Comparison of two CDMAM generations with respect to dose sensitivity

摘要

A contrast-detail phantom like the CDMAM phantom (Artinis Medical Systems, Zetten, NL) is suggested by the 'European protocol for the quality control of the physical and technical aspects of mammography screening' to evaluate image quality of digital mammography systems. In a recent paper the commonly used CDMAM 3.4 was evaluated according to its dose sensitivity in comparison to other phantoms. The successor phantom (CDMAM 4.0) features other disc diameters and thicknesses that were adapted to be more closely to the image quality which can be found in modern mammography systems. It seems to be obvious to compare this two generations of phantoms with respect to a potential improvement. The time-current product was varied within a range of clinically used values (40-160 mAs). Image evaluation was performed using the automatic evaluation software provided by Artinis. The relative dose sensitivity was compared in dependence of different diameters. Additionally, the IQFinv parameter, which averages over the diameters was computed to get a more global conclusion. We found that the dose is of a considerable smoother dependence with the CMDAM 4.0 phantom. Also the IQFinv parameter shows a more linear behaviour than with the CDMAM 3.4. As the automatic evaluation shows different results on the two phantoms, conversion factors from automatic to human readouts have to be adapted consequently.