scholarly journals Effect of differences in pixel size on image characteristics of digital intraoral radiographic systems: a physical and visual evaluation

2020 ◽  
Vol 49 (6) ◽  
pp. 20190378
Author(s):  
Taku Kuramoto ◽  
Shinya Takarabe ◽  
Kazutoshi Okamura ◽  
Kenshi Shiotsuki ◽  
Yusuke Shibayama ◽  
...  
Keyword(s):  
High Resolution ◽  
Image Quality ◽  
High Speed ◽  
Imaging Plate ◽  
Noise Power ◽  
International Electrotechnical Commission ◽  
Pixel Size ◽  
Modulation Transfer ◽  
Visual Evaluation ◽  
Exposure Conditions

Objectives: To quantify and validate the effect of pixel size on a digital intraoral radiographic system according to International Electrotechnical Commission standards through physical and visual evaluations. Methods: The digital intraoral radiographic system used was the photostimulable phosphor imaging plate and scanner system. The system had three image capture modes: high-speed (HS), high-resolution (HR), and super high-resolution (SHR) with different pixels. The physical characteristics of the system were evaluated using presampled modulation transfer function (MTF) and the normalized noise power spectrum (NNPS). An aluminum (Al) step phantom with different depths of holes was used to acquire images under various exposure conditions. The average number of perceptible holes from all steps was plotted against each exposure dose. The results were compared to analyze the effects of pixel size on image quality of intraoral radiographs. Results: The MTF was slightly higher with SHR than with HR and HS. The NNPS with SHR showed about a 40% decrease in magnitude compared to HS. The total number of perceptible holes in the Al step phantom was higher with SHR than with HS and HR in all exposure conditions. Conclusions: The MTF and NNPS obtained with different pixel size could be quantified by physical evaluation, and the differences were visually validated with Al step phantom. The SHR mode has the potential to decrease the radiation dose without compromising the image quality.

scholarly journals Throughput and resolution with a next-generation direct electron detector

IUCrJ ◽  
2019 ◽  
Vol 6 (6) ◽  
pp. 1007-1013 ◽  
Author(s):  
Joshua H. Mendez ◽  
Atousa Mehrani ◽  
Peter Randolph ◽  
Scott Stagg
Keyword(s):  
High Resolution ◽  
Image Quality ◽  
Low Frequency ◽  
Phase Plate ◽  
Noise Power ◽  
Modulation Transfer ◽  
Image Capture ◽  
Induced Motion ◽  
Counting Mode ◽  
New Generation

Direct electron detectors (DEDs) have revolutionized cryo-electron microscopy (cryo-EM) by facilitating the correction of beam-induced motion and radiation damage, and also by providing high-resolution image capture. A new-generation DED, the DE64, has been developed by Direct Electron that has good performance in both integrating and counting modes. The camera has been characterized in both modes in terms of image quality, throughput and resolution of cryo-EM reconstructions. The modulation transfer function, noise power spectrum and detective quantum efficiency (DQE) were determined for both modes, as well as the number of images per unit time. Although the DQE for counting mode was superior to that for integrating mode, the data-collection throughput for this mode was more than ten times slower. Since throughput and resolution are related in single-particle cryo-EM, data for apoferritin were collected and reconstructed using integrating mode, integrating mode in conjunction with a Volta phase plate (VPP) and counting mode. Only the counting-mode data resulted in a better than 3 Å resolution reconstruction with similar numbers of particles, and this increased performance could not be compensated for by the increased throughput of integrating mode or by the increased low-frequency contrast of integrating mode with the VPP. These data show that the superior image quality provided by counting mode is more important for high-resolution cryo-EM reconstructions than the superior throughput of integrating mode.

scholarly journals Image Quality Assessment of a CMOS/Gd2O2S:Pr,Ce,F X-Ray Sensor

