Monte Carlo dosimetric analyses on the use of 90 Y-IsoPet intratumoral therapy in canine subjects

To investigate different dosimetric aspects of Y-IsoPet™ intratumoral therapy in canine soft tissue sarcomas, model the spatial spread of the gel post-injection, evaluate absorbed dose to clinical target volumes, and assess dose distributions and treatment efficacy. Six canine cases treated with Y-I...

Full description

Saved in:
Bibliographic Details
Published in:Physics in medicine & biology Vol. 69; no. 16
Main Authors: Bobić, Mislav, Huesa-Berral, Carlos, Terry, Jack F, Kunz, Louis, Schuemann, Jan, Fisher, Darrell R, Maitz, Charles A, Bertolet, Alejandro
Format: Journal Article
Language:English
Published: England 21.08.2024
Subjects:
Animals
Dogs
Monte Carlo Method
Phantoms, Imaging
Positron Emission Tomography Computed Tomography
Radiometry
Radiotherapy Dosage
Sarcoma - radiotherapy
Sarcoma - veterinary
Yttrium Radioisotopes - therapeutic use
IsoPet
soft tissue sarcomas
dosimetry
dog cancer models
Y-90 therapy
RadioGel
comparative oncology
ISSN:1361-6560
Online Access:Get more information
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:To investigate different dosimetric aspects of Y-IsoPet™ intratumoral therapy in canine soft tissue sarcomas, model the spatial spread of the gel post-injection, evaluate absorbed dose to clinical target volumes, and assess dose distributions and treatment efficacy. Six canine cases treated with Y-IsoPet™ for soft tissue sarcoma at the Veterinary Health Center, University of Missouri are analyzed in this retrospective study. The dogs received intratumoral IsoPet™ injections, following a grid pattern to achieve a near-uniform dose distribution in the clinical target volume. Two dosimetry methods were performed retrospectively using the Monte Carlo toolkit OpenTOPAS: imaging-based dosimetry obtained from post-injection PET/CT scans, and stylized phantom-based dosimetry modeled from the planned injection points to the gross tumor volume. For the latter, a Gaussian parameter with variable sigma was introduced to reflect the spatial spread of IsoPet™. The two methods were compared using dose-volume histograms (DVHs) and dose homogeneity, allowing an approximation of the closest sigma for the spatial spread of the gel post-injection. In addition, we compared Monte Carlo-based dosimetry with voxel S-value (VSV)-based dosimetry to investigate the dosimetric differences. Imaging-based dosimetry showed differences between Monte Carlo and VSV calculations in tumor high-density areas with higher self-absorption. Stylized phantom-based dosimetry indicated a more homogeneous target dose with increasing sigma. The sigma approximation of the Y-IsoPet™ post-injection gel spread resulted in a median sigma of approximately 0.44 mm across all cases to reproduce the dose heterogeneity observed in Monte Carlo calculations. The results indicate that dose modeling based on planned injection points can serve as a first-order approximation for the delivered dose in Y-IsoPet™ therapy for canine soft tissue sarcomas. The dosimetry evaluation highlights the non-uniformity of absorbed doses despite the gel spread, emphasizing the importance of considering tumor dose heterogeneity in treatment evaluation. Our findings suggest that using Monte Carlo for dose calculation seems more suitable for this type of tumor where high-density areas might play an important role in dosimetry.
ISSN:1361-6560
DOI:10.1088/1361-6560/ad67a4