Phantoms allow repeated radiation exposure under standardized conditions without the challenges associated with human test subjects. Phantoms with simple geometric designs are widely used in radiology and radiation therapy for commissioning and consistency testing, but do not reflect clinical radiation exposure of patients. The purpose was to develop methods for 3D printing realistic anthropomorphic phantoms of individual patients. The developed technology uses inkjet technology together with radiopaque inks to print CT images on paper. Processing of the printed stacks with paper-based 3D printing methods creates phantoms with the shape, size and attenuation properties of the original patient. Materials and inks are designed to achieve tissue equivalent properties. Patient phantoms allow detailed simulation of patient radiation exposure and provide novel opportunities for the development, testing and quality assurance of imaging and therapy systems. An introduction to the background in imaging, an insight into the technology and key applications will be presented.