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.

scholarly journals Estimation of Modulation Transfer Function (MTF) of VNREDSat-1 satellite for image quality assessment by using the permanent test site

2021 ◽  
Vol 62 (1) ◽  
pp. 19-26
Author(s):  
Ngoc Minh Nguyen . ◽  
Anh Van Tran ◽  
Tuan Van Nghiem ◽  
Huy Xuan Chu ◽  
Thao Phuong Thi Do ◽  
...  
Keyword(s):  
Image Quality ◽  
Spatial Resolution ◽  
Image Quality Assessment ◽  
Image Data ◽  
Test Site ◽  
Modulation Transfer ◽  
Small Satellites ◽  
Satellite Systems ◽  
Edge Method ◽  
Along Track

MTF is a factor in evaluating image quality with respect to the contrast and sharpness of the payload, thus directly related to spatial resolution. Therefore, ensuring image quality is an important task, especially for small satellites with high spatial resolution. This study uses the slanted-edge method for the artificial permanent test site and VNREDSat-1 image data with spatial resolution of panchromatic band as 2.5 m to make an MTF value estimate. The MTF value during 5 years of operation averages about 0.2 compared to the threshold as 0.08 (for the test site at Salon de Provence, France, the MTF value ranged from 0.16÷0.27 in across-track direction and 0.16÷0.25 in along-track direction; and at the Buon Ma Thuot test site, these values were 0.16÷0.23 and 0.20÷0.24, the reflectivity of these two test sites are similar), proving that image quality is guaranteed throughout the design life of the satellite; moreover, they are also the basis for Vietnam to finalize regulations on validation and calibration of optical satellite systems in the future when we have own test site.

scholarly journals On the Response of a Micro Non-Destructive Testing X-ray Detector

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 888
Author(s):  
Dionysios Linardatos ◽  
Vaia Koukou ◽  
Niki Martini ◽  
Anastasios Konstantinidis ◽  
Athanasios Bakas ◽  
...  
Keyword(s):  
Performance Metrics ◽  
Coefficient Of Determination ◽  
Noise Power ◽  
Modulation Transfer ◽  
Destructive Testing ◽  
Transfer Property ◽  
X Ray ◽  
Cmos Sensor ◽  
Imaging Performance ◽  
Pixel Pitch

Certain imaging performance metrics are examined for a state-of-the-art 20 μm pixel pitch CMOS sensor (RadEye HR), coupled to a Gd2O2S:Tb scintillator screen. The signal transfer property (STP), the modulation transfer function (MTF), the normalized noise power spectrum (NNPS) and the detective quantum efficiency (DQE) were estimated according to the IEC 62220-1-1:2015 standard. The detector exhibits excellent linearity (coefficient of determination of the STP linear regression fit, R2 was 0.9978), while its DQE peaks at 33% and reaches 10% at a spatial frequency of 3 cycles/mm, for the measured with a Piranha RTI dosimeter (coefficient of variation CV = 0.03%) exposure value of 28.1 μGy DAK (detector Air Kerma). The resolution capabilities of the X-ray detector under investigation were compared to other commercial CMOS sensors, and were found in every case higher, except from the previous RadEye HR model (CMOS—Gd2O2S:Tb screen pair with 22.5 μm pixel pitch) version which had slightly better MTF. The present digital imager is designed for industrial inspection applications, nonetheless its applicability to medical imaging, as well as dual-energy is considered and certain approaches are discussed in this respect.

scholarly journals Patient doses and image quality in chest radiography: The influence of different beam qualities

2007 ◽  
Vol 22 (2) ◽  
pp. 48-52
Author(s):  
Olivera Ciraj-Bjelac ◽  
Milan Loncar ◽  
Dusko Kosutic ◽  
Milojko Kovacevic ◽  
Danijela Arandjic
Keyword(s):  
Image Quality ◽  
Image Quality Assessment ◽  
Beam Quality ◽  
Quality Criteria ◽  
Simple Method ◽  
A Value ◽  
Radiographic Technique ◽  
Patient Doses ◽  
Area Product ◽  
Dose Measurements

A simple method of assessing optimal X-ray beam quality in respect to patient exposure and image quality in chest screen-film radiography is presented here. Different beam qualities were generated by the use of various combinations of tube voltages (70 kV to 110 kV) and Al and Cu filter thick nesses. Patient doses were assessed by kerma-area product measurements. Simultaneously, image quality was evaluated by a twofold method: a clinical study applying European quality criteria for the radiographic technique of image on image of 126 patients and a multifunctional home-made dosimetric phantom with embedded test objects. The quantification of image quality criteria yields a simpler method of optimizing image quality and patient dose relationships. Modifications of radiographic practice, based on image quality assessment and dose measurements, resulted in significant dose reductions and preservation of image quality. Through the use of harder beam quality, dose reduction of up to a value of factor 3 were observed, compared to the doses from previously used radiographic techniques, implying that sufficient image quality does not necessarily imply higher doses. As a result of the optimization process, an optimal radiographic technique was suggested.

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 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 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.

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