[Article] A Single Centre Intercomparison Between Commercial Treatment Planning Systems for 90Y Radioembolization using Virtual and Experimental Phantoms

A single centre intercomparison between commercial treatment planning systems for 90Y radioembolization using virtual and experimental phantoms

Giuseppe Della Galaa, Miriam Santoroa, Garoson Albertine Rasoatsaratananya,b, Giulia Paolania, Silvia Strolina, Lidia Strigaria
a Department of Medical Physics, IRCCS Azienda Ospedaliero-Universitaria di Bologna, 40138, Bologna, Italy
b International Center for Theoretical Physics (ICTP), Strada Costiera, 11, 34151, Trieste, Italy


Introduction: Dedicated Treatment Planning Systems (TPSs) were developed to personalize 90Y-transarterial radioembolization. This study evaluated the agreement among four commercial TPSs assessing volumes of in-terest (VOIs) volumes and dose metrics. 

Methods: A homogeneous (EH) and an anthropomorphic phantom with hot and cold inserts (EA) filled with 99mTc-pertechnetate were acquired with a SPECT/CT scanner. Their virtual versions (VH and VA, respectively) and a phantom with activity inside a single voxel (VK) were generated by an in-house MATLAB script. Images and delineated VOIs were imported into the TPSs to compute voxel-based absorbed dose distributions with various dose deposition approaches: local deposition method (LDM) and dose kernel convolution (DKC) with/ without local density correction (LDC). VOI volumes and mean absorbed doses were assessed against their median value across TPSs. Dose-volume histograms (DVHs) and VK-derived dose profiles were evaluated.

Results: Small (<2.1 %) and large (up to 42.4 %) relative volume differences were observed on large (>500 ml) and small VOIs, respectively. Mean absorbed doses relative differences were < 3 % except for small VOIs with steep dose gradients (up to 89.1 % in the VA Cold Sphere VOI). Within the same TPS, LDC negligibly affected the mean absorbed dose, while DKC and LDM showed differences up to 63 %. DHVs were mostly overlapped in experimental phantoms, with some differences in the virtual versions. Dose profiles agreed within 1 %.

Conclusion: TPSs showed an overall good agreement except for small VOI volumes and mean absorbed doses of VOIs with steep dose gradients. These discrepancies should be considered in the dosimetry uncertainty assess-ment, thus requiring an appropriate harmonization.