Open AccessSafety Evaluation of a Long-Lived Tumour-Specific Gadolinium (Gd)-Based Imaging Agent in Proton Therapy
Author(s) -
Christian Velten,
Wolfgang A. Tomé
Publication year - 2020
Publication title -
journal of physics. conference series
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.21
H-Index - 85
eISSN - 1742-6596
pISSN - 1742-6588
DOI - 10.1088/1742-6596/1662/1/012033
Subject(s) - sobp , gadolinium , bragg peak , proton therapy , nuclear medicine , proton , neutron , materials science , radiochemistry , chemistry , physics , medicine , nuclear physics , metallurgy
We assessed the dosimetric safety of a potential diapeutic Gadolinium-based contrast agent for diagnostic MR imaging and MR-guided radiotherapy by calculating depth-dependent reactions rates in a spread-out Bragg peak (SOBP) in water. Energy-dependent cross-sections for inelastic proton reactions on Gadolinium were folded with proton energy spectra at depth. Particle transport, dose, and phase space scoring was performed using Geant4-based TOPAS Monte Carlo software. The isotopic Terbium yield at depth was calculated to be between 10 3 to 10 5 atoms/mmol natGd per Gray SOBP dose in a 2.4 cm 3 volume. At currently achievable Gadolinium concentrations of 0.2 μmol/cm 3 this yields approximately 26 atoms/(cm 3 Gy SOBP ), corresponding to less than 1 Bq activity. Additional dose from evaporation neutrons and subsequent capture gammas is on the order of 1 μSv/Gy SOBP . Thus, use of this long-lived contrast agent is dosimetrically safe at current concentrations and induced radioactivity is negligible.