Composite materials for 3D printing of medical phantoms

In medical imaging, phantoms are commonly used to mimic the imaging property of the structural material in the human body ranging from soft tissue such as fat and muscle to dense tissue such as bone. In this study, a variety of materials including ABS, PLA‚ and a combination of PLA and stainless-steel powder (SSP) were evaluated to resemble the imaging properties of materials in the human body. First, phantoms were made with existing off-the-shelf materials to mimic the computerized tomography image of a patient's forearm. Second, PLA/SSP composite filaments were manufactured to mimic the CT image of high density bones in the human body. Models of these materials were 3D printed and tested. The CT scans of printed phantoms made of ABS, PLA, and other materials revealed CT numbers, measured in Hounsfield units, of 810‚ 160‚ and -36 HU which resemble bone‚ muscle, and fat tissues‚ respectively. These readings were similar to those in the patient's CT image. The PLA/SSP material gave a high CT number of 5250 HU, however a 75% PLA (by mass) and 25% SSP composite filament produced a phantom with a CT number of 1255 HU which is slightly higher than that of dense bone. The 3D printed phantoms were cost effective and relatively easy to manufacture. Customized composite filaments can be manufactured to generate the wide range of electron densities commonly seen in patients. Models of this nature have the potential to be used as quality control tools and teaching aides for CT and X-ray functionalities.