Comparative Evaluation of Voxel-Level Dosimetry Methods in ⁹⁰Y-Microsphere Radioembolization Using PET/CT

Area of Science:

• Medical Physics
• Radiology
• Nuclear Medicine

Background:

• Yttrium-90 (⁹⁰Y) microsphere radioembolization is a standard treatment for liver cancer.
• Accurate post-treatment dosimetry is crucial for optimizing patient outcomes.
• Current voxel-level dosimetry methods require evaluation for clinical applicability.

Purpose of the Study:

• To compare the accuracy and computational efficiency of three dosimetry methods: Monte Carlo (MC), voxel S-value (VSV), and local energy deposition (LDM).
• To assess the clinical practicality of these methods for ⁹⁰Y radioembolization dose verification.

Main Methods:

• Analysis of post-treatment PET/CT data from 68 patients treated with ⁹⁰Y microspheres.
• MC simulations served as the reference standard for dosimetry.
• VSV method involved convolving PET images with a precomputed ⁹⁰Y kernel; LDM assumed complete local energy absorption.

Main Results:

• VSV achieved near-MC accuracy with significantly reduced computation time (seconds vs. hours for MC).
• LDM overestimated doses in high-dose regions and showed larger deviations compared to MC.
• VSV demonstrated high agreement with MC, with small differences in mean dose and EUBED, and tighter Bland-Altman limits.

Conclusions:

• VSV provides a clinically practical solution for rapid and reliable voxel-level dosimetry in ⁹⁰Y radioembolization.
• The VSV method combines MC-level accuracy with dramatically reduced computation time.
• VSV may support personalized treatment evaluation and dose verification in liver cancer therapy.