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Christos Michail
Keyword(s):  
Image Quality ◽  
Optical Sensor ◽  
Image Quality Assessment ◽  
Beam Quality ◽  
Detector Response ◽  
Noise Power ◽  
Modulation Transfer ◽  
Custom Made ◽  
Cmos Sensor ◽  
Edge Method

The aim of the present study was to examine the image quality performance of a CMOS digital imaging optical sensor coupled to custom made gadolinium oxysulfide powder scintillators, doped with praseodymium, cerium, and fluorine (Gd2O2S:Pr,Ce,F). The screens, with coating thicknesses 35.7 and 71.2 mg/cm2, were prepared in our laboratory from Gd2O2S:Pr,Ce,F powder (Phosphor Technology, Ltd.) by sedimentation on silica substrates and were placed in direct contact with the optical sensor. Image quality was determined through single index (information capacity, IC) and spatial frequency dependent parameters, by assessing the Modulation Transfer Function (MTF) and the Normalized Noise Power Spectrum (NNPS). The MTF was measured using the slanted-edge method. The CMOS sensor/Gd2O2S:Pr,Ce,F screens combinations were irradiated under the RQA-5 (IEC 62220-1) beam quality. The detector response function was linear for the exposure range under investigation. Under the general radiography conditions, both Gd2O2S:Pr,Ce,F screen/CMOS combinations exhibited moderate imaging properties, in terms of IC, with previously published scintillators, such as CsI:Tl, Gd2O2S:Tb, and Gd2O2S:Eu.

Measurement of Point-Spread Function of IP-System

1997 ◽  
Vol 3 (S2) ◽  
pp. 1103-1104
Author(s):  
T. Oikawa ◽  
F. Hosokawa ◽  
A. Taniyama ◽  
D. Shindo ◽  
M. Kersker
Keyword(s):  
Transfer Function ◽  
Point Spread Function ◽  
Electron Probe ◽  
Imaging Plate ◽  
Pixel Size ◽  
Modulation Transfer ◽  
Contrast Transfer Function ◽  
Point Spread ◽  
Spread Function ◽  
Resolution Estimation

For the resolution estimation of the Imaging Plate (IP)-system, several methods were carried out. One of them is the measurement of the modulation transfer function (MTF) from the phase contrast transfer function taken with an amorphous Ge film specimen. One of another is the measurement of the point-spread function (PSF) from the auto-correlation of the Poison noise obtained by the IP-system.In this experiment, the PSF of the IP-system were measured from the intensity distribution recorded with a 1.6 μm-diameter electron probe on the IP.When recording the electron intensity with a small enough electron probe as compared with the pixel size of the IP (25 μm × 25 μm), a single pixel detects the electron signal in case of ideal IP-resolution which is limited only by the pixel size. However, practical IP-resolution is limited by the electron diffusion, x-ray emission and the laser beam diffusion in the IP, and so on. Therefore, it is possible to measure the PSF from the intensity distributions of the patterns recorded with a small enough electron probe.

High Resolution Contrast-Enhanced MR Angiography in the Evaluation of Rabbit Carotid Artery

2005 ◽  
Vol 18 (5-6) ◽  
pp. 529-536
Author(s):  
R.-H. Wu ◽  
D.F. Kallmes
Keyword(s):  
High Resolution ◽  
Image Quality ◽  
Carotid Artery ◽  
Mr Angiography ◽  
Flip Angle ◽  
Acquisition Time ◽  
Pixel Size ◽  
Rabbit Carotid Artery ◽  
Contrast Enhanced ◽  
Venous Contamination

