coronary segments (270/289) with a mean image quality score of 3.04± 0.63. Systolic reconstruction intervals provided better image quality scores than diastolic reconstruction intervals (overall mean quality scores obtained with the systolic and diastolic reconstructions 3.03±1.06 and 2.73±1.11, respectively; P<0.001). Different systolic reconstruction intervals (35%, 40%, 45% of RR interval) did not yield to significant differences in image quality scores for the coronary segments (P=0.74). Reconstructions obtained at the systolic phase of the cardiac cycle allowed excellent diagnostic image quality coronary angiograms in heart transplant recipients undergoing DSCT coronary angiography. (orig.)

Contrast-enhanced magnetic resonance angiography in carotid artery disease: does automated image registration improve image quality?

International Nuclear Information System (INIS)

Menke, Jan; Larsen, Joerg

2009-01-01

Contrast-enhanced magnetic resonance angiography (MRA) is a noninvasive imaging alternative to digital subtraction angiography (DSA) for patients with carotid artery disease. In DSA, image quality can be improved by shifting the mask image if the patient has moved during angiography. This study investigated whether such image registration may also help to improve the image quality of carotid MRA. Data from 370 carotid MRA examinations of patients likely to have carotid artery disease were prospectively collected. The standard nonregistered MRAs were compared to automatically linear, affine and warp registered MRA by using three image quality parameters: the vessel detection probability (VDP) in maximum intensity projection (MIP) images, contrast-to-noise ratio (CNR) in MIP images, and contrast-to-noise ratio in three-dimensional image volumes. A body shift of less than 1 mm occurred in 96.2% of cases. Analysis of variance revealed no significant influence of image registration and body shift on image quality (p > 0.05). In conclusion, standard contrast-enhanced carotid MRA usually requires no image registration to improve image quality and is generally robust against any naturally occurring body shift. (orig.)

Readout-Segmented Echo-Planar Imaging in Diffusion-Weighted MR Imaging in Breast Cancer: Comparison with Single-Shot Echo-Planar Imaging in Image Quality

International Nuclear Information System (INIS)

Kim, Yun Ju; Kim, Sung Hun; Kang, Bong Joo; Park, Chang Suk; Kim, Hyeon Sook; Son, Yo Han; Porter, David Andrew; Song, Byung Joo

2014-01-01

The purpose of this study was to compare the image quality of standard single-shot echo-planar imaging (ss-EPI) and that of readout-segmented EPI (rs-EPI) in patients with breast cancer. Seventy-one patients with 74 breast cancers underwent both ss-EPI and rs-EPI. For qualitative comparison of image quality, three readers independently assessed the two sets of diffusion-weighted (DW) images. To evaluate geometric distortion, a comparison was made between lesion lengths derived from contrast enhanced MR (CE-MR) images and those obtained from the corresponding DW images. For assessment of image parameters, signal-to-noise ratio (SNR), lesion contrast, and contrast-to-noise ratio (CNR) were calculated. The rs-EPI was superior to ss-EPI in most criteria regarding the qualitative image quality. Anatomical structure distinction, delineation of the lesion, ghosting artifact, and overall image quality were significantly better in rs-EPI. Regarding the geometric distortion, lesion length on ss-EPI was significantly different from that of CE-MR, whereas there were no significant differences between CE-MR and rs-EPI. The rs-EPI was superior to ss-EPI in SNR and CNR. Readout-segmented EPI is superior to ss-EPI in the aspect of image quality in DW MR imaging of the breast

Deep supervised dictionary learning for no-reference image quality assessment

Science.gov (United States)

Huang, Yuge; Liu, Xuesong; Tian, Xiang; Zhou, Fan; Chen, Yaowu; Jiang, Rongxin

2018-03-01

We propose a deep convolutional neural network (CNN) for general no-reference image quality assessment (NR-IQA), i.e., accurate prediction of image quality without a reference image. The proposed model consists of three components such as a local feature extractor that is a fully CNN, an encoding module with an inherent dictionary that aggregates local features to output a fixed-length global quality-aware image representation, and a regression module that maps the representation to an image quality score. Our model can be trained in an end-to-end manner, and all of the parameters, including the weights of the convolutional layers, the dictionary, and the regression weights, are simultaneously learned from the loss function. In addition, the model can predict quality scores for input images of arbitrary sizes in a single step. We tested our method on commonly used image quality databases and showed that its performance is comparable with that of state-of-the-art general-purpose NR-IQA algorithms.

Clinical image quality evaluation for panoramic radiography in Korean dental clinics

Energy Technology Data Exchange (ETDEWEB)

Choi, Bo Ram; Choi, Da Hye; Huh, Kyung Hoe; Yi, Won Jin; Heo, Min Suk; Choi, Soon Chul; Bae, Kwang Hak; Lee, Sam Sun [School of Dentistry, Seoul National University, Seoul (Korea, Republic of)

2012-09-15

The purpose of this study was to investigate the level of clinical image quality of panoramic radiographs and to analyze the parameters that influence the overall image quality. Korean dental clinics were asked to provide three randomly selected panoramic radiographs. An oral and maxillofacial radiology specialist evaluated those images using our self-developed Clinical Image Quality Evaluation Chart. Three evaluators classified the overall image quality of the panoramic radiographs and evaluated the causes of imaging errors. A total of 297 panoramic radiographs were collected from 99 dental hospitals and clinics. The mean of the scores according to the Clinical Image Quality Evaluation Chart was 79.9. In the classification of the overall image quality, 17 images were deemed 'optimal for obtaining diagnostic information,' 153 were 'adequate for diagnosis,' 109 were 'poor but diagnosable,' and nine were 'unrecognizable and too poor for diagnosis'. The results of the analysis of the causes of the errors in all the images are as follows: 139 errors in the positioning, 135 in the processing, 50 from the radiographic unit, and 13 due to anatomic abnormality. Panoramic radiographs taken at local dental clinics generally have a normal or higher-level image quality. Principal factors affecting image quality were positioning of the patient and image density, sharpness, and contrast. Therefore, when images are taken, the patient position should be adjusted with great care. Also, standardizing objective criteria of image density, sharpness, and contrast is required to evaluate image quality effectively.

The Image Quality Translator – A Way to Support Specification of Imaging Requirements

DEFF Research Database (Denmark)

Kejser, Ulla Bøgvad; Bech, Mogens

2015-01-01

Archives, libraries, and museums run numerous imaging projects to digitize physical works and collections of cultural heritage. This study presents a tool called the 'Image Quality Translator' that is being designed at the Royal Library to support the planning of digitization projects and to make...... the process of specifying and controlling imaging requirements more efficient. The tool seeks to translate between the language used by collection managers and curators to express needs for image quality, and the more technical terms and metrics used by imaging experts and photographers to express...

Image quality assessment for CT used on small animals

Energy Technology Data Exchange (ETDEWEB)

Cisneros, Isabela Paredes, E-mail: iparedesc@unal.edu.co; Agulles-Pedrós, Luis, E-mail: lagullesp@unal.edu.co [Universidad Nacional de Colombia, Departamento de Física, Grupo de Física Médica (Colombia)

2016-07-07

Image acquisition on a CT scanner is nowadays necessary in almost any kind of medical study. Its purpose, to produce anatomical images with the best achievable quality, implies the highest diagnostic radiation exposure to patients. Image quality can be measured quantitatively based on parameters such as noise, uniformity and resolution. This measure allows the determination of optimal parameters of operation for the scanner in order to get the best diagnostic image. A human Phillips CT scanner is the first one minded for veterinary-use exclusively in Colombia. The aim of this study was to measure the CT image quality parameters using an acrylic phantom and then, using the computational tool MATLAB, determine these parameters as a function of current value and window of visualization, in order to reduce dose delivery by keeping the appropriate image quality.

Diagnostic image quality of video-digitized chest images

International Nuclear Information System (INIS)

Winter, L.H.; Butler, R.B.; Becking, W.B.; Warnars, G.A.O.; Haar Romeny, B. ter; Ottes, F.P.; Valk, J.-P.J. de

1989-01-01

The diagnostic accuracy obtained with the Philips picture archiving and communications subsystem was investigated by means of an observer performance study using receiver operating characteristic (ROC) analysis. The image qualities of conventional films and video digitized images were compared. The scanner had a 1024 x 1024 x 8 bit memory. The digitized images were displayed on a 60 Hz interlaced display monitor 1024 lines. Posteroanterior (AP) roetgenograms of a chest phantom with superimposed simulated interstitial pattern disease (IPD) were produced; there were 28 normal and 40 abnormal films. Normal films were produced by the chest phantom alone. Abnormal films were taken of the chest phantom with varying degrees of superimposed simulated intersitial disease (PND) for an observer performance study, because the results of a simulated interstitial pattern disease study are less likely to be influenced by perceptual capabilities. The conventional films and the video digitized images were viewed by five experienced observers during four separate sessions. Conventional films were presented on a viewing box, the digital images were displayed on the monitor described above. The presence of simulated intersitial disease was indicated on a 5-point ROC certainty scale by each observer. We analyzed the differences between ROC curves derived from correlated data statistically. The mean time required to evaluate 68 digitized images is approximately four times the mean time needed to read the convential films. The diagnostic quality of the video digitized images was significantly lower (at the 5% level) than that of the conventional films (median area under the curve (AUC) of 0.71 and 0.94, respectively). (author). 25 refs.; 2 figs.; 4 tabs

Subjective evaluation of compressed image quality

Science.gov (United States)

Lee, Heesub; Rowberg, Alan H.; Frank, Mark S.; Choi, Hyung-Sik; Kim, Yongmin

1992-05-01

Lossy data compression generates distortion or error on the reconstructed image and the distortion becomes visible as the compression ratio increases. Even at the same compression ratio, the distortion appears differently depending on the compression method used. Because of the nonlinearity of the human visual system and lossy data compression methods, we have evaluated subjectively the quality of medical images compressed with two different methods, an intraframe and interframe coding algorithms. The evaluated raw data were analyzed statistically to measure interrater reliability and reliability of an individual reader. Also, the analysis of variance was used to identify which compression method is better statistically, and from what compression ratio the quality of a compressed image is evaluated as poorer than that of the original. Nine x-ray CT head images from three patients were used as test cases. Six radiologists participated in reading the 99 images (some were duplicates) compressed at four different compression ratios, original, 5:1, 10:1, and 15:1. The six readers agree more than by chance alone and their agreement was statistically significant, but there were large variations among readers as well as within a reader. The displacement estimated interframe coding algorithm is significantly better in quality than that of the 2-D block DCT at significance level 0.05. Also, 10:1 compressed images with the interframe coding algorithm do not show any significant differences from the original at level 0.05.

Neonatal chest image quality addressed through training to enhance radiographer awareness

Directory of Open Access Journals (Sweden)

Hesta Friedrich-Nel

2018-03-01

Full Text Available Background: Diagnostic radiographers working in the neonatal intensive care unit primarily aim to produce an image of optimal quality using optimal exposure techniques without repeating exposures, to keep neonatal radiation dose to a minimum.   Objectives: The aim of the study was to determine whether radiographers were producing optimal quality chest images and, if not, whether additional training could contribute to reaching this goal in the Free State Province of South Africa.   Methods: Neonatal chest image quality was determined in the Neonatal Intensive Care Unit by using a checklist based on and compiled from published guidelines to evaluate the quality of 450 randomly-selected images. Thereafter, a training programme was designed, based on the evaluation criteria of the checklist and image quality areas identified. The training also referred to positioning techniques that should be applied to ensure optimal image quality. After presentation of the training, 450 newly-produced neonatal chest images were evaluated. These images were selected through purposive sampling as this evaluation only included images of participating radiographers who completed the training.   Results: Image quality that showed significant improvement included a reduction in electrocardiogram lines superimposed on chest anatomy, a tendency to centre closer to thoracic vertebra four, and visible four-sided collimation on images. Image quality areas with no significant enhancement were the absence of lead markers and radiation shielding.   Conclusion: The study has shown that a training programme has the potential to improve neonatal chest image quality.

Image quality influences the assessment of left ventricular function

DEFF Research Database (Denmark)

Grossgasteiger, Manuel; Hien, Maximilian D; Graser, Bastian

2014-01-01

divided by the total endocardial border. These ratings were used to generate groups of poor (0%-40%), fair (41%-70%), and good (71%-100%) image quality. The ejection fraction (EF), end-diastolic volume, and end-systolic volume were analyzed by the Simpson method of disks (biplane and monoplane), eyeball...... method yield better correlations with poor image quality. The eyeball method was unaffected by image quality....

Comparison of quality of ultrasonographic image of the pancreas: Tissue harmonic image vs. Fundamental image

International Nuclear Information System (INIS)

Seo, Young Lan; Choi, Chul Soon; Kim, Ho Chul; Yoon, Dae Young; Han, Dae Hee; Bae, Sang Hoon

2002-01-01

To compare the quality of ultrasonographic (US) images, tissue harmonic image (THI) versus fundamental image (FI), of the pancreas. During a recent 2 month period, forty one patients with the normal pancreas on US were included. All of them were free of abnormal clinical and laboratory findings suggestive of pancreatic disease, US was performed by an abdominal radiologist with a 2.5-5 MHz convex-array transducer (Sequoia 512: Acuson, Mountain View, Calif.U.S.A.). Comparison of THI and FI of the pancreas was done for the following parameters:conspicuity, intermal architecture, and delineation range. Grading was made by the consensus of two abdominal radiologist witha three-point scale. Statistical analysis was done using Wilcox signed rank sum test. For the evaluation of the US image quality of the pancreas THI showed better conspicuity (p=0.0130), clearer internal architecture (p=0.0029) and superior delineation range (p=0.0191) than those of FI. THI appears to show a superior image quality than FI in evaluation of the pancreas.

A fourier transform quality measure for iris images

CSIR Research Space (South Africa)

Makinana, S

2014-08-01

Full Text Available to ensure that good quality images are selected for feature extraction, in order to improve iris recognition system. In addition, this research proposes a measure of iris image quality using a Fourier Transform. The experimental results demonstrate...

Review of Image Quality Measures for Solar Imaging

Science.gov (United States)

Popowicz, Adam; Radlak, Krystian; Bernacki, Krzysztof; Orlov, Valeri

2017-12-01

Observations of the solar photosphere from the ground encounter significant problems caused by Earth's turbulent atmosphere. Before image reconstruction techniques can be applied, the frames obtained in the most favorable atmospheric conditions (the so-called lucky frames) have to be carefully selected. However, estimating the quality of images containing complex photospheric structures is not a trivial task, and the standard routines applied in nighttime lucky imaging observations are not applicable. In this paper we evaluate 36 methods dedicated to the assessment of image quality, which were presented in the literature over the past 40 years. We compare their effectiveness on simulated solar observations of both active regions and granulation patches, using reference data obtained by the Solar Optical Telescope on the Hinode satellite. To create images that are affected by a known degree of atmospheric degradation, we employed the random wave vector method, which faithfully models all the seeing characteristics. The results provide useful information about the method performances, depending on the average seeing conditions expressed by the ratio of the telescope's aperture to the Fried parameter, D/r0. The comparison identifies three methods for consideration by observers: Helmli and Scherer's mean, the median filter gradient similarity, and the discrete cosine transform energy ratio. While the first method requires less computational effort and can be used effectively in virtually any atmospheric conditions, the second method shows its superiority at good seeing (D/r0<4). The third method should mainly be considered for the post-processing of strongly blurred images.

Dynamic flat panel detector versus image intensifier in cardiac imaging: dose and image quality

Science.gov (United States)

Vano, E.; Geiger, B.; Schreiner, A.; Back, C.; Beissel, J.

2005-12-01

The practical aspects of the dosimetric and imaging performance of a digital x-ray system for cardiology procedures were evaluated. The system was configured with an image intensifier (II) and later upgraded to a dynamic flat panel detector (FD). Entrance surface air kerma (ESAK) to phantoms of 16, 20, 24 and 28 cm of polymethyl methacrylate (PMMA) and the image quality of a test object were measured. Images were evaluated directly on the monitor and with numerical methods (noise and signal-to-noise ratio). Information contained in the DICOM header for dosimetry audit purposes was also tested. ESAK values per frame (or kerma rate) for the most commonly used cine and fluoroscopy modes for different PMMA thicknesses and for field sizes of 17 and 23 cm for II, and 20 and 25 cm for FD, produced similar results in the evaluated system with both technologies, ranging between 19 and 589 µGy/frame (cine) and 5 and 95 mGy min-1 (fluoroscopy). Image quality for these dose settings was better for the FD version. The 'study dosimetric report' is comprehensive, and its numerical content is sufficiently accurate. There is potential in the future to set those systems with dynamic FD to lower doses than are possible in the current II versions, especially for digital cine runs, or to benefit from improved image quality.

Using image quality measures and features to choose good images for classification of ISAR imagery

CSIR Research Space (South Africa)

Steyn, JM

2014-10-01

Full Text Available the quality measures and to determine the minimum dwell-time for ISAR image formation. Keywords—ISAR (inverse synthetic aperture radar), Dwell-time, Quality Measure, Image Contrast, Image Entropy, SNR (signal-to-noise ratio), Maritime Vessels ...

Physics-based optimization of image quality in 3D X-ray flat-panel cone-beam imaging

NARCIS (Netherlands)

Snoeren, R.M.

2012-01-01

This thesis describes the techniques for modeling and control of 3D X-ray cardiovascular systems in terms of Image Quality and patient dose, aiming at optimizing the diagnostic quality. When aiming at maximum Image Quality (IQ), a cascaded system constituted from inter-dependent imaging components,

CCD Astrophotography High-Quality Imaging from the Suburbs

CERN Document Server

Stuart, Adam

2006-01-01

This is a reference book for amateur astronomers who have become interested in CCD imaging. Those glorious astronomical images found in astronomy magazines might seem out of reach to newcomers to CCD imaging, but this is not the case. Great pictures are attainable with modest equipment. Adam Stuart’s many beautiful images, reproduced in this book, attest to the quality of – initially – a beginner’s efforts. Chilled-chip astronomical CCD-cameras and software are also wonderful tools for cutting through seemingly impenetrable light-pollution. CCD Astrophotography from the Suburbs describes one man’s successful approach to the problem of getting high-quality astronomical images under some of the most light-polluted conditions. Here is a complete and thoroughly tested program that will help every CCD-beginner to work towards digital imaging of the highest quality. It is equally useful to astronomers who have perfect observing conditions, as to those who have to observe from light-polluted city skies.

Image quality optimization and evaluation of linearly mixed images in dual-source, dual-energy CT

International Nuclear Information System (INIS)

Yu Lifeng; Primak, Andrew N.; Liu Xin; McCollough, Cynthia H.

2009-01-01

In dual-source dual-energy CT, the images reconstructed from the low- and high-energy scans (typically at 80 and 140 kV, respectively) can be mixed together to provide a single set of non-material-specific images for the purpose of routine diagnostic interpretation. Different from the material-specific information that may be obtained from the dual-energy scan data, the mixed images are created with the purpose of providing the interpreting physician a single set of images that have an appearance similar to that in single-energy images acquired at the same total radiation dose. In this work, the authors used a phantom study to evaluate the image quality of linearly mixed images in comparison to single-energy CT images, assuming the same total radiation dose and taking into account the effect of patient size and the dose partitioning between the low-and high-energy scans. The authors first developed a method to optimize the quality of the linearly mixed images such that the single-energy image quality was compared to the best-case image quality of the dual-energy mixed images. Compared to 80 kV single-energy images for the same radiation dose, the iodine CNR in dual-energy mixed images was worse for smaller phantom sizes. However, similar noise and similar or improved iodine CNR relative to 120 kV images could be achieved for dual-energy mixed images using the same total radiation dose over a wide range of patient sizes (up to 45 cm lateral thorax dimension). Thus, for adult CT practices, which primarily use 120 kV scanning, the use of dual-energy CT for the purpose of material-specific imaging can also produce a set of non-material-specific images for routine diagnostic interpretation that are of similar or improved quality relative to single-energy 120 kV scans.

Body image quality of life in eating disorders

Directory of Open Access Journals (Sweden)

Ignacio Jáuregui Lobera

2011-03-01

Full Text Available Ignacio Jáuregui Lobera1, Patricia Bolaños Ríos21Department of Nutrition and Bromatology, Pablo de Olavide University, Seville, Spain; 2Behavior Sciences Institute, Seville, SpainPurpose: The objective was to examine how body image affects quality of life in an eating-disorder (ED clinical sample, a non-ED clinical sample, and a nonclinical sample. We hypothesized that ED patients would show the worst body image quality of life. We also hypothesized that body image quality of life would have a stronger negative association with specific ED-related variables than with other psychological and psychopathological variables, mainly among ED patients. On the basis of previous studies, the influence of gender on the results was explored, too.Patients and methods: The final sample comprised 70 ED patients (mean age 22.65 ± 7.76 years; 59 women and 11 men; 106 were patients with other psychiatric disorders (mean age 28.20 ± 6.52; 67 women and 39 men, and 135 were university students (mean age 21.57 ± 2.58; 81 women and 54 men, with no psychiatric history. After having obtained informed consent, the following questionnaires were administered: Body Image Quality of Life Inventory-Spanish version (BIQLI-SP, Eating Disorders Inventory-2 (EDI-2, Perceived Stress Questionnaire (PSQ, Self-Esteem Scale (SES, and Symptom Checklist-90-Revised (SCL-90-R.Results: The ED patients' ratings on the BIQLI-SP were the lowest and negatively scored (BIQLI-SP means: +20.18, +5.14, and —6.18, in the student group, the non-ED patient group, and the ED group, respectively. The effect of body image on quality of life was more negative in the ED group in all items of the BIQLI-SP. Body image quality of life was negatively associated with specific ED-related variables, more than with other psychological and psychopathological variables, but not especially among ED patients.Conclusion: Body image quality of life was affected not only by specific pathologies related to body

The use of the general image quality equation in the design and evaluation of imaging systems

Science.gov (United States)

Cota, Steve A.; Florio, Christopher J.; Duvall, David J.; Leon, Michael A.

2009-08-01

The design of any modern imaging system is the end result of many trade studies, each seeking to optimize image quality within real world constraints such as cost, schedule and overall risk. The National Imagery Interpretability Rating Scale (NIIRS) is a useful measure of image quality, because, by characterizing the overall interpretability of an image, it combines into one metric those contributors to image quality to which a human interpreter is most sensitive. The main drawback to using a NIIRS rating as a measure of image quality in engineering trade studies is the fact that it is tied to the human observer and cannot be predicted from physical principles and engineering parameters alone. The General Image Quality Equation (GIQE) of Leachtenauer et al. 1997 [Appl. Opt. 36, 8322-8328 (1997)] is a regression of actual image analyst NIIRS ratings vs. readily calculable engineering metrics, and provides a mechanism for using the expected NIIRS rating of an imaging system in the design and evaluation process. In this paper, we will discuss how we use the GIQE in conjunction with The Aerospace Corporation's Parameterized Image Chain Analysis & Simulation SOftware (PICASSO) to evaluate imager designs, taking a hypothetical high resolution commercial imaging system as an example.

Recognizable or Not: Towards Image Semantic Quality Assessment for Compression

Science.gov (United States)

Liu, Dong; Wang, Dandan; Li, Houqiang

2017-12-01

Traditionally, image compression was optimized for the pixel-wise fidelity or the perceptual quality of the compressed images given a bit-rate budget. But recently, compressed images are more and more utilized for automatic semantic analysis tasks such as recognition and retrieval. For these tasks, we argue that the optimization target of compression is no longer perceptual quality, but the utility of the compressed images in the given automatic semantic analysis task. Accordingly, we propose to evaluate the quality of the compressed images neither at pixel level nor at perceptual level, but at semantic level. In this paper, we make preliminary efforts towards image semantic quality assessment (ISQA), focusing on the task of optical character recognition (OCR) from compressed images. We propose a full-reference ISQA measure by comparing the features extracted from text regions of original and compressed images. We then propose to integrate the ISQA measure into an image compression scheme. Experimental results show that our proposed ISQA measure is much better than PSNR and SSIM in evaluating the semantic quality of compressed images; accordingly, adopting our ISQA measure to optimize compression for OCR leads to significant bit-rate saving compared to using PSNR or SSIM. Moreover, we perform subjective test about text recognition from compressed images, and observe that our ISQA measure has high consistency with subjective recognizability. Our work explores new dimensions in image quality assessment, and demonstrates promising direction to achieve higher compression ratio for specific semantic analysis tasks.

The relationship between compression force, image quality and ...

African Journals Online (AJOL)

Theoretically, an increase in breast compression gives a reduction in thickness without changing the density, resulting in improved image quality and reduced radiation dose. Aim. This study investigates the relationship between compression force, phantom thickness, image quality and radiation dose. The existence of a ...

Optimization of the alpha image reconstruction. An iterative CT-image reconstruction with well-defined image quality metrics

Energy Technology Data Exchange (ETDEWEB)

Lebedev, Sergej; Sawall, Stefan; Knaup, Michael; Kachelriess, Marc [German Cancer Research Center, Heidelberg (Germany).

2017-10-01

Optimization of the AIR-algorithm for improved convergence and performance. TThe AIR method is an iterative algorithm for CT image reconstruction. As a result of its linearity with respect to the basis images, the AIR algorithm possesses well defined, regular image quality metrics, e.g. point spread function (PSF) or modulation transfer function (MTF), unlike other iterative reconstruction algorithms. The AIR algorithm computes weighting images α to blend between a set of basis images that preferably have mutually exclusive properties, e.g. high spatial resolution or low noise. The optimized algorithm uses an approach that alternates between the optimization of rawdata fidelity using an OSSART like update and regularization using gradient descent, as opposed to the initially proposed AIR using a straightforward gradient descent implementation. A regularization strength for a given task is chosen by formulating a requirement for the noise reduction and checking whether it is fulfilled for different regularization strengths, while monitoring the spatial resolution using the voxel-wise defined modulation transfer function for the AIR image. The optimized algorithm computes similar images in a shorter time compared to the initial gradient descent implementation of AIR. The result can be influenced by multiple parameters that can be narrowed down to a relatively simple framework to compute high quality images. The AIR images, for instance, can have at least a 50% lower noise level compared to the sharpest basis image, while the spatial resolution is mostly maintained. The optimization improves performance by a factor of 6, while maintaining image quality. Furthermore, it was demonstrated that the spatial resolution for AIR can be determined using regular image quality metrics, given smooth weighting images. This is not possible for other iterative reconstructions as a result of their non linearity. A simple set of parameters for the algorithm is discussed that provides

Optimization of the alpha image reconstruction. An iterative CT-image reconstruction with well-defined image quality metrics

International Nuclear Information System (INIS)

Lebedev, Sergej; Sawall, Stefan; Knaup, Michael; Kachelriess, Marc

2017-01-01

Optimization of the AIR-algorithm for improved convergence and performance. TThe AIR method is an iterative algorithm for CT image reconstruction. As a result of its linearity with respect to the basis images, the AIR algorithm possesses well defined, regular image quality metrics, e.g. point spread function (PSF) or modulation transfer function (MTF), unlike other iterative reconstruction algorithms. The AIR algorithm computes weighting images α to blend between a set of basis images that preferably have mutually exclusive properties, e.g. high spatial resolution or low noise. The optimized algorithm uses an approach that alternates between the optimization of rawdata fidelity using an OSSART like update and regularization using gradient descent, as opposed to the initially proposed AIR using a straightforward gradient descent implementation. A regularization strength for a given task is chosen by formulating a requirement for the noise reduction and checking whether it is fulfilled for different regularization strengths, while monitoring the spatial resolution using the voxel-wise defined modulation transfer function for the AIR image. The optimized algorithm computes similar images in a shorter time compared to the initial gradient descent implementation of AIR. The result can be influenced by multiple parameters that can be narrowed down to a relatively simple framework to compute high quality images. The AIR images, for instance, can have at least a 50% lower noise level compared to the sharpest basis image, while the spatial resolution is mostly maintained. The optimization improves performance by a factor of 6, while maintaining image quality. Furthermore, it was demonstrated that the spatial resolution for AIR can be determined using regular image quality metrics, given smooth weighting images. This is not possible for other iterative reconstructions as a result of their non linearity. A simple set of parameters for the algorithm is discussed that provides

Assessing microscope image focus quality with deep learning.

Science.gov (United States)

Yang, Samuel J; Berndl, Marc; Michael Ando, D; Barch, Mariya; Narayanaswamy, Arunachalam; Christiansen, Eric; Hoyer, Stephan; Roat, Chris; Hung, Jane; Rueden, Curtis T; Shankar, Asim; Finkbeiner, Steven; Nelson, Philip

2018-03-15

Large image datasets acquired on automated microscopes typically have some fraction of low quality, out-of-focus images, despite the use of hardware autofocus systems. Identification of these images using automated image analysis with high accuracy is important for obtaining a clean, unbiased image dataset. Complicating this task is the fact that image focus quality is only well-defined in foreground regions of images, and as a result, most previous approaches only enable a computation of the relative difference in quality between two or more images, rather than an absolute measure of quality. We present a deep neural network model capable of predicting an absolute measure of image focus on a single image in isolation, without any user-specified parameters. The model operates at the image-patch level, and also outputs a measure of prediction certainty, enabling interpretable predictions. The model was trained on only 384 in-focus Hoechst (nuclei) stain images of U2OS cells, which were synthetically defocused to one of 11 absolute defocus levels during training. The trained model can generalize on previously unseen real Hoechst stain images, identifying the absolute image focus to within one defocus level (approximately 3 pixel blur diameter difference) with 95% accuracy. On a simpler binary in/out-of-focus classification task, the trained model outperforms previous approaches on both Hoechst and Phalloidin (actin) stain images (F-scores of 0.89 and 0.86, respectively over 0.84 and 0.83), despite only having been presented Hoechst stain images during training. Lastly, we observe qualitatively that the model generalizes to two additional stains, Hoechst and Tubulin, of an unseen cell type (Human MCF-7) acquired on a different instrument. Our deep neural network enables classification of out-of-focus microscope images with both higher accuracy and greater precision than previous approaches via interpretable patch-level focus and certainty predictions. The use of

Quality criteria for cardiac images: An update

International Nuclear Information System (INIS)

Bernardi, G.; Bar, O.; Jezewski, T.; Vano, E.; Maccia, C.; Trianni, A.; Padovani, R.

2008-01-01

The DIMOND II and III Cardiology Groups have agreed on quality criteria for cardiac images and developed a scoring system, to provide a tool to test quality of coronary angiograms, which was demonstrated to be of value in clinical practice. In the last years, digital flat panel technology has been introduced in cardiac angiographic systems and the radiological technique may have been influenced by the better performance of these new detectors. This advance in digital imaging, together with the lesson learned from previous studies, warranted the revision of the quality criteria for cardiac angiographic images as formerly defined. DIMOND criteria were reassessed to allow a simpler evaluation of angiograms. Clinical criteria were simplified and separated from technical criteria. Furthermore, the characteristics of an optimised angiographic technique have been outlined. (authors)

Quality Imaging - Comparison of CR Mammography with Screen-Film Mammography

International Nuclear Information System (INIS)

Gaona, E.; Azorin Nieto, J.; Iran Diaz Gongora, J. A.; Arreola, M.; Casian Castellanos, G.; Perdigon Castaneda, G. M.; Franco Enriquez, J. G.

