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3D printed non-uniform anthropomorphic phantoms for quantitative SPECT

Jessen, Lovisa LU ; Gustafsson, Johan LU ; Ljungberg, Michael LU ; Curkic-Kapidzic, Selma LU ; Imsirovic, Muris LU and Sjögreen-Gleisner, Katarina LU (2024) In EJNMMI Physics 11(1).
Abstract

Background: A 3D printing grid-based method was developed to construct anthropomorphic phantoms with non-uniform activity distributions, to be used for evaluation of quantitative SPECT images. The aims were to characterize the grid-based method and to evaluate its capability to provide realistically shaped phantoms with non-uniform activity distributions. Methods: Characterization of the grid structures was performed by printing grid-filled spheres. Evaluation was performed by micro-CT imaging to investigate the printing accuracy and by studying the modulation contrast (CM) in SPECT images for 177Lu and 99mTc as a function of the grid fillable-volume fraction (FVF) determined from weighing. The... (More)

Background: A 3D printing grid-based method was developed to construct anthropomorphic phantoms with non-uniform activity distributions, to be used for evaluation of quantitative SPECT images. The aims were to characterize the grid-based method and to evaluate its capability to provide realistically shaped phantoms with non-uniform activity distributions. Methods: Characterization of the grid structures was performed by printing grid-filled spheres. Evaluation was performed by micro-CT imaging to investigate the printing accuracy and by studying the modulation contrast (CM) in SPECT images for 177Lu and 99mTc as a function of the grid fillable-volume fraction (FVF) determined from weighing. The grid-based technique was applied for the construction of two kidney phantoms and two thyroid phantoms, designed using templates from the XCAT digital phantoms. The kidneys were constructed with a hollow outer container shaped as cortex, an inner grid-based structure representing medulla and a solid section representing pelvis. The thyroids consisted of two lobes printed as grid-based structures, with void hot spots within the lobes. The phantoms were filled with solutions of 177Lu (kidneys) or 99mTc (thyroids) and imaged with SPECT. For verification, Monte Carlo simulations of SPECT imaging were performed for activity distributions corresponding to those of the printed phantoms. Measured and simulated SPECT images were compared qualitatively and quantitatively. Results: Micro-CT images showed that printing inaccuracies were mainly uniform across the grid. The relationships between the FVF from weighing and CM were found to be linear (r = 0.9995 and r = 0.9993 for 177Lu and 99mTc, respectively). The FVF-deviations from the design were up to 15% for thyroids and 4% for kidneys, mainly related to possibilities of cleaning after printing. Measured and simulated SPECT images of kidneys and thyroids exhibited similar activity distributions and quantitative comparisons agreed well, thus verifying the grid-based method. Conclusions: We find the grid-based technique useful for the provision of 3D printed, realistically shaped, phantoms with non-uniform activity distributions, which can be used for evaluation of different quantitative methods in SPECT imaging.

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author
; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
3D printing, Kidneys, Monte Carlo, Phantom, Quantitative SPECT, Thyroid
in
EJNMMI Physics
volume
11
issue
1
article number
8
publisher
Springer
external identifiers
  • pmid:38252205
  • scopus:85182855422
ISSN
2197-7364
DOI
10.1186/s40658-024-00613-7
language
English
LU publication?
yes
id
a965e84f-56f8-4f5d-a6ae-79283090fede
date added to LUP
2024-02-22 10:37:05
date last changed
2024-04-21 20:21:53
@article{a965e84f-56f8-4f5d-a6ae-79283090fede,
  abstract     = {{<p>Background: A 3D printing grid-based method was developed to construct anthropomorphic phantoms with non-uniform activity distributions, to be used for evaluation of quantitative SPECT images. The aims were to characterize the grid-based method and to evaluate its capability to provide realistically shaped phantoms with non-uniform activity distributions. Methods: Characterization of the grid structures was performed by printing grid-filled spheres. Evaluation was performed by micro-CT imaging to investigate the printing accuracy and by studying the modulation contrast (C<sub>M</sub>) in SPECT images for <sup>177</sup>Lu and <sup>99m</sup>Tc as a function of the grid fillable-volume fraction (FVF) determined from weighing. The grid-based technique was applied for the construction of two kidney phantoms and two thyroid phantoms, designed using templates from the XCAT digital phantoms. The kidneys were constructed with a hollow outer container shaped as cortex, an inner grid-based structure representing medulla and a solid section representing pelvis. The thyroids consisted of two lobes printed as grid-based structures, with void hot spots within the lobes. The phantoms were filled with solutions of <sup>177</sup>Lu (kidneys) or <sup>99m</sup>Tc (thyroids) and imaged with SPECT. For verification, Monte Carlo simulations of SPECT imaging were performed for activity distributions corresponding to those of the printed phantoms. Measured and simulated SPECT images were compared qualitatively and quantitatively. Results: Micro-CT images showed that printing inaccuracies were mainly uniform across the grid. The relationships between the FVF from weighing and C<sub>M</sub> were found to be linear (r = 0.9995 and r = 0.9993 for <sup>177</sup>Lu and <sup>99m</sup>Tc, respectively). The FVF-deviations from the design were up to 15% for thyroids and 4% for kidneys, mainly related to possibilities of cleaning after printing. Measured and simulated SPECT images of kidneys and thyroids exhibited similar activity distributions and quantitative comparisons agreed well, thus verifying the grid-based method. Conclusions: We find the grid-based technique useful for the provision of 3D printed, realistically shaped, phantoms with non-uniform activity distributions, which can be used for evaluation of different quantitative methods in SPECT imaging.</p>}},
  author       = {{Jessen, Lovisa and Gustafsson, Johan and Ljungberg, Michael and Curkic-Kapidzic, Selma and Imsirovic, Muris and Sjögreen-Gleisner, Katarina}},
  issn         = {{2197-7364}},
  keywords     = {{3D printing; Kidneys; Monte Carlo; Phantom; Quantitative SPECT; Thyroid}},
  language     = {{eng}},
  number       = {{1}},
  publisher    = {{Springer}},
  series       = {{EJNMMI Physics}},
  title        = {{3D printed non-uniform anthropomorphic phantoms for quantitative SPECT}},
  url          = {{http://dx.doi.org/10.1186/s40658-024-00613-7}},
  doi          = {{10.1186/s40658-024-00613-7}},
  volume       = {{11}},
  year         = {{2024}},
}