A 3D Printed Cardiac Phantom for Nuclear Medicine Imaging

Abstract

Abstract Purpose: Commercially available phantoms for nuclear medicine myocardial perfusion scintigraphy (MPS) are expensive, simplified models of the left ventricle. With 3D printing becoming more widely accessible, centres are looking to develop and print their own phantoms. The purpose of this study was to design, print and validate a flexible, anthropomorphic cardiac phantom for MPS, matching the tissue properties to the 3D printed materials, and assessing print costs. Methods: A scoping review was undertaken to build upon previous work and inform the methodology used within this research. Materials available for 3D printing were analysed for their radiological imaging properties using Dual Energy Computed Tomography (DECT) and Single Energy CT (SECT). The electron density (ρe), effective atomic number (Zeff) and CT numbers across a range of energies, were measured. A freely available model of the heart in Standard Tessellation Language (STL) was downloaded into an open source, image computing platform and adapted into a phantom for nuclear medicine imaging. The myocardial wall was hollowed, and filling holes inserted. Prints were undertaken in hard and flexible material on two models of printer. The phantom was scanned on a 128-slice CT scanner, filled with Technetium-99m and scanned using a gamma camera. The images were analysed by a consultant radiologist. Material costs and man hours for different prints were assessed. Results: Measurement of the Zeff and ρe of the printed materials was obtained in a single DECT scan. The Zeff of all but one material was below that of water. The CT number of those materials increased with energy, comparable to adipose tissue and contra to muscle and normal tissue. Flexible prints were unsuccessful due to delamination of the material and difficulties in removing support material. The activity distribution within the cardiac phantom in nuclear medicine imaging was reported as normal, with a small reduction of activity towards the base of the anterior wall. Normal anatomy was visualised on CT. Material costs varied with the printer used and were cheaper or comparable with simple, commercial phantoms. Conclusions: An anthropomorphic cardiac phantom was developed with reproducible, normal uptake on nuclear medicine imaging. CT imaging of the model showed normal anatomy. Matching the material to tissue properties was difficult due to the range of materials available and the low effective atomic number of the materials. Due to complex geometries and removal of support material, further work is required to successfully print the model in flexible material. Print costs compared favourably to commercial phantoms.

Date of Award	1 Aug 2023
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Ranald Mackay (Supervisor)