2006-01-01

The aim of this work is a quality imaging comparison of CR mammography images printed to film by a laser printer with screen-film mammography. A Giotto and Elscintec dedicated mammography units with fully automatic exposure and a nominal large focal spot size of 0.3 mm were used for the image acquisition of phantoms in screen-film mammography. Four CR mammography units from two different manufacturers and three dedicated x-ray mammography units with fully automatic exposure and a nominal large focal spot size of 0.3 mm were used for the image acquisition of phantoms in CR mammography. The tests quality image included an assessment of system resolution, scoring phantom images, Artifacts, mean optical density and density difference (contrast). In this study, screen-film mammography with a quality control program offers a significantly greater level of quality image relative to CR mammography images printed on film

Decision theory on the quality evaluation of medical images

International Nuclear Information System (INIS)

Lessa, Patricia Silva

2001-10-01

The problem of quality has been a constant issue in every organization.One is always seeking to produce more, to do it at a lower cost, and to do it with better quality. However, in this country, there is no radiographic film quality control system for radiographic services. The tittle that actually gets done is essentially ad hoc and superficial. The implications of this gap, along with some other shortcomings that exist in process as a whole (the state of the x-ray equipment, the adequate to use in order to obtain a radiography, the quality of the film, the processing of the film, the brightness and homogeneity of the viewing boxes, the ability of the radiologist), have a very negative impact on the quality of the medical image, and, as result, to the quality of the medical diagnosis and therapy. It frequently happens that many radiographs have to be repeated, which leads to an increase of the patient's exposure to radiation, as well as of the cost of the procedure for the patient. Low quality radiographs that are not repeated greatly increase the probability of a wrong diagnosis, and consequently, of inadequate therapeutical procedures, thus producing increased incidence of bad outcomes and higher costs. The paradigm proposed in order to establish a system for the measurement of the image's quality is Decision Theory. The problem of the assessment of the image is studied by proposing a Decision Theory approach. The review of the literature reveals a great concern with the quality of the image, along with an absence of an adequate paradigm and several essentially empirical procedures. Image parameters are developed in order to formalize the problem in terms of Decision Theory, and various aspects of image digitalisation are exposed. Finally, a solution is presented, including a protocol for quality control. (author)

Free-breathing motion-corrected late-gadolinium-enhancement imaging improves image quality in children

International Nuclear Information System (INIS)

Olivieri, Laura; O'Brien, Kendall J.; Cross, Russell; Xue, Hui; Kellman, Peter; Hansen, Michael S.

2016-01-01

The value of late-gadolinium-enhancement (LGE) imaging in the diagnosis and management of pediatric and congenital heart disease is clear; however current acquisition techniques are susceptible to error and artifacts when performed in children because of children's higher heart rates, higher prevalence of sinus arrhythmia, and inability to breath-hold. Commonly used techniques in pediatric LGE imaging include breath-held segmented FLASH (segFLASH) and steady-state free precession-based (segSSFP) imaging. More recently, single-shot SSFP techniques with respiratory motion-corrected averaging have emerged. This study tested and compared single-shot free-breathing LGE techniques with standard segmented breath-held techniques in children undergoing LGE imaging. Thirty-two consecutive children underwent clinically indicated late-enhancement imaging using intravenous gadobutrol 0.15 mmol/kg. Breath-held segSSFP, breath-held segFLASH, and free-breathing single-shot SSFP LGE sequences were performed in consecutive series in each child. Two blinded reviewers evaluated the quality of the images and rated them on a scale of 1-5 (1 = poor, 5 = superior) based on blood pool-myocardial definition, presence of cardiac motion, presence of respiratory motion artifacts, and image acquisition artifact. We used analysis of variance (ANOVA) to compare groups. Patients ranged in age from 9 months to 18 years, with a mean +/- standard deviation (SD) of 13.3 +/- 4.8 years. R-R interval at the time of acquisition ranged 366-1,265 milliseconds (ms) (47-164 beats per minute [bpm]), mean +/- SD of 843+/-231 ms (72+/-21 bpm). Mean +/- SD quality ratings for long-axis imaging for segFLASH, segSSFP and single-shot SSFP were 3.1+/-0.9, 3.4+/-0.9 and 4.0+/-0.9, respectively (P < 0.01 by ANOVA). Mean +/- SD quality ratings for short-axis imaging for segFLASH, segSSFP and single-shot SSFP were 3.4+/-1, 3.8+/-0.9 and 4.3+/-0.7, respectively (P < 0.01 by ANOVA). Single-shot late

Free-breathing motion-corrected late-gadolinium-enhancement imaging improves image quality in children

Energy Technology Data Exchange (ETDEWEB)

Olivieri, Laura; O' Brien, Kendall J. [Children' s National Health System, Division of Cardiology, Washington, DC (United States); National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD (United States); Cross, Russell [Children' s National Health System, Division of Cardiology, Washington, DC (United States); Xue, Hui; Kellman, Peter; Hansen, Michael S. [National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD (United States)

2016-06-15

The value of late-gadolinium-enhancement (LGE) imaging in the diagnosis and management of pediatric and congenital heart disease is clear; however current acquisition techniques are susceptible to error and artifacts when performed in children because of children's higher heart rates, higher prevalence of sinus arrhythmia, and inability to breath-hold. Commonly used techniques in pediatric LGE imaging include breath-held segmented FLASH (segFLASH) and steady-state free precession-based (segSSFP) imaging. More recently, single-shot SSFP techniques with respiratory motion-corrected averaging have emerged. This study tested and compared single-shot free-breathing LGE techniques with standard segmented breath-held techniques in children undergoing LGE imaging. Thirty-two consecutive children underwent clinically indicated late-enhancement imaging using intravenous gadobutrol 0.15 mmol/kg. Breath-held segSSFP, breath-held segFLASH, and free-breathing single-shot SSFP LGE sequences were performed in consecutive series in each child. Two blinded reviewers evaluated the quality of the images and rated them on a scale of 1-5 (1 = poor, 5 = superior) based on blood pool-myocardial definition, presence of cardiac motion, presence of respiratory motion artifacts, and image acquisition artifact. We used analysis of variance (ANOVA) to compare groups. Patients ranged in age from 9 months to 18 years, with a mean +/- standard deviation (SD) of 13.3 +/- 4.8 years. R-R interval at the time of acquisition ranged 366-1,265 milliseconds (ms) (47-164 beats per minute [bpm]), mean +/- SD of 843+/-231 ms (72+/-21 bpm). Mean +/- SD quality ratings for long-axis imaging for segFLASH, segSSFP and single-shot SSFP were 3.1+/-0.9, 3.4+/-0.9 and 4.0+/-0.9, respectively (P < 0.01 by ANOVA). Mean +/- SD quality ratings for short-axis imaging for segFLASH, segSSFP and single-shot SSFP were 3.4+/-1, 3.8+/-0.9 and 4.3+/-0.7, respectively (P < 0.01 by ANOVA). Single-shot late

Improved radionuclide bone imaging agent injection needle withdrawal method can improve image quality

International Nuclear Information System (INIS)

Qin Yongmei; Wang Laihao; Zhao Lihua; Guo Xiaogang; Kong Qingfeng

2009-01-01

Objective: To investigate the improvement of radionuclide bone imaging agent injection needle withdrawal method on whole body bone scan image quality. Methods: Elbow vein injection syringe needle directly into the bone imaging agent in the routine group of 117 cases, with a cotton swab needle injection method for the rapid pull out the needle puncture point pressing, pressing moment. Improvement of 117 cases of needle injection method to put two needles into the skin swabs and blood vessels, pull out the needle while pressing two or more entry point 5min. After 2 hours underwent whole body bone SPECT imaging plane. Results: The conventional group at the injection site imaging agents uptake rate was 16.24%, improved group was 2.56%. Conclusion: The modified bone imaging agent injection needle withdrawal method, injection-site imaging agent uptake were significantly decreased whole body bone imaging can improve image quality. (authors)

Comprehensive model for predicting perceptual image quality of smart mobile devices.

Science.gov (United States)

Gong, Rui; Xu, Haisong; Luo, M R; Li, Haifeng

2015-01-01

An image quality model for smart mobile devices was proposed based on visual assessments of several image quality attributes. A series of psychophysical experiments were carried out on two kinds of smart mobile devices, i.e., smart phones and tablet computers, in which naturalness, colorfulness, brightness, contrast, sharpness, clearness, and overall image quality were visually evaluated under three lighting environments via categorical judgment method for various application types of test images. On the basis of Pearson correlation coefficients and factor analysis, the overall image quality could first be predicted by its two constituent attributes with multiple linear regression functions for different types of images, respectively, and then the mathematical expressions were built to link the constituent image quality attributes with the physical parameters of smart mobile devices and image appearance factors. The procedure and algorithms were applicable to various smart mobile devices, different lighting conditions, and multiple types of images, and performance was verified by the visual data.

Model-Based Referenceless Quality Metric of 3D Synthesized Images Using Local Image Description.

Science.gov (United States)

Gu, Ke; Jakhetiya, Vinit; Qiao, Jun-Fei; Li, Xiaoli; Lin, Weisi; Thalmann, Daniel

2017-07-28

New challenges have been brought out along with the emerging of 3D-related technologies such as virtual reality (VR), augmented reality (AR), and mixed reality (MR). Free viewpoint video (FVV), due to its applications in remote surveillance, remote education, etc, based on the flexible selection of direction and viewpoint, has been perceived as the development direction of next-generation video technologies and has drawn a wide range of researchers' attention. Since FVV images are synthesized via a depth image-based rendering (DIBR) procedure in the "blind" environment (without reference images), a reliable real-time blind quality evaluation and monitoring system is urgently required. But existing assessment metrics do not render human judgments faithfully mainly because geometric distortions are generated by DIBR. To this end, this paper proposes a novel referenceless quality metric of DIBR-synthesized images using the autoregression (AR)-based local image description. It was found that, after the AR prediction, the reconstructed error between a DIBR-synthesized image and its AR-predicted image can accurately capture the geometry distortion. The visual saliency is then leveraged to modify the proposed blind quality metric to a sizable margin. Experiments validate the superiority of our no-reference quality method as compared with prevailing full-, reduced- and no-reference models.

Applying image quality in cell phone cameras: lens distortion

Science.gov (United States)

Baxter, Donald; Goma, Sergio R.; Aleksic, Milivoje

2009-01-01

This paper describes the framework used in one of the pilot studies run under the I3A CPIQ initiative to quantify overall image quality in cell-phone cameras. The framework is based on a multivariate formalism which tries to predict overall image quality from individual image quality attributes and was validated in a CPIQ pilot program. The pilot study focuses on image quality distortions introduced in the optical path of a cell-phone camera, which may or may not be corrected in the image processing path. The assumption is that the captured image used is JPEG compressed and the cellphone camera is set to 'auto' mode. As the used framework requires that the individual attributes to be relatively perceptually orthogonal, in the pilot study, the attributes used are lens geometric distortion (LGD) and lateral chromatic aberrations (LCA). The goal of this paper is to present the framework of this pilot project starting with the definition of the individual attributes, up to their quantification in JNDs of quality, a requirement of the multivariate formalism, therefore both objective and subjective evaluations were used. A major distinction in the objective part from the 'DSC imaging world' is that the LCA/LGD distortions found in cell-phone cameras, rarely exhibit radial behavior, therefore a radial mapping/modeling cannot be used in this case.

Effect of image quality on calcification detection in digital mammography

International Nuclear Information System (INIS)

Warren, Lucy M.; Mackenzie, Alistair; Cooke, Julie; Given-Wilson, Rosalind M.; Wallis, Matthew G.; Chakraborty, Dev P.; Dance, David R.; Bosmans, Hilde; Young, Kenneth C.

2012-01-01

Purpose: This study aims to investigate if microcalcification detection varies significantly when mammographic images are acquired using different image qualities, including: different detectors, dose levels, and different image processing algorithms. An additional aim was to determine how the standard European method of measuring image quality using threshold gold thickness measured with a CDMAM phantom and the associated limits in current EU guidelines relate to calcification detection. Methods: One hundred and sixty two normal breast images were acquired on an amorphous selenium direct digital (DR) system. Microcalcification clusters extracted from magnified images of slices of mastectomies were electronically inserted into half of the images. The calcification clusters had a subtle appearance. All images were adjusted using a validated mathematical method to simulate the appearance of images from a computed radiography (CR) imaging system at the same dose, from both systems at half this dose, and from the DR system at quarter this dose. The original 162 images were processed with both Hologic and Agfa (Musica-2) image processing. All other image qualities were processed with Agfa (Musica-2) image processing only. Seven experienced observers marked and rated any identified suspicious regions. Free response operating characteristic (FROC) and ROC analyses were performed on the data. The lesion sensitivity at a nonlesion localization fraction (NLF) of 0.1 was also calculated. Images of the CDMAM mammographic test phantom were acquired using the automatic setting on the DR system. These images were modified to the additional image qualities used in the observer study. The images were analyzed using automated software. In order to assess the relationship between threshold gold thickness and calcification detection a power law was fitted to the data. Results: There was a significant reduction in calcification detection using CR compared with DR: the alternative FROC

Effect of image quality on calcification detection in digital mammography.

Science.gov (United States)

Warren, Lucy M; Mackenzie, Alistair; Cooke, Julie; Given-Wilson, Rosalind M; Wallis, Matthew G; Chakraborty, Dev P; Dance, David R; Bosmans, Hilde; Young, Kenneth C

2012-06-01

This study aims to investigate if microcalcification detection varies significantly when mammographic images are acquired using different image qualities, including: different detectors, dose levels, and different image processing algorithms. An additional aim was to determine how the standard European method of measuring image quality using threshold gold thickness measured with a CDMAM phantom and the associated limits in current EU guidelines relate to calcification detection. One hundred and sixty two normal breast images were acquired on an amorphous selenium direct digital (DR) system. Microcalcification clusters extracted from magnified images of slices of mastectomies were electronically inserted into half of the images. The calcification clusters had a subtle appearance. All images were adjusted using a validated mathematical method to simulate the appearance of images from a computed radiography (CR) imaging system at the same dose, from both systems at half this dose, and from the DR system at quarter this dose. The original 162 images were processed with both Hologic and Agfa (Musica-2) image processing. All other image qualities were processed with Agfa (Musica-2) image processing only. Seven experienced observers marked and rated any identified suspicious regions. Free response operating characteristic (FROC) and ROC analyses were performed on the data. The lesion sensitivity at a nonlesion localization fraction (NLF) of 0.1 was also calculated. Images of the CDMAM mammographic test phantom were acquired using the automatic setting on the DR system. These images were modified to the additional image qualities used in the observer study. The images were analyzed using automated software. In order to assess the relationship between threshold gold thickness and calcification detection a power law was fitted to the data. There was a significant reduction in calcification detection using CR compared with DR: the alternative FROC (AFROC) area decreased from

Objective assessment of image quality VI: imaging in radiation therapy

International Nuclear Information System (INIS)

Barrett, Harrison H; Kupinski, Matthew A; Müeller, Stefan; Halpern, Howard J; Morris, John C III; Dwyer, Roisin

2013-01-01

Earlier work on objective assessment of image quality (OAIQ) focused largely on estimation or classification tasks in which the desired outcome of imaging is accurate diagnosis. This paper develops a general framework for assessing imaging quality on the basis of therapeutic outcomes rather than diagnostic performance. By analogy to receiver operating characteristic (ROC) curves and their variants as used in diagnostic OAIQ, the method proposed here utilizes the therapy operating characteristic or TOC curves, which are plots of the probability of tumor control versus the probability of normal-tissue complications as the overall dose level of a radiotherapy treatment is varied. The proposed figure of merit is the area under the TOC curve, denoted AUTOC. This paper reviews an earlier exposition of the theory of TOC and AUTOC, which was specific to the assessment of image-segmentation algorithms, and extends it to other applications of imaging in external-beam radiation treatment as well as in treatment with internal radioactive sources. For each application, a methodology for computing the TOC is presented. A key difference between ROC and TOC is that the latter can be defined for a single patient rather than a population of patients. (paper)

Quality control in diagnostic mammography: myths, realities and their importance in the final image quality

International Nuclear Information System (INIS)

Mora Rodriguez, Patricia

2011-01-01

Mammography is the most used tool for early detection of breast cancer and reduce mortality from this cause. Studies with ionizing radiation it is important that be justified and provide a quality image to make the diagnosis, to get more benefits and fewer risks. The problem is the difficult to obtain an image of the breast. Therefore, the commitment to quality mammography is to maximize the contrast, definition, resolution and reliability, thus minimizing noise and dose. A mammogram performed without quality don't detect early breast cancer and the study doesn't have sense. Quality mammography requires trained and experienced staff, modern equipment and in good conditions, correct positioning, right technical factors and appropriate viewing conditions. In addition, quality programs are required to reach to ensure quality, control in testing techniques and image quality. (author) [es

Naturalness and image quality : saturation and lightness variation in color images of natural scenes

NARCIS (Netherlands)

Ridder, de H.

1996-01-01

The relation between perceived image quality and naturalness was investigated by varying the colorfulness of natural images at various lightness levels. At each lightness level, subjects assessed perceived colorfulness, naturalness, and quality as a function of average saturation by means of direct

Digital radiography: optimization of image quality and dose using multi-frequency software.

Science.gov (United States)

Precht, H; Gerke, O; Rosendahl, K; Tingberg, A; Waaler, D

2012-09-01

New developments in processing of digital radiographs (DR), including multi-frequency processing (MFP), allow optimization of image quality and radiation dose. This is particularly promising in children as they are believed to be more sensitive to ionizing radiation than adults. To examine whether the use of MFP software reduces the radiation dose without compromising quality at DR of the femur in 5-year-old-equivalent anthropomorphic and technical phantoms. A total of 110 images of an anthropomorphic phantom were imaged on a DR system (Canon DR with CXDI-50 C detector and MLT[S] software) and analyzed by three pediatric radiologists using Visual Grading Analysis. In addition, 3,500 images taken of a technical contrast-detail phantom (CDRAD 2.0) provide an objective image-quality assessment. Optimal image-quality was maintained at a dose reduction of 61% with MLT(S) optimized images. Even for images of diagnostic quality, MLT(S) provided a dose reduction of 88% as compared to the reference image. Software impact on image quality was found significant for dose (mAs), dynamic range dark region and frequency band. By optimizing image processing parameters, a significant dose reduction is possible without significant loss of image quality.

Image quality in digital radiographic systems

Directory of Open Access Journals (Sweden)

Almeida Solange Maria de

2003-01-01

Full Text Available The aim of the present study was to evaluate the image quality of four direct digital radiographic systems. Radiographs were made of the maxillary central incisor and mandibular left molar regions of a dry skull, and an aluminum step-wedge. The X-ray generator operated at 10 mA, 60 and 70 kVp, and images were acquired with 3, 5, 8, 12, 24 and 48 exposure pulses. Six well-trained observers classified the images by means of scores from 1 to 3. Collected data were submitted to nonparametric statistical analysis using Fisher's exact test. Statistical analysis showed significant differences (p<0.01 in image quality with the four systems. Based on the results, it was possible to conclude that: 1 all of the digital systems presented good performance in producing acceptable images for diagnosis, if the exposures of the step-wedge and the maxillary central incisor region were made at 5 pulses, as well as at 8 pulses for the mandibular left molar region, selecting 60 or 70kVp; 2 higher percentages of acceptable images were obtained with the administration of lower radiation doses in CCD-sensors (charge-coupled device; 3 the Storage Phosphor systems produced acceptable images at a large range of exposure settings, that included low, intermediate and high radiation doses.

Enhancement of digital radiography image quality using a convolutional neural network.

Science.gov (United States)

Sun, Yuewen; Li, Litao; Cong, Peng; Wang, Zhentao; Guo, Xiaojing

2017-01-01

Digital radiography system is widely used for noninvasive security check and medical imaging examination. However, the system has a limitation of lower image quality in spatial resolution and signal to noise ratio. In this study, we explored whether the image quality acquired by the digital radiography system can be improved with a modified convolutional neural network to generate high-resolution images with reduced noise from the original low-quality images. The experiment evaluated on a test dataset, which contains 5 X-ray images, showed that the proposed method outperformed the traditional methods (i.e., bicubic interpolation and 3D block-matching approach) as measured by peak signal to noise ratio (PSNR) about 1.3 dB while kept highly efficient processing time within one second. Experimental results demonstrated that a residual to residual (RTR) convolutional neural network remarkably improved the image quality of object structural details by increasing the image resolution and reducing image noise. Thus, this study indicated that applying this RTR convolutional neural network system was useful to improve image quality acquired by the digital radiography system.

Parameters related to the image quality in computed tomography -CT

International Nuclear Information System (INIS)

Alonso, T.C.; Silva, T.A.; Mourão, A.P.; Silva, T.A.

2015-01-01

Quality control programs in computed tomography, CT, should be continuously reviewed to always ensure the best image quality with the lowest possible dose for the patient in the diagnostic process. The quality control in CT aims to design and implement a set of procedures that allows the verification of their operating conditions within the specified requirements for its use. In Brazil, the Ministry of Health (MOH), the Technical Rules (Resolution NE in 1016.) - Radiology Medical - 'Equipment and Safety Performance' establishes a reference to the analysis of tests on TC. A large number of factors such as image noise, slice thickness (resolution of the Z axis), low contrast resolution and high contrast resolution and the radiation dose can be affected by the selection of technical parameters in exams. The purpose of this study was to investigate how changes in image acquisition protocols modify its quality and determine the advantages and disadvantages between the different aspects of image quality, especially the reduction of patient radiation dose. A preliminary procedure is to check the operating conditions of the CT measurements were performed on a scanner with 64-MDCT scanner (GE Healthcare, BrightSpeed) in the service of the Molecular Imaging Center (Cimol) of the Federal University of Minas Gerais (UFMG). When performing the image quality tests we used a simulator, Catphan-600, this device has five modules, and in each you can perform a series of tests. Different medical imaging practices have different requirements for acceptable image quality. The results of quality control tests showed that the analyzed equipment is in accordance with the requirements established by current regulations. [pt

Blind CT image quality assessment via deep learning strategy: initial study

Science.gov (United States)

Li, Sui; He, Ji; Wang, Yongbo; Liao, Yuting; Zeng, Dong; Bian, Zhaoying; Ma, Jianhua

2018-03-01

Computed Tomography (CT) is one of the most important medical imaging modality. CT images can be used to assist in the detection and diagnosis of lesions and to facilitate follow-up treatment. However, CT images are vulnerable to noise. Actually, there are two major source intrinsically causing the CT data noise, i.e., the X-ray photo statistics and the electronic noise background. Therefore, it is necessary to doing image quality assessment (IQA) in CT imaging before diagnosis and treatment. Most of existing CT images IQA methods are based on human observer study. However, these methods are impractical in clinical for their complex and time-consuming. In this paper, we presented a blind CT image quality assessment via deep learning strategy. A database of 1500 CT images is constructed, containing 300 high-quality images and 1200 corresponding noisy images. Specifically, the high-quality images were used to simulate the corresponding noisy images at four different doses. Then, the images are scored by the experienced radiologists by the following attributes: image noise, artifacts, edge and structure, overall image quality, and tumor size and boundary estimation with five-point scale. We trained a network for learning the non-liner map from CT images to subjective evaluation scores. Then, we load the pre-trained model to yield predicted score from the test image. To demonstrate the performance of the deep learning network in IQA, correlation coefficients: Pearson Linear Correlation Coefficient (PLCC) and Spearman Rank Order Correlation Coefficient (SROCC) are utilized. And the experimental result demonstrate that the presented deep learning based IQA strategy can be used in the CT image quality assessment.

Survey of the prevalence and methodology of quality assurance for B-mode ultrasound image quality among veterinary sonographers.

Science.gov (United States)

Hoscheit, Larry P; Heng, Hock Gan; Lim, Chee Kin; Weng, Hsin-Yi

2018-05-01

Image quality in B-mode ultrasound is important as it reflects the diagnostic accuracy and diagnostic information provided during clinical scanning. Quality assurance programs for B-mode ultrasound systems/components are comprised of initial quality acceptance testing and subsequent regularly scheduled quality control testing. The importance of quality assurance programs for B-mode ultrasound image quality using ultrasound phantoms is well documented in the human medical and medical physics literature. The purpose of this prospective, cross-sectional, survey study was to determine the prevalence and methodology of quality acceptance testing and quality control testing of image quality for ultrasound system/components among veterinary sonographers. An online electronic survey was sent to 1497 members of veterinary imaging organizations: the American College of Veterinary Radiology, the Veterinary Ultrasound Society, and the European Association of Veterinary Diagnostic Imaging, and a total of 167 responses were received. The results showed that the percentages of veterinary sonographers performing quality acceptance testing and quality control testing are 42% (64/151; 95% confidence interval 34-52%) and 26% (40/156: 95% confidence interval 19-33%) respectively. Of the respondents who claimed to have quality acceptance testing or quality control testing of image quality in place for their ultrasound system/components, 0% have performed quality acceptance testing or quality control testing correctly (quality acceptance testing 95% confidence interval: 0-6%, quality control testing 95% confidence interval: 0-11%). Further education and guidelines are recommended for veterinary sonographers in the area of quality acceptance testing and quality control testing for B-mode ultrasound equipment/components. © 2018 American College of Veterinary Radiology.

CT radiation dose and image quality optimization using a porcine model.

Science.gov (United States)

Zarb, Francis; McEntee, Mark F; Rainford, Louise

2013-01-01

To evaluate potential radiation dose savings and resultant image quality effects with regard to optimization of commonly performed computed tomography (CT) studies derived from imaging a porcine (pig) model. Imaging protocols for 4 clinical CT suites were developed based on the lowest milliamperage and kilovoltage, the highest pitch that could be set from current imaging protocol parameters, or both. This occurred before significant changes in noise, contrast, and spatial resolution were measured objectively on images produced from a quality assurance CT phantom. The current and derived phantom protocols were then applied to scan a porcine model for head, abdomen, and chest CT studies. Further optimized protocols were developed based on the same methodology as in the phantom study. The optimization achieved with respect to radiation dose and image quality was evaluated following data collection of radiation dose recordings and image quality review. Relative visual grading analysis of image quality criteria adapted from the European guidelines on radiology quality criteria for CT were used for studies completed with both the phantom-based or porcine-derived imaging protocols. In 5 out of 16 experimental combinations, the current clinical protocol was maintained. In 2 instances, the phantom protocol reduced radiation dose by 19% to 38%. In the remaining 9 instances, the optimization based on the porcine model further reduced radiation dose by 17% to 38%. The porcine model closely reflects anatomical structures in humans, allowing the grading of anatomical criteria as part of image quality review without radiation risks to human subjects. This study demonstrates that using a porcine model to evaluate CT optimization resulted in more radiation dose reduction than when imaging protocols were tested solely on quality assurance phantoms.

Effects of task and image properties on visual-attention deployment in image-quality assessment

Science.gov (United States)

Alers, Hani; Redi, Judith; Liu, Hantao; Heynderickx, Ingrid

2015-03-01

It is important to understand how humans view images and how their behavior is affected by changes in the properties of the viewed images and the task they are given, particularly the task of scoring the image quality (IQ). This is a complex behavior that holds great importance for the field of image-quality research. This work builds upon 4 years of research work spanning three databases studying image-viewing behavior. Using eye-tracking equipment, it was possible to collect information on human viewing behavior of different kinds of stimuli and under different experimental settings. This work performs a cross-analysis on the results from all these databases using state-of-the-art similarity measures. The results strongly show that asking the viewers to score the IQ significantly changes their viewing behavior. Also muting the color saturation seems to affect the saliency of the images. However, a change in IQ was not consistently found to modify visual attention deployment, neither under free looking nor during scoring. These results are helpful in gaining a better understanding of image viewing behavior under different conditions. They also have important implications on work that collects subjective image-quality scores from human observers.

Correlation of bone quality in radiographic images with clinical bone quality classification

Energy Technology Data Exchange (ETDEWEB)

Kim, Hyun Woo; Huh, Kyung Hoe; Kim, Jeong Hwa; Yi, Won Jin; Heo, Min Suk; Lee, Sam Sun; Choi, Soon Chul [Seoul National University, Seoul (Korea, Republic of); Park, Kwan Soo [Inje University, Seoul (Korea, Republic of)

2006-03-15

To investigate the validity of digital image processing on panoramic radiographs in estimating bone quality before endosseous dental implant installation by correlating bone quality in radiographic images with clinical bone quality classification. An experienced surgeon assessed and classified bone quality for implant sites with tactile sensation at the time of implant placement. Including fractal dimension eighteen morphologic features of trabecular pattern were examined in each anatomical sites on panoramic radiographs. Finally bone quality of 67 implant sites were evaluated in 42 patients. Pearson correlation analysis showed that three morphologic parameters had weak linear negative correlation with clinical bone quality classification showing correlation coefficients of -0.276, -0.280, and -0.289, respectively (p<0.05). And other three morphologic parameters had obvious linear negative correlation with clinical bone quality classification showing correlation coefficients of -0.346, -0.488, and -0.343 respectively (p<0.05). Fractal dimension also had a linear correlating with clinical bone quality classification with correlation coefficients -0.506 significantly (P<0.05). This study suggests that fractal and morphometric analysis using digital panoramic radiographs can be used to evaluate bone quality for implant recipient sites.

MO-DE-209-03: Assessing Image Quality

Energy Technology Data Exchange (ETDEWEB)

Zhao, W. [Stony Brook Medicine (United States)

2016-06-15

Digital Breast Tomosynthesis (DBT) is rapidly replacing mammography as the standard of care in breast cancer screening and diagnosis. DBT is a form of computed tomography, in which a limited set of projection images are acquired over a small angular range and reconstructed into tomographic data. The angular range varies from 15° to 50° and the number of projections varies between 9 and 25 projections, as determined by the equipment manufacturer. It is equally valid to treat DBT as the digital analog of classical tomography – that is, linear tomography. In fact, the name “tomosynthesis” stands for “synthetic tomography.” DBT shares many common features with classical tomography, including the radiographic appearance, dose, and image quality considerations. As such, both the science and practical physics of DBT systems is a hybrid between computed tomography and classical tomographic methods. In this lecture, we will explore the continuum from radiography to computed tomography to illustrate the characteristics of DBT. This lecture will consist of four presentations that will provide a complete overview of DBT, including a review of the fundamentals of DBT acquisition, a discussion of DBT reconstruction methods, an overview of dosimetry for DBT systems, and summary of the underlying image theory of DBT thereby relating image quality and dose. Learning Objectives: To understand the fundamental principles behind tomosynthesis image acquisition. To understand the fundamentals of tomosynthesis image reconstruction. To learn the determinants of image quality and dose in DBT, including measurement techniques. To learn the image theory underlying tomosynthesis, and the relationship between dose and image quality. ADM is a consultant to, and holds stock in, Real Time Tomography, LLC. ADM receives research support from Hologic Inc., Analogic Inc., and Barco NV.; ADM is a member of the Scientific Advisory Board for Gamma Medica Inc.; A. Maidment, Research Support

MO-DE-209-03: Assessing Image Quality

International Nuclear Information System (INIS)

Zhao, W.

2016-01-01

Digital Breast Tomosynthesis (DBT) is rapidly replacing mammography as the standard of care in breast cancer screening and diagnosis. DBT is a form of computed tomography, in which a limited set of projection images are acquired over a small angular range and reconstructed into tomographic data. The angular range varies from 15° to 50° and the number of projections varies between 9 and 25 projections, as determined by the equipment manufacturer. It is equally valid to treat DBT as the digital analog of classical tomography – that is, linear tomography. In fact, the name “tomosynthesis” stands for “synthetic tomography.” DBT shares many common features with classical tomography, including the radiographic appearance, dose, and image quality considerations. As such, both the science and practical physics of DBT systems is a hybrid between computed tomography and classical tomographic methods. In this lecture, we will explore the continuum from radiography to computed tomography to illustrate the characteristics of DBT. This lecture will consist of four presentations that will provide a complete overview of DBT, including a review of the fundamentals of DBT acquisition, a discussion of DBT reconstruction methods, an overview of dosimetry for DBT systems, and summary of the underlying image theory of DBT thereby relating image quality and dose. Learning Objectives: To understand the fundamental principles behind tomosynthesis image acquisition. To understand the fundamentals of tomosynthesis image reconstruction. To learn the determinants of image quality and dose in DBT, including measurement techniques. To learn the image theory underlying tomosynthesis, and the relationship between dose and image quality. ADM is a consultant to, and holds stock in, Real Time Tomography, LLC. ADM receives research support from Hologic Inc., Analogic Inc., and Barco NV.; ADM is a member of the Scientific Advisory Board for Gamma Medica Inc.; A. Maidment, Research Support

REQUIREMENTS FOR IMAGE QUALITY OF EMERGENCY SPACECRAFTS

Directory of Open Access Journals (Sweden)

A. I. Altukhov

2015-05-01

Full Text Available The paper deals with the method for formation of quality requirements to the images of emergency spacecrafts. The images are obtained by means of remote sensing of near-earth space orbital deployment in the visible range. of electromagnetic radiation. The method is based on a joint taking into account conditions of space survey, characteristics of surveillance equipment, main design features of the observed spacecrafts and orbital inspection tasks. Method. Quality score is the predicted linear resolution image that gives the possibility to create a complete view of pictorial properties of the space image obtained by electro-optical system from the observing satellite. Formulation of requirements to the numerical value of this indicator is proposed to perform based on the properties of remote sensing system, forming images in the conditions of outer space, and the properties of the observed emergency spacecraft: dimensions, platform construction of the satellite, on-board equipment placement. For method implementation the authors have developed a predictive model of requirements to a linear resolution for images of emergency spacecrafts, making it possible to select the intervals of space shooting and get the satellite images required for quality interpretation. Main results. To verify the proposed model functionality we have carried out calculations of the numerical values for the linear resolution of the image, ensuring the successful task of determining the gross structural damage of the spacecrafts and identifying changes in their spatial orientation. As input data were used with dimensions and geometric primitives corresponding to the shape of deemed inspected spacecrafts: Resurs-P", "Canopus-B", "Electro-L". Numerical values of the linear resolution images have been obtained, ensuring the successful task solution for determining the gross structural damage of spacecrafts.

