COMPARISON OF RESPONSE OF PASSIVE DOSIMETRY SYSTEMS IN SCANNING PROTON RADIOTHERAPY-A STUDY USING PAEDIATRIC...

Area of Science:

• Medical Physics
• Radiation Oncology
• Dosimetry

Background:

• Proton beam therapy offers advantages over photon radiotherapy, including precise dose delivery and sparing of healthy tissues.
• This is particularly crucial for pediatric cancer patients and tumors near critical organs.
• Proton interactions generate secondary radiation (neutrons, gamma rays), necessitating accurate dosimetry in mixed fields.

Purpose of the Study:

• To compare the performance of various passive dosimetry systems in a mixed radiation field.
• To assess dose measurements in anthropomorphic phantoms simulating pediatric patients (5 and 10 years old).
• To evaluate dosimetry for proton pencil beam scanning techniques in a pediatric context.

Main Methods:

• Irradiation of anthropomorphic phantoms using a proton pencil beam.
• Dose measurements in various organs using thermoluminescent dosimeters (MTS-7, MTS-6, MCP-N), radiophotoluminescent dosimeters (GD-352 M, GD-302M), bubble detectors, and PADC track detectors.
• Comparison of detector responses in the mixed neutron and gamma radiation field.

Main Results:

• Radiophotoluminescent (RPL) detectors demonstrated lower sensitivity to neutrons compared to LiF thermoluminescent dosimeters (TLDs).
• RPL detectors are suitable for measuring the gamma component of the dose within phantoms.
• Neutron doses measured by track detectors, bubble detectors, and MTS-7/MTS-6 pairs were consistent within uncertainty.

Conclusions:

• The study provides crucial data on dosimetry system performance in pediatric proton therapy scenarios.
• RPL detectors offer a viable option for assessing gamma radiation contributions in mixed fields.
• This research is the first to conduct such measurements on child anthropomorphic phantoms using pencil scanning proton beams.