B. Redmer, C. Bellon, B. Sölter, H.-J. Malitte:

Fifth EAN Workshop on“Industrial Radiography: Improvements in Radiation Protection”Rome, Italy, 17-19 Oktober 2001

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Reduction of Radiation ExposureThrough the Application of NewDetector Techniques in IndustrialRadiography

Reduction of Radiation ExposureThrough the Application of New Detector

Techniques in Industrial Radiography

Bernhard Redmer1, Carsten Bellon1, Barbara Sölter2,Hans-Joachim Malitte1

1 Bam Berlin2 DGZfP, Berlin

Present Trends in Digital Industrial Radiography

NDT Image Capture Technologies

Ref.: Soltani (Liberty)

Dose Minimisation through Reduction of the Exposure

Application

Image Plate System

Dose Minimisation through Reduction of the Exposure

Application

Image Plate System

Readout and Erasure

He-Ne Laser

PMT

IPData Output

filter

imaging plate

cassette

IP

exposure

Exposure of imaging plates

Ref.: Ewert, Zscherpel (2001)

Principle of an Image Plate System

Digital Image• readout procedure by a scanner• enhancement of the image

quality by image processing

Preparation of an Exposure• handling like a film

Image Plate System

(a)

Ewert, Zscherpel, BAM-VIII.3

(a) imaging plate (b) film

(b)

Comparison of Transfer Curves

(a) imaging plate (IP)(b) film

The image quality of theimaging plate system andthe X-ray film cannot becompared withouttransfer functionmatching.

Image Plate System

Ref.: Osterloh (July 2001)

corrosion of a pipe: wall thickness 5.9 mm, diameter 110 mm, Ir-192, FDD 1000 mm, 1min.

original image processed

Image Plate System

D4; C3D4; C3 D7; C5D7; C5 IPIP

Timed Detonator (WZD-6 Tsch;Ru) FFA = 1000 mm; U = 180 keV

Ref.: Beckmann, Onel, Ewert (Juni 2000)

Image Plate System

• limited spatial resolution• high sensitivity in a case of low energy radiation• different characteristic to the film

• high linearity• high sensitivity

– shorter exposure time• multiple use of the image plate• no dark room required• digital images available

– evaluation through digitalalgorithm possible

– high accuracy

Ref.: Beckmann, Onel, Ewert (Juni 2000)

Image Plate System

AdvantagesAdvantages DisadvantagesDisadvantages

Dose Minimisation trough Using ofFan Beam Geometry

Application

Radiometric Line Camera

Dose Minimisation trough Using ofFan Beam Geometry

Application

Radiometric Line Camera

Line Camera

Technical Parameter

Pixel Number 1856x1Pixel Size 83² µm²

(12 pixel/mm)Szintillator 200...250 µm

GdO2S

Scan Width 160 mmResolution 160...200 µm

Principle of an Line Camera System

Computer-Laminography (CL)with line scan technique

Computer-Laminography (CL)with line scan technique

Line Camera System

Camera trip through the object:Camera trip through the object:

Average reconstruction of the crack range after

filtering.

Average reconstruction of the crack range after

filtering.Surface peel off

Line Camera System

Reconstruction from theline scan measurementsat 180 kVp

Reconstruction from theline scan measurementsat 180 kVp

Surface representation ofthe crack range

Surface representation ofthe crack range

Magnified range:

Line Camera System

Flaw in an welding: stress corrosion

Ref.: Tillack, Bellon (2001)

Line Camera System

Dose Minimisation through Reductionof the Exposure

Application

Flat Panel Detector

Dose Minimisation through Reductionof the Exposure

Application

Flat Panel Detector

Direct Conversion

Direct Conversion

X-rays generate electron hole pairs in the semi-conductor.

Miniature electrodes are chargedand can be read outafter exposure.

Amorphous Se-detector ofSterling

35 x 42 cm8 Mega pixels139 µm resolution

35 x 42 cm8 Mega pixels139 µm resolution

AGFA αααα-Se-detector, Oct. 2000

New Detector in Radiology: Flat Panel

Ref.: Ewert, Zscherpel (July 2001)

Test in the Lab. (with test weld BAM 5):

Ref.: Ewert, Zscherpel (July 2001)

New Detector in Radiology: Flat Panel

New Detector in Radiology: Flat Panel

Ref.: Ewert, Zscherpel (July 2001)

Highpass Filtering:

DR : detector resolution limited through pixel size

DirectRay: BAM 5

at 120 kV, 1 mA1 mm Cu prefilteringFFA 0.5 m, 30 s exposure time without shutter

Varian Imaging System, Oct. 2000

Improved Application of in-House TestingImproved Application of in-House Testing

Flat Panel Applicationsneed less expensive manipulation techniquethan intensifiers

Automated pipeinspection,substituting film andIntensifier technology

Ref.: Ewert, Zscherpel (July 2001)

New Detector in Radiology: Flat Panel

• limited spatial resolution• different characteristic to the film• currently: high expenses for

temperature controlling– large readout-time per cycle

• direct process of radiationdetection

• high sensitivity– shorter exposure time

• no dark room required• digital images available

– evaluation through digitalalgorithm possible

– higher accuracy• easy handling (size, weight)• time integration on the detector

Ref.: Beckmann, Onel, Ewert (Juni 2000)

AdvantagesAdvantages DisadvantagesDisadvantages

New Detector in Radiology: Flat Panel

Ref.: Zscherpel (2000)

New Systems in Radiology: Film Printer

• pixel size: 40 µm (630 dpi)8.000x10.000 pixels on 35 x 43 cm²

• 8 bit digital input via programable densityfunction (LUT) scaled to 16 bit

• Dmin und Dmax between 0.2 and 3.6 ODadjustable

• data transmission up to 3 min. per film;laser imaging max. 40 sec.

• Development in NDT chemistry

Conclusion

Fan Beam Geometry• reduction of the radiation beam• smaller control zone• Application: line camera with slit collimator in front

Shorter Exposure Time• Minimisation of the exposure of persons• Application: Image Plates (up to 60%, limited resolution)

Flat Panel Detector

Mechanised Scanner-Principle• no film handling --> Minimisation of the exposure of

persons (e.g. Nuclear Power Plant)• one-time setup of the manipulator on the test object for

multiple repeated exposures