21-23 March 2022
Europe/Madrid timezone

In-vivo and inbeam monitoring of PET activation in proton therapy: tests in a chicken embryo model with 18O-enriched water

21 Mar 2022, 16:15
Red Temática de Física Nuclear (FNUC) Red FNUC (Red Temática de Física Nuclear)


Andrea Espinosa Rodríguez (Universidad Complutense de Madrid)


Clinical PET imaging for in-vivo 3D activation verification in proton therapy suffers from two major drawbacks: minimal activation near the Bragg Peak region and biological washout. Here, we investigate the possibility of using 18O-enriched water (18-W) for in-vivo range verification in a clinical scenario. PET images are acquired with a novel in-beam system that can detect and process on-the-fly PET activity produced during and after irradiation.

Head and neck cancer cells were grown as xenografts in an in-vivo chick embryo chorioallantoic membrane (CAM) model. Three tumours were infused with 18-W, in vivo and irradiated with a clinical 80-MeV proton beam at the Quironsalud proton therapy center. Activity was recorded in two separated periods, during irradiation (beam-on) and decay (beam-off) with a specific PET setup consisting of 6 phoswich detector blocks with 338 pixels each, with of 1.55x1.55 x LYSO (7mm)+GSO (8mm) . The system was coupled to a fast data acquisition system able to sustain rates up to 10 Msingles/sec.

Dynamic 3D maps of the activity in the eggs were reconstructed from coincidences during irradiation, showing the spot structure of the treatment plan. Measured decay curves were correlated with dynamic PET images and 3D activity maps and fitted to a sum of exponentials including the decay of 11C, 13N, 15O and 18F, to obtain the individual contribution for each isotope.

3D PET activity maps during irradiation can be reconstructed in a clinical scenario with sub-ms and sub-mm resolutions. Decay analysis shows specific activity of 18F close to the tumour area several minutes after irradiation. This validates the experimental setup for its use for in-beam on-the-fly reconstruction of the 3D activity spatial distribution as well as late specific 18F activity entrapped in the tumour.

Primary authors

Andrea Espinosa Rodríguez (Universidad Complutense de Madrid) Samuel España (Ghent University) Daniel Sanchez Parcerisa (Universidad Complutense de Madrid) Dr. Paloma Bragado (UCM) Dr. Álvaro Gutierrez-Uzquiza (UCM) Fernando Arias Valcayo (Universidad Complutense de Madrid) Paula Ibáñez García (Universidad Complutense de Madrid) Víctor Sánchez-Tembleque Verbo (Grupo de FIsica Nuclear) Víctor Valladolid Onecha Miguel García Díez (Grupo de Física Nuclear (GFN) Universidad Complutense de Madrid) Dr. Alejandro Mazal (Centro de Protonterapia Quironsalud, Madrid, Spain) Dr. Juan Antonio Vera Sanchez (Centro de Protonterapia Quironsalud, Madrid, Spain) Prof. Luis Fraile (Universidad Complutense de Madrid) Jose Udias (Universidad Complutense de Madrid)

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