Breast phantoms for 2D digital mammography with realistic anatomical structures and attenuation characteristics based on clinical images using 3D printing

: The aim of this work was to develop a production process for breast phantoms for 2D digital mammography (DM) with realistic anatomical structures and attenuation characteristics based on clinical images using 3D printing. The presented production process is based on PolyJet 3D printing technology using a polypropylene like printing material. First, an attenuation calibration function for this material and the achievable lateral resolution of the printing process of about 200 µm was determined. Subsequently, to generate the digital 3D model of the breast phantom, the pixel intensities of the unprocessed clinical image that are related to the attenuation along the z-axis of the breast, were converted to corresponding phantom heights using the calibration function. To validate the process, an image of the 3D printed breast phantom was acquired on the full field digital mammography (FFDM) system used for calibration and compared with the clinical image in terms of anatomical structures and associated attenuation characteristics. The exposure parameters and image impression of the phantom were evaluated using five other FFDM systems of different manufacturers and types. Results demonstrated that the anatomical structures in the images and the attenuation characteristics of a female breast and the derived phantom agreed on the FFDM system used for calibration. The automatic exposure control segmentation, the automatically selected exposure parameters and the image postprocessing of the clinical and phantom image indicated a high level of conformity. As shown, the phantom is also suitable for other FFDM systems. In conclusion, an approach to produce anthropomorphic breast phantoms for DM offering realistic anatomical structures and attenuation characteristics based on clinical images was successfully developed. As shown, the phantom realistically simulated the original female breast. Therefore, it is expected that such phantoms are promising to support bridging the gap between physical-technical and diagnostic image quality assessment. In addition, they enable a variety of practical and scientific applications for which present technical phantoms are not suitable.