The effect of radiation dose on the onset and progression of radiation-induced brain necrosis in the rat model

Abstract

Purpose: To provide a comprehensive understanding of how the selection of radiation dose affects the temporal and spatial progression of radiation-induced necrosis in the rat model.

Materials and methods: Necrosis was induced with a single fraction of radiation exposure, at doses ranging between 20 and 60 Gy, to the right hemisphere of 8-week-old Fischer rats from a linear accelerator. The development and progression of necrosis in the rats was monitored and quantified every other week with T1- and T2-weighted gadolinium contrast-enhanced MRI studies.

Results: The time to onset of necrosis was found to be dose-dependent, but after the initial onset, the necrosis progression rate and total volume generated was constant across different doses ranging between 30 and 60 Gy. Radiation doses less than 30 Gy did not develop necrosis within 33 weeks after treatment, indicating a dose threshold existing between 20 and 30 Gy.

Conclusion: The highest dose used in this study led to the shortest time to onset of radiation-induced necrosis, while producing comparable disease progression dynamics after the onset. Therefore, for the radiation-induced necrosis rat model using a linear accelerator, the most optimum results were generated from a dose of 60 Gy.

Keywords:

• Radiation
• necrosis
• brain
• animal model

Acknowledgements

The authors would like to acknowledge Paul Magee for assistance with rodent anesthesia during the radiotherapy.

Disclosure statement

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

Additional information

Funding

This work was supported by the National Cancer Institute under Grant R21 CA178578, and the University of California, Davis Comprehensive Cancer Center’s Brain Malignancies Innovation Group.