An analysis of particle track effects on solid mammalian tissues

Area of Science:

• Radiobiology
• Radiation Biophysics
• High-LET Radiation Effects

Background:

• Determining relative biological effectiveness (RBE) and quality factors (Q) for high-energy particles is crucial for radiation protection.
• Single-cell experiments often simplify particle interactions, potentially misrepresenting complex tissue responses.

Purpose of the Study:

• To investigate if RBE and Q values derived from single-cell studies accurately reflect biological damage in tissues exposed to high linear energy transfer (LET) radiation.
• To compare RBEs from tissue experiments with those from single-cell systems.

Main Methods:

• Reviewing experimental data on radiation effects in single-cell and animal tissue systems.
• Estimating the number of at-risk cells (p3n) per high-energy particle track within tissues.
• Calculating the ratio of RBE in tissues to RBE in corresponding single cells.

Main Results:

• High-energy particles (e.g., Ar, Fe ions) passing through tissues can hit multiple cells, with LET exceeding 200 keV/µm.
• Tissue RBEs for high LET radiation were found to be higher than single-cell RBEs.
• This discrepancy is more pronounced in tissues with a higher probability of cells expressing the measured endpoint (high p3n).

Conclusions:

• Single-cell RBEs may underestimate the biological impact of high-LET radiation in complex tissue environments.
• Accurate assessment of radiation risk requires considering tissue geometry and cellular response probability.
• Further research is needed to refine RBE and Q factor calculations for space radiation and radiotherapy applications.