3D high resolution clonogenic survival measurement of xrs-5 cells in low-dose region of carbon ion plans

Abstract

Purpose

In this study, we performed biological verification measurements of cell survival of a ¹²C ion irradiation plan employing a high-resolution 3D culture setup. This allowed, in particular, to access the cell inactivation in the low-dose regions close to the target area.

Materials and methods

We established the protocol for a 3D culture setup where xrs-5 cells were grown inside a layered matrigel structure in 384-well plates. Their radiosensitivity to conventional and ¹²C ion radiation was evaluated by irradiating them either with 250 kV X-rays at GSI or with monoenergetic ¹²C beams of 110 MeV/u at MIT, and compared with those of monolayers. A treatment plan for a rectangular target was prepared using the GSI research treatment planning system TRiP98. xrs-5 cells were seeded in the matrigel-based setup and irradiated in dose fall-off regions using active scanning ¹²C ion beams. In addition, film dosimetry utilizing radiochromic EBT3 film has been performed to assess the field homogeneity downstream of 384-well V-bottom plates with or without additional agarose coating of the well plate bottom.

Results

Dose response curves following X-ray and ¹²C ion irradiation had linear shape and showed a significant decrease in survival fraction at even moderate doses. Survival measurements in the low-dose regions of the plan for the extended target showed good agreement to the predicted survival fraction. The irradiated film profiles yielded a flat dose distribution without apparent artifacts or inhomogeneities for well plates both with and without agarose coating, confirming the suitability of the experimental setup.

Conclusions

We conclude that the V-bottom 384-well plates in combination with the radiation-sensitive xrs-5 cell line constitute a suitable radiobiological verification tool which can be used especially for low doses. Furthermore, the measured survival of xrs-5 cells show a good agreement with the expected survival in the low-dose out-of-field regions, both laterally and downstream of the target.

Keywords:

• xrs-5 cells
• 3D cell culture in ECM
• biological treatment plan verification
• carbon ion beam therapy

Acknowledgements

This work was carried out in collaboration with GSI/FAIR under Get Involved Programme framework. The authors wish to thank M. Witt and S. Felsing for operating the MIT irradiations and Dr. U. Schötz for providing laboratory space during the experiments. We also thank G. Camazzola for support during irradiations.

Disclosure statement

The authors report no conflicts of interest. All authors are not affiliated, funded by, or employed in any respect by the Government of Iran.

Additional information

Funding

This work was supported by Thailand Center of Excellent in Physics (ThEP) under Grant number ThEP-61-PHM-SUT4; Suranaree University of Technology (SUT) under SUT-PhD scholarship for ASEAN; Center of Excellent in High Energy Physics and Astrophysics; and Thailand Science Research and Innovation (TSRI) under Grant number IRN62W0006. Work is partially funded by the European Union’s H2020 Research and Innovation Programme under Grant Agreement No. 730983 (INSPIRE). The authors acknowledge funding and provision of beam time through the Förderprogramm MIT-Forschung of Philipps-Universität Marburg under grant number MIT-2018-03 funded by Hessisches Ministerium für Wissenschaft und Kunst.

Notes on contributors

Dea Kartini

Dea A. Kartini, PhD, is a PhD graduate student at the School of Physics, Suranaree University of Technology, Nakhon Ratchasima, Thailand.

Olga Sokol

Olga Sokol, PhD, is a Postdoctoral researcher at the Biophysics Department, GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt, Germany.

Chutima Talabnin

Chutima Talabnin, PhD, is an Assistant Professor at the School of Chemistry, Suranaree University of Technology, Nakhon Ratchasima, Thailand.

Chinorat Kobdaj

Chinorat Kobdaj, PhD, is an Assistant Professor at the School of Physics, Suranaree University of Technology, Nakhon Ratchasima, Thailand.

Marco Durante

Marco Durante, PhD, is a Professor at Institut für Physik Kondensierter Materie, Technische Universität Darmstadt and Scientific head of Biophysics Department, GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt, Germany.

Michael Krämer

Michael Krämer, PhD, is a Senior Scientist at the Biophysics Department, GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt, Germany.

Martina Fuss

Martina C. Fuss, PhD, is a Senior Postdoctoral researcher at the Biophysics Department, GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt, Germany.