Development of 3D-Printed Heterogeneous Tumour Phantom for Quantitative Analysis in PET/CT Imaging

Abstract

Tumours are heterogenous growths that consists of different types of cells with varying genetic expressions. The complex structure of the tumour makes cancer treatment difficult due to the heterogeneity of each of the cancer cells that react differently to radiation treatment. Therefore, effective treatment requires proper characterization of the tumour heterogeneity, which is difficult to be assessed by most of the current medical imaging technologies. The purpose of this study was to develop a 3D printed heterogenous tumour phantom with multiple compartments to simulate tumour heterogeneity and to assess the accuracy of tumour characterization using Positron Emission Tomography/Computed Tomography (PET/CT) imaging. The tumour phantom was designed and modelled using SolidWorks and then constructed using the fused deposition modelling (FDM) method of 3D printing with polylactide (PLA) filament as the material. Multiple layer of waterproof coating was applied and the phantom was carefully tested for any leakage prior to the study. Each of the compartments of the tumour phantom was filled with different activity of the radiopharmaceutical (18F-FDG). The phantom was then embedded in a water bath to simulate soft tissue and scanned under a PET/CT scanner using standard clinical protocol. The volume and radioactivity of each compartment were then measured using the clinical software as Standardized Uptake Values (SUVs). Results showed that PET/CT imaging able to delineate and quantify the radioactivity of each compartment within the tumour phantom, albeit some difficulties in detecting radioactivity below 100 μCi. Further research is required to improve the design of the tumour phantom to allow for easier injection of the radioactive solution as well as altering the dimensions of the internal compartments to better characterize actual tumour parameters.