The Essential Role of Monte Carlo Simulations for Lung Dosimetry in Liver Radioembolization—Part B: [sup.166]Ho Microspheres

• Published in: Applied sciences Vol. 15; no. 2
• Main Authors: d’Andrea, Edoardo, Politano, Andrea, Cassano, Bartolomeo, Lanconelli, Nico, Cremonesi, Marta, Patera, Vincenzo, Pacilio, Massimiliano
• Format: Journal Article
• Language: English
• Published: MDPI AG 01.01.2025
• Subjects: CT imaging; Liver; Monte Carlo method; Simulation methods; Italy
• ISSN: 2076-3417; 2076-3417
• DOI: 10.3390/app15020958

This study compares dosimetric approaches for lung dosimetry in [sup.166] radioembolization (Ho-TARE) with direct Monte Carlo (MC) simulations on a voxelized anthropomorphic phantom derived from a real patient’s CT scan, preserving the patient’s lung density distribution. Lung dosimetry was assessed for five lung shunt (LS) scenarios with conventional methods: the mono-compartmental organ-level approach (MIRD), voxel S-value convolution for soft tissue (kST, ICRU soft tissue with 1.04 g/cm[sup.3]) and lung tissue (kLT, ICRU lung tissue with 0.296 g/cm[sup.3]), local density rescaling (kSTL and kLTL, respectively, for soft tissue and lung tissue), or global rescaling for a lung mean density of 0.221 g/cm[sup.3] (kLT[sub.221]). Significant underestimations in the mean absorbed dose (AD) were observed, with relative differences with respect to the reference (MC) of −64% for MIRD, −93% for kST, −56% for kSTL, −76% for kLT, −68% for kLT[sub.221], and −60% for kLTL. Given the high heterogeneity of lung tissue, standard dosimetric approaches cannot accurately estimate the AD. Additionally, MC results for [sup.166]Ho showed notable spatial absorbed dose inhomogeneity, highlighting the need for tailored lung dosimetry in Ho-TARE accounting for the patient-specific lung density distribution. MC-based dosimetry thus proves to be essential for safe and effective radioembolization treatment planning in the presence of LS.