This study compared a high resolution contrast-enhanced MR angiography (MRA) sequence to conventional contrast-enhanced MRA sequence for imaging of rabbit carotid artery. Fifteen rabbits underwent an evaluation using both high resolution contrast-enhanced MRA sequence and conventional contrast-enhanced MRA sequence. Siemens 1.5 Tesla Magnetom Vision system was utilized. The parameters of high resolution sequence were: TR/TE= 6.2/2.0 msec, flip angle 25°, matrix 130×512, pixel size 0.96×0.49 mm, partition thickness 1.58 mm, acquisition time 24 sec. The parameters of conventional sequence were: TR/TE=3.8/1.4 msec, flip angle 35°, matrix 110×256, pixel size 1.48×1.02 mm, partition thickness 2mm, acquisition time 10 sec. Maximum intensity projection (MIP) images were created. Both original single slices and MIP images were used for image quality evaluation. Contrast-to-noise ratio (CNR), signal-to-noise ratio (SNR), distinctness of artery edge, and venous contamination were analyzed for both techniques. Higher average CNR and SNR were obtained with high resolution contrast-enhanced MRA, compared to average CNR and SNR with conventional contrast-enhanced MRA. The differences were statistically significant (P<0.01). The artery edge with high resolution method was more distinct than conventional method. Jugular venous contamination was found in five of 15 cases with high resolution contrast-enhanced MRA and in four of 15 cases with conventional contrast-enhanced MRA. High resolution contrast-enhanced MRA has significant potential for high quality noninvasive vascular imaging. The image quality with high resolution contrast-enhanced MRA sequence is better than conventional contrast-enhanced MRA sequence.

scholarly journals Evaluation of digital X-ray detectors for medical imaging applications

2011 ◽  
Author(s):  
Αναστάσιος Κωνσταντινίδης
Keyword(s):  
Thin Film Transistor ◽  
Complementary Metal Oxide Semiconductor ◽  
Metal Oxide Semiconductor ◽  
Oxide Semiconductor ◽  
Noise Power ◽  
International Electrotechnical Commission ◽  
Modulation Transfer ◽  
Large Area ◽  
X Ray ◽  
Active Pixel

Οι ψηφιακοί ανιχνευτές ακτίνων Χ είναι πλέον διαδεδομένοι σε αρκετές εξετάσεις με ακτίνες Χ. Άρχισαν να χρησιμοποιούνται στην κλινική ιατρική την τελευταία δεκαετία αλλά εξακολουθούν να υπάρχουν συνεχείς εξελίξεις στην τεχνολογία. Η τεχνολογία συμπληρωματικών ημιαγωγών μεταλλικού οξειδίου (complementary metal oxide semiconductor - CMOS) με αισθητήρα ενεργού εικονοστοιχείου (active pixel sensor - APS) είναι μια νέα ψηφιακή τεχνολογία που προσφέρει πλεονεκτήματα σε σύγκριση με μερικές από τις πιο καθιερωμένες τεχνολογίες (π.χ. α) συσκευές συζευγμένου φορτίου (charge-coupled devices - CCD), β) ανιχνευτές με τρανζίστορ λεπτών υμενίων (thin film transistor - TFT) και γ) CMOS με αισθητήρα παθητικού εικονοστοιχείου (passive pixel sensor - PPS)). Η συγκεκριμένη διδακτορική διατριβή εξετάζει την απόδοση των ψηφιακών ανιχνευτών νέας τεχνολογίας και επιχειρεί να προσδιορίσει το ρόλο τους σε μελλοντικές εφαρμογές ιατρικής απεικόνισης.Πιο συγκεκριμένα, παρουσιάζονται αξιολογήσεις (με χρήση ορατών φωτονίων και ακτίνων Χ) απόδοσης δύο νέων ανιχνευτών CMOS APS, ονομαστικά Large Area Sensor (LAS) και Dexela CMOS x-ray detector. Η αξιολόγηση έγινε χρησιμοποιώντας τις παρακάτω τεχνικές: α) καμπύλη μεταφοράς φωτονίων (photon transfer curve - PTC), β) συνάρτηση μεταφοράς διαμόρφωσης (modulation transfer function - MTF), γ) κανονικοποιημένο φάσμα ισχύος θορύβου (normalized noise power spectrum - NNPS) και δ) ανιχνευτική κβαντική αποδοτικότητα (detective quantum efficiency - DQE). Έγιναν κάποιες τροποποιήσεις ώστε να επεκταθούν οι υπάρχουσες τεχνικές με σκοπό την εξάλειψη τεχνικών περιορισμών. Η απόδοση των δύο νέων ψηφιακών ανιχνευτών συγκρίθηκε με τρία εμπορικά συστήματα ψηφιακών ανιχνευτών (α) Remote HR RadEye (CMOS APS), β) Hamamatsu C9732DK (CMOS PPS) και γ) Anrad SMAM (a-Se TFT)) σε τρία φάσματα ακτίνων Χ (28 kV για μαστογραφία και 52 kV και 74 kV για γενική ακτινοδιαγνωστική) με βάση τα πρότυπα της Διεθνούς Ηλεκτροτεχνικής Επιτροπής (International Electrotechnical Commission - ΙEC). Αμφότεροι οι νέοι ψηφιακοί ανιχνευτές παρουσιάζουν υψηλή απόδοση. Επίσης αξιολογήθηκε το φαινόμενο της ενδογενούς μη-γραμμικής μεταφοράς σήματος και θορύβου των ανιχνευτών CMOS APS.Τέλος, οι πειραματικά μετρημένες παράμετροι απόδοσης των ψηφιακών ανιχνευτών χρησιμοποιήθηκαν για να προσομοιώσουν εικόνες σε συνθήκες μαστογραφίας με σκοπό να διαπιστωθούν πιθανές εφαρμογές ιατρικής απεικόνισης για τους δύο νέους ψηφιακοί ανιχνευτές. Δύο ψηφιακά ομοιώματα (το ένα αντιπροσωπεύει ένα τρισδιάστατο μοντέλο μαστού και το άλλο το εργαλείο δοκιμής CDMAM) χρησιμοποιήθηκαν για να προσομοιώσουν διάφορες μαστογραφικές συνθήκες. Τα αποτελέσματα δείχνουν ότι αμφότεροι οι νέοι ανιχνευτές CMOS APS προσφέρουν υψηλή ποιότητα εικόνας σε σύγκριση με τα εμπορικά συστήματα ανιχνευτών.

