Toward quantitative X-ray CT phantoms of metastatic tumors using rapid prototyping technology

We are seeking ground-truth 3D X-ray CT phantoms with gradations of Hounsfield units that are indistinguishable from scans of human subjects. We modified a 3D printer, a ZCorp Spectrum 510, adding an iodine-based contrast agent, and printed physical models using a powder which consists mainly of cellulose and cornstarch. We scanned these 3D models with a Siemens Somatom Definition AS 128-slice CT scanner. By adjusting the level of iodine within the model, we are able to achieve Hounsfield units as high as 1056, mimicking bone, and as low as -450, similar to pulmonary tissue. We demonstrate how to generate grayscale images within a 3D model that can be imaged using a CT scanner. Unlike solid tumor phantoms, these models can accurately mimic lesions with indistinct boundaries similar to metastatic disease. Our intent is to evaluate the accuracy of computer aided diagnosis systems.