Publication: Publication Date: 1 February 2010Testing Method:
New Compensation Principles for Enhanced Image Quality in Industrial Radiology with Digital Detector Arrays
Contrast-to-noise ratio (CNR) management is the key element for image quality control in digital radiology. Modern digital detector array calibration techniques allow an extraordinary increase of CNR in comparison to other digital detectors and film. Contrast reduction due to an increase in X-ray energy can be overcompensated for by noise reduction. This enables the reduction of acquisition time and increase of the thickness range per radiograph. Even limitations in the spatial resolution, constrained by the individual picture element (pixel) size of the detector, can be compensated for with an increased CNR. Bad pixel management of digital detector arrays in combination with CNR enhancement enables the safe application of this technology for film replacement. Considering these points, three compensation principles have been formulated for the implementation of digital detector arrays as a viable film replacement technology. The first is compensation of reduced contrast (μeff) by increased signal-to-noise ratio (SNR): if optimization of contrast cannot be achieved, the noise must be reduced (increased SNR); if contrast can be increased, there is more tolerance for higher noise (moderate or lower SNR can be used). The second is compensation of insufficient detector sharpness (high unsharpness) by increased SNR. The third is compensation of interpolation unsharpness due to bad pixel correction by increased SNR.
References
ASTM, ASTM E 1742: Standard Practice for Radiographic Examination,
West Conshohocken, Pennsylvania, ASTM International, 2008a.
ASTM, ASTM E 1815: Standard Test Method for Classification of Film
Systems for Industrial Radiography, West Conshohocken, Pennsylvania,
ASTM International, 2008b.
ASTM E 2002: Standard Practice for Determining Total Image Unsharpness
in Radiology, West Conshohocken, Pennsylvania, ASTM International,
2009.
ASTM, ASTM E 2445: Standard Practice for Qualification and Long-Term
Stability of Computed Radiology Systems, West Conshohocken, Pennsylvania,
ASTM International, 2005a.
ASTM, ASTM E 2446: Standard Practice for Classification of Computed
Radiology Systems, West Conshohocken, Pennsylvania, ASTM International,
2005b.
ASTM, ASTM E 2597: Standard Practice for Manufacturing Characterization
of Digital Detector Arrays, West Conshohocken, Pennsylvania, ASTM
International, 2007.
Bavendiek, Klaus, Uwe Heike, William D. Meade, Uwe Zscherpel and Uwe
Ewert, “New Digital Radiography Procedure Exceeds Film Sensitivity
Considerably in Aerospace Applications,” 9th ECNDT, Berlin, 2006.
Bueno, C. and A.D. Matula, “Digital Radiography for Gas Turbine Components,”
ASM Gas Turbine Materials Technology Conference, P.J. Maziasz et
al., eds. Materials Park, Ohio, ASM International, 1998, pp. 119–122.
CEN, EN 462-1: Non-destructive Testing – Image Quality of Radiographs –
Image Quality Indicators (Wire Type) – Determination of Image Quality
Value, Brussels, European Committee for Standardization, 1994.
CEN, EN 462-5: Non-destructive Testing – Image Quality of Radiographs
Part 5: Image Quality Indicators (Duplex Wire Type), Determination of Image
Unsharpness Value (F), Brussels, European Committee for Standardization,
1996.
CEN, prEN 1435-2: Non-destructive Examination of Welds – Radiographic
Examination of Welded Joints, Brussels, European Committee for Standardization,
2009 draft.
CEN, EN 14784-1: Non-destructive Testing – Industrial Computed Radiography
with Storage Phosphor Imaging Plates – Part 1: Classification of
Systems, Brussels, European Committee for Standardization, 2005.
CEN, EN 14784-2: Non-destructive Testing – Industrial Computed Radiography
with Storage Phosphor Imaging Plates – Part 2: General Principles for
Testing of Metallic Materials Using X-rays and Gamma Rays, Brussels,
European Committee for Standardization, 2005.
ISO, ISO/DIS 10893-7: Non-destructive Testing of Steel Tubes – Part 7:
Digital Radiographic Testing of the Weld Seam of Welded Steel Tubes for the
Detection of Imperfections, Geneva, International Organization for Standardization,
2009 draft.
Metrics
| Usage | Shares |
|---|---|
Total Views 343 Page Views |
Total Shares 0 Tweets |
343 0 PDF Downloads |
0 0 Facebook Shares |
| Total Usage | |
| 343 |