Mammographic Phantoms Frequently Used to Determine Image Quality: A Comparative Study

Appropriate diagnosis depends on the image quality of the mammographic system. Phantoms are normally used, since they have physical properties similar to those of different human tissues, and are important tools for quality assurance of mammography equipment, evaluation of image quality, and accurate determination of patient dosage. The aim of this study was to evaluate various mammographic phantoms used to determine the image quality of digital mammographic equipment.

Three phantoms were used: an American College of Radiology accreditation phantom, an MTM 100/R, and a tissue-equivalent phantom. Tungsten/silver target/filter material was used with four variable exposures (25, 28, 30, and 32 kVp). In total, there were 12 images. The images were evaluated by scoring the visibility of the structures, and a total score out of 100% was recorded. Statistical analysis was conducted using non-parametric tests.

There was no significant difference in the visibility of structures among the phantoms at different kVp. However, there were significant differences (p=0.04) in the visibility of the tumor masses when the kVp was varied. In addition, visibility rates differed significantly between the three phantoms (p≤0.05).

All the phantoms used in this study were suitable for evaluating digital mammography systems. However, the exposure setting for evaluation must be carefully considered. The tissue-equivalent phantom performed better in terms of the visibility rate to assess image quality in the digital mammography units.