Assessment of FLASH Radiation Doses Using Polycrystalline Alanine Powder as a Passive Dosimeter

Area of Science:

• Medical Physics
• Radiation Oncology
• Dosimetry

Background:

• FLASH radiation therapy offers potential benefits for cancer treatment by reducing normal tissue toxicity.
• Conventional dosimetry methods face challenges at the ultra-high dose rates characteristic of FLASH therapy.
• Alanine dosimetry is a dose-rate independent and tissue-equivalent method suitable for high-dose measurements.

Purpose of the Study:

• To evaluate the effectiveness of alanine powder as a dosimeter for FLASH radiation therapy.
• To establish a reliable calibration and validation method for alanine powder in this context.

Main Methods:

• Irradiation of thirteen alanine powder dosimeters with doses ranging from 10 to 100 Gy using a 137Cs source.
• Construction of dose-response calibration curves using six samples and validation with the remaining seven.
• Normalization of electron paramagnetic resonance signal amplitudes using internal standards and sample density.

Main Results:

• Density-normalized dose estimates achieved accuracy within ±4.2% of expected values.
• The dose-response relationship exhibited strong linearity (R2 > 0.99).
• The method demonstrated clinical viability for FLASH dosimetry applications.

Conclusions:

• Alanine powder dosimeters are a viable and reliable tool for measuring high doses in FLASH radiation therapy.
• The technique provides accurate, dose-rate-independent measurements essential for this modality.
• Further optimization of post-processing time is needed, but alanine powder shows significant potential for FLASH dosimetry.