Radiation damage on sub-cellular scales: beyond DNA.

Area of Science:

• Medical Physics
• Radiation Biology
• Computational Biology

Background:

• Modern radiotherapy and microbeam studies expose healthy tissues to low-dose radiation.
• The cytoplasm's role as a radiation target is increasingly recognized, especially in low-dose scenarios.

Purpose of the Study:

• To investigate a model cell's response to low-dose radiation using Monte Carlo simulations.
• To quantify ionization and energy deposition in the nucleus and cytoplasm.
• To assess the impact of cell geometry and composition on radiation effects.

Main Methods:

• Monte Carlo simulations of mono-energetic electrons and photons (10-50 keV).
• Calculation of ionization number and energy deposit in nucleus and cytoplasm.
• Analysis of cell geometry, cytoplasm density, and chemical composition effects.

Main Results:

• Cytoplasm receives over ten times more ionizations than the nucleus at low doses (≤1 Gy).
• Cell geometry and cytoplasm density significantly influence energy deposition.
• Electron energy deposition is insensitive to chemical composition, while photon deposition is affected.

Conclusions:

• The cytoplasm is a critical target for low-dose radiation damage in healthy cells.
• Cellular structures beyond the nucleus, like cytoplasm and organelles, warrant further investigation for radiation effects.
• Findings are relevant for understanding radiation damage in healthy cells with small nuclei.