scholarly journals Scene-and-Process-Dependent Spatial Image Quality Metrics

2019 ◽  
Vol 63 (6) ◽  
pp. 60407-1-60407-13
Author(s):  
Edward W. S. Fry ◽  
Sophie Triantaphillidou ◽  
Robin B. Jenkin ◽  
Ralph E. Jacobson ◽  
John R. Jarvis
Keyword(s):  
Image Quality ◽  
Visual Masking ◽  
Quality Metrics ◽  
Noise Power ◽  
Modulation Transfer ◽  
Detection Model ◽  
Spatial Image ◽  
Contrast Detection ◽  
Visual Contrast ◽  
Image Quality Metrics

Abstract Spatial image quality metrics designed for camera systems generally employ the Modulation Transfer Function (MTF), the Noise Power Spectrum (NPS) and a visual contrast detection model. Prior art indicates that scene-dependent characteristics of non-linear, content-aware image processing are unaccounted for by MTFs and NPSs measured by traditional methods. The authors present two novel metrics: the log Noise Equivalent Quanta (log NEQ) and Visual log NEQ. They both employ Scene-and-Process-Dependent MTF (SPD-MTF) and NPS (SPD-NPS) measures, which account for signal transfer and noise scene dependency, respectively. The authors also investigate implementing contrast detection and discrimination models that account for scene-dependent visual masking. Also, three leading camera metrics are revised to use the above scene-dependent measures. All metrics are validated by examining correlations with the perceived quality of images produced by simulated camera pipelines. Metric accuracy improved consistently when the SPD-MTFs and SPD-NPSs were implemented. The novel metrics outperformed existing metrics of the same genre.

scholarly journals Figure of Image Quality and Information Capacity in Digital Mammography