Standardization of Image Quality Analysis – ISO 19264

DEFF Research Database (Denmark)

Wüller, Dietmar; Kejser, Ulla Bøgvad

2016-01-01

There are a variety of image quality analysis tools available for the archiving world, which are based on different test charts and analysis algorithms. ISO has formed a working group in 2012 to harmonize these approaches and create a standard way of analyzing the image quality for archiving...... systems. This has resulted in three documents that have been or are going to be published soon. ISO 19262 defines the terms used in the area of image capture to unify the language. ISO 19263 describes the workflow issues and provides detailed information on how the measurements are done. Last...... but not least ISO 19264 describes the measurements in detail and provides aims and tolerance levels for the different aspects. This paper will present the new ISO 19264 technical specification to analyze image quality based on a single capture of a multi-pattern test chart, and discuss the reasoning behind its...

How the task of evaluating image quality influences viewing behavior

NARCIS (Netherlands)

Alers, H.; Bos, Lennart; Heynderickx, I.E.J.

2011-01-01

Image quality scores collected in subjective experiments are widely used in image quality research, particularly in the design of objective quality assessment algorithms. It is therefore of vital importance to make sure that the collected scores reflect viewers' opinions in real-life situations.

The effect of image quality, repeated study, and assessment method on anatomy learning.

Science.gov (United States)

Fenesi, Barbara; Mackinnon, Chelsea; Cheng, Lucia; Kim, Joseph A; Wainman, Bruce C

2017-06-01

The use of two-dimensional (2D) images is consistently used to prepare anatomy students for handling real specimen. This study examined whether the quality of 2D images is a critical component in anatomy learning. The visual clarity and consistency of 2D anatomical images was systematically manipulated to produce low-quality and high-quality images of the human hand and human eye. On day 0, participants learned about each anatomical specimen from paper booklets using either low-quality or high-quality images, and then completed a comprehension test using either 2D images or three-dimensional (3D) cadaveric specimens. On day 1, participants relearned each booklet, and on day 2 participants completed a final comprehension test using either 2D images or 3D cadaveric specimens. The effect of image quality on learning varied according to anatomical content, with high-quality images having a greater effect on improving learning of hand anatomy than eye anatomy (high-quality vs. low-quality for hand anatomy P = 0.018; high-quality vs. low-quality for eye anatomy P = 0.247). Also, the benefit of high-quality images on hand anatomy learning was restricted to performance on short-answer (SA) questions immediately after learning (high-quality vs. low-quality on SA questions P = 0.018), but did not apply to performance on multiple-choice (MC) questions (high-quality vs. low-quality on MC questions P = 0.109) or after participants had an additional learning opportunity (24 hours later) with anatomy content (high vs. low on SA questions P = 0.643). This study underscores the limited impact of image quality on anatomy learning, and questions whether investment in enhancing image quality of learning aids significantly promotes knowledge development. Anat Sci Educ 10: 249-261. © 2016 American Association of Anatomists. © 2016 American Association of Anatomists.

Quality control: comparison of images quality with screen film system and digital mammography CR

International Nuclear Information System (INIS)

Alvarenga, Frederico L.; Nogueira, Maria do Socorro

2008-01-01

The mammography screen film system should be used as part of processing chemicals, revelation process, equipment and this system has have a progressive replacing by the digital technology Full Field Digital Mammography FFDM, Computed Radiography (CR) Mammography and hardcopy. This new acquisition process of medical images has improved radiology section; however it is necessary efficient means for evaluating of the quality parameters. It should be considered taking into account the adaptation of the existent equipment and that procedures adopted for the exam, as well the adaptation of the new mammography films, the radiologist view box constitutes a part of the quality control program. This program aims at obtaining radiography with good quality that allows obtaining more information for the diagnosis and decreases the patient dose. For evaluation the quality image, this article is focused on presenting the differences regarding the acquired images through simulator mammography radiographic PMMA (Poly methyl methacrylate) in CR Mammography system and screen film system. The tests were accomplished at the same equipment of Mammography with the Automatic Exposure Control using a tension of 28 kV for both systems. The quality tests evaluated the spatial resolution, the own structures of the phantom, artifacts, optical density and contrast with conventional and laser films by mammography system. The installation for the accomplishment of the test has a quality control program. The evaluation was based on the pattern developed by the competent organ of the State of Minas Gerais. In this study, it was verified that the suitable Phantom Mama used by the Brazilian School of Radiology for conventional mammography did not obtain satisfactory result for Spatial Resolution in the digital mammography system CR. The final aim of this work is to obtain parameters to characterize the reference phantom quality image in an objective way. These parameters will be used to compare

A quantitative image quality comparison of four different image guided radiotherapy devices

International Nuclear Information System (INIS)

Stuetzel, Julia; Oelfke, Uwe; Nill, Simeon

2008-01-01

Purpose: A study to quantitatively compare the image quality of four different image guided radiotherapy (IGRT) devices based on phantom measurements with respect to the additional dose delivered to the patient. Methods: Images of three different head-sized phantoms (diameter 16-18 cm) were acquired with the following four IGRT-CT solutions: (i) the Siemens Primatom single slice fan beam computed tomography (CT) scanner with an acceleration voltage of 130 kV, (ii) a Tomotherapy HI-ART II unit using a fan beam scanner with an energy of 3.5 MeV and (iii) the Siemens Artiste prototype, providing the possibility to perform kV (121 kV) and MV (6 MV) cone beam (CB) CTs. For each device three scan protocols (named low, normal, high) were selected to yield the same weighted computed tomography dose index (CTDI w ). Based on the individual inserts of the different phantoms the image quality achieved with each device at a certain dose level was characterized in terms of homogeneity, spatial resolution, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and electron density-to-CT-number conversion. Results: Based on the current findings for head-sized phantoms all devices show an electron density-to-CT-number conversion almost independent of the imaging parameters and hence can be suited for treatment planning purposes. The evaluation of the image quality, however, points out clear differences due to the different energies and geometries. The Primatom standard CT scanner shows throughout the best performance, especially for soft tissue contrast and spatial resolution with low imaging doses. Reasonable soft tissue contrast can be obtained with slightly higher doses compared to the CT scanner with the kVCB and the Tomotherapy unit. In order to get similar results with the MVCB system a much higher dose needs to be applied to the patient. Conclusion: Considering the entire investigations, especially in terms of contrast and spatial resolution, a rough tendency for

On sacrificing and self-preservation: One interpretation

Directory of Open Access Journals (Sweden)

Jovanović Đokica R.

2014-01-01

Full Text Available One of the initial points of departure is actually an idea by Branko Lazarević, an almost forgotten writer and critic, who stated that 'sacrifice and the only pure self-denial', adding that we are witness to two types of sacrifice: 'Bearing a cross signifies to a victim that one still remains on the other (non-spiritual, author's note side'. Sacrificing therefore means that one has entered this (spiritual, author's note side. In this paper the author is discussing the phenomenon of the so-called transparent, visible sacrifice, i.e. those sacrifices that are on 'this side', which, as such, is the only one detectable in sociological investigations. The basic premise of the paper claims that the basis of the phenomenon of sacrifice there is a need for co-participation, submissiveness towerds authority (be it military, religious, political… which is a condition for coexistence in a community. Survival is possible only as an extension of physical existence or as a participating part of a commemorative culture. The paper also analyses the assumption that the culture of sacrifice, among other things, constitutes itself under a set of possible punitive measures (physical or moral. Among others, some ideas by Russian authors stating that the institution of a sacrifice develops in a state of fear caused by ritual murder of a state's subjects, smerds, before the dead body of their supreme leader. The Russian writers naturally do not rule out a practice of ritual killing of subjects in different and older cultures other than that of Proto-Slavic ones.

Image Quality Assessment of JPEG Compressed Mars Science Laboratory Mastcam Images using Convolutional Neural Networks

Science.gov (United States)

Kerner, H. R.; Bell, J. F., III; Ben Amor, H.

2017-12-01

The Mastcam color imaging system on the Mars Science Laboratory Curiosity rover acquires images within Gale crater for a variety of geologic and atmospheric studies. Images are often JPEG compressed before being downlinked to Earth. While critical for transmitting images on a low-bandwidth connection, this compression can result in image artifacts most noticeable as anomalous brightness or color changes within or near JPEG compression block boundaries. In images with significant high-frequency detail (e.g., in regions showing fine layering or lamination in sedimentary rocks), the image might need to be re-transmitted losslessly to enable accurate scientific interpretation of the data. The process of identifying which images have been adversely affected by compression artifacts is performed manually by the Mastcam science team, costing significant expert human time. To streamline the tedious process of identifying which images might need to be re-transmitted, we present an input-efficient neural network solution for predicting the perceived quality of a compressed Mastcam image. Most neural network solutions require large amounts of hand-labeled training data for the model to learn the target mapping between input (e.g. distorted images) and output (e.g. quality assessment). We propose an automatic labeling method using joint entropy between a compressed and uncompressed image to avoid the need for domain experts to label thousands of training examples by hand. We use automatically labeled data to train a convolutional neural network to estimate the probability that a Mastcam user would find the quality of a given compressed image acceptable for science analysis. We tested our model on a variety of Mastcam images and found that the proposed method correlates well with image quality perception by science team members. When assisted by our proposed method, we estimate that a Mastcam investigator could reduce the time spent reviewing images by a minimum of 70%.

Saliency image of feature building for image quality assessment

Science.gov (United States)

Ju, Xinuo; Sun, Jiyin; Wang, Peng

2011-11-01

The purpose and method of image quality assessment are quite different for automatic target recognition (ATR) and traditional application. Local invariant feature detectors, mainly including corner detectors, blob detectors and region detectors etc., are widely applied for ATR. A saliency model of feature was proposed to evaluate feasibility of ATR in this paper. The first step consisted of computing the first-order derivatives on horizontal orientation and vertical orientation, and computing DoG maps in different scales respectively. Next, saliency images of feature were built based auto-correlation matrix in different scale. Then, saliency images of feature of different scales amalgamated. Experiment were performed on a large test set, including infrared images and optical images, and the result showed that the salient regions computed by this model were consistent with real feature regions computed by mostly local invariant feature extraction algorithms.

Image quality in conventional chest radiography. Evaluation using the postprocessing tool Diamond View

International Nuclear Information System (INIS)

Niemann, Tilo; Reisinger, Clemens; Rau, Philipp; Schwarz, Jochen; Ruis-Lopez, Laura; Bongartz, Georg

2010-01-01

The objective of this work was to evaluate the influence of the postprocessing tool Diamond View (Siemens AG Medical Solutions, Germany) on image quality in conventional chest radiography. Evaluation of image quality remains a challenge in conventional radiography. Based on the European Commission quality criteria we evaluated the improvement of image quality when applying the new postprocessing tool Diamond View (Siemens AG Medical solutions, Germany) to conventional chest radiographs. Three different readers prospectively evaluated 102 digital image pairs of chest radiographs. Statistical analysis was performed with a p value <0.05 considered as significant. Images were evaluated on basis of the modified imaging Quality Criteria by the Commission of the European Communities. Each of the 11 image quality criteria was evaluated separately using a five point classification. Statistical analysis showed an overall tendency for improved image quality for Diamond View (DV) for all criteria. Significant differences could be found in most of the criteria. In conclusion DV improves image quality in conventional chest radiographs.

IMPROVING THE QUALITY OF NEAR-INFRARED IMAGING OF IN VIVOBLOOD VESSELS USING IMAGE FUSION METHODS

DEFF Research Database (Denmark)

Jensen, Andreas Kryger; Savarimuthu, Thiusius Rajeeth; Sørensen, Anders Stengaard

2009-01-01

We investigate methods for improving the visual quality of in vivo images of blood vessels in the human forearm. Using a near-infrared light source and a dual CCD chip camera system capable of capturing images at visual and nearinfrared spectra, we evaluate three fusion methods in terms...... of their capability of enhancing the blood vessels while preserving the spectral signature of the original color image. Furthermore, we investigate a possibility of removing hair in the images using a fusion rule based on the "a trous" stationary wavelet decomposition. The method with the best overall performance...... with both speed and quality in mind is the Intensity Injection method. Using the developed system and the methods presented in this article, it is possible to create images of high visual quality with highly emphasized blood vessels....

Quality Evaluation in Wireless Imaging Using Feature-Based Objective Metrics

OpenAIRE

Engelke, Ulrich; Zepernick, Hans-Jürgen

2007-01-01

This paper addresses the evaluation of image quality in the context of wireless systems using feature-based objective metrics. The considered metrics comprise of a weighted combination of feature values that are used to quantify the extend by which the related artifacts are present in a processed image. In view of imaging applications in mobile radio and wireless communication systems, reduced-reference objective quality metrics are investigated for quantifying user-perceived quality. The exa...

Image quality control in radiodiagnostic in an University Hospital

International Nuclear Information System (INIS)

Almeida, Claudio Domingues de; Mota, Helvecio C.; Almeida, Carlos Eduardo de

1996-01-01

The image quality criteria proposed for European Union (UE) has been used to evaluate the chest x-ray examinations in a typical Department of Radiology of an University Hospital in Rio de Janeiro. The study includes information on x-ray beam parameters, film-screen combination, doses to the patients, film processing and image quality. Lateral and PA chest examinations of 63 patients were investigated. Only 10% of the patients presented entrance doses greater than the reference level proposed for UE and adopted by International Atomic Energy Agency and World Health Organization. The image quality has been approved for 87% of the examinations. (author)

Development of a quality assurance protocol for peripheral subtraction imaging applications

International Nuclear Information System (INIS)

Walsh, C.; Murphy, D.; O'Hare, N.

2002-01-01

Peripheral subtraction scanning is used to trace the blood vessels of upper and lower extremities. In some modern C-arm fluoroscopy systems this function is performed automatically. In this mode the system is programmed to advance and stop in a series of steps taking a mask image at each point. The system then repeats each step after the contrast agent has been injected, and produces a DSA image at each point. Current radiographic quality assurance protocols do not address this feature. This note reviews methods of measuring system vibration while images are being acquired in automated peripheral stepping. The effect on image quality pre- and post-image processing is assessed. Results show that peripheral stepping DSA does not provide the same degree of image quality as static DSA. In examining static test objects, the major cause of the reduction in image quality is misregistration due to vibration of the image intensifier during imaging. (author)

Implementation of quantitative methods of analysis of the image quality in mammography

International Nuclear Information System (INIS)

Ruiz Rodriguez, Ana Mariela

2012-01-01

A proper diagnosis of a mammogram requires optimal contrast and maximum resolution, this allows to visualize different structures with low contrast and diameter of the order of millimeters. The evaluation of image quality allows to characterize the physical properties of the system of image acquisition, such assessment is one of the cornerstones in a quality control program. The image quality of the ACR phantom was evaluated with the IAEA TECDOC 1517 protocol. Analytical methods have determined quality parameters of the dummy image TOR MAS. A method is developed to analyze the image quality of both mammographic phantoms by use of computational techniques with the ImageJ program, in doing this, more information was able to objectively characterize the image quality of the dummies. Furthermore, these parameters will serve to compare the images obtained at different mammographic centers of the Caja Costarricense de Seguro Social (CCSS) and eventually the time evolution in a particular installation. (author) [es

Image quality (IQ) guided multispectral image compression

Science.gov (United States)

Zheng, Yufeng; Chen, Genshe; Wang, Zhonghai; Blasch, Erik

2016-05-01

Image compression is necessary for data transportation, which saves both transferring time and storage space. In this paper, we focus on our discussion on lossy compression. There are many standard image formats and corresponding compression algorithms, for examples, JPEG (DCT -- discrete cosine transform), JPEG 2000 (DWT -- discrete wavelet transform), BPG (better portable graphics) and TIFF (LZW -- Lempel-Ziv-Welch). The image quality (IQ) of decompressed image will be measured by numerical metrics such as root mean square error (RMSE), peak signal-to-noise ratio (PSNR), and structural Similarity (SSIM) Index. Given an image and a specified IQ, we will investigate how to select a compression method and its parameters to achieve an expected compression. Our scenario consists of 3 steps. The first step is to compress a set of interested images by varying parameters and compute their IQs for each compression method. The second step is to create several regression models per compression method after analyzing the IQ-measurement versus compression-parameter from a number of compressed images. The third step is to compress the given image with the specified IQ using the selected compression method (JPEG, JPEG2000, BPG, or TIFF) according to the regressed models. The IQ may be specified by a compression ratio (e.g., 100), then we will select the compression method of the highest IQ (SSIM, or PSNR). Or the IQ may be specified by a IQ metric (e.g., SSIM = 0.8, or PSNR = 50), then we will select the compression method of the highest compression ratio. Our experiments tested on thermal (long-wave infrared) images (in gray scales) showed very promising results.

Effect of image quality on calcification detection in digital mammography

Energy Technology Data Exchange (ETDEWEB)

Warren, Lucy M.; Mackenzie, Alistair; Cooke, Julie; Given-Wilson, Rosalind M.; Wallis, Matthew G.; Chakraborty, Dev P.; Dance, David R.; Bosmans, Hilde; Young, Kenneth C. [National Co-ordinating Centre for the Physics of Mammography, Royal Surrey County Hospital NHS Foundation Trust, Guildford GU2 7XX, United Kingdom and Department of Physics, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, GU2 7XH (United Kingdom); Jarvis Breast Screening and Diagnostic Centre, Guildford GU1 1LJ (United Kingdom); Department of Radiology, St. George' s Healthcare NHS Trust, Tooting, London SW17 0QT (United Kingdom); Cambridge Breast Unit, Cambridge University Hospitals NHS Foundation Trust, Cambridge CB2 0QQ, United Kingdom and NIHR Cambridge Biomedical Research Centre, Cambridge CB2 0QQ (United Kingdom); Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania 15210 (United States); National Co-ordinating Centre for the Physics of Mammography, Royal Surrey County Hospital NHS Foundation Trust, Guildford GU2 7XX, United Kingdom and Department of Physics, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford GU2 7XH (United Kingdom); University Hospitals Leuven, Herestraat 49, 3000 Leuven (Belgium); National Co-ordinating Centre for the Physics of Mammography, Royal Surrey County Hospital NHS Foundation Trust, Guildford GU2 7XX, United Kingdom and Department of Physics, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford GU2 7XH (United Kingdom)

2012-06-15

Purpose: This study aims to investigate if microcalcification detection varies significantly when mammographic images are acquired using different image qualities, including: different detectors, dose levels, and different image processing algorithms. An additional aim was to determine how the standard European method of measuring image quality using threshold gold thickness measured with a CDMAM phantom and the associated limits in current EU guidelines relate to calcification detection. Methods: One hundred and sixty two normal breast images were acquired on an amorphous selenium direct digital (DR) system. Microcalcification clusters extracted from magnified images of slices of mastectomies were electronically inserted into half of the images. The calcification clusters had a subtle appearance. All images were adjusted using a validated mathematical method to simulate the appearance of images from a computed radiography (CR) imaging system at the same dose, from both systems at half this dose, and from the DR system at quarter this dose. The original 162 images were processed with both Hologic and Agfa (Musica-2) image processing. All other image qualities were processed with Agfa (Musica-2) image processing only. Seven experienced observers marked and rated any identified suspicious regions. Free response operating characteristic (FROC) and ROC analyses were performed on the data. The lesion sensitivity at a nonlesion localization fraction (NLF) of 0.1 was also calculated. Images of the CDMAM mammographic test phantom were acquired using the automatic setting on the DR system. These images were modified to the additional image qualities used in the observer study. The images were analyzed using automated software. In order to assess the relationship between threshold gold thickness and calcification detection a power law was fitted to the data. Results: There was a significant reduction in calcification detection using CR compared with DR: the alternative FROC

Image quality of conventional images of dual-layer SPECTRAL CT: a phantom study.

Science.gov (United States)

van Ommen, F; Bennink, E; Vlassenbroek, A; Dankbaar, J W; Schilham, A M R; Viergever, M A; de Jong, H W A M

2018-05-10

Spectral CT using a dual layer detector offers the possibility of retrospectively introducing spectral information to conventional CT images. In theory, the dual-layer technology should not come with a dose or image quality penalty for conventional images. In this study, we evaluate the influence of a dual-layer detector (IQon Spectral CT, Philips) on the image quality of conventional CT images, by comparing these images with those of a conventional but otherwise technically comparable single-layer CT scanner (Brilliance iCT, Philips), by means of phantom experiments. For both CT scanners conventional CT images were acquired using four adult scanning protocols: i) body helical, ii) body axial, iii) head helical and iv) head axial. A CATPHAN 600 phantom was scanned to conduct an assessment of image quality metrics at equivalent (CTDI) dose levels. Noise was characterized by means of noise power spectra (NPS) and standard deviation (SD) of a uniform region, and spatial resolution was evaluated with modulation transfer functions (MTF) of a tungsten wire. In addition, contrast-to-noise ratio (CNR), image uniformity, CT number linearity, slice thickness, slice spacing, and spatial linearity were measured and evaluated. Additional measurements of CNR, resolution and noise were performed in two larger phantoms. The resolution levels at 50%, 10% and 5% MTF of the iCT and IQon showed small but significant differences up to 0.25 lp/cm for body scans, and up to 0.2 lp/cm for head scans in favor of the IQon. The iCT and IQon showed perfect CT linearity for body scans, but for head scans both scanners showed an underestimation of the CT numbers of materials with a high opacity. Slice thickness was slightly overestimated for both scanners. Slice spacing was comparable and reconstructed correctly. In addition, spatial linearity was excellent for both scanners, with a maximum error of 0.11 mm. CNR was higher on the IQon compared to the iCT for both normal and larger phantoms with

Commentary: progress in optimization of patient dose and image quality in x-ray diagnostics

International Nuclear Information System (INIS)

Carlsson, G.A.; Chan, H.-P.

1999-01-01

into the technical performance and limitations of clinical x-ray equipment and the functioning of x-ray image intensifiers (XRIIs), and discuss the problem in an educational manner. The authors have succeeded in producing a paper that combines high scientific merit and valuable practical guidelines towards the optimization of paediatric fluoroscopy and radiography. This information, if properly utilized by practitioners, will contribute to significant (50%) reduction in radiation doses without sacrificing image quality and diagnostic accuracy. Fluoroscopy using XRIIs is one of the x-ray procedures that allows the possibility of bringing patient doses to an absolute minimum: quantum-noise due to the inevitable stochastic nature of the interactions of x-rays with the image receptor will ultimately limit the possibility for further dose reduction. In a well designed (quantum-noise limited) system, patient dose ( D) increases proportionally with the square of signal-to-noise ratio (SNR). The SNR of the ideal observer (ICRU 1996) may be used as image quality descriptor. To ascertain minimum patient dose, the just detectable SNR level of critical image details in a given diagnostic procedure should be determined. The dose-to-information conversion factor SNR 2 /D is independent of patient dose, thus providing a useful figure-of-merit for optimization of the technique parameters of an imaging task. In the cited study, the strategy for optimization is to maximize the SNR 2 /D ratio, leaving the absolute requirement on SNR (and patient dose) to be determined by the user. Technique factors which strongly influence the SNR 2 /D ratio are the energy spectrum (tube potential and total filtration) and the choice of anti-scatter technique. These can be adjusted by the user of clinical x-ray equipment and are focussed in the paper. A powerful tool used in executing the study is a carefully developed and validated computational model of the imaging chain (Tapiovaara and Sandborg 1995

Comparison of image quality and radiation exposure from digital and 105-mm film images in pediatric fluoroscopy

International Nuclear Information System (INIS)

Drake, D.G.; Day, D.L.; Alford, B.A.; Geise, R.; Thompson, W.M.

1987-01-01

This study was designed to compare image quality of digitally acquired films compared with conventional 105-mm films in pediatric gastrointestinal and genitourinary fluoroscopic studies. Films were acquired digitally in 1,024 x 1,024 matrix, 512 x 512 matrix, and 105-mm film. Based on the observers' median scoring, the 1,024 x 1,024 reduced to 512 x 512 matrix provided similar overall image quality to the 105-mm films. The digital images produced a patient radiation exposure of 25% to 30% that of the 105-mm images on their equipment. The authors conclude that digital images provide similar image quality to 105-mm images with a significant reduction in patient radiation exposure

The Importance of Store Image and Retail Service Quality in Private Brand Image-Building

Directory of Open Access Journals (Sweden)

Adi Alić

2017-03-01

Full Text Available Objective: The purpose of this research is to highlight the role which store image and retail service quality can play in private brand image-building in the context of an emerging market in South-Eastern Europe (i.e. Bosnia and Herzegovina. We propose to address this issue by seeking answers to the following questions: (1 Does a ‘halo effect’ take place between the store image and the private brand image? (2 How does consumer’s evaluation of the quality of the service delivered by a retailer affect the image of its private brand? Research Design & Methods: Data were collected through a field survey via the store-intercept method. The sample consisted of 699 customers of two large retail chains. The data were analysed using the Structural Equation Modelling technique. Findings: The findings of the present study suggest that store image and retail service quality are important factors in the formation of the image of product-branded products. Implications & Recommendations: This study offers some important insights for retailers who intend to develop their private brand. First, the image transfer from store brand to private brand suggests that retailers should consider the introduction of a private brand as a brand extension, with their stores as the parent brand. Second, we recommend that retailers put more emphasis on quality improvement initiatives related to the store environment attributes. Contribution & Value Added: This study enhances the discussion on the phenomenon of private branding by analysing the store-level factors which underpin the formation of private brand image in the context of less developed European markets.

Image quality testing of assembled IR camera modules

Science.gov (United States)

Winters, Daniel; Erichsen, Patrik

2013-10-01

Infrared (IR) camera modules for the LWIR (8-12_m) that combine IR imaging optics with microbolometer focal plane array (FPA) sensors with readout electronics are becoming more and more a mass market product. At the same time, steady improvements in sensor resolution in the higher priced markets raise the requirement for imaging performance of objectives and the proper alignment between objective and FPA. This puts pressure on camera manufacturers and system integrators to assess the image quality of finished camera modules in a cost-efficient and automated way for quality control or during end-of-line testing. In this paper we present recent development work done in the field of image quality testing of IR camera modules. This technology provides a wealth of additional information in contrast to the more traditional test methods like minimum resolvable temperature difference (MRTD) which give only a subjective overall test result. Parameters that can be measured are image quality via the modulation transfer function (MTF) for broadband or with various bandpass filters on- and off-axis and optical parameters like e.g. effective focal length (EFL) and distortion. If the camera module allows for refocusing the optics, additional parameters like best focus plane, image plane tilt, auto-focus quality, chief ray angle etc. can be characterized. Additionally, the homogeneity and response of the sensor with the optics can be characterized in order to calculate the appropriate tables for non-uniformity correction (NUC). The technology can also be used to control active alignment methods during mechanical assembly of optics to high resolution sensors. Other important points that are discussed are the flexibility of the technology to test IR modules with different form factors, electrical interfaces and last but not least the suitability for fully automated measurements in mass production.

An approach for quantitative image quality analysis for CT

Science.gov (United States)

Rahimi, Amir; Cochran, Joe; Mooney, Doug; Regensburger, Joe

2016-03-01

An objective and standardized approach to assess image quality of Compute Tomography (CT) systems is required in a wide variety of imaging processes to identify CT systems appropriate for a given application. We present an overview of the framework we have developed to help standardize and to objectively assess CT image quality for different models of CT scanners used for security applications. Within this framework, we have developed methods to quantitatively measure metrics that should correlate with feature identification, detection accuracy and precision, and image registration capabilities of CT machines and to identify strengths and weaknesses in different CT imaging technologies in transportation security. To that end we have designed, developed and constructed phantoms that allow for systematic and repeatable measurements of roughly 88 image quality metrics, representing modulation transfer function, noise equivalent quanta, noise power spectra, slice sensitivity profiles, streak artifacts, CT number uniformity, CT number consistency, object length accuracy, CT number path length consistency, and object registration. Furthermore, we have developed a sophisticated MATLAB based image analysis tool kit to analyze CT generated images of phantoms and report these metrics in a format that is standardized across the considered models of CT scanners, allowing for comparative image quality analysis within a CT model or between different CT models. In addition, we have developed a modified sparse principal component analysis (SPCA) method to generate a modified set of PCA components as compared to the standard principal component analysis (PCA) with sparse loadings in conjunction with Hotelling T2 statistical analysis method to compare, qualify, and detect faults in the tested systems.

DAF: differential ACE filtering image quality assessment by automatic color equalization

Science.gov (United States)

Ouni, S.; Chambah, M.; Saint-Jean, C.; Rizzi, A.

2008-01-01

Ideally, a quality assessment system would perceive and measure image or video impairments just like a human being. But in reality, objective quality metrics do not necessarily correlate well with perceived quality [1]. Plus, some measures assume that there exists a reference in the form of an "original" to compare to, which prevents their usage in digital restoration field, where often there is no reference to compare to. That is why subjective evaluation is the most used and most efficient approach up to now. But subjective assessment is expensive, time consuming and does not respond, hence, to the economic requirements [2,3]. Thus, reliable automatic methods for visual quality assessment are needed in the field of digital film restoration. The ACE method, for Automatic Color Equalization [4,6], is an algorithm for digital images unsupervised enhancement. It is based on a new computational approach that tries to model the perceptual response of our vision system merging the Gray World and White Patch equalization mechanisms in a global and local way. Like our vision system ACE is able to adapt to widely varying lighting conditions, and to extract visual information from the environment efficaciously. Moreover ACE can be run in an unsupervised manner. Hence it is very useful as a digital film restoration tool since no a priori information is available. In this paper we deepen the investigation of using the ACE algorithm as a basis for a reference free image quality evaluation. This new metric called DAF for Differential ACE Filtering [7] is an objective quality measure that can be used in several image restoration and image quality assessment systems. In this paper, we compare on different image databases, the results obtained with DAF and with some subjective image quality assessments (Mean Opinion Score MOS as measure of perceived image quality). We study also the correlation between objective measure and MOS. In our experiments, we have used for the first image

Quality assessment of the digitalization process of analog x-ray images

International Nuclear Information System (INIS)

Georgieva, D.

2014-01-01

Computer-assisted diagnosis enabled doctors for a second point-of-view on the test results. This improves the diseases' early detection and significantly reduces the chance of errors. These methods very nicely complemented the possibilities of digital medical imaging apparatus, but in analog images their applicability and results entirely depend on the quality of analog images digitalisation. Today many standards and remarks for good practices discuss the digital apparatus image quality but the digitalisation process of analog medical images is not a part of them. Medical imaging apparatus have become digital, but within an entirely digital medical environment is necessary for their ability to blend with the old analog medical imaging carriers. The life of patients doesn't start with the beginning of digital era and for the aim of tracking diseases it is necessary to use the new digital images as well as older analog ones. For the generation of 40-50 years a large archive of images is piled up, which should be accounted of in the diagnosis process. This article is the author's study of the digitalized image quality problem. It offers a new approach to the x-ray image digitalisation - getting the HDR-image by optical sensor. After the HDR-image generation method offers to be used a digital signal processing to improve the quality of the final 16 bit gray scale medical image. The new method for medical image enhancement is proposed - it improves the image contrast, it increases or preserves the dynamic range and it doesn't lead to the loss of small low contrast structures in the image. Key words: Quality of Digital X-Rays Images

Assessment of image quality and patient doses in mammography in Tanzania

International Nuclear Information System (INIS)

Muhogora, W.E.; Lema, U.S.; Lyimo, R.; Dharsee, J.D.

