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Updated: Mar 17, 2026
Multimodal 3D Printing of Phantoms to Simulate Biological Tissue
Published on: January 11, 2020
Organ-specific SPECT activity calibration using 3D printed phantoms for molecular radiotherapy dosimetry
Andrew P Robinson1, Jill Tipping2, David M Cullen3
1Schuster Laboratory, School of Physics and Astronomy, The University of Manchester, Manchester, M13 9PL, UK. andrew.paul.robinson@manchester.ac.uk.
Background:
Patient-specific absorbed dose calculations for molecular radiotherapy require accurate activity quantification. This is commonly derived from Single-Photon Emission Computed Tomography (SPECT) imaging using a calibration factor relating detected counts to known activity in a phantom insert.
Methods:
A series of phantom inserts, based on the mathematical models underlying many clinical dosimetry calculations, have been produced using 3D printing techniques. SPECT/CT data for the phantom inserts has been used to calculate new organ-specific calibration factors for (99m) Tc and (177)Lu. The measured calibration factors are compared to predicted values from calculations using a Gaussian kernel.
Results:
Measured SPECT calibration factors for 3D printed organs display a clear dependence on organ shape for (99m) Tc and (177)Lu. The observed variation in calibration factor is reproduced using Gaussian kernel-based calculation over two orders of magnitude change in insert volume for (99m) Tc and (177)Lu. These new organ-specific calibration factors show a 24, 11 and 8 % reduction in absorbed dose for the liver, spleen and kidneys, respectively.
Conclusions:
Non-spherical calibration factors from 3D printed phantom inserts can significantly improve the accuracy of whole organ activity quantification for molecular radiotherapy, providing a crucial step towards individualised activity quantification and patient-specific dosimetry. 3D printed inserts are found to provide a cost effective and efficient way for clinical centres to access more realistic phantom data.
