Recent advances on the development of phantoms using 3D printing for imaging with CT, MRI, PET, SPECT, and ultrasound

Abstract

Purpose: Printing technology, capable of producing three-dimensional (3D) objects, has evolved in recent years and provides potential for developing reproducible and sophisticated physical phantoms. 3D printing technology can help rapidly develop relatively low cost phantoms with appropriate complexities, which are useful in imaging or dosimetry measurements. The need for more realistic phantoms is emerging since imaging systems are now capable of acquiring multimodal and multiparametric data. This review addresses three main questions about the 3D printers currently in use, and their produced materials. The first question investigates whether the resolution of 3D printers is sufficient for existing imaging technologies. The second question explores if the materials of 3D-printed phantoms can produce realistic images representing various tissues and organs as taken by different imaging modalities such as computer tomography (CT), positron emission tomography (PET), single-photon emission computed tomography (SPECT), magnetic resonance imaging (MRI), ultrasound (US), and mammography. The emergence of multimodal imaging increases the need for phantoms that can be scanned using different imaging modalities. The third question probes the feasibility and easiness of "printing" radioactive or nonradioactive solutions during the printing process.

Methods: A systematic review of medical imaging studies published after January 2013 is performed using strict inclusion criteria. The databases used were Scopus and Web of Knowledge with specific search terms. In total, 139 papers were identified; however, only 50 were classified as relevant for this paper. In this review, following an appropriate introduction and literature research strategy, all 50 articles are presented in detail. A summary of tables and example figures of the most recent advances in 3D printing for the purposes of phantoms across different imaging modalities are provided.

Results: All 50 studies printed and scanned phantoms in either CT, PET, SPECT, mammography, MRI, and US-or a combination of those modalities. According to the literature, different parameters were evaluated depending on the imaging modality used. Almost all papers evaluated more than two parameters, with the most common being Hounsfield units, density, attenuation and speed of sound.

Conclusions: The development of this field is rapidly evolving and becoming more refined. There is potential to reach the ultimate goal of using 3D phantoms to get feedback on imaging scanners and reconstruction algorithms more regularly. Although the development of imaging phantoms is evident, there are still some limitations to address: One of which is printing accuracy, due to the printer properties. Another limitation is the materials available to print: There are not enough materials to mimic all the tissue properties. For example, one material can mimic one property-such as the density of real tissue-but not any other property, like speed of sound or attenuation.

Keywords: CT; MR; PET; SPECT; US; 3D printing; image quality; mammography; phantoms.

Figure 1

Search strategy of the review article.

Figure 2

Research articles published per year between 2007 and 2018 in Scopus database.

Figure 3

Number of research articles that used these imaging modalities to scan the 3D printed phantoms (starting with CT clockwise).

Figure 4

MRI 3D printed phantom.58 Figure license: Kasten, et al. #bib2016 #bib3D‐printed Shepp‐Logan phantom as a real‐world benchmark for MRI. Copyright maintained by John Wiley and sons, all rights reserved.

Figure 5

SPECT 3D printed phantom.34 Figure license: Robinson, et al. #bib2016, Organ‐specific SPECT activity calibration using 3D printed phantoms for molecular radiotherapy dosimetry. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License ( http://creativecommons.org/licenses/by/4.0/).

Figure 6

(I) PET phantom, (II) 3D printed lesions.59 Figure license: Wollenweber, et al. #bib2016, A phantom design for assessment of detectability in PET imaging. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License ( http://creativecommons.org/licenses/by/4.0/).

Figure 7

(I) Indirectly 3D printed CT and US phantoms made of (a) silicone elastomer, (b) agarose gel and (c) PDMS, (II) Ultrasound images of (a) real organ, (b) silicone elastomer, (c) agarose gel, and (d) PDMS phantoms.21 Figure license: Adams, et al. #bib2016, Soft 3D‐printed phantom of the human kidney with collecting system. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License ( http://creativecommons.org/licenses/by/4.0/)

Figure 8

(I) (a) Singlet, (b) Doublet, (II) Mammogram.48Figure license: Kiarashi, et al. #bib2015, Development of realistic physical breast phantoms matched to virtual breast phantoms based on human subject data. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License ( http://creativecommons.org/licenses/by/4.0/).

Figure 9

(I) (a) Lesion design, (b) Lesion filling, (c) Connection port, (II) (a) Lesion and support rods placement at the phantom base, (b) Phantom base fitted to the phantom body.32 Figure license: Gear, et al. #bib2016, Abdo‐Man: 3D printed anthropomorphic phantom for validating quantitative SIRT. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License ( http://creativecommons.org/licenses/by/4.0/), Changes: Addition of (I) and (II) on top of the pictures, in their original form these two figures are separated.

Figure 10

Sub‐resolution sandwich phantom with radioactive paper sheets between each slab.41 Figure license: Negus, et al. #bib2016, Technical Note: Development of a 3D printed subresolution sandwich phantom for validation of brain SPECT analysis (Copyright by John Wiley and sons).

Figure 11

(a) Diagram and (b) photograph of 3D printed PET/MRI normalization phantom. (c) Diagram and (d) photograph of a 3D printed PET/MRI resolution phantom with hot and cold rods.10 Figure license: Bieniosek, et al. #bib2015, Technical Note: Characterization of custom 3D printed multimodality imaging phantoms. (Copyright by John Wiley and sons).

Figure 12

(I) Three different geometries of carotid bifurcation vessel tubes, (II) Ultrasound flow images for the different geometric phantoms.68 Reprinted from Ultrasound in Medicine and Biology, Vol. 3, Lai SSM, Yiu BYS, Poon AKK, Yu ACH, Design of anthropomorphic flow phantoms based on rapid prototyping of compliant vessel geometries #bib1654‐1664, 2013, with permission from Elsevier.

Figure 13

Procedures that affect the accuracy of the phantom.

Figure 14

Diagram of the steps involved in the 3D printing process.