The Design and Fabrication of a Full Field Quantitative Mammographic Phantom

Abstract

Breast cancer is among the major causes of death in women worldwide. Screenfilm mammography (SFM) is still the standard method used to detect early breast cancer thus leading to early treatment. Digital mammography (DM) has recently been designated as the imaging technology with the greatest potential for improving the diagnosis of breast cancer. For successful mammography, high quality images must be achieved and maintained, and reproducible quantitative quality control (QC) testing is thus required. Assessing images of known reference phantoms is one accepted method of doing QC testing. Quantitative QC techniques are useful for the long-term follow-up of mammographic quality. Following a comprehensive critical evaluation of available mammography phantoms, it was concluded that a more suitable phantom for DM could be designed. A new relatively inexpensive Applied Physics Group (APG) phantom was designed to be fast and easy to use, to provide the user with quantitative and qualitative measures of high and low contrast resolution over the full field of view and to demonstrate any geometric distortions. It was designed to cover the entire image receptor so as to assess the heel effect, and to be suitable for SFM and DM. The APG phantom was designed and fabricated with embedded test objects and accompanied by software routines to provide a complete toolkit for SFM and DM QC. The test objects were investigated before embedding them. The locally sourced, relatively low cost materials (fishing lines, marble stone chips, epoxy resin, tantalum plates and aluminium step wedges) used for these objects were chosen to have X-ray absorption characteristics that spanned the visibility of features in mammographic images. Validation of the APG phantom