Safety Evaluation of a Long-Lived Tumour-Specific Gadolinium (Gd)-Based Imaging Agent in Proton Therapy

Christian Velten, Wolfgang A. Tomé

Research output: Contribution to journalConference articlepeer-review


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 103 to 105 atoms/mmolnatGd per Gray SOBP dose in a 2.4 cm3 volume. At currently achievable Gadolinium concentrations of 0.2 µmol/cm3 this yields approximately 26 atoms/(cm3 GySOBP), corresponding to less than 1 Bq activity. Additional dose from evaporation neutrons and subsequent capture gammas is on the order of 1 µSv/GySOBP. Thus, use of this long-lived contrast agent is dosimetrically safe at current concentrations and induced radioactivity is negligible.

Original languageEnglish (US)
Article number012033
JournalJournal of Physics: Conference Series
Issue number1
StatePublished - Oct 16 2020
Event20th Biannual Micro-Mini and Nano Dosimetry and Innovative Technologies in Radiation Oncology, MMND ITRO 2020 - Wollongong, Australia
Duration: Feb 10 2020Feb 16 2020

ASJC Scopus subject areas

  • General Physics and Astronomy


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