Until now there does not exist an IEC standard for Acceptance resp. constancy tests at CR and DR  systems.

In Germany after a successful acceptance test according DIN V 6868-58 the constancy test is carried out on the basis of the German Standard DIN 6868-13 which was published in February 2003.

The following criteria have to be determined:

• Dose 
• Dose indicator (e.g. dose K   at image reception area, S-value or LgM-value)  
• Luminance (resp. optical density at laserprints) 
• Spatial resolution 
• Contrast resolution 
• Alignment  of light field and X-ray field 
• Artifact test

The scope of the test is set out in the German Standard noted above and is described on our CD “Constancy Test at CR and DR systems” in detail.

To carry out the Test the following items are required:

• the Test Device DIGI-13 with

- Dynamic Cu-step wedge: 0.00, 0.30, 0.65, 1.00, 1.40, 1.85 and 2.3 mm Cu

- Low contrast objecdts (al disks with a diameter of 10 mm): 0.8 %, 1.2%, 2.0 %, 2.8 % 4.0 % and 5.6 %

- Resolution test: 0.6 – 5.0 lp/mm, 45° rotated

- Marked areas for signal standardization and check of homogeneity

- Alignment marks for formats sizes 180 x 240 and 260 x 260 mm

• a 25 mm aluminium pre-attenuator (optional) 
• a suitable Dosimeter (e.g. DOSIMAX plus duo) with sensor and 
• the luminance meter LXcan (or a densitometer when laser films are used).

The Double Dosemeter Philosophy

A double dosimeter DOSIMAX plus duo makes a  simultaneous measurement of the entrance (D1) and exit dose (D2) passing through an attenuator, the Sandwich detector, possible. Such a dual-channel dosemeter is recommended  in the German Standard 6868-13, annex B, for Quality Assurance in CR and DR radiography. In case of an automatic signal normalisation there is no relationship anymore between the dose at the image receptor area and the optical density of the laser film ( resp. the luminance of an image display device). The measurement of the exit dose takes the place of the former  density measurement of the film. The user is now able, in this way, to reduce the scope of the test while at the same time gathering additional information about the technical condition of the X-ray installation.


The Constancy Test Device for Digital Fluoroscopic X-ray installations is specified in the new version of the German Standard 6868-4 which is being worked on at the present time. It is due to be published in summer 2006.
The test device described therein will be offered by IBA Dosimetry on a timely basis.