2008-01-01

Full text: The objective of this work was to investigate on pilot scale the potential for optimization of screen-film based mammography practice in Tanzania. Two hospitals participated in the study and were Samaritan (with Siemens unit, model MAMMOMAT 5427901X059) and AgaKhan Medical Centre (with a Philips unit, model MD 4000). Image quality assessment was done by the radiologist at the hospital in two phases each of 2 weeks by scoring the images with assistance of image quality criteria supplied by IAEA. The causes for poor image quality were also identified. A quality assurance (QA) program was then implemented and corrective actions applied based on image quality assessment and equipment performance. In the second phase, image quality assessment was repeated followed by the estimation of entrance surface air kerma (ESAK) on 4.5 cm PMMA. The results show that the magnitude of poor image quality was up to 50% for Siemens in the first phase and decreased up to 30% after implementation of QA programme. With Philips unit, the magnitude of poor image quality was up to 70% and decreased up to 39% after implementation of QA programme. Generally, the main causes of poor images at all hospitals were over and under exposure, artefacts and breast misplacement. Others were unsharpness of skin structure (rosette from pores) along pectoral muscle, unsharpness of vascular structure (seen through most dense parenchyma), media breast tissue, and vessels and fibrous strands, pectoral muscle margin. Major image quality improvement in terms of percentage points were 10 (over or under exposure), 11 (artefacts) and 9 (skin structure (rosettes from pores-visually not sharp). However, the influence of some causes could not be reduced with QA program, presumably due to skill or equipment related reasons. The ESAK was determined to be 7.1 mGy (30 kVp, Mo/Mo) for Siemens and 3.1 mGy (28 kVp, Mo/Mo) for Philips unit. The ESAK values were well below the recommended diagnostic reference level

Improvement of material decomposition and image quality in dual-energy radiography by reducing image noise

International Nuclear Information System (INIS)

Lee, D.; Choi, S.; Kim, H.; Kim, H.-J.; Kim, Y.-S.; Choi, S.; Lee, H.; Jo, B.D.; Jeon, P.-H.; Kim, H.; Kim, D.

2016-01-01

Although digital radiography has been widely used for screening human anatomical structures in clinical situations, it has several limitations due to anatomical overlapping. To resolve this problem, dual-energy imaging techniques, which provide a method for decomposing overlying anatomical structures, have been suggested as alternative imaging techniques. Previous studies have reported several dual-energy techniques, each resulting in different image qualities. In this study, we compared three dual-energy techniques: simple log subtraction (SLS), simple smoothing of a high-energy image (SSH), and anti-correlated noise reduction (ACNR) with respect to material thickness quantification and image quality. To evaluate dual-energy radiography, we conducted Monte Carlo simulation and experimental phantom studies. The Geant 4 Application for Tomographic Emission (GATE) v 6.0 and tungsten anode spectral model using interpolation polynomials (TASMIP) codes were used for simulation studies and digital radiography, and human chest phantoms were used for experimental studies. The results of the simulation study showed improved image contrast-to-noise ratio (CNR) and coefficient of variation (COV) values and bone thickness estimation accuracy by applying the ACNR and SSH methods. Furthermore, the chest phantom images showed better image quality with the SSH and ACNR methods compared to the SLS method. In particular, the bone texture characteristics were well-described by applying the SSH and ACNR methods. In conclusion, the SSH and ACNR methods improved the accuracy of material quantification and image quality in dual-energy radiography compared to SLS. Our results can contribute to better diagnostic capabilities of dual-energy images and accurate material quantification in various clinical situations.

Real-time computer treatment of THz passive device images with the high image quality

Science.gov (United States)

Trofimov, Vyacheslav A.; Trofimov, Vladislav V.

2012-06-01

We demonstrate real-time computer code improving significantly the quality of images captured by the passive THz imaging system. The code is not only designed for a THz passive device: it can be applied to any kind of such devices and active THz imaging systems as well. We applied our code for computer processing of images captured by four passive THz imaging devices manufactured by different companies. It should be stressed that computer processing of images produced by different companies requires using the different spatial filters usually. The performance of current version of the computer code is greater than one image per second for a THz image having more than 5000 pixels and 24 bit number representation. Processing of THz single image produces about 20 images simultaneously corresponding to various spatial filters. The computer code allows increasing the number of pixels for processed images without noticeable reduction of image quality. The performance of the computer code can be increased many times using parallel algorithms for processing the image. We develop original spatial filters which allow one to see objects with sizes less than 2 cm. The imagery is produced by passive THz imaging devices which captured the images of objects hidden under opaque clothes. For images with high noise we develop an approach which results in suppression of the noise after using the computer processing and we obtain the good quality image. With the aim of illustrating the efficiency of the developed approach we demonstrate the detection of the liquid explosive, ordinary explosive, knife, pistol, metal plate, CD, ceramics, chocolate and other objects hidden under opaque clothes. The results demonstrate the high efficiency of our approach for the detection of hidden objects and they are a very promising solution for the security problem.

The mobile image quality survey game

Science.gov (United States)

Rasmussen, D. René

2012-01-01

In this paper we discuss human assessment of the quality of photographic still images, that are degraded in various manners relative to an original, for example due to compression or noise. In particular, we examine and present results from a technique where observers view images on a mobile device, perform pairwise comparisons, identify defects in the images, and interact with the display to indicate the location of the defects. The technique measures the response time and accuracy of the responses. By posing the survey in a form similar to a game, providing performance feedback to the observer, the technique attempts to increase the engagement of the observers, and to avoid exhausting observers, a factor that is often a problem for subjective surveys. The results are compared with the known physical magnitudes of the defects and with results from similar web-based surveys. The strengths and weaknesses of the technique are discussed. Possible extensions of the technique to video quality assessment are also discussed.

Clinical evaluation of a new set of image quality criteria for mammography

International Nuclear Information System (INIS)

Grahn, A.; Hemdal, B.; Andersson, I.; Ruschin, M.; Thilander-Klang, A.; Boerjesson, S.; Tingberg, A.; Mattsson, S.; Haakansson, M.; Baath, M.; Maansson, L. G.; Medin, J.; Wanninger, F.; Panzer, W.

2005-01-01

The European Commission (EC) quality criteria for screen-film mammography are used as a tool to asses image quality. A new set of criteria was developed and initially tested in a previous study. In the present study, these criteria are further evaluated using screen-film mammograms that have been digitised, manipulated to simulated different image quality level and reprinted on film. Expert radiologists have evaluated these manipulated to simulate different image quality levels and reprinted on film. Expert radiologists have evaluated these manipulated images using both the original (EC) and the new criteria. A comparison of three different simulated dose levels that the new criteria yield a larger separation of image criteria scores than the old ones. These results indicated that the new set of image quality criteria has a higher discriminative power than the old set and thus seems to be more suitable for evaluation of image quality in mammography. (authors)

Fundamental factors influencing portal image quality

International Nuclear Information System (INIS)

Jaffray, D.A.

1995-01-01

It has been recognized that improved methods of verifying radiation field placement in external beam radiotherapy are required in order to make frequent checks of field placement feasible. As a result, a large number of electronic portal imaging systems have been developed as possible replacements for film. These developments have produced digital systems with faster acquisition and improved display contrast, however, the quality of the images acquired with such systems is still disappointing. This presentation examines many of the fundamental factors which limit the quality of radiographs obtained with a megavoltage radiotherapy beam. The size and shape of the radiation sources (focal and extra-focal) in radiotherapy machines and their influence on the spatial resolution of portal images are examined. Monte Carlo simulations of x-ray interactions within the patient determined that a significant fraction of the x-ray scatter generated in the patient is due to bremsstrahlung and positron annihilation. Depending on the detector, the scatter signal can reduce the differential signal-to-noise by 20%. Furthermore, a Monte Carlo study of the interaction of x-rays within typical fluoroscopic imaging detectors (metal plate/phosphor screen) demonstrates the degrading effect of energy absorption noise on the detective quantum efficiency of fluoroscopic based imaging systems. Finally, the spatial frequency content in the x-ray shadowgram is demonstrated to change with x-ray energy, resulting in images that appear to have reduced spatial resolution at megavoltage energies. The relative magnitude of each of these factors will be presented and recommendations for the next generation of portal imaging systems will be made

Indicators of image quality and doses in mammography

International Nuclear Information System (INIS)

Gaona, E.; Franco E, J.G.; Azorin N, J.; Diaz G, J.A.I.; Arreola, M.

2007-01-01

Full text: The purpose of the study was to determine the values of the image quality indicators and their relationship with the dose in mammography of screen-film that they allowed the detection of a bigger number of objects in the images obtained with the mannequin (phantom) authorized of the ACR/FDA. The study was carried out in four mammography services in a period of 12 months. The indicators of the image quality are the half optic density (DOM), contrast (differences of densities), the number of observed objects in the images and the dose for image. The minimum acceptable values by the ACR/FDA are a half optical density of 1.4, contrast of 0.4 and the one numbers minimum of objects observed in the image of the mannequin of mammography of 10 (4 fibers, 3 groups of calcifications and 3 masses), with a maximum dose by image of 3 mGy. The found results are half optical density of 1.9, contrast of 0.56 and the average number of objects observed in the images of 12, with a dose in the interval of 1.6 mGy to 2.4 mGy. The doses were measured by thermoluminescent dosimetry and ionization chamber. Once carried out the analysis of the tendencies of the indicators of image quality and their distributions is found that for a p < 0.05, the bigger number of objects observed in the images is in the interval from 1.8 to 1.9 of DOM. When comparing both mammography system, the system screen-film has a lower variability in the distribution of objects associated to a DOM. (Author)

Pre-analytic process control: projecting a quality image.

Science.gov (United States)

Serafin, Mark D

2006-09-26

Within the health-care system, the term "ancillary department" often describes the laboratory. Thus, laboratories may find it difficult to define their image and with it, customer perception of department quality. Regulatory requirements give laboratories who so desire an elegant way to address image and perception issues--a comprehensive pre-analytic system solution. Since large laboratories use such systems--laboratory service manuals--I describe and illustrate the process for the benefit of smaller facilities. There exist resources to help even small laboratories produce a professional service manual--an elegant solution to image and customer perception of quality.

A factorial experiment on image quality and radiation dose

International Nuclear Information System (INIS)

Norrman, E.; Persliden, J.

2005-01-01

To find if factorial experiments can be used in the optimisation of diagnostic imaging, a factorial experiment was performed to investigate some of the factors that influence image quality, kerma area product (KAP) and effective dose (E). In a factorial experiment the factors are varied together instead of one at a time, making it possible to discover interactions between the factors as well as major effects. The factors studied were tube potential, tube loading, focus size and filtration. Each factor was set to two levels (low and high). The influence of the factors on the response variables (image quality, KAP and E) was studied using a direct digital detector. The major effects of each factor on the response variables were estimated as well as the interaction effects between factors. The image quality, KAP and E were mainly influenced by tube loading, tube potential and filtration. There were some active interactions, for example, between tube potential and filtration and between tube loading and filtration. The study shows that factorial experiments can be used to predict the influence of various parameters on image quality and radiation dose. (authors)

Spectral CT imaging in patients with Budd-Chiari syndrome: investigation of image quality.

Science.gov (United States)

Su, Lei; Dong, Junqiang; Sun, Qiang; Liu, Jie; Lv, Peijie; Hu, Lili; Yan, Liangliang; Gao, Jianbo

2014-11-01

To assess the image quality of monochromatic imaging from spectral CT in patients with Budd-Chiari syndrome (BCS), fifty patients with BCS underwent spectral CT to generate conventional 140 kVp polychromatic images (group A) and monochromatic images, with energy levels from 40 to 80, 40 + 70, and 50 + 70 keV fusion images (group B) during the portal venous phase (PVP) and the hepatic venous phase (HVP). Two-sample t tests compared vessel-to-liver contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR) for the portal vein (PV), hepatic vein (HV), inferior vena cava. Readers' subjective evaluations of the image quality were recorded. The highest SNR values in group B were distributed at 50 keV; the highest CNR values in group B were distributed at 40 keV. The higher CNR values and SNR values were obtained though PVP of PV (SNR 18.39 ± 6.13 vs. 10.56 ± 3.31, CNR 7.81 ± 3.40 vs. 3.58 ± 1.31) and HVP of HV (3.89 ± 2.08 vs. 1.27 ± 1.55) in the group B; the lower image noise for group B was at 70 keV and 50 + 70 keV (15.54 ± 8.39 vs. 18.40 ± 4.97, P = 0.0004 and 18.97 ± 7.61 vs. 18.40 ± 4.97, P = 0.0691); the results show that the 50 + 70 keV fusion image quality was better than that in group A. Monochromatic energy levels of 40-70, 40 + 70, and 50 + 70 keV fusion image can increase vascular contrast and that will be helpful for the diagnosis of BCS, we select the 50 + 70 keV fusion image to acquire the best BCS images.

Reducing radiation dose without compromising image quality in preoperative perforator flap imaging with CTA using ASIR technology.

Science.gov (United States)

Niumsawatt, Vachara; Debrotwir, Andrew N; Rozen, Warren Matthew

2014-01-01

Computed tomographic angiography (CTA) has become a mainstay in preoperative perforator flap planning in the modern era of reconstructive surgery. However, the increased use of CTA does raise the concern of radiation exposure to patients. Several techniques have been developed to decrease radiation dosage without compromising image quality, with varying results. The most recent advance is in the improvement of image reconstruction using an adaptive statistical iterative reconstruction (ASIR) algorithm. We sought to evaluate the image quality of ASIR in preoperative deep inferior epigastric perforator (DIEP) flap surgery, through a direct comparison with conventional filtered back projection (FBP) images. A prospective review of 60 consecutive ASIR and 60 consecutive FBP CTA images using similar protocol (except for radiation dosage) was undertaken, analyzed by 2 independent reviewers. In both groups, we were able to accurately identify axial arteries and their perforators. Subjective analysis of image quality demonstrated no statistically significant difference between techniques. ASIR can thus be used for preoperative imaging with similar image quality to FBP, but with a 60% reduction in radiation delivery to patients.

Dosimetry and image quality assessment in a direct radiography system

Energy Technology Data Exchange (ETDEWEB)

Oliveira, Bruno Beraldo; Paixao, Lucas; Nogueira, Maria do Socorro, E-mail: boliveira.mg@gmail.com [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil); Oliveira, Marcio Alves de [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Fac. de Medicina. Dept. de Anatomia e Imagem; Teixeira, Maria Helena Araujo [Clinica Dra. Maria Helena Araujo Teixeira, Belo Horizonte, MG (Brazil)

2014-11-15

Objective: to evaluate the mean glandular dose with a solid state detector and the image quality in a direct radiography system, utilizing phantoms. Materials and methods: Irradiations were performed with automatic exposure control and polymethyl methacrylate slabs with different thicknesses to calculate glandular dose values. The image quality was evaluated by means of the structures visualized on the images of the phantoms. Results: considering the uncertainty of the measurements, the mean glandular dose results are in agreement with the values provided by the equipment and with internationally adopted reference levels. Results obtained from images of the phantoms were in agreement with the reference values. Conclusion: the present study contributes to verify the equipment conformity as regards dose values and image quality. (author)

Automated daily quality control analysis for mammography in a multi-unit imaging center.

Science.gov (United States)

Sundell, Veli-Matti; Mäkelä, Teemu; Meaney, Alexander; Kaasalainen, Touko; Savolainen, Sauli

2018-01-01

Background The high requirements for mammography image quality necessitate a systematic quality assurance process. Digital imaging allows automation of the image quality analysis, which can potentially improve repeatability and objectivity compared to a visual evaluation made by the users. Purpose To develop an automatic image quality analysis software for daily mammography quality control in a multi-unit imaging center. Material and Methods An automated image quality analysis software using the discrete wavelet transform and multiresolution analysis was developed for the American College of Radiology accreditation phantom. The software was validated by analyzing 60 randomly selected phantom images from six mammography systems and 20 phantom images with different dose levels from one mammography system. The results were compared to a visual analysis made by four reviewers. Additionally, long-term image quality trends of a full-field digital mammography system and a computed radiography mammography system were investigated. Results The automated software produced feature detection levels comparable to visual analysis. The agreement was good in the case of fibers, while the software detected somewhat more microcalcifications and characteristic masses. Long-term follow-up via a quality assurance web portal demonstrated the feasibility of using the software for monitoring the performance of mammography systems in a multi-unit imaging center. Conclusion Automated image quality analysis enables monitoring the performance of digital mammography systems in an efficient, centralized manner.

TH-B-207B-00: Pediatric Image Quality Optimization

International Nuclear Information System (INIS)

2016-01-01

This imaging educational program will focus on solutions to common pediatric image quality optimization challenges. The speakers will present collective knowledge on best practices in pediatric imaging from their experience at dedicated children’s hospitals. One of the most commonly encountered pediatric imaging requirements for the non-specialist hospital is pediatric CT in the emergency room setting. Thus, this educational program will begin with optimization of pediatric CT in the emergency department. Though pediatric cardiovascular MRI may be less common in the non-specialist hospitals, low pediatric volumes and unique cardiovascular anatomy make optimization of these techniques difficult. Therefore, our second speaker will review best practices in pediatric cardiovascular MRI based on experiences from a children’s hospital with a large volume of cardiac patients. Learning Objectives: To learn techniques for optimizing radiation dose and image quality for CT of children in the emergency room setting. To learn solutions for consistently high quality cardiovascular MRI of children

TH-B-207B-00: Pediatric Image Quality Optimization

Energy Technology Data Exchange (ETDEWEB)

NONE

2016-06-15

This imaging educational program will focus on solutions to common pediatric image quality optimization challenges. The speakers will present collective knowledge on best practices in pediatric imaging from their experience at dedicated children’s hospitals. One of the most commonly encountered pediatric imaging requirements for the non-specialist hospital is pediatric CT in the emergency room setting. Thus, this educational program will begin with optimization of pediatric CT in the emergency department. Though pediatric cardiovascular MRI may be less common in the non-specialist hospitals, low pediatric volumes and unique cardiovascular anatomy make optimization of these techniques difficult. Therefore, our second speaker will review best practices in pediatric cardiovascular MRI based on experiences from a children’s hospital with a large volume of cardiac patients. Learning Objectives: To learn techniques for optimizing radiation dose and image quality for CT of children in the emergency room setting. To learn solutions for consistently high quality cardiovascular MRI of children.

Image quality assessment using two-dimensional complex mel-cepstrum

Science.gov (United States)

Cakir, Serdar; Cetin, A. Enis

2016-11-01

Assessment of visual quality plays a crucial role in modeling, implementation, and optimization of image- and video-processing applications. The image quality assessment (IQA) techniques basically extract features from the images to generate objective scores. Feature-based IQA methods generally consist of two complementary phases: (1) feature extraction and (2) feature pooling. For feature extraction in the IQA framework, various algorithms have been used and recently, the two-dimensional (2-D) mel-cepstrum (2-DMC) feature extraction scheme has provided promising results in a feature-based IQA framework. However, the 2-DMC feature extraction scheme completely loses image-phase information that may contain high-frequency characteristics and important structural components of the image. In this work, "2-D complex mel-cepstrum" is proposed for feature extraction in an IQA framework. The method tries to integrate Fourier transform phase information into the 2-DMC, which was shown to be an efficient feature extraction scheme for assessment of image quality. Support vector regression is used for feature pooling that provides mapping between the proposed features and the subjective scores. Experimental results show that the proposed technique obtains promising results for the IQA problem by making use of the image-phase information.

Optimization of image quality and patient dose in mammography

International Nuclear Information System (INIS)

Shafqat Faaruq; Jaferi, R.A.; Nafeesa Nazlee

2007-01-01

Complete test of publication follows. Optimization of patient dose and image quality can be defined as to get the best image quality with minimum possible radiation dose to the patient by setting various parameters and modes of operation available in mammography machines. The optimization procedures were performed on two mammography units from M/S GE and Metaltronica, available at NORI, using standard mammographic accreditation phantom (Model: BR-156) and acrylic sheets of variable thicknesses. Quality assurance and quality control (QC) tests being the essential part of optimization. The QC tests as recommended by American College of Radiology, were first performed on both machines as well as X-ray film processor. In the second step, different affecting the image quality and radiation dose to patient, like film screen combination (FSC), phantom optical density (PD), kVp, mAs etc, were adjusted for various phantom thicknesses ranging from 3 cm to 6.5 cm in various modes of operation in the machines (semi-auto- and manual in GE, Auto-, semi-auto- and manual mode in Metaltronica). The image quality was studied for these optimized parameters on the basis of the number of test objects of the phantom visible in these images. Finally the linear relationship between mAs and skin entrance dose (mGy) was verified using ionization chamber with the phantom and the actual patients. Despite some practical limitations, the results of the quality assurance tests were within acceptable limits defined by ACR. The dose factor for GE was 68.0 y/mAs, while 76.0 mGy/mAs for Metaltronica at 25 kVp. Before the start of this study the only one mammography unit GE, was routinely used at NORI and normal mode of operation of this unit was semi-auto mode with fixed kVp independent of compressed breast thickness, but in this study it was concluded that selecting kVp according to beast thickness result in an appreciable dose reduction (4-5 times less) without any compromise in image quality. The

Image quality enhancement for skin cancer optical diagnostics

Science.gov (United States)

Bliznuks, Dmitrijs; Kuzmina, Ilona; Bolocko, Katrina; Lihachev, Alexey

2017-12-01

The research presents image quality analysis and enhancement proposals in biophotonic area. The sources of image problems are reviewed and analyzed. The problems with most impact in biophotonic area are analyzed in terms of specific biophotonic task - skin cancer diagnostics. The results point out that main problem for skin cancer analysis is the skin illumination problems. Since it is often not possible to prevent illumination problems, the paper proposes image post processing algorithm - low frequency filtering. Practical results show diagnostic results improvement after using proposed filter. Along that, filter do not reduces diagnostic results' quality for images without illumination defects. Current filtering algorithm requires empirical tuning of filter parameters. Further work needed to test the algorithm in other biophotonic applications and propose automatic filter parameter selection.

Performance comparison of different graylevel image fusion schemes through a universal image quality index

NARCIS (Netherlands)

Toet, A.; Hogervorst, M.A.

2003-01-01

We applied a recently introduced universal image quality index Q that quantifies the distortion of a processed image relative to its original version, to assess the performance of different graylevel image fusion schemes. The method is as follows. First, we adopt an original test image as the

Fourier transform based scalable image quality measure.

Science.gov (United States)

Narwaria, Manish; Lin, Weisi; McLoughlin, Ian; Emmanuel, Sabu; Chia, Liang-Tien

2012-08-01

We present a new image quality assessment (IQA) algorithm based on the phase and magnitude of the 2D (twodimensional) Discrete Fourier Transform (DFT). The basic idea is to compare the phase and magnitude of the reference and distorted images to compute the quality score. However, it is well known that the Human Visual Systems (HVSs) sensitivity to different frequency components is not the same. We accommodate this fact via a simple yet effective strategy of nonuniform binning of the frequency components. This process also leads to reduced space representation of the image thereby enabling the reduced-reference (RR) prospects of the proposed scheme. We employ linear regression to integrate the effects of the changes in phase and magnitude. In this way, the required weights are determined via proper training and hence more convincing and effective. Lastly, using the fact that phase usually conveys more information than magnitude, we use only the phase for RR quality assessment. This provides the crucial advantage of further reduction in the required amount of reference image information. The proposed method is therefore further scalable for RR scenarios. We report extensive experimental results using a total of 9 publicly available databases: 7 image (with a total of 3832 distorted images with diverse distortions) and 2 video databases (totally 228 distorted videos). These show that the proposed method is overall better than several of the existing fullreference (FR) algorithms and two RR algorithms. Additionally, there is a graceful degradation in prediction performance as the amount of reference image information is reduced thereby confirming its scalability prospects. To enable comparisons and future study, a Matlab implementation of the proposed algorithm is available at http://www.ntu.edu.sg/home/wslin/reduced_phase.rar.

Physical foundations of image quality in nuclear medicine. Methods for its evaluation

International Nuclear Information System (INIS)

Perez Diaz, Marlen; Diaz Rizo, Oscar

2007-01-01

The present paper describes the main physical factors which characterize image quality in Nuclear Medicine from the physical and mathematical point of view. A conceptual description of how image system (gamma camera) degrades the information emitted by the object is also presented. A critical review of some qualitative and quantitative methods for grading image quality, collateral to equipment quality control, follows this material. Among these methods we present the ROC analysis, Clustering Techniques and Discriminant Analysis. As a part of the two last ones, we also analyze the main factors which determine image quality and how they produce changes in the quantitative physical variables measured on the images. A comparison among the methods is also presented, remarking their utility to check image quality, as well as the main advantages and disadvantages of each one (au)

Detection and optimization of image quality and dose in digital mammography systems

International Nuclear Information System (INIS)

Semturs, F.

2015-01-01

Background and purpose: During the last few years, mammography institutes have replaced their conventional mammography systems (FSM) with digital mammography systems (FFDM). This happened mainly in direction to digital computed radiography systems (FFDM-CR), where the mammography device could be kept in operation. Consequently also the AEC-parameters have not been changed and therefore the same dose as for FFM was used. Following the main theme of the thesis "Optimization of image quality and dose", also measurements with such CR-Systems have been performed in relation to image quality and dose behavior. Optimization in this context means - in following the ALARA principle - the reduction of dose while ensuring required clinical image quality. With other words - image quality is of higher value compared to dose. Considering this, it has been found out through measurements during this thesis, that FFDM-CR Systems need considerable more dose for achieving image quality comparable with FFM. On the other hand, it has been shown with measurements during this thesis, that the newest FFDM-CR technology (needle structure) supports dose reduction (optimization) to a certain degree without compromising image quality. Dose increase, as recommended in this thesis, could also increase the danger of more radiation induced carcinoma. There are several studies (which are also discussed in this thesis), which show that the benefit of not missing cancers because of higher dose dramatically overrides any health concerns. Such an optimization of image quality and dose is now described in more detail by comparing the new CR needle technology with the older power based CR technology. Material and Methods: The image quality and dose behavior for multiple breast thicknesses (simulated with PMMA slabs) of a CR needle crystal detector system is optimized by considering also different beam qualities. Technical image quality is determined with a low contrast phantom (CDMAM phantom) and from

Synthesized view comparison method for no-reference 3D image quality assessment

Science.gov (United States)

Luo, Fangzhou; Lin, Chaoyi; Gu, Xiaodong; Ma, Xiaojun

2018-04-01

We develop a no-reference image quality assessment metric to evaluate the quality of synthesized view rendered from the Multi-view Video plus Depth (MVD) format. Our metric is named Synthesized View Comparison (SVC), which is designed for real-time quality monitoring at the receiver side in a 3D-TV system. The metric utilizes the virtual views in the middle which are warped from left and right views by Depth-image-based rendering algorithm (DIBR), and compares the difference between the virtual views rendered from different cameras by Structural SIMilarity (SSIM), a popular 2D full-reference image quality assessment metric. The experimental results indicate that our no-reference quality assessment metric for the synthesized images has competitive prediction performance compared with some classic full-reference image quality assessment metrics.

The semantics of image quality

NARCIS (Netherlands)

Janssen, T.J.W.M.; Blommaert, F.J.J.

1996-01-01

In this contribution we will discuss image quality in the context of the visuo-cognitive system as an information-processing system. To this end, we subdivide the information-processing as performed by the visuo-cognitive system into three distinct processes: (1) the construction of a visual

Physical image quality of computed radiography in mammography system

International Nuclear Information System (INIS)

Norriza Mohd Isa; Muhammad Jamal Isa; Wan Muhamad Saridan Wan Hassan; Fatimah Othman

2013-01-01

Full-text: Mammography is a screening procedure that mostly used for early detection of breast cancer. In digital imaging system, Computed Radiography is a cost-effective technology that applied indirect conversion detector. The paper presents physical image quality parameter measurements namely modulation transfer function (MTF), normalized noise power spectrum (NNPS) and detective quantum efficiency (DQE) of Computed Radiography in mammography system. MTF was calculated from two different orientations of slanted images of an edge test device and NNPS was estimated using flat-field image. Both images were acquired using a standard mammography beam quality. DQE was determined by applying the MTF and NNPS values into our developed software program. Both orientations have similar DQE characteristics. (author)

Radiation dose optimization in pediatric temporal bone computed tomography: influence of tube tension on image contrast and image quality

International Nuclear Information System (INIS)

Nauer, Claude Bertrand; Zubler, Christoph; Weisstanner, Christian; Stieger, Christof; Senn, Pascal; Arnold, Andreas

2012-01-01

The purpose of this experimental study was to investigate the effect of tube tension reduction on image contrast and image quality in pediatric temporal bone computed tomography (CT). Seven lamb heads with infant-equivalent sizes were scanned repeatedly, using four tube tensions from 140 to 80 kV while the CT-Dose Index (CTDI) was held constant. Scanning was repeated with four CTDI values from 30 to 3 mGy. Image contrast was calculated for the middle ear as the Hounsfield unit (HU) difference between bone and air and for the inner ear as the HU difference between bone and fluid. The influence of tube tension on high-contrast detail delineation was evaluated using a phantom. The subjective image quality of eight middle and inner ear structures was assessed using a 4-point scale (scores 1-2 = insufficient; scores 3-4 = sufficient). Middle and inner ear contrast showed a near linear increase with tube tension reduction (r = -0.94/-0.88) and was highest at 80 kV. Tube tension had no influence on spatial resolution. Subjective image quality analysis showed significantly better scoring at lower tube tensions, with highest image quality at 80 kV. However, image quality improvement was most relevant for low-dose scans. Image contrast in the temporal bone is significantly higher at low tube tensions, leading to a better subjective image quality. Highest contrast and best quality were found at 80 kV. This image quality improvement might be utilized to further reduce the radiation dose in pediatric low-dose CT protocols. (orig.)

MATLAB-based Applications for Image Processing and Image Quality Assessment – Part II: Experimental Results

Directory of Open Access Journals (Sweden)

L. Krasula

2012-04-01

Full Text Available The paper provides an overview of some possible usage of the software described in the Part I. It contains the real examples of image quality improvement, distortion simulations, objective and subjective quality assessment and other ways of image processing that can be obtained by the individual applications.

Comparison of dose and image quality of a Flat-panel detector and an image intensifier

International Nuclear Information System (INIS)

Lazzaro, M.; Friedrich, B.Q.; Luz, R.M. da; Silva, A.M.M. da

2016-01-01

With the development of new technologies, have emerged new conversion methods of X-ray image, such as flat panel detectors. The aim of this work is the comparison of entrance surface air kerma (ESAK) and image quality between an image intensifier type of detector (A) and a flat panel (B). The ESAK was obtained by placing a ionization chamber under PMMA simulators of 10, 20 and 30 cm and the image quality was obtained by using the TOR "1"8FG simulator. The ESAK to the equipment A is higher when compared to the equipment B. The high contrast resolution is better for the equipment A for all thicknesses of simulators. The equipment A has low contrast resolution with a better viewing threshold for thicknesses of 10 and 20 cm, and a worse performance for 30 cm. It is concluded that the equipment B has ESAK smaller and despite having lower resolution, in almost all cases, have appropriate image quality for diagnosis. (author)

Face detection on distorted images using perceptual quality-aware features

Science.gov (United States)

Gunasekar, Suriya; Ghosh, Joydeep; Bovik, Alan C.

2014-02-01

We quantify the degradation in performance of a popular and effective face detector when human-perceived image quality is degraded by distortions due to additive white gaussian noise, gaussian blur or JPEG compression. It is observed that, within a certain range of perceived image quality, a modest increase in image quality can drastically improve face detection performance. These results can be used to guide resource or bandwidth allocation in a communication/delivery system that is associated with face detection tasks. A new face detector based on QualHOG features is also proposed that augments face-indicative HOG features with perceptual quality-aware spatial Natural Scene Statistics (NSS) features, yielding improved tolerance against image distortions. The new detector provides statistically significant improvements over a strong baseline on a large database of face images representing a wide range of distortions. To facilitate this study, we created a new Distorted Face Database, containing face and non-face patches from images impaired by a variety of common distortion types and levels. This new dataset is available for download and further experimentation at www.ideal.ece.utexas.edu/˜suriya/DFD/.

