Reducing Radiation Exposure in Industrial Radiography

1. BAM - Berlin Reduction of Radiation Exposure by Modern Methods of Digital Industrial Radiography Uwe EWERT, Barbara SÖLTER, Bernhard REDMER, Uwe ZSCHERPEL, Matthias PURSCHKE August 2006

2. Legal Implementation European HASS Directive 2003/122/EURATOM Council Directive 96/29/EURATOM Transport was modified High Activity Radiation Sources Act – HRQ - 12.08.2005 Atomic Energy Act modified: 12.08.2005 Radiological Protection Ordiance modified: 12.08.2005

3. Reduction of Dose for Population and Limitations for Transport • New stringent European (Euratom Basic Norm 1996) and national standards on radiation protection limit annual personnel dosage • Reduction of annual effective dose for • population (1 mSv old: 1.5 mSv) • NDT personal (20 mSv old: 50 mSv) • Further limitation in handling and transport of gamma sources • New act (High Activity Radiation Sources Act) on surveillance of highly radioactive sources • All this regulations limit the application of mobile radiological methods in its conventional way • New digital detectors enable reduction of dosage in industrial radiology without lost of testing quality • New opportunities of digital industrial radiology enhances the application area

4. Boundary of the Radiation Controlled Area Radiation protection officer has to monitor the controlled areas! Non-stationary operation (mobilê) 40 µSv/h (6 mSv/150h) Stationary operation 6 mSv/h/2000 h = 3 µSv/h 6 mSv/h/1200 h = 5 µSv/h

5. New Digital Techniques Scanner for Imaging Plates Data Transmission Imaging Plates Reporting Computed Radiography Standards available now Archive Film Digitizer Networking Digital Detector Arrays Hard Copy Grayscale Printer Agfa Radiology with Digital Detector Arrays

6. Filmless Radiography Computed Radiography with Phosphor Imaging Plates

7. The Imaging Plate Cycle Scanning the IP , Digitising and Erasing the residual Image Exposure of Imaging Plate Cassette Imaging Plate Exposure Lead filter Processing Station

9. Increased Efficiency in CR depending on the Thickness of the Phosphor Layer Laser beam Photo stimulated luminescence Higher attenuation Thin phosphor layer Thick phosphor layer The laser beam stimulates more luminescence centers in a thick phosphor layer than in a thin layer due to the optical scatter of the laser light in the phosphor layer. Cost and/or time savings are higher for imaging plates with higher unsharpness but the reduced spatial resolution limits its application in NDT The efficiency depends basically on the scintillator thickness

10. New Standards on Digital Industrial Radiology • Since 2005 complete set of standards for Computed Radiology • CR can be applied for NDT now!!!

11. Filmless Radiography Some CR Applications

12. Principle of projection radiography: Magnification tangential penetration of pipe wall f = film focus distance r = outer pipe radius R = outer radius of insulation w = projection of wall thickness w on the detector plane Example: VEBA-OEL in Gelsenkirchen 63% of all NDT: Radiography (2000) with ~ 50,000 films per year w` measured on film

13. Deposit Blocks Valve Function New Applications due to higher sensitivity of detectors  this may even increase dose load to the environment but also enhance economy and safety

14. Southern Region of London Hong Kong MTR and KCR Corporations Eurotunnel Controlled area < 1m System Se-75 and CR with collimation tube CoMech, UK

15. CR System Classification for FUJI XG-1 (DynamiX) - Admissible Dose Reduction - 220 kV, 8 mm Cu, 0,1mm Pb screen with ST-VI IP Imaging Plate and X-ray film systems with comparable image quality

16. Filmless Radiography Digital Detector Arrays The new High Contrast Sensitivity Technique

17. Increased Efficiency by New Digital Detector Array Technology The efficiency depends on the pixel area and the scintillator thickness High number of photons per time unit Low number of photons per time unit Cost and/or time savings are higher for detectors with large pixels but the low spatial resolution limits its application in NDT X-Rays Thick scintillator Thin scintillator Small photo diode Large photo diode

18. Pipe Inspection New System: X-ray tube, Image intensifier Less expensive manipulation technique Flat panels substitute film and intensifier technology Unit: Varian flat panel detector

19. Motivation for Film Replacement by DDA‘s • Shorter test and interpretation time • Less radiation dose • New application areas by higher inspection quality and wall thickness range • No chemicals and dangerous waste • Less consumables Film (D4) Flachdetektor (Hamamatsu) High Contrast Sensitivity Technology by nonlinear DDA calibration

20. Summary: • New digital detectors (e.g. imaging plates, digital detectors arrays) permit the computer based analysis of radiometric images as well as taking them within a shorter exposure time or with less active sources. • The computed radiography (CR) with imaging plates (IP) can be applied for in-service and in-house inspection very efficiently. The exposure time is more than 50% shorter in comparison to an X-ray film-lead combination. • Systems with large effective pixel size enable an extraordinary reduction of exposure dose • Digital detector arrays (DDA or flat panels) permit the acquisition of images in few seconds. A main application field is the inspection of serial parts in production lines. • This also allows the extended usage of radiation methods for improvement of safety and reliability in industry since the new digital techniques can be applied even with enforced radiation protection laws. • The new classification standards (EN 14784, ASTM E 2446) permit the calculation of the dose reduction in comparison to NDT film systems. • New calibration methods enable the High Contrast Sensitivity Technology for radiographic inspection, which exceeds the contrast sensitivity of the best film systems.

21. End BAM-Berlin, Lab. VIII.3 Unter den Eichen 87 12005 Berlin Tel. (030) 81041831 FAX (030) 811 5089 e-mail: uwe.ewert@bam.de http://www.bam.de