Direct proton range verification using oxygen-18 enriched water as a contrast agent



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España Palomares, Samuel and Sánchez Parcerisa, Daniel and Ibáñez García, Paula Beatriz and Sánchez Tembleque, Víctor and Udías Moinelo, José Manuel and Valladolid Onecha, Víctor and Gutierrez Uzquiza, Álvaro and Bäcker, Claus Maximilian and Bäumer, Christian and Herrmann, Ken and Fragoso Costa, Pedro and Timmermann, Beate and Fraile Prieto, Luis Mario (2021) Direct proton range verification using oxygen-18 enriched water as a contrast agent. Radiation Physics and Chemistry, 182 . p. 109385. ISSN 0969-806X

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We propose the use of O-enriched water as a suitable contrast agent for potential in-vivo range verification in proton therapy. The low energy production threshold of 18F (2.6 MeV, proton range in water of 115 μm) leads to tissue activation in very close proximity to the maximum dose deposition, facilitating accurate range verification with off-line PET imaging.
This idea has been explored in a phantom experiment. A 3D-printed phantom containing inserts with 18Oenriched water was irradiated with a 100-MeV, 8 × 8 cm2 proton beam, and the induced activity was measured with a small-animal PET-CT 30 min after irradiation. The images obtained were compared against Monte Carlo simulation using TOPAS.
Good agreement was observed between reconstructed and simulated activity profiles (within 40% for specific 18F activity), with excellent spatial match to the simulated dose deposition. Because of the long half-life of 18F, the specific activity of the contrast agent could be separated and was clearly observed for more than 2 h after irradiation. Activity distribution maps were used to determine the position of the Bragg peak within 2 mm for three different regions of interest. These results show the potential of 18O-enriched water as a contrast agent in proton therapy.

Item Type:Article
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CRUE-CSIC (Acuerdos Transformativos 2021)

Uncontrolled Keywords:18O, Phantom, Activation, Range verification, Protontherapy
Subjects:Sciences > Physics
Sciences > Physics > Nuclear physics
ID Code:70592
Deposited On:18 Feb 2022 12:30
Last Modified:18 Oct 2022 09:06

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