| The benefits of Computed Radiography |
| Cycle-time |
PSPs are 10x more sensitive than film allowing reduced exposure times.
Plates can be scanned and produce digital images in less than one minute
Auto-interpretation improves consistency and saves time.
|
| Environment |
The process uses less consumables (film and developer chemicals)
and generates no waste (spent developer chemicals are classified as hazardous
due to heavy-metal content).
|
| Safety |
PSP sensitivity extends the range of wall thickness over which safe radiographic technique,
using Se75 source, can be used
Film – 10 to 25 mm PSPs - 10 to 80 mm.
|
| Cost |
Process is cheaper as it saves film and developer cost.
Shorter cycle-time - improved productivity leading to lower cost.
Portable equipment – can be transported in flight case.
|
| Quality |
Comparable image quality to film – enhanced interpretation capability.
QC checks built in to software less reliance upon inspectors.
Digital back-up and archiving (to DVDs).
|
| Computed Radiography equipment |
| Source |
Either low power x-ray tube or gamma source may be used
(Se75 is preferred both for personnel safety and the resulting image quality).
|
| Film |
Radiographic images are captured using re-usable,
photo-stimulable phosphor imaging plates (PSPs) in place of conventional film.
|
| Developer |
Following exposure, the plates are scanned using a red-light laser in order
to generate a digital image. Once the image has been acquired the plate is
erased by exposure to bright, white light.
|
| Viewer/light-box |
The images are stored on a high-end PC equipped with a high definition screen.
Software allows manipulation and enhancement of the images (brightness, contrast, magnification etc).
|
| Film archive |
Digital image files are stored on a secure hard-drive with auto-back-up facility.
Periodically the images can be written to DVD for long-term archive.
|
For most industrial applications Computed Radiography (CR) will replace film techniques
just as digital cameras have largely replaced film in photography.
| Cost comparison |
| |
Film radiography |
Computed radiography |
| Equipment |
Automatic developer
Film scanner (eg Kodak SL75)
Computer + screen
Approx $100 k
|
Scanner – AllPro Scan X14
Computer + screen
Approx $60 k
|
| Consumables |
Film
Chemicals
Approx $ 2,000/1,000 welds
|
PSPs
Approx $1,000/1,000 welds
|
| Crew |
2 no, ASNT level II @ 400/day
2 no ASNT level I @ 150/day
|
Once software is trained can be used by ASNT Level I with remote supervision by ASNT Level II
|
| Cycle-time |
4-7 mins
(assumes scanning dry films off-line)
|
2-3 mins
|
Annual cost
- equipment
- consumables
- labour
Total
|
kUS$
100
24
220
344
|
kUS$
60
12
140
212
|
The payback for adopting Computed Radiography (CR) is normally less than three months.
A complete equipment spread