Dosimetric assessment of Gadolinium-159 for hepatic radioembolization: Tomographic images and Monte Carlo simulation

A common therapeutic radionuclide used in hepatic radioembolization is yttrium-90 (⁹⁰Y). However, the absence of gamma emissions makes it difficult to verify the post-treatment distribution of ⁹⁰Y microspheres. Gadolinium-159 (¹⁵⁹Gd) has physical properties that are suitable for therapy and post-treatment imaging in hepatic radioembolization procedures. The current study is innovative for conducting a dosimetric investigation of the use of ¹⁵⁹Gd in hepatic radioembolization by simulating tomographic images using the Geant4 application for tomographic emission (GATE) Monte Carlo (MC) simulation. For registration and segmentation, tomographic images of five patients with hepatocellular carcinoma (HCC) who had undergone transarterial radioembolization (TARE) therapy were processed using a 3D slicer. The tomographic images with ¹⁵⁹Gd and ⁹⁰Y separately were simulated using the GATE MC Package. The output of simulation (dose image) was uploaded to 3D slicer to compute the absorbed dose for each organ of interests. ¹⁵⁹Gd were able to provide a recommended dose of 120 Gy to the tumour, with normal liver and lungs absorbed doses close to that of ⁹⁰Y and less than the respective maximum permitted doses of 70 Gy and 30 Gy, respectively. Compared to ⁹⁰Y, ¹⁵⁹Gd requires higher administered activity approximately 4.92 times to achieve a tumour dose of 120 Gy. Thus; this research gives new insights into the use of ¹⁵⁹Gd as a theranostic radioisotope, with the potential to be used as a⁹⁰Y alternative for liver radioembolization.