MEASUREMENT OF SECONDARY NEUTRONS GENERATED DURING PROTON THERAPY.

Area of Science:

• Medical Physics
• Radiation Dosimetry
• Nuclear Engineering

Background:

• Proton therapy offers precise radiation delivery but can generate secondary neutrons.
• Understanding neutron radiation is vital for patient safety and treatment optimization.
• Secondary neutrons pose a potential risk to patients and medical staff.

Purpose of the Study:

• To evaluate patient exposure risks to secondary neutrons during proton therapy.
• To quantify neutron spectral fluences generated by phantoms and range shifters.
• To determine the contribution of treatment components to neutron production.

Main Methods:

• Utilized an extended Bonner sphere spectrometer (EBS) for neutron spectral fluence measurements.
• Employed passive thermoluminescent detectors (TLDs) with 6LiF and 7LiF chips.
• Conducted measurements behind a Nylon 6 phantom and near a range shifter irradiated with 200 MeV protons.

Main Results:

• Presented secondary neutron spectral fluences measured by the EBS.
• Quantified neutron generation from both the Nylon 6 phantom and the range shifter.
• Calculated effective dose values derived from the measured neutron spectral fluences.

Conclusions:

• Provided essential data for assessing secondary neutron risks in proton therapy.
• Highlighted the role of phantoms and range shifters in neutron production.
• Contributed to improving radiation safety protocols in proton therapy centers.