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Fluoroscopic performance tests using a portable computer/frame grabber: Wiener spectra measurements

 

作者: Lee W. Goldman,  

 

期刊: Medical Physics  (WILEY Available online 1998)
卷期: Volume 19, issue 1  

页码: 45-52

 

ISSN:0094-2405

 

年代: 1998

 

DOI:10.1118/1.596891

 

出版商: American Association of Physicists in Medicine

 

数据来源: WILEY

 

摘要:

Currently, routine tests of fluoroscopic image quality in common use are highly subjective. As part of an effort to develop more quantitative routine tests of fluoroscopic image quality, a method was developed to quickly and easily measure Wiener spectra (WS) of TV‐viewed fluoroscopic systems that considers both spatial and temporal noise correlations. A PC‐mounted frame grabber captures images at the TV frame rate to form a three‐dimensional (3‐D) array of pixels. Scans of a “two‐dimensional slit” are then synthesized from which a one‐dimensional central section of a 3‐D WS is calculated. To avoid errors due to coarse (8‐bit) quantization, a video amplifier is used to expand a portion of the signal to the full digitizer range. A reference signal (2 mm of aluminum) is then used to normalize image contrast. Ensemble averages of 250 spectra were obtained in ∼1 min, including all processing. Results are presented to demonstrate reproducibility, sensitivity, and behavior of the WS. The eventual goal of this work is to use this method in conjunction with measurements of an MTF to calculate fundamental descriptors of image quality, such as SNR and NEQ.

 

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