Correlation of the clinical and physical image quality in chest radiography for average adults with a computed radiography imaging system.

Science.gov (United States)

Moore, C S; Wood, T J; Beavis, A W; Saunderson, J R

2013-07-01

The purpose of this study was to examine the correlation between the quality of visually graded patient (clinical) chest images and a quantitative assessment of chest phantom (physical) images acquired with a computed radiography (CR) imaging system. The results of a previously published study, in which four experienced image evaluators graded computer-simulated postero-anterior chest images using a visual grading analysis scoring (VGAS) scheme, were used for the clinical image quality measurement. Contrast-to-noise ratio (CNR) and effective dose efficiency (eDE) were used as physical image quality metrics measured in a uniform chest phantom. Although optimal values of these physical metrics for chest radiography were not derived in this work, their correlation with VGAS in images acquired without an antiscatter grid across the diagnostic range of X-ray tube voltages was determined using Pearson's correlation coefficient. Clinical and physical image quality metrics increased with decreasing tube voltage. Statistically significant correlations between VGAS and CNR (R=0.87, pchest CR images acquired without an antiscatter grid. A statistically significant correlation has been found between the clinical and physical image quality in CR chest imaging. The results support the value of using CNR and eDE in the evaluation of quality in clinical thorax radiography.

Radiation dose and image quality for paediatric interventional cardiology

Science.gov (United States)

Vano, E.; Ubeda, C.; Leyton, F.; Miranda, P.

2008-08-01

Radiation dose and image quality for paediatric protocols in a biplane x-ray system used for interventional cardiology have been evaluated. Entrance surface air kerma (ESAK) and image quality using a test object and polymethyl methacrylate (PMMA) phantoms have been measured for the typical paediatric patient thicknesses (4-20 cm of PMMA). Images from fluoroscopy (low, medium and high) and cine modes have been archived in digital imaging and communications in medicine (DICOM) format. Signal-to-noise ratio (SNR), figure of merit (FOM), contrast (CO), contrast-to-noise ratio (CNR) and high contrast spatial resolution (HCSR) have been computed from the images. Data on dose transferred to the DICOM header have been used to test the values of the dosimetric display at the interventional reference point. ESAK for fluoroscopy modes ranges from 0.15 to 36.60 µGy/frame when moving from 4 to 20 cm PMMA. For cine, these values range from 2.80 to 161.10 µGy/frame. SNR, FOM, CO, CNR and HCSR are improved for high fluoroscopy and cine modes and maintained roughly constant for the different thicknesses. Cumulative dose at the interventional reference point resulted 25-45% higher than the skin dose for the vertical C-arm (depending of the phantom thickness). ESAK and numerical image quality parameters allow the verification of the proper setting of the x-ray system. Knowing the increases in dose per frame when increasing phantom thicknesses together with the image quality parameters will help cardiologists in the good management of patient dose and allow them to select the best imaging acquisition mode during clinical procedures.

Radiation dose and image quality for paediatric interventional cardiology

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Vano, E [Radiology Department, Medicine School, Complutense University and San Carlos University Hospital, 28040 Madrid (Spain); Ubeda, C [Clinical Sciences Department, Faculty of the Science of Health, Tarapaca University, 18 de Septiembre 2222, Arica (Chile); Leyton, F [Institute of Public Health of Chile, Marathon 1000, Nunoa, Santiago (Chile); Miranda, P [Hemodynamic Department, Cardiovascular Service, Luis Calvo Mackenna Hospital, Avenida Antonio Varas 360, Providencia, Santiago (Chile)], E-mail: eliseov@med.ucm.es

2008-08-07

Radiation dose and image quality for paediatric protocols in a biplane x-ray system used for interventional cardiology have been evaluated. Entrance surface air kerma (ESAK) and image quality using a test object and polymethyl methacrylate (PMMA) phantoms have been measured for the typical paediatric patient thicknesses (4-20 cm of PMMA). Images from fluoroscopy (low, medium and high) and cine modes have been archived in digital imaging and communications in medicine (DICOM) format. Signal-to-noise ratio (SNR), figure of merit (FOM), contrast (CO), contrast-to-noise ratio (CNR) and high contrast spatial resolution (HCSR) have been computed from the images. Data on dose transferred to the DICOM header have been used to test the values of the dosimetric display at the interventional reference point. ESAK for fluoroscopy modes ranges from 0.15 to 36.60 {mu}Gy/frame when moving from 4 to 20 cm PMMA. For cine, these values range from 2.80 to 161.10 {mu}Gy/frame. SNR, FOM, CO, CNR and HCSR are improved for high fluoroscopy and cine modes and maintained roughly constant for the different thicknesses. Cumulative dose at the interventional reference point resulted 25-45% higher than the skin dose for the vertical C-arm (depending of the phantom thickness). ESAK and numerical image quality parameters allow the verification of the proper setting of the x-ray system. Knowing the increases in dose per frame when increasing phantom thicknesses together with the image quality parameters will help cardiologists in the good management of patient dose and allow them to select the best imaging acquisition mode during clinical procedures.

Image and diagnosis quality of X-ray image transmission via cell phone camera: a project study evaluating quality and reliability.

Directory of Open Access Journals (Sweden)

Hans Goost

Full Text Available INTRODUCTION: Developments in telemedicine have not produced any relevant benefits for orthopedics and trauma surgery to date. For the present project study, several parameters were examined during assessment of x-ray images, which had been photographed and transmitted via cell phone. MATERIALS AND METHODS: A total of 100 x-ray images of various body regions were photographed with a Nokia cell phone and transmitted via email or MMS. Next, the transmitted photographs were reviewed on a laptop computer by five medical specialists and assessed regarding quality and diagnosis. RESULTS: Due to their poor quality, the transmitted MMS images could not be evaluated and this path of transmission was therefore excluded. Mean size of transmitted x-ray email images was 394 kB (range: 265-590 kB, SD ± 59, average transmission time was 3.29 min ± 8 (CI 95%: 1.7-4.9. Applying a score from 1-10 (very poor - excellent, mean image quality was 5.8. In 83.2 ± 4% (mean value ± SD of cases (median 82; 80-89%, there was agreement between final diagnosis and assessment by the five medical experts who had received the images. However, there was a markedly low concurrence ratio in the thoracic area and in pediatric injuries. DISCUSSION: While the rate of accurate diagnosis and indication for surgery was high with a concurrence ratio of 83%, considerable differences existed between the assessed regions, with lowest values for thoracic images. Teleradiology is a cost-effective, rapid method which can be applied wherever wireless cell phone reception is available. In our opinion, this method is in principle suitable for clinical use, enabling the physician on duty to agree on appropriate measures with colleagues located elsewhere via x-ray image transmission on a cell phone.

Naturalness and image quality : chroma and hue variation in color images of natural scenes

NARCIS (Netherlands)

Ridder, de H.; Blommaert, F.J.J.; Fedorovskaya, E.A.; Rogowitz, B.E.; Allebach, J.P.

1995-01-01

The relation between perceptual image quality and naturalness was investigated by varying the colorfulness and hue of color images of natural scenes. These variations were created by digitizing the images, subsequently determining their color point distributions in the CIELUV color space and finally

Naturalness and image quality: Chroma and hue variation in color images of natural scenes

NARCIS (Netherlands)

Ridder, de H.; Blommaert, F.J.J.; Fedorovskaya, E.A.; Eschbach, R.; Braun, K.

1997-01-01

The relation between perceptual image quality and natural ness was investigated by varying the colorfulness and hue of color images of natural scenes. These variations were created by digitizing the images, subsequently determining their color point distributions in the CIELUV color space and

Defining Quality in Cardiovascular Imaging: A Scientific Statement From the American Heart Association.

Science.gov (United States)

Shaw, Leslee J; Blankstein, Ron; Jacobs, Jill E; Leipsic, Jonathon A; Kwong, Raymond Y; Taqueti, Viviany R; Beanlands, Rob S B; Mieres, Jennifer H; Flamm, Scott D; Gerber, Thomas C; Spertus, John; Di Carli, Marcelo F

2017-12-01

The aims of the current statement are to refine the definition of quality in cardiovascular imaging and to propose novel methodological approaches to inform the demonstration of quality in imaging in future clinical trials and registries. We propose defining quality in cardiovascular imaging using an analytical framework put forth by the Institute of Medicine whereby quality was defined as testing being safe, effective, patient-centered, timely, equitable, and efficient. The implications of each of these components of quality health care are as essential for cardiovascular imaging as they are for other areas within health care. Our proposed statement may serve as the foundation for integrating these quality indicators into establishing designations of quality laboratory practices and developing standards for value-based payment reform for imaging services. We also include recommendations for future clinical research to fulfill quality aims within cardiovascular imaging, including clinical hypotheses of improving patient outcomes, the importance of health status as an end point, and deferred testing options. Future research should evolve to define novel methods optimized for the role of cardiovascular imaging for detecting disease and guiding treatment and to demonstrate the role of cardiovascular imaging in facilitating healthcare quality. © 2017 American Heart Association, Inc.

Radiation dose optimization in pediatric temporal bone computed tomography: influence of tube tension on image contrast and image quality.

Science.gov (United States)

Nauer, Claude Bertrand; Zubler, Christoph; Weisstanner, Christian; Stieger, Christof; Senn, Pascal; Arnold, Andreas

2012-03-01

The purpose of this experimental study was to investigate the effect of tube tension reduction on image contrast and image quality in pediatric temporal bone computed tomography (CT). Seven lamb heads with infant-equivalent sizes were scanned repeatedly, using four tube tensions from 140 to 80 kV while the CT-Dose Index (CTDI) was held constant. Scanning was repeated with four CTDI values from 30 to 3 mGy. Image contrast was calculated for the middle ear as the Hounsfield unit (HU) difference between bone and air and for the inner ear as the HU difference between bone and fluid. The influence of tube tension on high-contrast detail delineation was evaluated using a phantom. The subjective image quality of eight middle and inner ear structures was assessed using a 4-point scale (scores 1-2 = insufficient; scores 3-4 = sufficient). Middle and inner ear contrast showed a near linear increase with tube tension reduction (r = -0.94/-0.88) and was highest at 80 kV. Tube tension had no influence on spatial resolution. Subjective image quality analysis showed significantly better scoring at lower tube tensions, with highest image quality at 80 kV. However, image quality improvement was most relevant for low-dose scans. Image contrast in the temporal bone is significantly higher at low tube tensions, leading to a better subjective image quality. Highest contrast and best quality were found at 80 kV. This image quality improvement might be utilized to further reduce the radiation dose in pediatric low-dose CT protocols.

Self-Organizing Maps for Fingerprint Image Quality Assessment

DEFF Research Database (Denmark)

Olsen, Martin Aastrup; Tabassi, Elham; Makarov, Anton

2013-01-01

Fingerprint quality assessment is a crucial task which needs to be conducted accurately in various phases in the biometric enrolment and recognition processes. Neglecting quality measurement will adversely impact accuracy and efficiency of biometric recognition systems (e.g. verification and iden......Fingerprint quality assessment is a crucial task which needs to be conducted accurately in various phases in the biometric enrolment and recognition processes. Neglecting quality measurement will adversely impact accuracy and efficiency of biometric recognition systems (e.g. verification...... machine learning techniques. We train a self-organizing map (SOM) to cluster blocks of fingerprint images based on their spatial information content. The output of the SOM is a high-level representation of the finger image, which forms the input to a Random Forest trained to learn the relationship between...

Quality image and incident air kerma evaluation in X-ray chest exams

International Nuclear Information System (INIS)

Campos de O, P. M.; Do Carmo S, P.; De Sousa L, M. A.; Da Silva, T. A.

2017-10-01

The procedures optimization for obtaining diagnostic quality images is an important factor to the patients radiation levels submitted to diagnostic radiology examinations was the lowest as reasonably practicable. Two methodologies for image quality parameters evaluation were applied in the routine of three diagnostic radiology clinics (A, B and C), two with digital image processing and one with chemical processing in Belo Horizonte, Brazil. The incident air kerma was evaluated for the radiographic techniques used in the clinic routine chest exams, approved in accordance with European Image Quality Criteria. It was possible to determine that the Fluke Biomedical X-ray Phantom test objects coupled to the Leeds Test Objects (TOR CDR) obtained better results than Gammex s Radiographic Survey Phantom (RSV), because the low and high contrast structures present in the RSV were not visualized in lower energies. The three clinics presented very similar results in all image quality parameters in the evaluation with the TOR CDR test object. However, clinic C presented an low contrast structures result 28.1 % lower than clinical B, although the average Ka,i to obtain their images was 33.4 % superior. The clinic A results present the best relation between image quality and radiation dose in patients. It was verified the optimization doses possibility in diagnostic radiology services with digital processing system, without significant reduction in image quality. Patients submitted to the highest radiation levels belonged to the clinic that presented the worst results in the image quality parameters evaluated. (Author)

High-resolution dynamic imaging and quantitative analysis of lung cancer xenografts in nude mice using clinical PET/CT.

Science.gov (United States)

Wang, Ying Yi; Wang, Kai; Xu, Zuo Yu; Song, Yan; Wang, Chu Nan; Zhang, Chong Qing; Sun, Xi Lin; Shen, Bao Zhong

2017-08-08

Considering the general application of dedicated small-animal positron emission tomography/computed tomography is limited, an acceptable alternative in many situations might be clinical PET/CT. To estimate the feasibility of using clinical PET/CT with [F-18]-fluoro-2-deoxy-D-glucose for high-resolution dynamic imaging and quantitative analysis of cancer xenografts in nude mice. Dynamic clinical PET/CT scans were performed on xenografts for 60 min after injection with [F-18]-fluoro-2-deoxy-D-glucose. Scans were reconstructed with or without SharpIR method in two phases. And mice were sacrificed to extracting major organs and tumors, using ex vivo γ-counting as a reference. Strikingly, we observed that the image quality and the correlation between the all quantitive data from clinical PET/CT and the ex vivo counting was better with the SharpIR reconstructions than without. Our data demonstrate that clinical PET/CT scanner with SharpIR reconstruction is a valuable tool for imaging small animals in preclinical cancer research, offering dynamic imaging parameters, good image quality and accurate data quatification.

SU-E-J-36: Comparison of CBCT Image Quality for Manufacturer Default Imaging Modes

International Nuclear Information System (INIS)

Nelson, G

2015-01-01

Purpose CBCT is being increasingly used in patient setup for radiotherapy. Often the manufacturer default scan modes are used for performing these CBCT scans with the assumption that they are the best options. To quantitatively assess the image quality of these scan modes, all of the scan modes were tested as well as options with the reconstruction algorithm. Methods A CatPhan 504 phantom was scanned on a TrueBeam Linear Accelerator using the manufacturer scan modes (FSRT Head, Head, Image Gently, Pelvis, Pelvis Obese, Spotlight, & Thorax). The Head mode scan was then reconstructed multiple times with all filter options (Smooth, Standard, Sharp, & Ultra Sharp) and all Ring Suppression options (Disabled, Weak, Medium, & Strong). An open source ImageJ tool was created for analyzing the CatPhan 504 images. Results The MTF curve was primarily dictated by the voxel size and the filter used in the reconstruction algorithm. The filters also impact the image noise. The CNR was worst for the Image Gently mode, followed by FSRT Head and Head. The sharper the filter, the worse the CNR. HU varied significantly between scan modes. Pelvis Obese had lower than expected HU values than most while the Image Gently mode had higher than expected HU values. If a therapist tried to use preset window and level settings, they would not show the desired tissue for some scan modes. Conclusion Knowing the image quality of the set scan modes, will enable users to better optimize their setup CBCT. Evaluation of the scan mode image quality could improve setup efficiency and lead to better treatment outcomes

Relationships between body image, sexual satisfaction, and relationship quality in romantic couples.

Science.gov (United States)

van den Brink, Femke; Vollmann, Manja; Smeets, Monique A M; Hessen, David J; Woertman, Liesbeth

2018-03-08

Previous studies found important associations between body image, sexual satisfaction, and perceived romantic relationship quality, but mainly focused on one individual's perceptions rather than both partners. To take the interdependency of romantic partners into account, the present study examined these associations in romantic couples with a dyadic approach. In a cross-sectional design, 151 Dutch heterosexual couples completed an online survey measuring body image, sexual satisfaction, and perceived relationship quality. Hypotheses were tested using the actor-partner interdependence model (APIM) and an APIM extended with a mediator (APIMeM), with couple members' body image as predictors, couple members' sexual satisfaction as mediators, and couple members' relationship quality as outcomes. Results indicated that within individuals, a more positive body image was linked to higher perceived romantic relationship quality through greater sexual satisfaction. No gender differences were found, implying that body image and sexual satisfaction are equally strongly associated with perceived relationship quality in women and men. Results revealed no associations of an individual's body image and sexual satisfaction with the partner's perceived relationship quality. These findings implicate that interventions focusing on developing and maintaining a positive body image may be helpful in building on a more satisfying sex life and higher perceived relationship quality. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Relationship between image quality and changes in spatial resolution for the gamma camera

International Nuclear Information System (INIS)

Ikeda, Hozumi; Kishimoto, Kenji; Shimonishi, Yoshihiro; Ohmura, Masahiro; Kosakai, Kazuhisa; Hamada, Kunio; Ochi, Hironobu.

1989-01-01

The purpose of this study is to examine quantitatively the relationship between visual image quality and degradation in spatial resolution for a gamma camera by the increase in distance from collimator. The relationship between the proportion (p) of images identified the difference of image quality and the difference (δFWHM) in FWHM between paired images was showed in a sigmoid curve. Using Dendy's method, minimum level to be correctly identified the difference of image quality on three out of four occasions (p=0.75) was corresponded to 0.4 mm in δFWHM. Using fuzzy theory, the level to be identified the difference of image quality was examind under various conditions. The truth-value of fuzzy sets-degraded or slightly degraded and not-degraded in image quality between paired images-was gained the peak at 0.5 mm of δFWHM. It was founded that changes of 0.4-0.5 mm in FWHM-corresponding about 2 cm distance from collimator-could be sufficiently identified in the difference of image quality. (author)

Tin-filter enhanced dual-energy-CT: image quality and accuracy of CT numbers in virtual noncontrast imaging.

Science.gov (United States)

Kaufmann, Sascha; Sauter, Alexander; Spira, Daniel; Gatidis, Sergios; Ketelsen, Dominik; Heuschmid, Martin; Claussen, Claus D; Thomas, Christoph

2013-05-01

To measure and compare the objective image quality of true noncontrast (TNC) images with virtual noncontrast (VNC) images acquired by tin-filter-enhanced, dual-source, dual-energy computed tomography (DECT) of upper abdomen. Sixty-three patients received unenhanced abdominal CT and enhanced abdominal DECT (100/140 kV with tin filter) in portal-venous phase. VNC images were calculated from the DECT datasets using commercially available software. The mean attenuation of relevant tissues and image quality were compared between the TNC and VNC images. Image quality was rated objectively by measuring image noise and the sharpness of object edges using custom-designed software. Measurements were compared using Student two-tailed t-test. Correlation coefficients for tissue attenuation measurements between TNC and VNC were calculated and the relative deviations were illustrated using Bland-Altman plots. Mean attenuation differences between TNC and VNC (HUTNC - HUVNC) image sets were as follows: right liver lobe -4.94 Hounsfield units (HU), left liver lobe -3.29 HU, vena cava -2.19 HU, spleen -7.46 HU, pancreas 1.29 HU, fat -11.14 HU, aorta 1.29 HU, bone marrow 36.83 HU (all P VNC and TNC series were observed for liver, vena portae, kidneys, pancreas, muscle and bone marrow (Pearson's correlation coefficient ≥0.75). Mean image noise was significantly higher in TNC images (P VNC and TNC images (P = .19). The Hounsfield units in VNC images closely resemble TNC images in the majority of the organs of the upper abdomen (kidneys, liver, pancreas). In spleen and fat, Hounsfield numbers in VNC images are tend to be higher than in TNC images. VNC images show a low image noise and satisfactory edge sharpness. Other criteria of image quality and the depiction of certain lesions need to be evaluated additionally. Copyright © 2013 AUR. Published by Elsevier Inc. All rights reserved.

A No Reference Image Quality Assessment Metric Based on Visual Perception

Directory of Open Access Journals (Sweden)

Yan Fu

2016-12-01

Full Text Available Nowadays, how to evaluate image quality reasonably is a basic and challenging problem. In view of the present no reference evaluation methods, they cannot reflect the human visual perception of image quality accurately. In this paper, we propose an efficient general-purpose no reference image quality assessment (NRIQA method based on visual perception, and effectively integrates human visual characteristics into the NRIQA fields. First, a novel algorithm for salient region extraction is presented. Two characteristics graphs of texture and edging of the original image are added to the Itti model. Due to the normalized luminance coefficients of natural images obey the generalized Gauss probability distribution, we utilize this characteristic to extract statistical features in the regions of interest (ROI and regions of non-interest respectively. Then, the extracted features are fused to be an input to establish the support vector regression (SVR model. Finally, the IQA model obtained by training is used to predict the quality of the image. Experimental results show that this method has good predictive ability, and the evaluation effect is better than existing classical algorithms. Moreover, the predicted results are more consistent with human subjective perception, which can accurately reflect the human visual perception to image quality.

Predicting perceptual quality of images in realistic scenario using deep filter banks

Science.gov (United States)

Zhang, Weixia; Yan, Jia; Hu, Shiyong; Ma, Yang; Deng, Dexiang

2018-03-01

Classical image perceptual quality assessment models usually resort to natural scene statistic methods, which are based on an assumption that certain reliable statistical regularities hold on undistorted images and will be corrupted by introduced distortions. However, these models usually fail to accurately predict degradation severity of images in realistic scenarios since complex, multiple, and interactive authentic distortions usually appear on them. We propose a quality prediction model based on convolutional neural network. Quality-aware features extracted from filter banks of multiple convolutional layers are aggregated into the image representation. Furthermore, an easy-to-implement and effective feature selection strategy is used to further refine the image representation and finally a linear support vector regression model is trained to map image representation into images' subjective perceptual quality scores. The experimental results on benchmark databases present the effectiveness and generalizability of the proposed model.

Impact of Computed Tomography Image Quality on Image-Guided Radiation Therapy Based on Soft Tissue Registration

International Nuclear Information System (INIS)

Morrow, Natalya V.; Lawton, Colleen A.; Qi, X. Sharon; Li, X. Allen

2012-01-01

Purpose: In image-guided radiation therapy (IGRT), different computed tomography (CT) modalities with varying image quality are being used to correct for interfractional variations in patient set-up and anatomy changes, thereby reducing clinical target volume to the planning target volume (CTV-to-PTV) margins. We explore how CT image quality affects patient repositioning and CTV-to-PTV margins in soft tissue registration-based IGRT for prostate cancer patients. Methods and Materials: Four CT-based IGRT modalities used for prostate RT were considered in this study: MV fan beam CT (MVFBCT) (Tomotherapy), MV cone beam CT (MVCBCT) (MVision; Siemens), kV fan beam CT (kVFBCT) (CTVision, Siemens), and kV cone beam CT (kVCBCT) (Synergy; Elekta). Daily shifts were determined by manual registration to achieve the best soft tissue agreement. Effect of image quality on patient repositioning was determined by statistical analysis of daily shifts for 136 patients (34 per modality). Inter- and intraobserver variability of soft tissue registration was evaluated based on the registration of a representative scan for each CT modality with its corresponding planning scan. Results: Superior image quality with the kVFBCT resulted in reduced uncertainty in soft tissue registration during IGRT compared with other image modalities for IGRT. The largest interobserver variations of soft tissue registration were 1.1 mm, 2.5 mm, 2.6 mm, and 3.2 mm for kVFBCT, kVCBCT, MVFBCT, and MVCBCT, respectively. Conclusions: Image quality adversely affects the reproducibility of soft tissue-based registration for IGRT and necessitates a careful consideration of residual uncertainties in determining different CTV-to-PTV margins for IGRT using different image modalities.

Impact of Computed Tomography Image Quality on Image-Guided Radiation Therapy Based on Soft Tissue Registration

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Morrow, Natalya V.; Lawton, Colleen A. [Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, Wisconsin (United States); Qi, X. Sharon [Department of Radiation Oncology, University of Colorado Denver, Denver, Colorado (United States); Li, X. Allen, E-mail: ali@mcw.edu [Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, Wisconsin (United States)

2012-04-01

Purpose: In image-guided radiation therapy (IGRT), different computed tomography (CT) modalities with varying image quality are being used to correct for interfractional variations in patient set-up and anatomy changes, thereby reducing clinical target volume to the planning target volume (CTV-to-PTV) margins. We explore how CT image quality affects patient repositioning and CTV-to-PTV margins in soft tissue registration-based IGRT for prostate cancer patients. Methods and Materials: Four CT-based IGRT modalities used for prostate RT were considered in this study: MV fan beam CT (MVFBCT) (Tomotherapy), MV cone beam CT (MVCBCT) (MVision; Siemens), kV fan beam CT (kVFBCT) (CTVision, Siemens), and kV cone beam CT (kVCBCT) (Synergy; Elekta). Daily shifts were determined by manual registration to achieve the best soft tissue agreement. Effect of image quality on patient repositioning was determined by statistical analysis of daily shifts for 136 patients (34 per modality). Inter- and intraobserver variability of soft tissue registration was evaluated based on the registration of a representative scan for each CT modality with its corresponding planning scan. Results: Superior image quality with the kVFBCT resulted in reduced uncertainty in soft tissue registration during IGRT compared with other image modalities for IGRT. The largest interobserver variations of soft tissue registration were 1.1 mm, 2.5 mm, 2.6 mm, and 3.2 mm for kVFBCT, kVCBCT, MVFBCT, and MVCBCT, respectively. Conclusions: Image quality adversely affects the reproducibility of soft tissue-based registration for IGRT and necessitates a careful consideration of residual uncertainties in determining different CTV-to-PTV margins for IGRT using different image modalities.

PLÉIADES PROJECT: ASSESSMENT OF GEOREFERENCING ACCURACY, IMAGE QUALITY, PANSHARPENING PERFORMENCE AND DSM/DTM QUALITY

Directory of Open Access Journals (Sweden)

H. Topan

2016-06-01

Full Text Available Pléiades 1A and 1B are twin optical satellites of Optical and Radar Federated Earth Observation (ORFEO program jointly running by France and Italy. They are the first satellites of Europe with sub-meter resolution. Airbus DS (formerly Astrium Geo runs a MyGIC (formerly Pléiades Users Group program to validate Pléiades images worldwide for various application purposes. The authors conduct three projects, one is within this program, the second is supported by BEU Scientific Research Project Program, and the third is supported by TÜBİTAK. Assessment of georeferencing accuracy, image quality, pansharpening performance and Digital Surface Model/Digital Terrain Model (DSM/DTM quality subjects are investigated in these projects. For these purposes, triplet panchromatic (50 cm Ground Sampling Distance (GSD and VNIR (2 m GSD Pléiades 1A images were investigated over Zonguldak test site (Turkey which is urbanised, mountainous and covered by dense forest. The georeferencing accuracy was estimated with a standard deviation in X and Y (SX, SY in the range of 0.45m by bias corrected Rational Polynomial Coefficient (RPC orientation, using ~170 Ground Control Points (GCPs. 3D standard deviation of ±0.44m in X, ±0.51m in Y, and ±1.82m in Z directions have been reached in spite of the very narrow angle of convergence by bias corrected RPC orientation. The image quality was also investigated with respect to effective resolution, Signal to Noise Ratio (SNR and blur coefficient. The effective resolution was estimated with factor slightly below 1.0, meaning that the image quality corresponds to the nominal resolution of 50cm. The blur coefficients were achieved between 0.39-0.46 for triplet panchromatic images, indicating a satisfying image quality. SNR is in the range of other comparable space borne images which may be caused by de-noising of Pléiades images. The pansharpened images were generated by various methods, and are validated by most common

Image quality and stability of image-guided radiotherapy (IGRT) devices: A comparative study.

Science.gov (United States)

Stock, Markus; Pasler, Marlies; Birkfellner, Wolfgang; Homolka, Peter; Poetter, Richard; Georg, Dietmar

2009-10-01

Our aim was to implement standards for quality assurance of IGRT devices used in our department and to compare their performances with that of a CT simulator. We investigated image quality parameters for three devices over a period of 16months. A multislice CT was used as a benchmark and results related to noise, spatial resolution, low contrast visibility (LCV) and uniformity were compared with a cone beam CT (CBCT) at a linac and simulator. All devices performed well in terms of LCV and, in fact, exceeded vendor specifications. MTF was comparable between CT and linac CBCT. Integral nonuniformity was, on average, 0.002 for the CT and 0.006 for the linac CBCT. Uniformity, LCV and MTF varied depending on the protocols used for the linac CBCT. Contrast-to-noise ratio was an average of 51% higher for the CT than for the linac and simulator CBCT. No significant time trend was observed and tolerance limits were implemented. Reasonable differences in image quality between CT and CBCT were observed. Further research and development are necessary to increase image quality of commercially available CBCT devices in order for them to serve the needs for adaptive and/or online planning.

Improvement of the image quality of a high-temperature vision system

International Nuclear Information System (INIS)

Fabijańska, Anna; Sankowski, Dominik

2009-01-01

In this paper, the issues of controlling and improving the image quality of a high-temperature vision system are considered. The image quality improvement is needed to measure the surface properties of metals and alloys. Two levels of image quality control and improvement are defined in the system. The first level in hardware aims at adjusting the system configuration to obtain the highest contrast and weakest aura images. When optimal configuration is obtained, the second level in software is applied. In this stage, image enhancement algorithms are applied which have been developed with consideration of distortions arising from the vision system components and specificity of images acquired during the measurement process. The developed algorithms have been applied in the vision system to images. The influence on the accuracy of wetting angles and surface tension determination are considered

Image quality and cancer visibility of T2-weighted Magnetic Resonance Imaging of the prostate at 7 Tesla

International Nuclear Information System (INIS)

Vos, E.K.; Lagemaat, M.W.; Barentsz, J.O.; Fuetterer, J.J.; Zamecnik, P.; Roozen, H.; Maas, M.C.; Orzada, S.; Bitz, A.K.; Scheenen, T.W.J.

2014-01-01

To assess the image quality of T2-weighted (T2w) magnetic resonance imaging of the prostate and the visibility of prostate cancer at 7 Tesla (T). Seventeen prostate cancer patients underwent T2w imaging at 7T with only an external transmit/receive array coil. Three radiologists independently scored images for image quality, visibility of anatomical structures, and presence of artefacts. Krippendorff's alpha and weighted kappa statistics were used to assess inter-observer agreement. Visibility of prostate cancer lesions was assessed by directly linking the T2w images to the confirmed location of prostate cancer on histopathology. T2w imaging at 7T was achievable with 'satisfactory' (3/5) to 'good' (4/5) quality. Visibility of anatomical structures was predominantly scored as 'satisfactory' (3/5) and 'good' (4/5). If artefacts were present, they were mostly motion artefacts and, to a lesser extent, aliasing artefacts and noise. Krippendorff's analysis revealed an α = 0.44 between three readers for the overall image quality scores. Clinically significant cancer lesions in both peripheral zone and transition zone were visible at 7T. T2w imaging with satisfactory to good quality can be routinely acquired, and cancer lesions were visible in patients with prostate cancer at 7T using only an external transmit/receive body array coil. (orig.)

