Wide area surface dosimetry with conformal scintillator array for external beam radiotherapy.

Area of Science:

• Medical Physics
• Radiotherapy Technology
• Dosimetry

Background:

• In vivo dosimetry is crucial for radiotherapy verification but faces challenges with current methods.
• Limitations include logistical issues, accuracy, temporal resolution, and handling non-uniform patient anatomy.
• Optical scintillation imaging presents a potential solution to these dosimetry challenges.

Purpose of the Study:

• To characterize a conformable scintillator array for real-time surface dose imaging in photon external beam radiotherapy.
• To evaluate dose, angular deviation, repetition rate, and field geometry variability.
• To assess performance in field edge detection and measurement reproducibility using an anthropomorphic phantom.

Main Methods:

• A modular scintillator array with 101 hexagonal elements was employed.
• A dual-camera stereovision system facilitated 3D localization; a Cherenkov imaging system detected optical scintillation.
• Characterization included water equivalent thickness, dose linearity, repetition rate stability, and angular dependence; field edge detection was compared to radiochromic film.

Main Results:

• The scintillator array showed high dose linearity (R²=0.999) and minimal beam perturbation (1.21 mm water equivalent thickness).
• Consistent response within 5% was observed across all LINAC repetition rates and clinically relevant gantry angles (0°-75°).
• Field edge detection achieved 99.98% gamma pass rate (3%/3 mm) compared to film, with inter-delivery reproducibility of ±1 cGy.

Conclusions:

• The conformable scintillator array enables spatially resolved, dynamic surface dosimetry with minimal workflow disruption.
• It addresses key limitations of current in vivo dosimetry by mapping dose on complex surfaces with angular correction.
• This technology shows promise for clinical integration in radiotherapy, especially for treatments requiring wide-area surface dosimetry.