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Tutorial - Overview
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Quality control for compliance with state guidelines |
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ABSTRACT
The recommended methods to test the performance of computed radiography (CR) systems have been established
by The American Association of Physicists in Medicine, Report No. 93, “Acceptance Testing and Quality Control
of Photostimulable Storage Phosphor Imaging Systems”.1 The quality assurance tests are categorized by how
frequently they need to be performed. Quality assurance of CR systems is the responsibility of the facility that
performs the exam and is governed by the state in which the facility is located. For Example, the New York State
Department of Health has established a guide which lists the tests that a CR facility must perform for quality
assurance.2 This study aims at educating the reader about the new quality assurance requirements defined by
the state. It further demonstrates an easy to use software tool, henceforth referred to as the Digital Physicist,
developed to aid a radiologic facility in conforming with state guidelines and monitoring quality assurance of
CR/DR imaging systems. The Digital Physicist provides a vendor independent procedure for quality assurance
of CR/DR systems. Further it, generates a PDF report with a brief description of these tests and the obtained
results.
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Read more...
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Contrast-to-Noise Ratio (CNR), Modulation Transfer Function (MTF), |
Authors: Nikunj Desai, Abhinav Singh, and Daniel J Valentino
Proceedings of SPIE Medical Imaging 2010
Date: February, 2010
ABSTRACT
A number of complementary metrics are available to assess the performance of digital X-ray imaging systems. However, the sensitivity of these metrics to changes in the electro-optical imaging chain is poorly understood. Some of the commonly used metrics include Contrast to Noise ratio (CNR), limiting spatial resolution, Modulation Transfer Function (MTF), Noise Power Spectrum (NPS) and the Detective Quantum Efficiency (DQE). We evaluated the utility of these metrics in characterizing the imaging plate, imaging system optics and electronic components of computed radiography (CR) systems. We developed practical and easy to use test objects (phantoms) and implemented software to aid in calculating each metric. The results of this research will facilitate the characterization of differences in CR systems using the appropriate metrics.
 Practical Evaluation of Image Quality (421.89 kB)
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Authors: Abhinav Singh, Nikunj Desai and Daniel J Valentino
Proceedings of SPIE Medical Imaging 2010
Date: February, 2010
ABSTRACT
Computed Radiography (CR) is a cost-effective technology for digital mammography. In order to optimize the quality of images obtained using CR Mammography, we characterized the effect on image quality of the electrooptical components of the CR imaging chain. The metrics used to assess the image quality included the Contrast to Noise Ratio (CNR), Modulation Transfer Function (MTF), Noise Power Spectrum (NPS), Detective Quantum Efficiency (DQE) and Contrast Detail Response Phantom (CDMAM 3.4 Artinis Medical Systems). An 18x24 cm high-resolution granular phosphor imaging plate (AGFA MM3.0) was used to acquire the images. Contrast detail was measured using a GUI developed for the CDMAM phantom that was scored by independent observers. The range of theoretically acceptable values measured for the CR laser was (5-36) mW and voltage range for PMT’s was (4-8) V. The light detection amplifier was investigated, and the optimal Laser Power and PMT gain used for scanning was measured. The tools that we used (CNR, MTF, NPS, DQE and Contrast-detail phantom) provided an effective means of selecting optimal values for the electro-optical components of the system. The procedure enabled us to obtain good quality CR mammograms that have less noise and improved contrast. Keywords: Computed Radiography, Mammography, Modulation Transfer Function, Noise Power Spectrum, Detective Quantum Efficiency, Photomultiplier tube, CDMAM 3.4 Phantom
Performance Characterization of Computed Radiography (638.08 kB)
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