Body image and quality of life in a Spanish population

Directory of Open Access Journals (Sweden)

Ignacio Jáuregui Lobera

2011-01-01

Full Text Available Ignacio Jáuregui Lobera1, Patricia Bolaños Ríos21Department of Nutrition and Bromatology, Pablo de Olavide University, Seville, Spain; 2Behavior Science Institute, Seville, SpainPurpose: The aim of the current study was to analyze the psychometric properties, factor structure, and internal consistency of the Spanish version of the Body Image Quality of Life Inventory (BIQLI-SP as well as its test–retest reliability. Further objectives were to analyze different relationships with key dimensions of psychosocial functioning (ie, self-esteem, presence of psychopathological symptoms, eating and body image-related problems, and perceived stress and to evaluate differences in body image quality of life due to gender.Patients and methods: The sample comprised 417 students without any psychiatric history, recruited from the Pablo de Olavide University and the University of Seville. There were 140 men (33.57% and 277 women (66.43%, and the mean age was 21.62 years (standard deviation = 5.12. After obtaining informed consent from all participants, the following questionnaires were administered: BIQLI, Eating Disorder Inventory-2 (EDI-2, Perceived Stress Questionnaire (PSQ, Self-Esteem Scale (SES, and Symptom Checklist-90-Revised (SCL-90-R.Results: The BIQLI-SP shows adequate psychometric properties, and it may be useful to determine the body image quality of life in different physical conditions. A more positive body image quality of life is associated with better self-esteem, better psychological wellbeing, and fewer eating-related dysfunctional attitudes, this being more evident among women.Conclusion: The BIQLI-SP may be useful to determine the body image quality of life in different contexts with regard to dermatology, cosmetic and reconstructive surgery, and endocrinology, among others. In these fields of study, a new trend has emerged to assess body image-related quality of life.Keywords: body appreciation, wellbeing, self-esteem, social

Specific developed phantoms and software to assess radiological equipment image quality

International Nuclear Information System (INIS)

Verdu, G.; Rodenas, F.

2011-01-01

The use of radiographic phantoms specifically designed to evaluate the operation of the radiographic equipment lets the study of the image quality obtained by this equipment in an objective way. In digital radiographic equipment, the analysis of the image quality can be automatized because the acquisition of the image is possible in different technologies that are, computerized radiography or phosphor plate and direct radiography or detector. In this work we have shown an application to assess automatically the constancy quality image in the image chain of the radiographic equipment. This application is integrated by designed radiographic phantoms which are adapted to conventional, dental equipment and specific developed software for the automatic evaluation of the phantom image quality. The software is based on digital image processing techniques that let the automatic detection of the different phantom tests by edge detector, morphological operators, threshold histogram techniques, etc. The utility developed is enough sensitive to the radiographic equipment of operating conditions of voltage (kV) and charge (mAs). It is a friendly user programme connected with a data base of the hospital or clinic where it has been used. After the phantom image processing the user can obtain an inform with a resume of the imaging system state with accepting and constancy results. (author)

Specific developed phantoms and software to assess radiological equipment image quality

Energy Technology Data Exchange (ETDEWEB)

Verdu, G., E-mail: gverdu@iqn.upv.es [Universidad Politecnica de Valencia (Spain). Dept. de Ingenieria Quimica y Nuclear; Mayo, P., E-mail: p.mayo@titaniast.com [TITANIA Servicios Teconologicos, Valencia (Spain); Rodenas, F., E-mail: frodenas@mat.upv.es [Universidad Politecnica de Valencia (Spain). Dept. de Matematica Aplicada; Campayo, J.M., E-mail: j.campayo@lainsa.com [Logistica y Acondicionamientos Industriales S.A.U (LAINSA), Valencia (Spain)

2011-07-01

The use of radiographic phantoms specifically designed to evaluate the operation of the radiographic equipment lets the study of the image quality obtained by this equipment in an objective way. In digital radiographic equipment, the analysis of the image quality can be automatized because the acquisition of the image is possible in different technologies that are, computerized radiography or phosphor plate and direct radiography or detector. In this work we have shown an application to assess automatically the constancy quality image in the image chain of the radiographic equipment. This application is integrated by designed radiographic phantoms which are adapted to conventional, dental equipment and specific developed software for the automatic evaluation of the phantom image quality. The software is based on digital image processing techniques that let the automatic detection of the different phantom tests by edge detector, morphological operators, threshold histogram techniques, etc. The utility developed is enough sensitive to the radiographic equipment of operating conditions of voltage (kV) and charge (mAs). It is a friendly user programme connected with a data base of the hospital or clinic where it has been used. After the phantom image processing the user can obtain an inform with a resume of the imaging system state with accepting and constancy results. (author)

SEGMENTATION AND QUALITY ANALYSIS OF LONG RANGE CAPTURED IRIS IMAGE

Directory of Open Access Journals (Sweden)

Anand Deshpande

2016-05-01

Full Text Available The iris segmentation plays a major role in an iris recognition system to increase the performance of the system. This paper proposes a novel method for segmentation of iris images to extract the iris part of long range captured eye image and an approach to select best iris frame from the iris polar image sequences by analyzing the quality of iris polar images. The quality of iris image is determined by the frequency components present in the iris polar images. The experiments are carried out on CASIA-long range captured iris image sequences. The proposed segmentation method is compared with Hough transform based segmentation and it has been determined that the proposed method gives higher accuracy for segmentation than Hough transform.

TU-AB-207A-03: Image Quality, Dose, and Clinical Applications

Energy Technology Data Exchange (ETDEWEB)

Dong, F. [The Cleveland Clinic (United States)

2016-06-15

Practicing medical physicists are often time charged with the tasks of evaluating and troubleshooting complex image quality issues related to CT scanners. This course will equip them with a solid and practical understanding of common CT imaging chain and its major components with emphasis on acquisition physics and hardware, reconstruction, artifacts, image quality, dose, and advanced clinical applications. The core objective is to explain the effects of these major system components on the image quality. This course will not focus on the rapid-changing advanced technologies given the two-hour time limit, but the fundamental principles discussed in this course may facilitate better understanding of those more complicated technologies. The course will begin with an overview of CT acquisition physics and geometry. X-ray tube and CT detector are important acquisition hardware critical to the overall image quality. Each of these two subsystems consists of several major components. An in-depth description of the function and failure modes of these components will be provided. Examples of artifacts related to these failure modes will be presented: off-focal radiation, tube arcing, heel effect, oil bubble, offset drift effect, cross-talk effect, and bad pixels. The fundamentals of CT image reconstruction will first be discussed on an intuitive level. Approaches that do not require rigorous derivation of mathematical formulations will be presented. This is followed by a detailed derivation of the Fourier slice theorem: the foundation of the FBP algorithm. FBP for parallel-beam, fan-beam, and cone-beam geometries will be discussed. To address the issue of radiation dose related to x-ray CT, recent advances in iterative reconstruction, their advantages, and clinical applications will also be described. Because of the nature of fundamental physics and mathematics, limitations in data acquisition, and non-ideal conditions of major system components, image artifact often arise

TU-AB-207A-03: Image Quality, Dose, and Clinical Applications

International Nuclear Information System (INIS)

Dong, F.

2016-01-01

Practicing medical physicists are often time charged with the tasks of evaluating and troubleshooting complex image quality issues related to CT scanners. This course will equip them with a solid and practical understanding of common CT imaging chain and its major components with emphasis on acquisition physics and hardware, reconstruction, artifacts, image quality, dose, and advanced clinical applications. The core objective is to explain the effects of these major system components on the image quality. This course will not focus on the rapid-changing advanced technologies given the two-hour time limit, but the fundamental principles discussed in this course may facilitate better understanding of those more complicated technologies. The course will begin with an overview of CT acquisition physics and geometry. X-ray tube and CT detector are important acquisition hardware critical to the overall image quality. Each of these two subsystems consists of several major components. An in-depth description of the function and failure modes of these components will be provided. Examples of artifacts related to these failure modes will be presented: off-focal radiation, tube arcing, heel effect, oil bubble, offset drift effect, cross-talk effect, and bad pixels. The fundamentals of CT image reconstruction will first be discussed on an intuitive level. Approaches that do not require rigorous derivation of mathematical formulations will be presented. This is followed by a detailed derivation of the Fourier slice theorem: the foundation of the FBP algorithm. FBP for parallel-beam, fan-beam, and cone-beam geometries will be discussed. To address the issue of radiation dose related to x-ray CT, recent advances in iterative reconstruction, their advantages, and clinical applications will also be described. Because of the nature of fundamental physics and mathematics, limitations in data acquisition, and non-ideal conditions of major system components, image artifact often arise

Comparison of applied dose and image quality in staging CT of neuroendocrine tumor patients using standard filtered back projection and adaptive statistical iterative reconstruction

International Nuclear Information System (INIS)

Böning, G.; Schäfer, M.; Grupp, U.; Kaul, D.; Kahn, J.; Pavel, M.; Maurer, M.; Denecke, T.; Hamm, B.; Streitparth, F.

2015-01-01

.001). Conclusion: In clinical practice ASIR can be used to reduce radiation dose without sacrificing image quality and diagnostic confidence in staging CT of NET patients. This may be beneficial for patients with frequent follow-up and significant cumulative radiation exposure

Comparison of applied dose and image quality in staging CT of neuroendocrine tumor patients using standard filtered back projection and adaptive statistical iterative reconstruction

Energy Technology Data Exchange (ETDEWEB)

Böning, G., E-mail: georg.boening@charite.de [Department of Radiology, Charité, Humboldt-University Medical School, Charitéplatz 1, 10117 Berlin (Germany); Schäfer, M.; Grupp, U. [Department of Radiology, Charité, Humboldt-University Medical School, Charitéplatz 1, 10117 Berlin (Germany); Kaul, D. [Department of Radiation Oncology, Charité, Humboldt-University Medical School, Charitéplatz 1, 10117 Berlin (Germany); Kahn, J. [Department of Radiology, Charité, Humboldt-University Medical School, Charitéplatz 1, 10117 Berlin (Germany); Pavel, M. [Department of Gastroenterology, Charité, Humboldt-University Medical School, Charitéplatz 1, 10117 Berlin (Germany); Maurer, M.; Denecke, T.; Hamm, B.; Streitparth, F. [Department of Radiology, Charité, Humboldt-University Medical School, Charitéplatz 1, 10117 Berlin (Germany)

2015-08-15

.001). Conclusion: In clinical practice ASIR can be used to reduce radiation dose without sacrificing image quality and diagnostic confidence in staging CT of NET patients. This may be beneficial for patients with frequent follow-up and significant cumulative radiation exposure.

An image quality comparison study between XVI and OBI CBCT systems.

Science.gov (United States)

Kamath, Srijit; Song, William; Chvetsov, Alexei; Ozawa, Shuichi; Lu, Haibin; Samant, Sanjiv; Liu, Chihray; Li, Jonathan G; Palta, Jatinder R

2011-02-04

The purpose of this study is to evaluate and compare image quality characteristics for two commonly used and commercially available CBCT systems: the X-ray Volumetric Imager and the On-Board Imager. A commonly used CATPHAN image quality phantom was used to measure various image quality parameters, namely, pixel value stability and accuracy, noise, contrast to noise ratio (CNR), high-contrast resolution, low contrast resolution and image uniformity. For the XVI unit, we evaluated the image quality for four manufacturer-supplied protocols as a function of mAs. For the OBI unit, we did the same for the full-fan and half-fan scanning modes, which were respectively used with the full bow-tie and half bow-tie filters. For XVI, the mean pixel values of regions of interest were found to generally decrease with increasing mAs for all protocols, while they were relatively stable with mAs for OBI. Noise was slightly lower on XVI and was seen to decrease with increasing mAs, while CNR increased with mAs for both systems. For XVI and OBI, the high-contrast resolution was approximately limited by the pixel resolution of the reconstructed image. On OBI images, up to 6 and 5 discs of 1% and 0.5% contrast, respectively, were visible for a high mAs setting using the full-fan mode, while none of the discs were clearly visible on the XVI images for various mAs settings when the medium resolution reconstruction was used. In conclusion, image quality parameters for XVI and OBI have been quantified and compared for clinical protocols under various mAs settings. These results need to be viewed in the context of a recent study that reported the dose-mAs relationship for the two systems and found that OBI generally delivered higher imaging doses than XVI.

Measures of Image Quality. Chapter 4

Energy Technology Data Exchange (ETDEWEB)

Maidment, A. D.A. [University of Pennsylvania, Philadelphia (United States)

2014-09-15

A medical image is a pictorial representation of a measurement of an object or function of the body. This information can be acquired in one to three spatial dimensions. It can be static or dynamic, meaning that it can also be measured as a function of time. Certain fundamental properties can be associated with all of these data. Firstly, no image can exactly represent the object or function; at best, one has a measurement with an associated error equal to the difference between the true object and the measured image. Secondly, no two images will be identical, even if acquired with the same imaging system of the same anatomic region; this variability is generally referred to as noise. There are many different ways to acquire medical image data; the various mechanisms of acquisition are described in detail in the subsequent chapters. However, regardless of the method of image formation, one must be able to judge the fidelity of the image in an attempt to answer the question “How accurately does the image portray the body or the bodily function?” This judgement falls under the rubric of ‘image quality’. In this chapter, methods of quantifying image quality are described.

Image quality indicators for radiography and recommendations for their use - 1966

Energy Technology Data Exchange (ETDEWEB)

1976-01-01

This Standard covers dimensional requirements, materials, construction and marking of wire type and step/hole type image quality indicators for assessing quality of radiographs on materials from 3 mm to 250 mm thick. Standard models of each type; use of image quality indicators (with obtainable sensitivity values) and charts for calculations. (Metric)

Quality Control of Mega Voltage Portal Imaging System

International Nuclear Information System (INIS)

Diklic, A.; Dundara Debeljuh, D.; Jurkovic, S.; Smilovic Radojcic, D.; Svabic Kolacio; Kasabasic, M.; Faj, D.

2013-01-01

The Electronic Portal Imaging Device (EPID) is a system used to verify either the correct positioning of the patient during radiotherapy treatment or the linear accelerator beam parameters. The correct position of the patient corresponds to the position at which the patient was scanned at the CT simulator and according to which the therapy plan was made and optimized. Regarding this, besides the advanced treatment planning system and optimized treatment planning techniques, the day-to-day reproduction of simulated conditions is of great importance for the treatment outcome. Therefore, to verify the patient set-up portal imaging should be applied prior to the first treatment session and repeated according to treatment prescriptions during the treatment. In order to achieve full functionality and precision of the EPID, it must be included in radiotherapy Quality Control (QC) programme. The QC of the Mega Voltage portal imaging system was separated in two parts. In the first, the QC of the detector parameters should be performed. For this purpose, the FC2 and QC3 phantoms should be used, along with the Portal Image Processing System program (PIPSpro) package for data analysis. The second part of the QC of the linear accelerator's portal imaging system should include the QC of the CBCT. In this part a set of predefined manufacturer's tests using two different phantoms, one for the geometry calibration and the other for the image quality evaluation, should be performed. Also, the treatment conditions should be simulated using anthropomorphic phantoms and dose distributions for particular EPID protocols should be measured. Procedures for quality control of the portal imaging system developed and implemented at University Hospital Rijeka are presented in this paper.(author)

Learning a No-Reference Quality Assessment Model of Enhanced Images With Big Data.

Science.gov (United States)

Gu, Ke; Tao, Dacheng; Qiao, Jun-Fei; Lin, Weisi

2018-04-01

In this paper, we investigate into the problem of image quality assessment (IQA) and enhancement via machine learning. This issue has long attracted a wide range of attention in computational intelligence and image processing communities, since, for many practical applications, e.g., object detection and recognition, raw images are usually needed to be appropriately enhanced to raise the visual quality (e.g., visibility and contrast). In fact, proper enhancement can noticeably improve the quality of input images, even better than originally captured images, which are generally thought to be of the best quality. In this paper, we present two most important contributions. The first contribution is to develop a new no-reference (NR) IQA model. Given an image, our quality measure first extracts 17 features through analysis of contrast, sharpness, brightness and more, and then yields a measure of visual quality using a regression module, which is learned with big-data training samples that are much bigger than the size of relevant image data sets. The results of experiments on nine data sets validate the superiority and efficiency of our blind metric compared with typical state-of-the-art full-reference, reduced-reference and NA IQA methods. The second contribution is that a robust image enhancement framework is established based on quality optimization. For an input image, by the guidance of the proposed NR-IQA measure, we conduct histogram modification to successively rectify image brightness and contrast to a proper level. Thorough tests demonstrate that our framework can well enhance natural images, low-contrast images, low-light images, and dehazed images. The source code will be released at https://sites.google.com/site/guke198701/publications.

Assessing the quality of restored images in optical long-baseline interferometry

Science.gov (United States)

Gomes, Nuno; Garcia, Paulo J. V.; Thiébaut, Éric

2017-03-01

Assessing the quality of aperture synthesis maps is relevant for benchmarking image reconstruction algorithms, for the scientific exploitation of data from optical long-baseline interferometers, and for the design/upgrade of new/existing interferometric imaging facilities. Although metrics have been proposed in these contexts, no systematic study has been conducted on the selection of a robust metric for quality assessment. This article addresses the question: what is the best metric to assess the quality of a reconstructed image? It starts by considering several metrics and selecting a few based on general properties. Then, a variety of image reconstruction cases are considered. The observational scenarios are phase closure and phase referencing at the Very Large Telescope Interferometer (VLTI), for a combination of two, three, four and six telescopes. End-to-end image reconstruction is accomplished with the MIRA software, and several merit functions are put to test. It is found that convolution by an effective point spread function is required for proper image quality assessment. The effective angular resolution of the images is superior to naive expectation based on the maximum frequency sampled by the array. This is due to the prior information used in the aperture synthesis algorithm and to the nature of the objects considered. The ℓ1-norm is the most robust of all considered metrics, because being linear it is less sensitive to image smoothing by high regularization levels. For the cases considered, this metric allows the implementation of automatic quality assessment of reconstructed images, with a performance similar to human selection.

Paediatric x-ray radiation dose reduction and image quality analysis.

Science.gov (United States)

Martin, L; Ruddlesden, R; Makepeace, C; Robinson, L; Mistry, T; Starritt, H

2013-09-01

Collaboration of multiple staff groups has resulted in significant reduction in the risk of radiation-induced cancer from radiographic x-ray exposure during childhood. In this study at an acute NHS hospital trust, a preliminary audit identified initial exposure factors. These were compared with European and UK guidance, leading to the introduction of new factors that were in compliance with European guidance on x-ray tube potentials. Image quality was assessed using standard anatomical criteria scoring, and visual grading characteristics analysis assessed the impact on image quality of changes in exposure factors. This analysis determined the acceptability of gradual radiation dose reduction below the European and UK guidance levels. Chest and pelvis exposures were optimised, achieving dose reduction for each age group, with 7%-55% decrease in critical organ dose. Clinicians confirmed diagnostic image quality throughout the iterative process. Analysis of images acquired with preliminary and final exposure factors indicated an average visual grading analysis result of 0.5, demonstrating equivalent image quality. The optimisation process and final radiation doses are reported for Carestream computed radiography to aid other hospitals in minimising radiation risks to children.

Paediatric x-ray radiation dose reduction and image quality analysis

International Nuclear Information System (INIS)

Martin, L; Ruddlesden, R; Mistry, T; Starritt, H; Makepeace, C; Robinson, L

2013-01-01

Collaboration of multiple staff groups has resulted in significant reduction in the risk of radiation-induced cancer from radiographic x-ray exposure during childhood. In this study at an acute NHS hospital trust, a preliminary audit identified initial exposure factors. These were compared with European and UK guidance, leading to the introduction of new factors that were in compliance with European guidance on x-ray tube potentials. Image quality was assessed using standard anatomical criteria scoring, and visual grading characteristics analysis assessed the impact on image quality of changes in exposure factors. This analysis determined the acceptability of gradual radiation dose reduction below the European and UK guidance levels. Chest and pelvis exposures were optimised, achieving dose reduction for each age group, with 7%–55% decrease in critical organ dose. Clinicians confirmed diagnostic image quality throughout the iterative process. Analysis of images acquired with preliminary and final exposure factors indicated an average visual grading analysis result of 0.5, demonstrating equivalent image quality. The optimisation process and final radiation doses are reported for Carestream computed radiography to aid other hospitals in minimising radiation risks to children. (paper)

Sensitometric properties and image quality of radiographic film and paper

International Nuclear Information System (INIS)

Domanus, J.C.

1985-01-01

When using X-ray film or radiographic paper for industrial applications one is interested in knowing not only their sensitometric properties (such as speed and contrast) but also the image quality obtainable with a particular brand of film or paper. Although standard methods for testing sensitometric properties and image quality separately are available, it is desirable to find a method by the use of which all the relevant properties could be tested together. The sensitometric properties are usually determined at constant kilovoltage and filtration at the X-ray tube, whereas the radiographic image quality is tested at different kilovoltages and for different material thicknesses

Statistical Quality Assessment of Pre-fried Carrots Using Multispectral Imaging

DEFF Research Database (Denmark)

Sharifzadeh, Sara; Clemmensen, Line Katrine Harder; Løje, Hanne

2013-01-01

Multispectral imaging is increasingly being used for quality assessment of food items due to its non-invasive benefits. In this paper, we investigate the use of multispectral images of pre-fried carrots, to detect changes over a period of 14 days. The idea is to distinguish changes in quality from...

Optimisation of radiation dose and image quality in mobile neonatal chest radiography.

Science.gov (United States)

Hinojos-Armendáriz, V I; Mejía-Rosales, S J; Franco-Cabrera, M C

2018-05-01

To optimise the radiation dose and image quality for chest radiography in the neonatal intensive care unit (NICU) by increasing the mean beam energy. Two techniques for the acquisition of NICU AP chest X-ray images were compared for image quality and radiation dose. 73 images were acquired using a standard technique (56 kV, 3.2 mAs and no additional filtration) and 90 images with a new technique (62 kV, 2 mAs and 2 mm Al filtration). The entrance surface air kerma (ESAK) was measured using a phantom and compared between the techniques and against established diagnostic reference levels (DRL). Images were evaluated using seven image quality criteria independently by three radiologists. Images quality and radiation dose were compared statistically between the standard and new techniques. The maximum ESAK for the new technique was 40.20 μGy, 43.7% of the ESAK of the standard technique. Statistical evaluation demonstrated no significant differences in image quality between the two acquisition techniques. Based on the techniques and acquisition factors investigated within this study, it is possible to lower the radiation dose without any significant effects on image quality by adding filtration (2 mm Al) and increasing the tube potential. Such steps are relatively simple to undertake and as such, other departments should consider testing and implementing this dose reduction strategy within clinical practice where appropriate. Copyright © 2017 The College of Radiographers. Published by Elsevier Ltd. All rights reserved.

Development of a new compact intraoperative magnetic resonance imaging system: concept and initial experience.

Science.gov (United States)

Morita, Akio; Sameshima, Tetsuro; Sora, Shigeo; Kimura, Toshikazu; Nishimura, Kengo; Itoh, Hirotaka; Shibahashi, Keita; Shono, Naoyuki; Machida, Toru; Hara, Naoko; Mikami, Nozomi; Harihara, Yasushi; Kawate, Ryoichi; Ochiai, Chikayuki; Wang, Weimin; Oguro, Toshiki

2014-06-01

Magnetic resonance imaging (MRI) during surgery has been shown to improve surgical outcomes, but the current intraoperative MRI systems are too large to install in standard operating suites. Although 1 compact system is available, its imaging quality is not ideal. We developed a new compact intraoperative MRI system and evaluated its use for safety and efficacy. This new system has a magnetic gantry: a permanent magnet of 0.23 T and an interpolar distance of 32 cm. The gantry system weighs 2.8 tons and the 5-G line is within the circle of 2.6 m. We created a new field-of-view head coil and a canopy-style radiofrequency shield for this system. A clinical trial was initiated, and the system has been used in 44 patients. This system is significantly smaller than previous intraoperative MRI systems. High-quality T2 images could discriminate tumor from normal brain tissue and identify anatomic landmarks for accurate surgery. The average imaging time was 45.5 minutes, and no clinical complications or MRI system failures occurred. Floating organisms or particles were minimal (1/200 L maximum). This intraoperative, compact, low-magnetic-field MRI system can be installed in standard operating suites to provide relatively high-quality images without sacrificing safety. We believe that such a system facilitates the introduction of the intraoperative MRI.

Improving the quality of brain CT image from Wavelet filters

International Nuclear Information System (INIS)

Pita Machado, Reinaldo; Perez Diaz, Marlen; Bravo Pino, Rolando

2012-01-01

An algorithm to reduce Poisson noise is described using Wavelet filters. Five tomographic images of patients and a head anthropomorphic phantom were used. They were acquired with two different CT machines. Due to the original images contain the acquisition noise; some simulated free noise lesions were added to the images and after that the whole images were contaminated with noise. Contaminated images were filtered with 9 Wavelet filters at different decomposition levels and thresholds. Image quality of filtered and unfiltered images was graded using the Signal to Noise ratio, Normalized Mean Square Error and the Structural Similarity Index, as well as, by the subjective JAFROC methods with 5 observers. Some filters as Bior 3.7 and dB45 improved in a significant way head CT image quality (p<0.05) producing an increment in SNR without visible structural distortions

Image Quality Improvement after Implementation of a CT Accreditation Program

International Nuclear Information System (INIS)

Kim, You Sung; Jung, Seung Eun; Choi, Byung Gil; Shin, Yu Ri; Hwang, Seong Su; Ku, Young Mi; Lim, Yeon Soo; Lee, Jae Mun

2010-01-01

The purpose of this study was to evaluate any improvement in the quality of abdominal CTs after the utilization of the nationally based accreditation program. Approval was obtained from the Institutional Review Board, and informed consent was waived. We retrospectively analyzed 1,011 outside abdominal CTs, from 2003 to 2007. We evaluated images using a fill-up sheet form of the national accreditation program, and subjectively by grading for the overall CT image quality. CT scans were divided into two categories according to time periods; before and after the implementation of the accreditation program. We compared CT scans between two periods according to parameters pertaining to the evaluation of images. We determined whether there was a correlation between the results of a subjective assessment of the image quality and the evaluation scores of the clinical image. The following parameters were significantly different after the implementation of the accreditation program: identifying data, display parameters, scan length, spatial and contrast resolution, window width and level, optimal contrast enhancement, slice thickness, and total score. The remaining parameters were not significantly different between scans obtained from the two different periods: scan parameters, film quality, and artifacts. After performing the CT accreditation program, the quality of the outside abdominal CTs show marked improvement, especially for the parameters related to the scanning protocol

Super-resolution convolutional neural network for the improvement of the image quality of magnified images in chest radiographs

Science.gov (United States)

Umehara, Kensuke; Ota, Junko; Ishimaru, Naoki; Ohno, Shunsuke; Okamoto, Kentaro; Suzuki, Takanori; Shirai, Naoki; Ishida, Takayuki

2017-02-01

Single image super-resolution (SR) method can generate a high-resolution (HR) image from a low-resolution (LR) image by enhancing image resolution. In medical imaging, HR images are expected to have a potential to provide a more accurate diagnosis with the practical application of HR displays. In recent years, the super-resolution convolutional neural network (SRCNN), which is one of the state-of-the-art deep learning based SR methods, has proposed in computer vision. In this study, we applied and evaluated the SRCNN scheme to improve the image quality of magnified images in chest radiographs. For evaluation, a total of 247 chest X-rays were sampled from the JSRT database. The 247 chest X-rays were divided into 93 training cases with non-nodules and 152 test cases with lung nodules. The SRCNN was trained using the training dataset. With the trained SRCNN, the HR image was reconstructed from the LR one. We compared the image quality of the SRCNN and conventional image interpolation methods, nearest neighbor, bilinear and bicubic interpolations. For quantitative evaluation, we measured two image quality metrics, peak signal-to-noise ratio (PSNR) and structural similarity (SSIM). In the SRCNN scheme, PSNR and SSIM were significantly higher than those of three interpolation methods (pmethods without any obvious artifacts. These preliminary results indicate that the SRCNN scheme significantly outperforms conventional interpolation algorithms for enhancing image resolution and that the use of the SRCNN can yield substantial improvement of the image quality of magnified images in chest radiographs.

New patient-controlled abdominal compression method in radiography: radiation dose and image quality.

Science.gov (United States)

Piippo-Huotari, Oili; Norrman, Eva; Anderzén-Carlsson, Agneta; Geijer, Håkan

2018-05-01

The radiation dose for patients can be reduced with many methods and one way is to use abdominal compression. In this study, the radiation dose and image quality for a new patient-controlled compression device were compared with conventional compression and compression in the prone position . To compare radiation dose and image quality of patient-controlled compression compared with conventional and prone compression in general radiography. An experimental design with quantitative approach. After obtaining the approval of the ethics committee, a consecutive sample of 48 patients was examined with the standard clinical urography protocol. The radiation doses were measured as dose-area product and analyzed with a paired t-test. The image quality was evaluated by visual grading analysis. Four radiologists evaluated each image individually by scoring nine criteria modified from the European quality criteria for diagnostic radiographic images. There was no significant difference in radiation dose or image quality between conventional and patient-controlled compression. Prone position resulted in both higher dose and inferior image quality. Patient-controlled compression gave similar dose levels as conventional compression and lower than prone compression. Image quality was similar with both patient-controlled and conventional compression and was judged to be better than in the prone position.

Development of an image processing system in splendid squid quality classification

Science.gov (United States)

Masunee, Niyada; Chaiprapat, Supapan; Waiyagan, Kriangkrai

2013-07-01

Agricultural products typically exhibit high variance in quality characteristics. To assure customer satisfaction and control manufacturing productivity, quality classification is necessary to screen off defective items and to grade the products. This article presents an application of image processing techniques on squid grading and defect discrimination. A preliminary study indicated that surface color was an efficient determinant to justify quality of splendid squids. In this study, a computer vision system (CVS) was developed to examine the characteristics of splendid squids. Using image processing techniques, squids could be classified into three different quality grades as in accordance with an industry standard. The developed system first sifted through squid images to reject ones with black marks. Qualified squids were graded on a proportion of white, pink, and red regions appearing on their bodies by using fuzzy logic. The system was evaluated on 100 images of squids at different quality levels. It was found that accuracy obtained by the proposed technique was 95% compared with sensory evaluation of an expert.

A Machine Learning Regression scheme to design a FR-Image Quality Assessment Algorithm

OpenAIRE

Charrier , Christophe; Lezoray , Olivier; Lebrun , Gilles

2012-01-01

International audience; A crucial step in image compression is the evaluation of its performance, and more precisely available ways to measure the quality of compressed images. In this paper, a machine learning expert, providing a quality score is proposed. This quality measure is based on a learned classification process in order to respect that of human observers. The proposed method namely Machine Learning-based Image Quality Measurment (MLIQM) first classifies the quality using multi Supp...

Mammography practice in Serbia: Evaluation and optimisation of image quality and the technical aspects of the mammographic imaging chain

International Nuclear Information System (INIS)

Kosutic, D.; Ciraj-Bjelac, O.; Arandjic, D.

2010-01-01

The purpose of this work was to assess mammography practice in Serbia and its appropriateness for both diagnostic service and potential screening by implementing quality control (QC) protocol in three large teaching hospitals. Corrective actions were suggested, accordingly. In addition to technical aspects of QC, image quality was assessed using image grading before and after the introduction of corrective measures. The survey demonstrated considerable variations in technical parameters that affect image quality and patients doses. Average glandular doses ranged from 1.8 to 2.8 mGy, while reference optical density (OD) ranged from 1.0 to 2.6. Image grading resulted in a very high percentage of images with poor quality (12-70% for cranio-caudal projection and 8-66% for medio-lateral oblique projection). Main problems were associated with film processing, viewing conditions and OD control. Following introduction of corrective measures, the image grading results were improved in some hospitals, so the percentage of images without any remarks has been increased. (authors)

Image quality analysis of vibration effects In C-arm-flat panel X-ray imaging

NARCIS (Netherlands)

Snoeren, R.M.; Kroon, J.N.; With, de P.H.N.

