Charged photoparticle production in tissue during radiotherapy

Area of Science:

• Medical physics
• Radiation biology
• Nuclear physics

Background:

• Understanding photon interactions in biological tissues is crucial for radiation therapy and diagnostics.
• Quantifying particle emission (protons, alpha particles, neutrons) is essential for accurate dose calculations.
• Previous methods established by the authors provide a basis for current estimations.

Purpose of the Study:

• To estimate photon-induced proton and alpha particle production in tissue.
• To compare charged particle emission with neutron emission across a specific photon energy range.
• To analyze the energy-dependent relationship between charged particle and neutron yields.

Main Methods:

• Utilized previously established methods for estimating photonuclear reactions.
• Focused on photon energy range from 3 to 28 MeV.
• Calculated yields of protons, alpha particles, and neutrons.

Main Results:

• Charged particle emission exceeds neutron emission for photon energies above 11 MeV.
• The ratio of charged particle to neutron emission reaches a maximum of 7.0 at 17 MeV.
• Above 17 MeV, neutron yield increases sharply, reducing the charged particle to neutron emission ratio.

Conclusions:

• Charged particle production is significant in photon-irradiated tissue, particularly at intermediate energies.
• The relative contributions of charged particles and neutrons change markedly with photon energy.
• These findings have implications for radiation dosimetry and understanding biological effects.