Preparation of a radiobiology beam line at CNA
In an article recently published in Physica Medica, OMA Fellow Anna Baratto-Roldán and her colleagues from the National Centre of Accelerators (CNA) and the University of Seville, Spain, have presented the radiobiology beam line designed at the 18 MeV proton cyclotron facility of CNA, to perform irradiations of mono-layer cell cultures.
The lack of accurate biological data in the Bragg peak region of proton therapy beams, makes it difficult to implement biophysically optimized treatment plans in clinical practice. In this context, low energy proton accelerator facilities provide the perfect environment to collect good radiobiological data, as they can produce high Linear Energy Transfer beams with narrow energy distributions.
To ensure that all the cells receive the same dose with a suitable dose rate, low beam intensities and broad and homogeneous beam profiles are necessary. To do so, Anna and her colleagues used an unfocused beam, broadened with a 500 μm thick aluminium scattering foil. Thus, they obtained homogeneous dose profiles, with deviations lower than 10%, over a circular surface of 35 mm diameter for an incident average energy of 12.8 MeV.
The team also developed a specific Monte Carlo application with Geant4 to simulate the beam line and the experimental setup. The code was benchmarked and validated towards measurements, reproducing with a very good agreement experimental data in what concerned both the beam energy distribution and dose profiles, with differences generally lower than 1%. Once validated, the code was used, together with an ionization chamber, for dosimetry studies, to characterize the beam and monitor the dose.
Finally, the researchers managed to irradiate successfully cultures of Human Bone Osteosarcoma cells (U2OS) at the radiobiology beam line, investigating the effects of radiation in terms of DNA damage induction.
The article is part of a special issue of the European Journal of Medical Physics – Physica Medica edited on occasion of the International Conference on Medical Accelerators, organised by the OMA network in Seville (Spain) in September 2019.
The full article can be found here:
Anna Baratto-Roldán, María del Carmen Jiménez-Ramosa, Sonia Jimeno, Pablo Huertas, Javier García-López, María Isabel Gallardo, Miguel Antonio Cortés-Giraldo, José Manuel Espino, “Preparation of a radiobiology beam line at the 18 MeV proton cyclotron facility at CNA”, Physica Medica 74, 19–29 (2020).
https://doi.org/10.1016/j.ejmp.2020.04.022