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08:34
Proton Therapy Delivery and Its Clinical Application in Select Solid Tumor Malignancies
Published on: February 6, 2019
Nuclear collision processes around the Bragg peak in proton therapy
Yuka Matsuzaki1, Hiroyuki Date, Kenneth Lee Sutherland
1Graduate School of Engineering, Hokkaido University, Kita-ku, Sapporo, Japan. matsuzak@pop.qe.eng.hokudai.ac.jp
Radiological Physics and Technology
|September 8, 2010
Summary
Proton therapy involves nuclear reactions in biomaterials, producing secondary particles. These particles, especially recoil protons, significantly contribute to the absorbed dose behind the Bragg peak.
Area of Science:
- Medical Physics
- Radiation Biology
- Nuclear Physics
Background:
- Proton interactions in biomaterials primarily transfer energy to electrons.
- Ionization and excitation are concentrated near the Bragg peak, where nuclear reactions also occur.
Purpose of the Study:
- Investigate energy deposition processes from proton and water molecule interactions, including nuclear reactions.
- Analyze particle production from nuclear reactions and charge-changing processes at low energies relevant to proton therapy.
Main Methods:
- Utilized Monte Carlo simulation to model proton interactions in water molecules.
- Focused on low-energy interactions (below 1 MeV) and charge-changing processes (below a few hundred keV).
- Evaluated the total absorbed dose and contributions from primary protons and secondary particles.
Main Results:
- Proton interactions generate neutrons, which produce recoil protons via elastic collisions with hydrogen.
- Around the Bragg peak, primary protons dominate the absorbed dose (80-90%), with secondary protons contributing 5-20%.
- Beyond the Bragg peak, secondary protons from (1)H(n, p) reactions contribute approximately 70% to the absorbed dose.
Conclusions:
- Nuclear reactions significantly influence dose distribution in proton therapy.
- Secondary protons become the dominant dose contributor posterior to the Bragg peak.
- Understanding these interactions is crucial for optimizing proton therapy treatment planning.
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