Imaging plates are reusable
What is Computed Radiography?
How does it work?
Computed Radiography (CR) is the digital replacement of conventional X-ray film radiography and offers enormous advantages for inspection tasks – the use of consumables is virtually eliminated and the time to produce an image is drastically shortened.
No darkroom or chemicals needed
Reduction in exposure and processing time
Software-based evaluation and reporting
Simple digital data exchange and archiving
Furthermore, more details are visible and analyzable with Computed Radiography due to a higher dynamic range when compared to film. Other advantages over film include a more simplified workflow, a safer working environment for operators and a more environmentally-friendly chemical-free process.
How exactly does Computed Radiography work?
In Computed Radiography, when imaging plates are exposed to X-rays or gamma rays, the energy of the incoming radiation is stored in a special phosphor layer. A specialized machine known as a scanner is then used to read out the latent image from the plate by stimulating it with a very finely focused laser beam. When stimulated, the plate emits blue light with intensity proportional to the amount of radiation received during the exposure. The light is then detected by a highly sensitive analog device known as a photomultiplier (PMT) and converted to a digital signal using an analog-to-digital converter (ADC). The generated digital X-ray image can then be viewed on a computer monitor and evaluated. After an imaging plate is read, it is erased by a high-intensity light source and can immediately be re-used - imaging plates can typically be used up to 1000 times or more depending on the application.
What should be considered when deciding for CR?
Basically, Computed Radiography can be considered as the digital replacement of conventional X-ray film. Imaging plates are used with the same radiographic inspections methods and techniques as film and are also available in different system classes (image quality) which have different required exposure times. However, with Computed Radiography it is not just the imaging plate type that affects image quality - the scan settings used by the scanner are also crucial. In particular, the resolution capability of the scanner (basic spatial resolution or SRb) plays an important part in determining image quality.
With this in mind, DÜRR NDT developed the HD-CR 35 - the world's first scanner that achieves a basic spatial resolution of 30 μm with a laser focus of merely 12.5 μm (when used with high-resolution imaging plates). This performance was confirmed via certification by the Federal Institute for Materials Research and Testing (BAM). With its variable laser focus size, the HD-CR 35 can also be easily adapted for inspection applications with less demanding basic spatial resolution requirements. If only low resolution is required, the CR 35 with a fixed laser focus of 50 μm may also be perfectly suitable.
Computed Radiography and film comparison
| Computed Radiography | Film | |
| Exposure medium | Imaging plate (reusable) | Film |
| Processing | No darkroom conditions or chemistry required | Darkroom conditions and chemistry required |
| Processing time | 1-3 minutes (depending on scan resolution) | 8 minutes |
| Evaluation | Computer with viewing/analysis software | Film viewer |
| Archiving | PC, cloud / remote network server | Film archive room (humidity and temperature-controlled) |
| Availability | Unlimited copies with possibility to access from any location | Unique master copy |
Exposure time
| Cost savings* | Company A | Company B |
| Exposures per day | 25 | 150 |
| Savings per exposure | EUR 2,39 | EUR 2,11 |
| Savings per year (250 work days) |
EUR 14.910,95 | EUR 79.154,70 |
*including film developer/fixer, cleaning, archiving costs. 10 x 48 cm film/imaging plate format, 500 cycles per imaging plate. Based on 2017 German market prices (MRRP).
Computed Radiography applications
Computed Radiography Products
HD-CR 35 NDT
High resolution Computed Radiography imaging plate scanner for all NDT radiography applications - weld testing, profile images and aerospace.
Imaging Plates
IPs are available in different resolutions and all standard formats and, on request, in special sizes and custom shapes.
D-Tect X-ray Inspection Software
All functions from image acquisition, image evaluation and report generation to data import and export are included.