3D printed phantom kidneys to test radiation dose in nuclear medicine

Published on: Wednesday, 07 December 2016

A team of researchers from the University of Würzburg in Germany are using 3D printed organ models for clinical prototyping to test dosage amounts of radioactive materials.

When it comes to nuclear medicine, the goal is to keep radiation exposure at a minimum, but enough to get quality images. Determine the optimal dosing for every individual patient can be hard to determine. The 3D printed organ models meet the size and shape of every patient, thus allowing to perform tests to find the optimal dosage.

These models have been made with a low-cost FFF 3D printer with a waterproof and chemically stable plastic material. These 3D printed phantom kidneys are refillable, so the researchers can tests different amounts of radioactive materials within them to see how much is needed for a SPECT or CT scan.

The CAD model was made with Autodesk Inventor. The team used a Renkforce RF1000 3D FFF printer loaded with PLA to make the models. A 1.2 mm wall thikness was selected to give enough rigidity to the models.

Nucler medicine works by injecting small amounts of radioactive materials into the body, which are then captured through external detectors and which give doctors a clear indication on how abnormalities and diseases are manifesting within the body.

For the study, a set of four single-compartment kidney dosimetry phantoms and their spherical counterparts with filling volumes between 8 mL (newborn) and 123 mL (adult) were designed based on the outer kidney dimensions provided by Medical Internal Radiation Dose (MIRD) guidelines. Nuclide-dependent SPECT/CT calibration factors for technetium-99m (Tc-99m), lutetium-177 (Lu-177), and iodine-131 (I-131) were then determined to assess the accuracy of quantitative imaging for internal renal dosimetry.

The study concludes that "3D printing is a promising prototyping technique for geometry-specific calibration of SPECT/CT systems. Although the underlying radionuclide and the related collimator have a major influence on the calibration, no relevant differences between kidney-shaped and spherically shaped uniform-activity phantoms were observed. With comparably low costs and submillimeter resolution, 3D printing techniques hold the potential for manufacturing individualized anthropomorphic phantoms in many clinical applications in nuclear medicine".

The study "Design and Fabrication of Kidney Phantoms for Internal Radiation Dosimetry Using 3D Printing Technology" is authored by Johannes Tran-Gia, Susanne Schlögl and Michael Lassmann and has been published in the December issue of The Journal of Nuclear Medicine.