Initial testing of a pixelated silicon detector prototype in proton therapy

Area of Science:

• Medical Physics
• Radiation Oncology
• Detector Technology

Background:

• Advancements in radiation therapy require dosimetry tools with higher spatial resolution for small targets.
• Current dosimetry methods need to evolve to meet the demands of precise radiation delivery.
• Proton therapy offers conformal treatment but necessitates accurate real-time dosimetry for small fields.

Purpose of the Study:

• To evaluate the performance of the dose magnifying glass (DMG) detector prototype for proton radiation dosimetry.
• To assess the DMG's capabilities in measuring depth dose and lateral beam profiles in proton beams used for radiosurgery.
• To compare DMG measurements with established dosimetry methods and Monte Carlo simulations.

Main Methods:

• The DMG, a pixelated silicon detector, was tested using proton beams with energies and modulations typical for proton radiosurgery.
• Depth dose profiles and lateral beam profiles were measured using the DMG.
• Measurements were compared against a PTW parallel-plate ionization chamber, a PTW proton-specific dosimetry diode, EBT3 Gafchromic film, and Monte Carlo simulations.

Main Results:

• The DMG demonstrated good agreement with Monte Carlo simulations, ionization chamber, and diode measurements for depth dose profiles.
• Accurate Bragg peak location was determined by scanning the depth dose profile with the DMG.
• Relative response of the DMG was within 2.5% of the dosimetry diode across tested proton energies and modulations.
• Real-time lateral profile measurements showed high spatial resolution, with FWHM and FW90 within ±1 channel (0.1 mm) of reference data.

Conclusions:

• The DMG is a valuable tool for real-time dosimetry in proton therapy, providing accurate depth dose profiles.
• Its stable response across the spread-out Bragg peak and high spatial resolution enable precise 1D profile measurements of small radiation fields.
• The detector minimizes partial volume averaging effects, enhancing accuracy in small-field dosimetry.