The study aims to identify and predict radiopharmaceutical extravasation events using new semi-quantitative parameters and machine learning models. It involves dose rate measurements to develop metrics for real-time monitoring. It also investigates the correlation between extravasation and SUV correction in PET/CT diagnostics, providing an estimate of the correction factor necessary for accurate SUV evaluation in case of an extravasation event.

This is a descriptive, observational, non-profit study aimed at detecting and predicting extravasation events during the administration of radiopharmaceuticals for diagnostic and therapeutic purposes in nuclear medicine. Extravasation can lead to local tissue damage and compromise the accuracy of semi-quantitative imaging parameters such as the Standardized Uptake Value (SUV), widely used in PET/CT for diagnosis, staging, and therapy response evaluation. Literature reports that extravasation may cause a 21-50% change in SUV, potentially leading to incorrect assessment of tumor response.

The study will use a CE-marked portable spectroscopic personal radiation detector (RadEye SPRD-ER, Thermo Fisher Scientific™), already validated in a previous Ethics Committee-approved study, to record dose-rate (DR) curves during radiopharmaceutical injections. Using these data, new dosimetric metrics will be developed to characterize correct, abnormal, and extravasation events. Machine learning (ML) algorithms will be trained on patient clinical data, injection metrics, and DR curves to classify injection events in real time and to estimate correction factors for SUV quantification. Monte Carlo simulations (MCNP code, anthropomorphic phantoms, and reconstructed patient geometries) will be performed to evaluate absorbed dose distributions in extravascular regions.

The project is structured into three phases:

Phase 1 (Data Acquisition & Analysis): Real-time monitoring with RadEye SPRD-ER, extraction of quantitative metrics (DRmax, DRmean, Δp, t*, Δt), development of ML classifiers and regression models for SUV correction.

Phase 2 (Monte Carlo Simulations): Activity and dose calibration, dose distribution modeling in extravascular tissues.

Phase 3 (Dissemination): Scientific publications and presentation of results at international conferences.

This study has the potential to improve safety, diagnostic reliability, and accuracy of radiopharmaceutical administrations by introducing predictive monitoring and real-time correction of quantitative imaging parameters.

Inclusion Criteria:

• patients undergoing PET/CT scans or therapeutic treatments with radiopharmaceuticals labelled with alpha or beta emitting nuclides

Exclusion Criteria:

• patients whose clinical or psychological conditions do not allow for their involvement

Adult patients undergoing standard-of-care nuclear medicine procedures (PET/CT or therapeutic α/β radiopharmaceutical administrations).