Extravasation modeling from a PET/CT imaging for a possible digital twin approach

Extravasation of radiopharmaceuticals during PET procedures can compromise both diagnostic accuracy and patient safety by altering tracer pharmacokinetics and delivering unintended local radiation doses. A clinically observed 18F-FDG extravasation case has been reconstructed through a superposition of co-recorded CT and PET DICOM scan images to localize and quantify the extravasated activity. Building on advances in personalized computational modeling, the Digital Twin paradigm could offer a powerful framework for patient-specific dosimetry. Anatomical segmentation has been performed using Synopsys (R) SimplewareTM Medical to generate an accurate 3D model of the injection site and surrounding tissues. This Digital Twin has been completed through the build-up of an Unstructured Mesh domain that can be studied with the MCNP6 (c) Monte Carlo code for particle transport simulations, incorporating the effective half-life of 18F-FDG to reflect dynamic radiotracer clearance. The digital twin has been benchmarked through OLINDA/EXM (R) code and thanks to dose-rate measurement performed with the Thermo Fisher Scientific Inc.(c) RadEye SPRD detector directly on the oncological injected patient. By embodying a patient's anatomy, physiology, and radiotracer kinetics in a digital twin, this methodology provides a robust tool for personalized dosimetry of extravasation events. The framework is readily extensible to other radiopharmaceuticals and therapeutic contexts, supporting safer and more effective nuclear medicine practices.