REDUCING STRAY RADIATION DOSE FOR A PEDIATRIC PATIENT RECEIVING PROTON CRANIOSPINAL IRRADIATION

Area of Science:

• Medical Physics
• Radiation Oncology
• Pediatric Oncology

Background:

• Proton therapy is an advanced cancer treatment, but stray neutron radiation poses a risk, especially for pediatric patients undergoing craniospinal irradiation.
• Quantifying and mitigating this stray radiation is crucial for patient safety and treatment efficacy.

Purpose of the Study:

• To quantify neutron radiation dose from a proton treatment unit during craniospinal irradiation for a pediatric patient.
• To evaluate the effectiveness of nozzle modifications in reducing stray radiation dose.

Main Methods:

• Monte Carlo simulations were used to estimate organ equivalent doses and effective dose from stray radiation.
• Simulations utilized a passive scattering proton treatment unit and a voxelized anatomy model of a 10-year-old male patient.
• Stray radiation was assessed for a standard nozzle and a modified nozzle with enhanced shielding and increased source-to-patient distance.

Main Results:

• The effective dose from stray radiation with the standard nozzle was estimated at 322 mSv.
• Modifications to the nozzle reduced the effective dose by as much as 43%.
• Local shielding enhancements and increased distance were key factors in dose reduction.

Conclusions:

• Modest enhancements to proton treatment units can significantly reduce effective stray neutron radiation dose.
• These findings support the implementation of improved shielding strategies in pediatric proton therapy.
• Reducing stray radiation is vital for minimizing long-term risks in pediatric cancer survivors.