... Quality control in breast cancer screening ...

Introduction In the screening of large populations on breast cancer, there are two conflicting demands: on one hand the radiation dose must be as low as possible and on the other hand no tumors may be left undetected. To fulfil both demands as good as possible, the equipment which is used in the screening, has to operate as close as possible to the physical limits which are technically feasible. Therefore quality measurement and above all quality assurance is of the utmost importance. The Artinis Quality Assurance Mammography Phantom 3.0 was developed for the Dutch government. In the Netherlands it is used in more then 60 breast cancer screening units. This phantom is state of the art and a "must" for every breast cancer center.

Construction The QAMAM phantom consist of a Perspex (PMMA) block which contains embedded test pieces for the measurement of radiation quality, low contrast resolution and spatial resolution. All test pieces are embedded in such a way, that over the whole phantom an equivalent PMMA thickness of 45 mm is obtained. The positioning of the test elements, leaves large areas to evaluate the homogeneity of the X-ray.

• For the measurement of spatial resolution there are 2 perpendicular test patterns, so both the resolution parallel and perpendicular to the anode-cathode axis can be measured at the same time. Both test patterns have a double set of lines, forwards and backwards, while their spacing is varying continuously from 6 to 20 lines per mm. Beside each set of lines there are markers which enables a computer to automatically evaluate the spatial resolution.

• A pure aluminum step wedge with linear increasing thickness can be used to evaluate both qualitative and quantitative the contrast resolution over the whole dynamic range. 

• Specially for mammography there is a low contrast test element, made of a pure aluminum base plate with 10 gold discs. The thickness of the gold discs increases logarithmically.

• A metal strip at one side of the phantom shields X-rays, leaving the use for a light sensitometer.

• There are several engraved markers (with lead inlet) and a ridge at the breast side for position referencing.

The Artinis QAMAM phantom is an ideal companion of the Artinis CDMAM phantom. 

The Artinis QAMAM 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.

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