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Christos M. Michail ◽  
Nektarios E. Kalyvas ◽  
Ioannis G. Valais ◽  
Ioannis P. Fudos ◽  
George P. Fountos ◽  
...  
Keyword(s):  
Image Quality ◽  
Digital Filters ◽  
Simple Technique ◽  
Image Data ◽  
Quality Characteristics ◽  
Information Capacity ◽  
Noise Power ◽  
Modulation Transfer ◽  
Spatial Frequencies ◽  
Image Quality Index

Objectives. In this work, a simple technique to assess the image quality characteristics of the postprocessed image is developed and an easy to use figure of image quality (FIQ) is introduced. This FIQ characterizes images in terms of resolution and noise. In addition information capacity, defined within the context of Shannon’s information theory, was used as an overall image quality index.Materials and Methods. A digital mammographic image was postprocessed with three digital filters. Resolution and noise were calculated via the Modulation Transfer Function (MTF), the coefficient of variation, and the figure of image quality. In addition, frequency dependent parameters such as the noise power spectrum (NPS) and noise equivalent quanta (NEQ) were estimated and used to assess information capacity.Results. FIQs for the “raw image” data and the image processed with the “sharpen edges” filter were found 907.3 and 1906.1, correspondingly. The information capacity values were60.86×103and78.96×103 bits/mm2.Conclusion. It was found that, after the application of the postprocessing techniques (even commercial nondedicated software) on the raw digital mammograms, MTF, NPS, and NEQ are improved for medium to high spatial frequencies leading to resolving smaller structures in the final image.

A Flat-Panel X-Ray Imaging Module for Medical Imaging and Nondestructive Testing

2006 ◽  
Vol 321-323 ◽  
pp. 1004-1007
Author(s):  
Hyo Sung Cho ◽  
Sung Il Choi ◽  
Bong Soo Lee ◽  
Sin Kim
Keyword(s):  
Medical Imaging ◽  
Nondestructive Testing ◽  
System Response ◽  
Detective Quantum Efficiency ◽  
Noise Power ◽  
Pixel Size ◽  
Modulation Transfer ◽  
Flat Panel ◽  
X Ray ◽  
X Ray Imaging

In this study, we designed a flat-panel digital X-ray imaging module based upon the amorphous silicon (a-Si) technology and tested potential for medical imaging and nondestructive testing. The module employs a commercially available a-Si photosensor array of a 143 μm x 143 μm pixel size and a 42.9 cm x 42.9 cm active area, coupled with a CsI(Tl) scintillator of a 550 μm thickness, and a readout IC board which can be accessed through our home made GUI software. The experimental test was performed to evaluate the system response with exposure, modulation transfer function (MTF), noise power spectrum (NPS), and detective quantum efficiency (DQE).

Image quality vs data obtainment in biological electron microscopy

1986 ◽  
Vol 44 ◽  
pp. 42-43
Author(s):  
J. E. Johnson
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Electron Beam ◽  
Image Quality ◽  
High Speed ◽  
Early Period ◽  
Early Years ◽  
Fluorescent Screen ◽  
Embedding Medium

In the early years of biological electron microscopy, scientists had their hands full attempting to describe the cellular microcosm that was suddenly before them on the fluorescent screen. Mitochondria, Golgi, endoplasmic reticulum, and other myriad organelles were being examined, micrographed, and documented in the literature. A major problem of that early period was the development of methods to cut sections thin enough to study under the electron beam. A microtome designed in 1943 moved the specimen toward a rotary “Cyclone” knife revolving at 12,500 RPM, or 1000 times as fast as an ordinary microtome. It was claimed that no embedding medium was necessary or that soft embedding media could be used. Collecting the sections thus cut sounded a little precarious: “The 0.1 micron sections cut with the high speed knife fly out at a tangent and are dispersed in the air. They may be collected... on... screens held near the knife“.

Sign in / Sign up

Export Citation Format

Share Document