CDMAM 3.4
... Quality control in mammography ...
Introduction
In mammography it is essential that objects with very small contrast and diameter can be distinguished. Therefore the quality of the technical aspects of the mammography equipment should be monitored at regular time-intervals. The Artinis CDMAM 3.4 phantom is specially developed to facilitate this task in analog and digital mammography systems, i.e. detecting very low contrast and detecting very small details. The CDMAM is considered to be the world gold standard and is described in the European Protocol for quality assurance in Digital Mammography.
Applications
- Determination if mammographic images are indicating objects with very low contrast and very small diameter
- Monitors the image information contact with the Contrast-Detail curve and the spatial resolution
- Determination of the optimum exposure technique, e.g., by variation of tube potential
- Comparison of image quality at various object thicknesses by variation of the amount of PMMA thickness
- Comparison of image quality with various film-screen combinations
- Determination of the optimum background density
- Comparison of different mammography systems
- For full-field analog and digital units
Technical specifications
The Artinis CDMAM phantom consists of an aluminum base with gold discs (99.99% pure gold) of various thickness and diameter. The gold discs are arranged in a matrix of 16 rows by 16 columns. Within a row the disc diameter is constant, with (partly) logarithmic increasing thickness and within a column the thickness of the discs is constant and the diameter increases logarithmic. The thickness is between 0.03 and 2.00 µm and the diameter is 0.06 between 2.0 mm. Each square contains two identical discs (same thickness, same diameter), one in the center and one in a randomly chosen corner. The total matrix is rotated by 45 degrees and the corners of the matrix are skipped. The matrix grid is silkscreen printed with X-ray contrasting paint.
The aluminium base (0.05 mm thick Al 1050, 99.5% pure aluminum) is attached to a Plexiglas® cover (5 mm, PMMA). Under normal mammography-radiation conditions (Mo anode, 30 mm Mo filter, 28 kV) the aluminum base and PMMA cover together have an equivalent PMMA thickness of 10 mm. The phantom is delivered with 4 PMMA plates, each 10 mm thickness, which are used for the simulation of different breast thicknesses. Every plate has an engraved marker with lead inlet for identification. The phantom and Plexiglas® plates match the standard mammography film size (18 x 24 cm). The actual attenuation of the CDMAM Phantom depends on the configuration of the phantom and Plexiglas® plates. The effective energy of the phantom plane will be higher when more Plexiglas® is added to the top and bottom of the phantom.
Measurements
To make an X-ray image, the Artinis CDMAM phantom (in combination with one or more Plexiglas® plates) should be positioned on the bucky with the smallest disc diameters at the thorax side. After the film has been processed, the density of the film should be checked. In a series of Contrast-Detail images, all the images should have approximately the same densities in a reference position on the film. After this pre-processing the images can be analysed in CDMAM Analyser to determine the Contrast-Detail curve and used for evaluation of the image quality.
Literature
1. Bijkerk, K.R., Thijssen, M.A.O. and Arnoldussen, Th.J.M. 2000. IWDM 2000 report: Modification of the CDMAM contrast-detail phantom for image quality of Full Field Digital Mammography systems. Radboud University Nijmegen, the Netherlands.
2. Bijkerk, KR, Lindeijer, JM, Thijssen, MAO: The CDMAM phantom: a
contrast-detail phantom specifically for mammography. Radiology 185(P), 395 (1993).
3. Burger, G.C.E. 1950. Phantom tests with X-rays. Philips Technical Review, Vol. 11 (10) 291-298.
4. Thijssen, M., Veldkamp, W., van Engen, R., Swinkels, M., Karssemeijer, N. and Hendriks, J. 2000. IWDM 2000 report: Comparison of the Detectability of Small Details in a Film-screen and a Digital Mammography System by the Imaging of a New CDMAM-phantom. Radboud University Nijmegen, the Netherlands.
5. Warren, L.M., Mackenzie, A., Cooke, J., Given-Wilson, R., Wallis, M.G., Chakraborty, D.P., Dance D.R., and Young K.C. Mammographic calcification cluster detection and threshold gold thickness measurements. Proc. SPIE 8313, 83130J (2012);
6. More literature
The Artinis CDMAM 3.4 phantom is a result of the project: "Quality Assurance in Mammography, Department of Radiology, University Medical Centre Nijmegen, the Netherlands." By M.A.O. Thijssen, Ph.D., K.R. Bijkerk, M.Sc. and J.M. Lindeyer, B.Sc.
Specifications are subject to change without notice. Always read product labelling/inserts for complete instructions, warnings and restrictions.
