Can CT Phantoms Produce Realistic CT Images of Human Anatomy? Physics-Based Evaluation of Multimaterial 3D-Printed CT Phantoms From CT Data
Year: 2026
Type: article
Abstract: OBJECTIVES: Patient-specific computed tomography (CT) phantoms can be produced using a novel 3D-printing technique that aims at replicating measured CT image volumes with high anatomic fidelity and accurate CT values. The purpose of this study is a comprehensive physics-based evaluation of both technical phantoms and a full-size adult abdominal phantom with regard to image-quality metrics and the reproducibility of CT values. In addition, the visualization of abdominal pathologies will be assessed. MATERIALS AND METHODS: The study was conducted in 3 steps. First, a geometric reference disc phantom (40 mm thickness, 150 mm diameter) was 3D-printed using multimaterial jetting and scanned on a commercial photon-counting detector CT (PCD-CT) to assess the CT values of the base materials used for printing and to evaluate the influence of the printing process on spatial resolution and noise properties. Second, CT images of the reference phantom reconstructed with a medium-sharp and a sharp kernel were used as templates to print 2 CT-derived disc phantoms using multimaterial jetting with voxel-based material mapping. These phantoms were then scanned to assess how template image sharpness propagates into the image-quality properties of the final printed phantoms. Spatial resolution was evaluated using edge spread function (ESF) analysis and edge rise distance (ERD), whereas noise characteristics were assessed using noise power spectrum (NPS) analysis. Third, as a proof of concept, a full-size adult abdominal phantom was 3D-printed with a patient CT data set as template. Phantom images were compared with patient images regarding CT values, spatial resolution, noise properties, and the depiction of pathologic structures. RESULTS: Evaluation of the CT attenuation of the base materials showed that CT values ranging from -37 HU to 995 HU in virtual monoenergetic images at 60 keV can be printed.For the reference disc, measured ESF curves showed close agreement with theoretical expectations across all reconstruction kernels, indicating preservation of spatial resolution by the printing process. CT-derived discs showed minor edge smoothing compared with the reference for smooth and medium-sharp reconstructions. For sharp reconstructions, edge smoothing was severe, with an ERD increase of up to 32% compared with the reference. Edge smoothing was more pronounced for the disc based on a sharp template. NPS were highly consistent across all discs, with only minor differences in peak amplitude. In the abdominal phantom images ESF and NPS closely matched those of the patient CT images. Measured attenuation agreed well for tissues with positive CT values up to 1000 HU. Fat was represented with increased CT values because of print material limitations. Clinically relevant pathologic structures, including a large hepatocellular carcinoma and a smaller focal liver lesion, were displayed comparably in the phantom images. CONCLUSIONS: CT phantoms generated from CT image volumes using 3D printing with multimaterial mapping on a voxel level accurately reproduce the template images in terms of image sharpness, noise characteristics, and attenuation properties of tissues with positive CT values not exceeding 1000 HU. The achievable spatial resolution is limited to medium-sharp levels and does not improve by using sharper template images. These findings support the use of image-based multimaterial 3D printing to produce realistic anthropomorphic phantoms for advanced CT image-quality assessment and optimization, and for validation of reconstruction algorithms and quantitative CT imaging methods.
Source: Investigative Radiology
Language: English
Subfield: Biomedical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
OpenAlex ID: W7225627893