Quality indicator, image

Contrast Sensitivity S For this purpose a test piece is used whose least material thickness to be resolved in the video signal corresponds to the contrast sensitivity. The test piece can be a step/hole image quality indicator as per EN 462-2. 

In general, the performance of a radioscopic system should always be checked via test pieces with natural flaws. To ensure an additional comparability, standardized image quality indicators have to be used to control the essential image quality parameters such as spatial resolution (unsharpness) and contrast sensitivity. 

Kupinski M, Giger ML (1999) Feature selection with limited datasets. Med Phys 26 2176-2182 Leichter I, Fields S, Nirel R, et al (2000) Improved mammographic interpretation of masses using computer-aided diagnosis. Eur Radiol 10 377-383 Loo L-N, Doi K, Metz CE (1984) A comparison of physical image quality indices and observer performance in the radiographic detection of nylon beads. Phys Med Biol 29 837-856... 

Image quality indicators (IQIs) were fabricated for use in development and acceptance testing of the ultrasonic inspection system. Silicon nitride test uars (3.5x4.5x50 mm) with known internal voids, characterized by microfocus radiography, are being utilized to benchmark the pulse-echo imaging capability. 

Fig. 3 A comparison of the image quality for a SIT video camera versus a cooled CCD camera. The sample is DAPI-stained, phenol-extracted bacteriophage T4 DNA. Images (top panels) and the intensity profile along the horizontal dotted lines (bottom panels) are shown for the SIT camera (a) and the cooled CCD camera (b). The intensities of single DNA molecules are indicated by the arrows in the bottom panels. The asterisk in lower panel b corresponds to a bundle of two DNA molecules. (Reproduced with permission from Hiraoka et al. (1987).)...

Other authors used a 2.5-beam collimation protocol and demonstrated that, despite a perceptible worsening of image quality, the sensitivity for detection of polyps was equal at 100, 50, and 30 effective mAs (Van Gelder et al. 2002). These results indicated that CTC with MDCT can be reliably performed with an effective dose of 3.6 mSv. 

For all clinical applications, collimation should be 14 X 1.2 mm in order to avoid excess image noise. Careful patient positioning will greatly improve image quality and help to overcome technical limitations. Continued research with DECT will help to determine the optimal utilization and indications of this new technology. 

The image was derived from IP Axis cameras whose main characteristics are given in Table 3. The server performs additional video compression using bilinear interpolation based on the designated bandwidth. Throughput restriction is performed by the client application. It reduces the bandwidth of the client interface to the value declared in the application window. The measurement results are related to quality indicators defined in the following recommendations (ITU-T G.lOlO Recommendation, 2001), (ITU-T P.800 Recommendation, 1996). 

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