2011-01-01

The motion of C-arm scanning X-ray systems may result in vibrations of the imaging sub-system. In this paper, we connect C-arm system vibrations to Image Quality (IQ) deterioration for 2D angiography and 3D cone beam X-ray imaging, using large Flat Panel detectors. Vibrations will affect the

Image quality and stability of image-guided radiotherapy (IGRT) devices: A comparative study

International Nuclear Information System (INIS)

Stock, Markus; Pasler, Marlies; Birkfellner, Wolfgang; Homolka, Peter; Poetter, Richard; Georg, Dietmar

2009-01-01

Introduction: Our aim was to implement standards for quality assurance of IGRT devices used in our department and to compare their performances with that of a CT simulator. Materials and methods: We investigated image quality parameters for three devices over a period of 16 months. A multislice CT was used as a benchmark and results related to noise, spatial resolution, low contrast visibility (LCV) and uniformity were compared with a cone beam CT (CBCT) at a linac and simulator. Results: All devices performed well in terms of LCV and, in fact, exceeded vendor specifications. MTF was comparable between CT and linac CBCT. Integral nonuniformity was, on average, 0.002 for the CT and 0.006 for the linac CBCT. Uniformity, LCV and MTF varied depending on the protocols used for the linac CBCT. Contrast-to-noise ratio was an average of 51% higher for the CT than for the linac and simulator CBCT. No significant time trend was observed and tolerance limits were implemented. Discussion: Reasonable differences in image quality between CT and CBCT were observed. Further research and development are necessary to increase image quality of commercially available CBCT devices in order for them to serve the needs for adaptive and/or online planning.

Evaluating phantom image quality parameters to optimise patient radiation dose in dental digital radiology.

Science.gov (United States)

Gonzalez, Luciano; Vano, Eliseo; Fernandez, Ramon; Ziraldo, Viviana; Delgado, Jaime; Delgado, Victor; Moro, Javier; Ubeda, Carlos

2012-08-01

Our objective was to obtain images of a predictable level of quality using an intraoral X-ray system with digital imaging, avoiding patient overexposure. A polymethylmethacrylate (PMMA) physical test phantom was imaged at different exposure times and at various PMMA thicknesses using a dental imaging coupled charge device. Two identical regions of interest (ROIs) were chosen in every image file, and quality was numerically evaluated by measuring high-contrast spatial resolutions, low-contrast thresholds and signal-to-noise ratios. In addition, three practitioners proposed personal quality scores by image inspection. Numerical contents in the ROIs, related to the image quality, were plotted against exposure time. From here, a simple expression linking the exposure time with the thickness to obtain images of comparable quality was deduced. As a result, the optimum exposure time for imaging with a predictable level of quality can be inferred. The potential effect could imply savings above 1000 man Sv, roughly 20 % of the collective dose due to dental imaging, over a population of 1540 millions.

Evaluating Picture Quality of Image Plates in Digital CR Systems

Energy Technology Data Exchange (ETDEWEB)

Kwak, Byung Joon [Dept. of Radiological Tecnology, Choonhae College of Health Science, Ulsan (Korea, Republic of); Ji Tae Jeong [Dept. of Radiological Science, Kaya University, Kimhae (Korea, Republic of)

2011-12-15

Lab effectively supplemented the effects of outside radiation on image plates in the process of image acquisition of CR (computed radiography) systems and conducted for effective utilization in the case of clinical application. For this, Lab classified the storage places and time periods of image plates and compared and analyzed the differences between small dark spots. Lab also assessed the concentration distribution within the boundaries of images. Lab compared and measured the number of dark spots in a light room and a dark room depending on the storage places of image plates and found that dark spots slightly increased in an image plate when stored in a light room on the first and second days. Dark spots increased in proportion to the length of time stored. In the case of the image plate stored in a dark room, the number of dark spots remarkably decreased. With regard to picture quality as related to the location of image plates, the damage to picture quality could be reduced by locating regions of interest in the center. With regard to differences in sharpness following changes in the thickness of subjects, fewer scatter rays occurred and sharpness improved by reducing the thickness of subjects as much as possible. To get medical images of excellent quality, image plates should be managed effectively and it is desirable to keep images plates in dark iron plate boxes and not to expose them to outside radiation for a long time.

Evaluating Picture Quality of Image Plates in Digital CR Systems

International Nuclear Information System (INIS)

Kwak, Byung Joon; Ji Tae Jeong

2011-01-01

Lab effectively supplemented the effects of outside radiation on image plates in the process of image acquisition of CR (computed radiography) systems and conducted for effective utilization in the case of clinical application. For this, Lab classified the storage places and time periods of image plates and compared and analyzed the differences between small dark spots. Lab also assessed the concentration distribution within the boundaries of images. Lab compared and measured the number of dark spots in a light room and a dark room depending on the storage places of image plates and found that dark spots slightly increased in an image plate when stored in a light room on the first and second days. Dark spots increased in proportion to the length of time stored. In the case of the image plate stored in a dark room, the number of dark spots remarkably decreased. With regard to picture quality as related to the location of image plates, the damage to picture quality could be reduced by locating regions of interest in the center. With regard to differences in sharpness following changes in the thickness of subjects, fewer scatter rays occurred and sharpness improved by reducing the thickness of subjects as much as possible. To get medical images of excellent quality, image plates should be managed effectively and it is desirable to keep images plates in dark iron plate boxes and not to expose them to outside radiation for a long time.

Experimental Investigation of Quality of Lensless Ghost Imaging with Pseudo-Thermal Light

International Nuclear Information System (INIS)

Xia, Shen; Yan-Feng, Bai; Tao, Qin; Shen-Sheng, Han

2008-01-01

Factors influencing the quality of lensless ghost imaging are investigated. According to the experimental results, we find that the imaging quality is determined by the number of independent sub light sources on the imaging plane of the reference arm. A qualitative picture based on advanced wave optics is presented to explain the physics behind the experimental phenomena. The present results will be helpful to provide a basis for improving the quality of ghost imaging systems in future works. (fundamental areas of phenomenology(including applications))

Image quality and dose optimisation for infant CT using a paediatric phantom

Energy Technology Data Exchange (ETDEWEB)

Lambert, Jack W.; Phelps, Andrew S.; Courtier, Jesse L.; Gould, Robert G.; MacKenzie, John D. [University of California, San Francisco, Department of Radiology and Biomedical Imaging, San Francisco, CA (United States)

2016-05-15

To optimise image quality and reduce radiation exposure for infant body CT imaging. An image quality CT phantom was created to model the infant body habitus. Image noise, spatial resolution, low contrast detectability and tube current modulation (TCM) were measured after adjusting CT protocol parameters. Reconstruction method (FBP, hybrid iterative and model-based iterative), image quality reference parameter, helical pitch and beam collimation were systematically investigated for their influence on image quality and radiation output. Both spatial and low contrast resolution were significantly improved with model-based iterative reconstruction (p < 0.05). A change in the helical pitch from 0.969 to 1.375 resulted in a 23 % reduction in total TCM, while a change in collimation from 20 to 40 mm resulted in a 46 % TCM reduction. Image noise and radiation output were both unaffected by changes in collimation, while an increase in pitch enabled a dose length product reduction of ∝6 % at equivalent noise. An optimised protocol with ∝30 % dose reduction was identified using model-based iterative reconstruction. CT technology continues to evolve and require protocol redesign. This work provides an example of how an infant-specific phantom is essential for leveraging this technology to maintain image quality while reducing radiation exposure. (orig.)

Standard practice for determining relative image quality response of industrial radiographic imaging systems

CERN Document Server

American Society for Testing and Materials. Philadelphia

2007-01-01

1.1 This standard provides a practice whereby industrial radiographic imaging systems may be comparatively assessed using the concept of relative image quality response (RIQR). The RIQR method presented within this practice is based upon the use of equivalent penetrameter sensitivity (EPS) described within Practice E 1025 and subsection 5.2 of this practice. Figure 1 illustrates a relative image quality indicator (RIQI) that has four different steel plaque thicknesses (.015, .010, .008, and .005 in.) sequentially positioned (from top to bottom) on a ¾-in. thick steel plate. The four plaques contain a total of 14 different arrays of penetrameter-type hole sizes designed to render varied conditions of threshold visibility ranging from 1.92 % EPS (at the top) to .94 % EPS (at the bottom) when exposed to nominal 200 keV X-ray radiation. Each “EPS” array consists of 30 identical holes; thus, providing the user with a quantity of threshold sensitivity levels suitable for relative image qualitative response com...

Improved quality of intrafraction kilovoltage images by triggered readout of unexposed frames

DEFF Research Database (Denmark)

Poulsen, Per Rugaard; Jonassen, Johnny; Schmidt, Mai Lykkegaard

2015-01-01

of unexposed kV frames as a means to improve the kV image quality in a series of experiments and a theoretical model of the observed image quality improvements. Methods: A series of fluoroscopic images were acquired of a solid water phantom with an embedded gold marker and an air cavity with and without...... absolute error of 2.0% for the gold marker. Conclusions: A device that triggers readout of unexposed frames during kV fluoroscopy was built and shown to greatly improve the quality of intratreatment kV images. A simple theoretical model successfully described the CNR improvements with the device.......Purpose: The gantry-mounted kilovoltage (kV) imager of modern linear accelerators can be used forreal-time tumor localization during radiation treatment delivery. However, the kV image quality often suffers from cross-scatter from the megavoltage (MV) treatment beam. This study investigates readout...

Quality control of the interpretation monitors of digital radiological images

International Nuclear Information System (INIS)

Favero, Mariana S.; Goulart, Adriano Oliveira S.

2016-01-01

The performance monitors has great importance in image quality of digital radiographic systems. In environments without films, it became necessary to implement acceptance testing and quality control monitors used for interpretation of medical images. The monitors dedicated to radiodiagnostic should provide information that represent slight differences in x-ray attenuation or minor differences in some anatomical region of interest. This should also result in small differences in luminance of an image represented. Factors affecting the quality of medical imaging are contrast, noise, resolution, artifacts and distortions. Therefore, a monitor must have specific characteristics, making it possible for the observer to carry out an assessment that leads to better diagnosis. Based on the need to evaluate diagnostic monitors in various radiological applications, this paper presents a summary for implementation and standardization of tests that are recommended by the publication AAPM Report 03. (author)

Comparative evaluation of image quality in computed radiology systems using imaging plates with different usage time

International Nuclear Information System (INIS)

Lazzaro, M.V.; Luz, R.M. da; Capaverde, A.S.; Silva, A.M. Marques da

2015-01-01

Computed Radiology (CR) systems use imaging plates (IPs) for latent image acquisition. Taking into account the quality control (QC) of these systems, imaging plates usage time is undetermined. Different recommendations and publications on the subject suggest tests to evaluate these systems. The objective of this study is to compare the image quality of IPs of a CR system, in a mammography service, considering the usage time and consistency of assessments. 8 IPs were used divided into two groups: the first group included 4 IPs with 3 years of use (Group A); the second group consisted of 4 new IPs with no previous exposure (Group B). The tests used to assess the IP's quality were: Uniformity, Differential Signal to Noise Ratio (SDNR), Ghost Effect and Figure of Merit (FOM). Statistical results show that the proposed tests are shown efficient in assessing the conditions of image quality obtained in CR systems in mammography and can be used as determining factors for the replacement of IP's. Moreover, comparing the two sets of IP, results led to the replacement of all the set of IP’s with 3 years of use. This work demonstrates the importance of an efficient quality control, not only with regard to the quality of IP's used, but in the acquisition system as a whole. From this work, these tests will be conducted on an annual basis, already targeting as future work, monitoring the wear of IP's Group B and the creation of a baseline for analysis and future replacements. (author)

Image quality assessment based on multiscale geometric analysis.

Science.gov (United States)

Gao, Xinbo; Lu, Wen; Tao, Dacheng; Li, Xuelong

2009-07-01

Reduced-reference (RR) image quality assessment (IQA) has been recognized as an effective and efficient way to predict the visual quality of distorted images. The current standard is the wavelet-domain natural image statistics model (WNISM), which applies the Kullback-Leibler divergence between the marginal distributions of wavelet coefficients of the reference and distorted images to measure the image distortion. However, WNISM fails to consider the statistical correlations of wavelet coefficients in different subbands and the visual response characteristics of the mammalian cortical simple cells. In addition, wavelet transforms are optimal greedy approximations to extract singularity structures, so they fail to explicitly extract the image geometric information, e.g., lines and curves. Finally, wavelet coefficients are dense for smooth image edge contours. In this paper, to target the aforementioned problems in IQA, we develop a novel framework for IQA to mimic the human visual system (HVS) by incorporating the merits from multiscale geometric analysis (MGA), contrast sensitivity function (CSF), and the Weber's law of just noticeable difference (JND). In the proposed framework, MGA is utilized to decompose images and then extract features to mimic the multichannel structure of HVS. Additionally, MGA offers a series of transforms including wavelet, curvelet, bandelet, contourlet, wavelet-based contourlet transform (WBCT), and hybrid wavelets and directional filter banks (HWD), and different transforms capture different types of image geometric information. CSF is applied to weight coefficients obtained by MGA to simulate the appearance of images to observers by taking into account many of the nonlinearities inherent in HVS. JND is finally introduced to produce a noticeable variation in sensory experience. Thorough empirical studies are carried out upon the LIVE database against subjective mean opinion score (MOS) and demonstrate that 1) the proposed framework has

Digital imaging in diagnostic radiology. Image quality - radiation exposure

International Nuclear Information System (INIS)

Schmidt, T.; Stieve, F.E.

1996-01-01

The publication contains the 37 lectures of the symposium on digital imaging in diagnostic radiology, held in November 1995 at Kloster Seeon, as well as contributions enhancing the information presented in the lectures. The publication reflects the state of the art in this subject field, discusses future trends and gives recommendations and information relating to current practice in radiology. In-depth information is given about R and D activities for the digitalisation of X-ray pictures and the image quality required to meet the purposes of modern diagnostics. Further aspects encompass radiological protection and dose optimization as well as optimization of examination methods. (vhe) [de

Image Acquisition and Quality in Digital Radiography.

Science.gov (United States)

Alexander, Shannon

2016-09-01

Medical imaging has undergone dramatic changes and technological breakthroughs since the introduction of digital radiography. This article presents information on the development of digital radiography and types of digital radiography systems. Aspects of image quality and radiation exposure control are highlighted as well. In addition, the article includes related workplace changes and medicolegal considerations in the digital radiography environment. ©2016 American Society of Radiologic Technologists.

Image quality assessment using the CD-DISC phantom for vascular radiology and vascular surgery

International Nuclear Information System (INIS)

Struelens, Lara; Hambach, Lionel; Buls, Nico; Smans, Kristien; Malchair, Francoise; Hoornaert, Marie-Therese; Vanhavere, Filip; Bosmans, Hilde

2008-01-01

The purpose of the study was to evaluate image quality (IQ) associated with vascular radiology and vascular surgery procedures in Belgium and to determine reference values for future image quality assessment. IQ was evaluated with the CD-DISC contrast-detail phantom. This circular PMMA phantom contains 225 holes with different diameter and depth, to quantify resolution and contrast. Images of the phantom were acquired for both fluoroscopy and subtraction images on 21 systems. Three observers evaluated the images by determining the threshold contrast visible for every diameter. This results in contrast-detail curves and image quality figures. We observed a large difference in IQ between the centres. No straightforward correlation could be found with radiation dose or other exposure settings. A comparison was made with the image quality evaluation of the systems performed with the TOR[18FG] phantom for fluoroscopy. There is no clear correlation observed between the results of the CD-DISC phantom and the TOR phantom. However, systems with very poor or very good image quality could be detected by both phantoms. An important result is that a 75th percentile reference contrast-detail curve could be proposed to separate the best centres from these with poorer quality. Some centres had also a significantly better image quality than others. Therefore, we introduced also a 25th percentile. Centres with IQ above this value are recommended to lower the dose and work with acceptable rather than excellent image quality. The CD-DISC phantom thus allows to guide the image quality setting

Objective image quality parameters of relevance in practice, measured for film-screen combinations - a contribution to quality assurance activities

International Nuclear Information System (INIS)

Angerstein, W.; Wolf, M.

1986-01-01

Objective measurement of the physico-technical parameters determining the image quality is the fastest and most accurate method of quality testing of the systems. The parameters in case of X-ray intensifying screens are imaging quality, servicable life, and mechanical properties. (orig./DG) [de

Survey of mammography practice in Croatia: Equipment performance, image quality and dose

International Nuclear Information System (INIS)

Faj, D.; Stimac, D.; Ivezic, Z.; Kasabasic, M.; Ivkovic, A.; Posedel, D.; Kubelka, D.; Ilakovac, V.; Brnic, Z.; Bjelac, O.C.

2008-01-01

A national audit of mammography equipment performance, image quality and dose has been conducted in Croatia. Film-processing parameters, optical density (OD), average glandular dose (AGD) to the standard breast, viewing conditions and image quality were examined using TOR(MAM) test object. Average film gradient ranged from 2.6 to 3.7, with a mean of 3.1. Tube voltage used for imaging of the standard 45 mm polymethylmethacrylate phantom ranged from 24 to 34 kV, and OD ranged from 0.75 to 1.94 with a mean of 1.26. AGD to the standard breast ranged from 0.4 to 2.3 mGy with a mean of 1.1 mGy. Besides clinical conditions, the authors have imaged the standard phantom in the referent conditions with 28 kV and OD as close as possible to 1.5. Then, AGD ranged from 0.5 to 2.6 mGy with a mean of 1.3 mGy. Image viewing conditions were generally unsatisfying with ambient light up to 500 lx and most of the viewing boxes with luminance between 1000 and 2000 cd per m 2 . TOR(MAM) scoring of images taken in clinical and referent conditions was done by local radiologists in local image viewing conditions and by the referent radiologist in good image viewing conditions. Importance of OD and image viewing conditions for diagnostic information were analysed. The survey showed that the main problem in Croatia is the lack of written quality assurance/quality control (QA/QC) procedures. Consequently, equipment performance, image quality and dose are unstable and activities to improve image quality or to reduce the dose are not evidence-based. This survey also had an educational purpose, introducing in Croatia the QC based on European Commission Guidelines. (authors)

WE-G-207-05: Relationship Between CT Image Quality, Segmentation Performance, and Quantitative Image Feature Analysis

Energy Technology Data Exchange (ETDEWEB)

Lee, J; Nishikawa, R [University of Pittsburgh, Pittsburgh, PA (United States); Reiser, I [The University of Chicago, Chicago, IL (United States); Boone, J [UC Davis Medical Center, Sacramento, CA (United States)

2015-06-15

Purpose: Segmentation quality can affect quantitative image feature analysis. The objective of this study is to examine the relationship between computed tomography (CT) image quality, segmentation performance, and quantitative image feature analysis. Methods: A total of 90 pathology proven breast lesions in 87 dedicated breast CT images were considered. An iterative image reconstruction (IIR) algorithm was used to obtain CT images with different quality. With different combinations of 4 variables in the algorithm, this study obtained a total of 28 different qualities of CT images. Two imaging tasks/objectives were considered: 1) segmentation and 2) classification of the lesion as benign or malignant. Twenty-three image features were extracted after segmentation using a semi-automated algorithm and 5 of them were selected via a feature selection technique. Logistic regression was trained and tested using leave-one-out-cross-validation and its area under the ROC curve (AUC) was recorded. The standard deviation of a homogeneous portion and the gradient of a parenchymal portion of an example breast were used as an estimate of image noise and sharpness. The DICE coefficient was computed using a radiologist’s drawing on the lesion. Mean DICE and AUC were used as performance metrics for each of the 28 reconstructions. The relationship between segmentation and classification performance under different reconstructions were compared. Distributions (median, 95% confidence interval) of DICE and AUC for each reconstruction were also compared. Results: Moderate correlation (Pearson’s rho = 0.43, p-value = 0.02) between DICE and AUC values was found. However, the variation between DICE and AUC values for each reconstruction increased as the image sharpness increased. There was a combination of IIR parameters that resulted in the best segmentation with the worst classification performance. Conclusion: There are certain images that yield better segmentation or classification

Improvements in image quality with pseudo-parallel imaging in the phase-scrambling fourier transform technique

International Nuclear Information System (INIS)

Ito, Satoshi; Kawawa, Yasuhiro; Yamada, Yoshifumi

2010-01-01

The signal obtained in the phase-scrambling Fourier transform (PSFT) imaging technique can be transformed to the signal described by the Fresnel transform of the objects, in which the amplitude of the PSFT presents some kind of blurred image of the objects. Therefore, the signal can be considered to exist in the object domain as well as the Fourier domain of the object. This notable feature makes it possible to assign weights to the reconstructed images by applying a weighting function to the PSFT signal after data acquisition, and as a result, pseudo-parallel image reconstruction using these aliased image data with different weights on the images is feasible. In this study, the improvements in image quality with such pseudo-parallel imaging were examined and demonstrated. The weighting function of the PSFT signal that provides a given weight on the image is estimated using the obtained image data and is iteratively updated after sensitivity encoding (SENSE)-based image reconstruction. Simulation studies showed that reconstruction errors were dramatically reduced and that the spatial resolution was also improved in almost all image spaces. The proposed method was applied to signals synthesized from MR image data with phase variations to verify its effectiveness. It was found that the image quality was improved and that images almost entirely free of aliasing artifacts could be obtained. (author)

Characteristics of a New X-Ray Imaging System for Interventional Procedures: Improved Image Quality and Reduced Radiation Dose.

Science.gov (United States)

Schernthaner, Ruediger E; Haroun, Reham R; Nguyen, Sonny; Duran, Rafael; Sohn, Jae Ho; Sahu, Sonia; Chapiro, Julius; Zhao, Yan; Radaelli, Alessandro; van der Bom, Imramsjah M; Mauti, Maria; Hong, Kelvin; Geschwind, Jean-François H; Lin, MingDe

2018-03-01

To compare image quality and radiation exposure between a new angiographic imaging system and the preceding generation system during uterine artery embolization (UAE). In this retrospective, IRB-approved two-arm study, 54 patients with symptomatic uterine fibroids were treated with UAE on two different angiographic imaging systems. The new system includes optimized acquisition parameters and real-time image processing algorithms. Air kerma (AK), dose area product (DAP) and acquisition time for digital fluoroscopy (DF) and digital subtraction angiography (DSA) were recorded. Body mass index was noted as well. DF image quality was assessed objectively by image noise measurements. DSA image quality was rated by two blinded, independent readers on a four-rank scale. Statistical differences were assessed with unpaired t tests and Wilcoxon rank-sum tests. There was no significant difference between the patients treated on the new (n = 36) and the old system (n = 18) regarding age (p = 0.10), BMI (p = 0.18), DF time (p = 0.35) and DSA time (p = 0.17). The new system significantly reduced the cumulative AK and DAP by 64 and 72%, respectively (median 0.58 Gy and 145.9 Gy*cm 2 vs. 1.62 Gy and 526.8 Gy*cm 2 , p < 0.01 for both). Specifically, DAP for DF and DSA decreased by 59% (75.3 vs. 181.9 Gy*cm 2 , p < 0.01) and 78% (67.6 vs. 312.2 Gy*cm 2 , p < 0.01), respectively. The new system achieved a significant decrease in DF image noise (p < 0.01) and a significantly better DSA image quality (p < 0.01). The new angiographic imaging system significantly improved image quality and reduced radiation exposure during UAE procedures.

METHOD OF IMAGE QUALITY ENHANCEMENT FOR SPACE OBJECTS

Directory of Open Access Journals (Sweden)

D. S. Korshunov

2014-07-01

Full Text Available The paper deals with an approach for image quality improvement of the space objects in the visible range of electromagnetic wave spectrum. The proposed method is based on the joint taking into account of both the motion velocity of the space supervisory apparatus and a space object observed in the near-earth space when the time of photo-detector exposure is chosen. The timing of exposure is carried out by light-signal characteristics, which determines the optimal value of the charge package formed in the charge-coupled device being irradiated. Thus, the parameters of onboard observation equipment can be selected, which provides space images suitable for interpretation. The linear resolving capacity is used as quality indicator for space images, giving a complete picture for the image contrast and geometric properties of the object on the photo. Observation scenario modeling of the space object, done by sputnik-inspector, has shown the possibility of increasing the linear resolution up to10% - 20% or up to 40% - 50% depending on the non-complanarity angle at the movement along orbits. The proposed approach to the increase of photographs quality provides getting sharp and highcontrast images of space objects by the optical-electronic equipment of the space-based remote sensing. The usage of these images makes it possible to detect in time the space technology failures, which are the result of its exploitation in the nearearth space. The proposed method can be also applied at the stage of space systems design for optical-electronic surveillance in computer models used for facilities assessment of the shooting equipment information tract.

Comparison of the perceived image quality between two digital imaging systems for neonatal bedside radiography – A case study

International Nuclear Information System (INIS)

Zyl, S.A. van; Kekana, R.M.

2015-01-01

Background: Chest X-rays are performed daily in the neonatal intensive care and high care units. The skill of the radiographer is critical for obtaining the best image quality and limiting the patient's radiation exposure. The literature states that indirect flat panel detectors produce images of superior quality in comparison to computed radiography systems. At Steve Biko Academic Hospital a decision was made to revert from the direct digital radiography (DR) system to the computed radiography (CR) system, due to poor image quality experienced. Method: The case study objective was to conduct a comparative analysis describing key technical factors contributing to image quality. The analysis entailed retrospectively comparing the images obtained during 2010 and 2011. An image analysis form was utilised in evaluating the technical aspects of the image. A total of 160 images were viewed by 16 participants sampled from the radiography, radiology and paediatric departments. The participants were asked to re-evaluate two of their allotted images after five days to determine their reliability. Results: Findings were that the DR system provides significantly better image quality than the CR system (p < 0.05) for all the technical factors evaluated. However technical improvements are recommended. A wide variance in intra-observer reliability was also found. Conclusion: This case study demonstrated that DR images were considered to be superior to CR images. Recommendations include: a standardised technique for imaging the neonates; optimisation of the imaging software for the digital detectors, improved feedback systems in terms of exposure index values, and the training of radiographers and referring physicians in technical image analysis. - Highlights: • DR system provides better image quality than the CR system for all technical factors evaluated. • The average values obtained from the VAS showed that the DR system still needs to be optimised. • There is need

Effects of sparse sampling schemes on image quality in low-dose CT

International Nuclear Information System (INIS)

Abbas, Sajid; Lee, Taewon; Cho, Seungryong; Shin, Sukyoung; Lee, Rena

2013-01-01

Purpose: Various scanning methods and image reconstruction algorithms are actively investigated for low-dose computed tomography (CT) that can potentially reduce a health-risk related to radiation dose. Particularly, compressive-sensing (CS) based algorithms have been successfully developed for reconstructing images from sparsely sampled data. Although these algorithms have shown promises in low-dose CT, it has not been studied how sparse sampling schemes affect image quality in CS-based image reconstruction. In this work, the authors present several sparse-sampling schemes for low-dose CT, quantitatively analyze their data property, and compare effects of the sampling schemes on the image quality.Methods: Data properties of several sampling schemes are analyzed with respect to the CS-based image reconstruction using two measures: sampling density and data incoherence. The authors present five different sparse sampling schemes, and simulated those schemes to achieve a targeted dose reduction. Dose reduction factors of about 75% and 87.5%, compared to a conventional scan, were tested. A fully sampled circular cone-beam CT data set was used as a reference, and sparse sampling has been realized numerically based on the CBCT data.Results: It is found that both sampling density and data incoherence affect the image quality in the CS-based reconstruction. Among the sampling schemes the authors investigated, the sparse-view, many-view undersampling (MVUS)-fine, and MVUS-moving cases have shown promising results. These sampling schemes produced images with similar image quality compared to the reference image and their structure similarity index values were higher than 0.92 in the mouse head scan with 75% dose reduction.Conclusions: The authors found that in CS-based image reconstructions both sampling density and data incoherence affect the image quality, and suggest that a sampling scheme should be devised and optimized by use of these indicators. With this strategic

Public Satisfaction And Quality Of Service Corner Driving License Forming Image Police

Directory of Open Access Journals (Sweden)

Asmara Indahingwati

2017-03-01

Full Text Available 46 sampling research taking care of people who are driving license (SIM in the police force aims to examine the relationship between service quality and satisfaction with the public image of the police institution. Data were collected through questionnaires and analyzed using the Likert model of multiple regression techniques. Results of hypothesis testing showed R = 0.619; F = 44.422; and p = 0.000 (p <0.05 showed that the quality of services and satisfaction of the people together influenced the image of the police. The coefficient of determination explains that the simultaneous quality of services and satisfaction of the people were able to contribute effectively to the image of the police amounted to 38.3%. The results of partial analysis shows that the relationship between service quality and image of the police has a value of p = 0.000 (p <5%, and r = 0.361, which means the quality of service to the image of the police institution is low. Partial assay analysis results between people's satisfaction with the image of the police obtained value of p = 0.000 (p <0.05; r = 0.322, which means people's satisfaction with the image of the police institutions have a significant positive correlation with the level of relationships is low

The influence of software filtering in digital mammography image quality

Science.gov (United States)

Michail, C.; Spyropoulou, V.; Kalyvas, N.; Valais, I.; Dimitropoulos, N.; Fountos, G.; Kandarakis, I.; Panayiotakis, G.

2009-05-01

Breast cancer is one of the most frequently diagnosed cancers among women. Several techniques have been developed to help in the early detection of breast cancer such as conventional and digital x-ray mammography, positron and single-photon emission mammography, etc. A key advantage in digital mammography is that images can be manipulated as simple computer image files. Thus non-dedicated commercially available image manipulation software can be employed to process and store the images. The image processing tools of the Photoshop (CS 2) software usually incorporate digital filters which may be used to reduce image noise, enhance contrast and increase spatial resolution. However, improving an image quality parameter may result in degradation of another. The aim of this work was to investigate the influence of three sharpening filters, named hereafter sharpen, sharpen more and sharpen edges on image resolution and noise. Image resolution was assessed by means of the Modulation Transfer Function (MTF).In conclusion it was found that the correct use of commercial non-dedicated software on digital mammograms may improve some aspects of image quality.

The influence of software filtering in digital mammography image quality

International Nuclear Information System (INIS)

Michail, C; Spyropoulou, V; Valais, I; Panayiotakis, G; Kalyvas, N; Fountos, G; Kandarakis, I; Dimitropoulos, N

2009-01-01

Breast cancer is one of the most frequently diagnosed cancers among women. Several techniques have been developed to help in the early detection of breast cancer such as conventional and digital x-ray mammography, positron and single-photon emission mammography, etc. A key advantage in digital mammography is that images can be manipulated as simple computer image files. Thus non-dedicated commercially available image manipulation software can be employed to process and store the images. The image processing tools of the Photoshop (CS 2) software usually incorporate digital filters which may be used to reduce image noise, enhance contrast and increase spatial resolution. However, improving an image quality parameter may result in degradation of another. The aim of this work was to investigate the influence of three sharpening filters, named hereafter sharpen, sharpen more and sharpen edges on image resolution and noise. Image resolution was assessed by means of the Modulation Transfer Function (MTF).In conclusion it was found that the correct use of commercial non-dedicated software on digital mammograms may improve some aspects of image quality.

16-slice multi-detector row CT coronary angiography: image quality and optimization of the image reconstruction window

International Nuclear Information System (INIS)

Kim, Yoo Kyung; Shim, Sung Shine; Lim, Soo Mee; Hwang, Ji Young; Kim, Yoon Kyung

2005-01-01

The purpose of this experiment is to investigate the image quality of CT coronary angiography using a 16-slice multi-detector row CT and to determine the optimal image reconstruction window. CT coronary angiography was obtained in 36 nonsymptomatic volunteers using a 16-slice multi-detector row CT (SOMATOM Sensation, Siemens Medical System). The mean heart rates were 70 beats per minute (bpm) or less in 18 persons and more than 70 bpm in 18 persons. Eleven data sets were obtained for each patient (reconstructed at 30%-80% of the cardiac cycle with an increment of 5%). Image quality of the eight coronary segments [left main coronary artery (LM), proximal and middle segments of left anterior descending artery (p-LAD, m-LAN) and left circumflex coronary artery (p-LCx, m-LCx) and proximal, middle and distal segments of right coronary artery (p-RCA, m-RCA, d-RCA)] was assessed. The optimal reconstruction windows in the cardiac cycle for the best image quality were 60-70% for the segments of the LM, LAD, and LC arteries in two groups (bpm 70) and 55-65% (bpm 70) for the segments of the RCA. On the best dataset for each coronary segment, the following diagnostic image quality was achieved in the two groups: LM: 100%, 83%; p-LAD: 100%, 88% m-LAD: 100%, 72%; p-LCx: 100%, 72%; m-LCx: 100%, 72%; p-RCA: 94%, 72%; m-RCA: 61%, 50%; d-RCA: 100%, 80%. The 16 slice multi-detector row CT scan provided visualization of the coronary arteries with high resolution. Especially in the group with a mean heart rate of 70 bpm or less, all the coronary segments except the RCA showed diagnostic image quality. Optimal image quality was achieved with a 60-70% trigger delay for all coronary arterial segments, but the best images of RCA were achieved in the earlier cardiac phase in the patients with a mean heart rate of more than 70 bpm

RADARSAT-1 Image Quality Excellence in the Extended Mission

National Research Council Canada - National Science Library

Srivastava, S. K; Cote, S; Le Dantec, P; Hawkins, R. K

2005-01-01

... after its launch on November 4, 1995. Both single beams and ScanSAR imagery are still monitored routinely for radiometric calibration performance based on images of the Amazon Rainforest, and for image quality performance using imagery...

Image quality assessment based on inter-patch and intra-patch similarity.

Directory of Open Access Journals (Sweden)

Fei Zhou

Full Text Available In this paper, we propose a full-reference (FR image quality assessment (IQA scheme, which evaluates image fidelity from two aspects: the inter-patch similarity and the intra-patch similarity. The scheme is performed in a patch-wise fashion so that a quality map can be obtained. On one hand, we investigate the disparity between one image patch and its adjacent ones. This disparity is visually described by an inter-patch feature, where the hybrid effect of luminance masking and contrast masking is taken into account. The inter-patch similarity is further measured by modifying the normalized correlation coefficient (NCC. On the other hand, we also attach importance to the impact of image contents within one patch on the IQA problem. For the intra-patch feature, we consider image curvature as an important complement of image gradient. According to local image contents, the intra-patch similarity is measured by adaptively comparing image curvature and gradient. Besides, a nonlinear integration of the inter-patch and intra-patch similarity is presented to obtain an overall score of image quality. The experiments conducted on six publicly available image databases show that our scheme achieves better performance in comparison with several state-of-the-art schemes.

Image quality in non-gated versus gated reconstruction of tongue motion using magnetic resonance imaging: a comparison using automated image processing

Energy Technology Data Exchange (ETDEWEB)

Alvey, Christopher; Orphanidou, C.; Coleman, J.; McIntyre, A.; Golding, S.; Kochanski, G. [University of Oxford, Oxford (United Kingdom)

2008-11-15

The use of gated or ECG triggered MR is a well-established technique and developments in coil technology have enabled this approach to be applied to areas other than the heart. However, the image quality of gated (ECG or cine) versus non-gated or real-time has not been extensively evaluated in the mouth. We evaluate two image sequences by developing an automatic image processing technique which compares how well the image represents known anatomy. Four subjects practised experimental poly-syllabic sentences prior to MR scanning. Using a 1.5 T MR unit, we acquired comparable gated (using an artificial trigger) and non-gated sagittal images during speech. We then used an image processing algorithm to model the image grey along lines that cross the airway. Each line involved an eight parameter non-linear equation to model of proton densities, edges, and dimensions. Gated and non-gated images show similar spatial resolution, with non-gated images being slightly sharper (10% better resolution, less than 1 pixel). However, the gated sequences generated images of substantially lower inherent noise, and substantially better discrimination between air and tissue. Additionally, the gated sequences demonstrate a very much greater temporal resolution. Overall, image quality is better with gated imaging techniques, especially given their superior temporal resolution. Gated techniques are limited by the repeatability of the motions involved, and we have shown that speech to a metronome can be sufficiently repeatable to allow high-quality gated magnetic resonance imaging images. We suggest that gated sequences may be useful for evaluating other types of repetitive movement involving the joints and limb motions. (orig.)

Image quality in non-gated versus gated reconstruction of tongue motion using magnetic resonance imaging: a comparison using automated image processing

International Nuclear Information System (INIS)

Alvey, Christopher; Orphanidou, C.; Coleman, J.; McIntyre, A.; Golding, S.; Kochanski, G.

2008-01-01

The use of gated or ECG triggered MR is a well-established technique and developments in coil technology have enabled this approach to be applied to areas other than the heart. However, the image quality of gated (ECG or cine) versus non-gated or real-time has not been extensively evaluated in the mouth. We evaluate two image sequences by developing an automatic image processing technique which compares how well the image represents known anatomy. Four subjects practised experimental poly-syllabic sentences prior to MR scanning. Using a 1.5 T MR unit, we acquired comparable gated (using an artificial trigger) and non-gated sagittal images during speech. We then used an image processing algorithm to model the image grey along lines that cross the airway. Each line involved an eight parameter non-linear equation to model of proton densities, edges, and dimensions. Gated and non-gated images show similar spatial resolution, with non-gated images being slightly sharper (10% better resolution, less than 1 pixel). However, the gated sequences generated images of substantially lower inherent noise, and substantially better discrimination between air and tissue. Additionally, the gated sequences demonstrate a very much greater temporal resolution. Overall, image quality is better with gated imaging techniques, especially given their superior temporal resolution. Gated techniques are limited by the repeatability of the motions involved, and we have shown that speech to a metronome can be sufficiently repeatable to allow high-quality gated magnetic resonance imaging images. We suggest that gated sequences may be useful for evaluating other types of repetitive movement involving the joints and limb motions. (orig.)

Relationships among muscle dysmorphia characteristics, body image quality of life, and coping in males.

Science.gov (United States)

Tod, D; Edwards, C

2015-09-01

The purpose of this study was to examine relationships among bodybuilding dependence, muscle satisfaction, body image-related quality of life and body image-related coping strategies, and test the hypothesis that muscle dysmorphia characteristics may predict quality of life via coping strategies. Participants (294 males, Mage=20.5 years, SD=3.1) participated in a cross-sectional survey. Participants completed questionnaires assessing muscle satisfaction, bodybuilding dependence, body image-related quality of life and body image-related coping. Quality of life was correlated positively with muscle satisfaction and bodybuilding dependence but negatively with body image coping (P<0.05). Body image coping was correlated positively with bodybuilding dependence and negatively with muscle satisfaction (P<0.05). Mediation analysis found that bodybuilding dependence and muscle satisfaction predicted quality of life both directly and indirectly via body image coping strategies (as evidenced by the bias corrected and accelerated bootstrapped confidence intervals). These results provide preliminary evidence regarding the ways that muscularity concerns might influence body image-related quality of life. Copyright © 2014 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Implementation of dictionary pair learning algorithm for image quality improvement

Science.gov (United States)

Vimala, C.; Aruna Priya, P.

2018-04-01

This paper proposes an image denoising on dictionary pair learning algorithm. Visual information is transmitted in the form of digital images is becoming a major method of communication in the modern age, but the image obtained after transmissions is often corrupted with noise. The received image needs processing before it can be used in applications. Image denoising involves the manipulation of the image data to produce a visually high quality image.

Objective assessment of image quality and dose reduction in CT iterative reconstruction

Energy Technology Data Exchange (ETDEWEB)

Vaishnav, J. Y., E-mail: jay.vaishnav@fda.hhs.gov; Jung, W. C. [Diagnostic X-Ray Systems Branch, Office of In Vitro Diagnostic Devices and Radiological Health, Center for Devices and Radiological Health, United States Food and Drug Administration, 10903 New Hampshire Avenue, Silver Spring, Maryland 20993 (United States); Popescu, L. M.; Zeng, R.; Myers, K. J. [Division of Imaging and Applied Mathematics, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, United States Food and Drug Administration, 10903 New Hampshire Avenue, Silver Spring, Maryland 20993 (United States)

2014-07-15

Purpose: Iterative reconstruction (IR) algorithms have the potential to reduce radiation dose in CT diagnostic imaging. As these algorithms become available on the market, a standardizable method of quantifying the dose reduction that a particular IR method can achieve would be valuable. Such a method would assist manufacturers in making promotional claims about dose reduction, buyers in comparing different devices, physicists in independently validating the claims, and the United States Food and Drug Administration in regulating the labeling of CT devices. However, the nonlinear nature of commercially available IR algorithms poses challenges to objectively assessing image quality, a necessary step in establishing the amount of dose reduction that a given IR algorithm can achieve without compromising that image quality. This review paper seeks to consolidate information relevant to objectively assessing the quality of CT IR images, and thereby measuring the level of dose reduction that a given IR algorithm can achieve. Methods: The authors discuss task-based methods for assessing the quality of CT IR images and evaluating dose reduction. Results: The authors explain and review recent literature on signal detection and localization tasks in CT IR image quality assessment, the design of an appropriate phantom for these tasks, possible choices of observers (including human and model observers), and methods of evaluating observer performance. Conclusions: Standardizing the measurement of dose reduction is a problem of broad interest to the CT community and to public health. A necessary step in the process is the objective assessment of CT image quality, for which various task-based methods may be suitable. This paper attempts to consolidate recent literature that is relevant to the development and implementation of task-based methods for the assessment of CT IR image quality.

Body image, self-esteem, and quality of life in patients with psoriasis

Directory of Open Access Journals (Sweden)

Hulya Nazik

2017-01-01

Full Text Available Background: Psoriasis is a chronic inflammatory disease of the skin that may affect the visible areas of body. Hence, the quality of life, self-esteem, and body image can be affected in psoriasis patients. Objectives: We aimed in the present study to assess the effects of psoriasis on the quality of life, self-esteem, and body image. Materials and Methods: The study included 92 patients with psoriasis, along with 98 control participants. The sociodemographic characteristics of the patients were assessed, their Psoriasis Area Severity Index (PASI scores were calculated to determine the clinical severity of the psoriasis, and the values were recorded. In addition, Dermatology Life Quality Index (DLQI, Body Image Scale, and Rosenberg Self-Esteem Scale results were evaluated. Results: When the control and psoriasis groups were evaluated regarding the DLQI, self-esteem, and body image, quality of life was found to be more negatively affected in the psoriasis group than the controls, which was statistically significant (P < 0.001, and self-esteem (P < 0.001 and body image (P < 0.001 were found to be significantly lower. Educational status significantly affected self-esteem (P < 0.001 and body image (P = 0.021, however, quality of life was not significantly affected by this parameter (P = 0.345. PASI was positively correlated with the quality of life (r = 0.703 and self-esteem (r = 0.448, however, it was negatively correlated with the body image (r = −0.423. Conclusions: Psoriasis may negatively affect quality of life, self-esteem, and body image, and may also cause psychosocial problems. An assessment of new approaches on this issue may contribute to developments in the treatment of and rehabilitation from this disease.

Objective assessment of image quality and dose reduction in CT iterative reconstruction

International Nuclear Information System (INIS)

Vaishnav, J. Y.; Jung, W. C.; Popescu, L. M.; Zeng, R.; Myers, K. J.

2014-01-01

Purpose: Iterative reconstruction (IR) algorithms have the potential to reduce radiation dose in CT diagnostic imaging. As these algorithms become available on the market, a standardizable method of quantifying the dose reduction that a particular IR method can achieve would be valuable. Such a method would assist manufacturers in making promotional claims about dose reduction, buyers in comparing different devices, physicists in independently validating the claims, and the United States Food and Drug Administration in regulating the labeling of CT devices. However, the nonlinear nature of commercially available IR algorithms poses challenges to objectively assessing image quality, a necessary step in establishing the amount of dose reduction that a given IR algorithm can achieve without compromising that image quality. This review paper seeks to consolidate information relevant to objectively assessing the quality of CT IR images, and thereby measuring the level of dose reduction that a given IR algorithm can achieve. Methods: The authors discuss task-based methods for assessing the quality of CT IR images and evaluating dose reduction. Results: The authors explain and review recent literature on signal detection and localization tasks in CT IR image quality assessment, the design of an appropriate phantom for these tasks, possible choices of observers (including human and model observers), and methods of evaluating observer performance. Conclusions: Standardizing the measurement of dose reduction is a problem of broad interest to the CT community and to public health. A necessary step in the process is the objective assessment of CT image quality, for which various task-based methods may be suitable. This paper attempts to consolidate recent literature that is relevant to the development and implementation of task-based methods for the assessment of CT IR image quality

Feasibility, safety and image quality of cardiac FDG studies during hyperinsulinaemic-euglycaemic clamping

International Nuclear Information System (INIS)

Bax, Jeroen J.; Visser, Frans C.; Lingen, Arthur van; Visser, Cees A.; Poldermans, Don; Elhendy, Abdou; Boersma, Eric

2002-01-01

Fluorine-18 fluorodeoxyglucose (FDG) imaging for the assessment of myocardial viability has become an integral part of the diagnostic and prognostic work-up of patients with ischaemic cardiomyopathy. To ensure good image quality, in particular in patients with diabetes mellitus, hyperinsulinaemic-euglycaemic clamping has been proposed. In this study we evaluated the safety and the image quality of cardiac FDG imaging during clamping in a large group of patients, including a subgroup with diabetes mellitus. The incidence of viability (on both a segment and a patient basis) was also determined for patients with and without diabetes mellitus. The safety and image quality of cardiac FDG studies during clamping were evaluated in 131 patients, including 19 with diabetes mellitus. Image quality was assessed visually and quantitatively using heart-to-lung (H/L), heart-to-liver (H/Li) and myocardium-to-background (M/B) ratios. Blood samples were drawn at baseline and at the time of FDG injection to determine levels of glucose, free fatty acids and insulin. The metabolic circumstances were optimal for FDG imaging: high insulin levels, low free fatty acid levels and glucose levels in the normal range (levels of substrates were comparable between patients with and patients without diabetes mellitus). No serious side-effects occurred in any patient. Image quality (assessed visually) was good in all patients. The quantitative parameters of image quality (H/L, H/Li and M/B) were comparable between patients with and patients without diabetes mellitus. The incidence of viability was high: 38% of patients without and 58% of patients with diabetes mellitus had substantial viability despite contractile dysfunction. It is concluded that cardiac FDG imaging during clamping is safe and provides excellent image quality, including in patients with diabetes mellitus. The incidence of viability is high, in particular in patients with diabetes mellitus. (orig.)

Automatic analysis of quality of images from X-ray digital flat detectors

International Nuclear Information System (INIS)

Le Meur, Y.

2009-04-01

Since last decade, medical imaging has grown up with the development of new digital imaging techniques. In the field of X-ray radiography, new detectors replace progressively older techniques, based on film or x-ray intensifiers. These digital detectors offer a higher sensibility and reduced overall dimensions. This work has been prepared with Trixell, the world leading company in flat detectors for medical radiography. It deals with quality control on digital images stemming from these detectors. High quality standards of medical imaging impose a close analysis of the defects that can appear on the images. This work describes a complete process for quality analysis of such images. A particular focus is given on the detection task of the defects, thanks to methods well adapted to our context of spatially correlated defects in noise background. (author)

No-reference image quality assessment based on statistics of convolution feature maps

Science.gov (United States)

Lv, Xiaoxin; Qin, Min; Chen, Xiaohui; Wei, Guo

2018-04-01

We propose a Convolutional Feature Maps (CFM) driven approach to accurately predict image quality. Our motivation bases on the finding that the Nature Scene Statistic (NSS) features on convolution feature maps are significantly sensitive to distortion degree of an image. In our method, a Convolutional Neural Network (CNN) is trained to obtain kernels for generating CFM. We design a forward NSS layer which performs on CFM to better extract NSS features. The quality aware features derived from the output of NSS layer is effective to describe the distortion type and degree an image suffered. Finally, a Support Vector Regression (SVR) is employed in our No-Reference Image Quality Assessment (NR-IQA) model to predict a subjective quality score of a distorted image. Experiments conducted on two public databases demonstrate the promising performance of the proposed method is competitive to state of the art NR-IQA methods.

Assessment of image quality in x-ray radiography imaging using a small plasma focus device

International Nuclear Information System (INIS)

Kanani, A.; Shirani, B.; Jabbari, I.; Mokhtari, J.

2014-01-01

This paper offers a comprehensive investigation of image quality parameters for a small plasma focus as a pulsed hard x-ray source for radiography applications. A set of images were captured from some metal objects and electronic circuits using a low energy plasma focus at different voltages of capacitor bank and different pressures of argon gas. The x-ray source focal spot of this device was obtained to be about 0.6 mm using the penumbra imaging method. The image quality was studied by several parameters such as image contrast, line spread function (LSF) and modulation transfer function (MTF). Results showed that the contrast changes by variations in gas pressure. The best contrast was obtained at a pressure of 0.5 mbar and 3.75 kJ stored energy. The results of x-ray dose from the device showed that about 0.6 mGy is sufficient to obtain acceptable images on the film. The measurements of LSF and MTF parameters were carried out by means of a thin stainless steel wire 0.8 mm in diameter and the cut-off frequency was obtained to be about 1.5 cycles/mm. - Highlights: • We investigated a small plasma focus as pulsed x-ray source for radiography applications. • The image quality was studied by several parameters such as image contrast, LSF and MTF. • The x-ray source focal spot was obtained to be ∼0.6 mm using the penumbra imaging method. • The x-ray dose measurement showed that about 0.6 mGy is sufficient to obtain acceptable images on the film. • The profiles of LSF and MTF showed that the cut-off frequency is about 1.5 cycles/mm

Improving image quality of parallel phase-shifting digital holography

International Nuclear Information System (INIS)

Awatsuji, Yasuhiro; Tahara, Tatsuki; Kaneko, Atsushi; Koyama, Takamasa; Nishio, Kenzo; Ura, Shogo; Kubota, Toshihiro; Matoba, Osamu

2008-01-01

The authors propose parallel two-step phase-shifting digital holography to improve the image quality of parallel phase-shifting digital holography. The proposed technique can increase the effective number of pixels of hologram twice in comparison to the conventional parallel four-step technique. The increase of the number of pixels makes it possible to improve the image quality of the reconstructed image of the parallel phase-shifting digital holography. Numerical simulation and preliminary experiment of the proposed technique were conducted and the effectiveness of the technique was confirmed. The proposed technique is more practical than the conventional parallel phase-shifting digital holography, because the composition of the digital holographic system based on the proposed technique is simpler.

Digital mammography--DQE versus optimized image quality in clinical environment: an on site study

Science.gov (United States)

Oberhofer, Nadia; Fracchetti, Alessandro; Springeth, Margareth; Moroder, Ehrenfried

2010-04-01

The intrinsic quality of the detection system of 7 different digital mammography units (5 direct radiography DR; 2 computed radiography CR), expressed by DQE, has been compared with their image quality/dose performances in clinical use. DQE measurements followed IEC 62220-1-2 using a tungsten test object for MTF determination. For image quality assessment two different methods have been applied: 1) measurement of contrast to noise ratio (CNR) according to the European guidelines and 2) contrast-detail (CD) evaluation. The latter was carried out with the phantom CDMAM ver. 3.4 and the commercial software CDMAM Analyser ver. 1.1 (both Artinis) for automated image analysis. The overall image quality index IQFinv proposed by the software has been validated. Correspondence between the two methods has been shown figuring out a linear correlation between CNR and IQFinv. All systems were optimized with respect to image quality and average glandular dose (AGD) within the constraints of automatic exposure control (AEC). For each equipment, a good image quality level was defined by means of CD analysis, and the corresponding CNR value considered as target value. The goal was to achieve for different PMMA-phantom thicknesses constant image quality, that means the CNR target value, at minimum dose. All DR systems exhibited higher DQE and significantly better image quality compared to CR systems. Generally switching, where available, to a target/filter combination with an x-ray spectrum of higher mean energy permitted dose savings at equal image quality. However, several systems did not allow to modify the AEC in order to apply optimal radiographic technique in clinical use. The best ratio image quality/dose was achieved by a unit with a-Se detector and W anode only recently available on the market.

Sensitometric properties and image quality of radiographic film and paper

International Nuclear Information System (INIS)

Domanus, J.C.

1985-09-01

When using X-ray film or radiographic paper for industrial applications one is interested in knowing not only their sensitometric properties (such as speed and contrast) but also the image quality obtainable with a particular brand of film or paper. Although standard methods for testing both properties separately are available it is desirable that the method permits the assessment of all the relevant properties together. The sensitometric properties are usually determined at constant kilovoltage and filtration at the X-ray tube, whereas radiographic image thicknesses. The use of the constant exposure technique could be used to compare both the sensitometric properties as well as the image quality for different radiographic materials. It consist of exposing different film or paper brands at a chosen, constant mAmin exposure when testing radiographic image quality for different thicknesses of a given material. From the results obtained with the constant exposure technique conclusions are drawn about its applicability as a standard method for assessing radiographic film and paper. (author)

Effect of exercise supplementation on dipyridamole thallium-201 image quality

International Nuclear Information System (INIS)

Stern, S.; Greenberg, I.D.; Corne, R.

1991-01-01

To determine the effect of different types of exercise supplementation on dipyridamole thallium image quality, 78 patients were prospectively randomized to one of three protocols: dipyridamole infusion alone, dipyridamole supplemented with isometric handgrip, and dipyridamole with low-level treadmill exercise. Heart-to-lung, heart-to-liver, and heart-to-adjacent infradiaphragmatic activity ratios were generated from anterior images acquired immediately following the test. Additionally, heart-to-total infradiaphragmatic activity was graded semiquantitatively. Results showed a significantly higher ratio of heart to subdiaphragmatic activity in the treadmill group as compared with dipyridamole alone (p less than 0.001) and dipyridamole supplemented with isometric handgrip exercise (p less than 0.001). No significant difference was observed between patients receiving the dipyridamole infusion, and dipyridamole supplemented with isometric handgrip exercise. The authors conclude that low-level treadmill exercise supplementation of dipyridamole infusion is an effective means of improving image quality. Supplementation with isometric handgrip does not improve image quality over dipyridamole alone

Image quality assessment for video stream recognition systems

Science.gov (United States)

Chernov, Timofey S.; Razumnuy, Nikita P.; Kozharinov, Alexander S.; Nikolaev, Dmitry P.; Arlazarov, Vladimir V.

2018-04-01

Recognition and machine vision systems have long been widely used in many disciplines to automate various processes of life and industry. Input images of optical recognition systems can be subjected to a large number of different distortions, especially in uncontrolled or natural shooting conditions, which leads to unpredictable results of recognition systems, making it impossible to assess their reliability. For this reason, it is necessary to perform quality control of the input data of recognition systems, which is facilitated by modern progress in the field of image quality evaluation. In this paper, we investigate the approach to designing optical recognition systems with built-in input image quality estimation modules and feedback, for which the necessary definitions are introduced and a model for describing such systems is constructed. The efficiency of this approach is illustrated by the example of solving the problem of selecting the best frames for recognition in a video stream for a system with limited resources. Experimental results are presented for the system for identity documents recognition, showing a significant increase in the accuracy and speed of the system under simulated conditions of automatic camera focusing, leading to blurring of frames.

Microfocus X-ray imaging of Brazil nuts for quality control

Energy Technology Data Exchange (ETDEWEB)

Franco, Margareth Kazuyo Kobayashi Dias, E-mail: mkfranco@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Yokaichiya, Fabiano, E-mail: fabiano.yokaichiya@helmholtz-berlin.de [Department Quantum Phenomena in Novel Materials, Helmholtz Zentrum Berlim für Materialien und Energie GmbH, Berlin (Germany); Kardjilov, Nikolay, E-mail: kardjilov@helmholtz-berlim.de [Institut Angewandte Materialforschung, Helmholtz Zentrum Berlim für Materialien und Energie GmbH, Berlin (Germany); Ferraz, Antonio Carlos de Oliveira, E-mail: carlos@feagri.unicamp.br [Universidade Estadual de Campinas (FEAGRI/UNICAMP), SP (Brazil). Faculdade de Engenharia Agricola

2015-07-15

Non-destructive quality assessment of food prior to processing is desirable in commercial facilities due to its non-invasive nature, for economic reasons and for its safety appeals. Grading Brazil nuts in this way allows for the separation of undesirable nuts to avoid contamination during the automatic nut shelling process. The aim of this study was to evaluate the feasibility of X-ray phase contrast enhanced imaging in assessing nut quality. For this goal, details of the imaging technique are described and phase contrast X-ray and microtomography imaging of nut samples are investigated. Both high quality (i.e. 'sound' nuts as well as treated nuts were examined. It was concluded that both the X-ray imaging and tomography techniques have the potential to discriminate morphological features of the nut and to identify 'sound' kernels from atypical ones. Larger nuts and nuts with a larger gap area between shell and kernel were concluded to have more atypical formations. Both techniques also seemed promising for use in automatic sorting lines. However, by using microtomography, the visualization of finer formations not noticeable in the X-ray images was possible. Further studies shall be carried out to investigate the nature of these formations, how they affect nut quality and their evolution with storage time. (author)

Microfocus X-ray imaging of Brazil nuts for quality control

International Nuclear Information System (INIS)

Franco, Margareth Kazuyo Kobayashi Dias; Yokaichiya, Fabiano; Kardjilov, Nikolay; Ferraz, Antonio Carlos de Oliveira

2015-01-01

Non-destructive quality assessment of food prior to processing is desirable in commercial facilities due to its non-invasive nature, for economic reasons and for its safety appeals. Grading Brazil nuts in this way allows for the separation of undesirable nuts to avoid contamination during the automatic nut shelling process. The aim of this study was to evaluate the feasibility of X-ray phase contrast enhanced imaging in assessing nut quality. For this goal, details of the imaging technique are described and phase contrast X-ray and microtomography imaging of nut samples are investigated. Both high quality (i.e. 'sound' nuts as well as treated nuts were examined. It was concluded that both the X-ray imaging and tomography techniques have the potential to discriminate morphological features of the nut and to identify 'sound' kernels from atypical ones. Larger nuts and nuts with a larger gap area between shell and kernel were concluded to have more atypical formations. Both techniques also seemed promising for use in automatic sorting lines. However, by using microtomography, the visualization of finer formations not noticeable in the X-ray images was possible. Further studies shall be carried out to investigate the nature of these formations, how they affect nut quality and their evolution with storage time. (author)

Improving lateral resolution and image quality of optical coherence tomography by the multi-frame superresolution technique for 3D tissue imaging.

Science.gov (United States)

Shen, Kai; Lu, Hui; Baig, Sarfaraz; Wang, Michael R

2017-11-01

The multi-frame superresolution technique is introduced to significantly improve the lateral resolution and image quality of spectral domain optical coherence tomography (SD-OCT). Using several sets of low resolution C-scan 3D images with lateral sub-spot-spacing shifts on different sets, the multi-frame superresolution processing of these sets at each depth layer reconstructs a higher resolution and quality lateral image. Layer by layer processing yields an overall high lateral resolution and quality 3D image. In theory, the superresolution processing including deconvolution can solve the diffraction limit, lateral scan density and background noise problems together. In experiment, the improved lateral resolution by ~3 times reaching 7.81 µm and 2.19 µm using sample arm optics of 0.015 and 0.05 numerical aperture respectively as well as doubling the image quality has been confirmed by imaging a known resolution test target. Improved lateral resolution on in vitro skin C-scan images has been demonstrated. For in vivo 3D SD-OCT imaging of human skin, fingerprint and retina layer, we used the multi-modal volume registration method to effectively estimate the lateral image shifts among different C-scans due to random minor unintended live body motion. Further processing of these images generated high lateral resolution 3D images as well as high quality B-scan images of these in vivo tissues.

Preclinical imaging characteristics and quantification of Platinum-195m SPECT

Energy Technology Data Exchange (ETDEWEB)

Aalbersberg, E.A.; Wit-van der Veen, B.J. de; Vegt, E.; Vogel, Wouter V. [The Netherlands Cancer Institute (NKI-AVL), Department of Nuclear Medicine, Amsterdam (Netherlands); Zwaagstra, O.; Codee-van der Schilden, K. [Nuclear Research and Consultancy Group (NRG), Petten (Netherlands)

2017-08-15

In vivo biodistribution imaging of platinum-based compounds may allow better patient selection for treatment with chemo(radio)therapy. Radiolabeling with Platinum-195m ({sup 195m}Pt) allows SPECT imaging, without altering the chemical structure or biological activity of the compound. We have assessed the feasibility of {sup 195m}Pt SPECT imaging in mice, with the aim to determine the image quality and accuracy of quantification for current preclinical imaging equipment. Enriched (>96%) {sup 194}Pt was irradiated in the High Flux Reactor (HFR) in Petten, The Netherlands (NRG). A 0.05 M HCl {sup 195m}Pt-solution with a specific activity of 33 MBq/mg was obtained. Image quality was assessed for the NanoSPECT/CT (Bioscan Inc., Washington DC, USA) and U-SPECT{sup +}/CT (MILabs BV, Utrecht, the Netherlands) scanners. A radioactivity-filled rod phantom (rod diameter 0.85-1.7 mm) filled with 1 MBq {sup 195m}Pt was scanned with different acquisition durations (10-120 min). Four healthy mice were injected intravenously with 3-4 MBq {sup 195m}Pt. Mouse images were acquired with the NanoSPECT for 120 min at 0, 2, 4, or 24 h after injection. Organs were delineated to quantify {sup 195m}Pt concentrations. Immediately after scanning, the mice were sacrificed, and the platinum concentration was determined in organs using a gamma counter and graphite furnace - atomic absorption spectroscopy (GF-AAS) as reference standards. A 30-min acquisition of the phantom provided visually adequate image quality for both scanners. The smallest visible rods were 0.95 mm in diameter on the NanoSPECT and 0.85 mm in diameter on the U-SPECT{sup +}. The image quality in mice was visually adequate. Uptake was seen in the kidneys with excretion to the bladder, and in the liver, blood, and intestine. No uptake was seen in the brain. The Spearman correlation between SPECT and gamma counter was 0.92, between SPECT and GF-AAS it was 0.84, and between GF-AAS and gamma counter it was0.97 (all p < 0

Collimation effects on the radiation detectors in the iCT image quality

International Nuclear Information System (INIS)

Carvalho, Diego Vergacas de Sousa; Kirita, Rodrigo; Mesquita, Carlos Henrique de; Hamada, Margarida Mizue; Ferreira, Erick Oliveira; Dantas, Carlos Costa

2013-01-01

This work studies the collimation effect in radiation detectors on the image quality of the iCT scanner, in which the path traversed by radiation beams is similar to a fan. The collimators were made of lead, 5 cm deep and 12 cm high, with rectangular holes (slits) of 2 x 5 mm, 4 x 10 mm (width x height) and circular hole of 5 mm diameter. The matrix images reconstructed from the data obtained with these collimation holes are presented. The spatial resolution of the image depends on the geometry of the collimator. One of the major advantages of narrow beam transmission tomography is the so-called hard field property. This property is capable of producing high quality images, though it decreases the count value and it takes a longer time. In contrast, a large collimation diameter produces a fuzzy image but with a faster scanning time. Moreover, the enlargement of the aperture from 2 x 5 mm to 4 x 10 mm barely affects the image quality. The aperture from 4 x 10 mm and 5 mm diameter presented similar quality image. (author)

Collimation effects on the radiation detectors in the iCT image quality

Energy Technology Data Exchange (ETDEWEB)

Carvalho, Diego Vergacas de Sousa; Kirita, Rodrigo; Mesquita, Carlos Henrique de; Hamada, Margarida Mizue, E-mail: dvcarvalho@usp.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Ferreira, Erick Oliveira; Dantas, Carlos Costa [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Energia Nuclear

2013-07-01

This work studies the collimation effect in radiation detectors on the image quality of the iCT scanner, in which the path traversed by radiation beams is similar to a fan. The collimators were made of lead, 5 cm deep and 12 cm high, with rectangular holes (slits) of 2 x 5 mm, 4 x 10 mm (width x height) and circular hole of 5 mm diameter. The matrix images reconstructed from the data obtained with these collimation holes are presented. The spatial resolution of the image depends on the geometry of the collimator. One of the major advantages of narrow beam transmission tomography is the so-called hard field property. This property is capable of producing high quality images, though it decreases the count value and it takes a longer time. In contrast, a large collimation diameter produces a fuzzy image but with a faster scanning time. Moreover, the enlargement of the aperture from 2 x 5 mm to 4 x 10 mm barely affects the image quality. The aperture from 4 x 10 mm and 5 mm diameter presented similar quality image. (author)

INCITS W1.1 development update: appearance-based image quality standards for printers

Science.gov (United States)

Zeise, Eric K.; Rasmussen, D. René; Ng, Yee S.; Dalal, Edul; McCarthy, Ann; Williams, Don

2008-01-01