The DOSIMAP, a high spatial resolution tissue equivalent 2D dosimeter for LINAC QA and IMRT verification

Area of Science:

• Medical Physics
• Radiation Oncology
• Dosimetry

Background:

• Accurate radiation therapy requires high spatial resolution and dose accuracy.
• Intensity Modulated Radiation Therapy (IMRT) demands precise monitoring of multileaf collimator positions due to high spatial gradients.

Purpose of the Study:

• To develop and present a novel 2D tissue-equivalent dosimeter with high spatial resolution.
• To enable precise, real-time dose mapping for advanced radiation therapy techniques like IMRT.

Main Methods:

• A 2D tissue-equivalent dosimeter using a plastic scintillator sheet between polystyrene blocks.
• A high-resolution camera captures emitted light, with a new procedure distinguishing scintillation from Cerenkov radiation.
• Image processing of sequential images (10/s) provides quasi-real-time dose mapping.

Main Results:

• The dosimeter is tissue-equivalent (ICRU-44) and functional for both electrons and photons without complex adjustments.
• Calibration is simple and independent of irradiation conditions.
• Measurements show excellent spatial resolution, accuracy, and repeatability, validated against ionization chambers and treatment planning system simulations.

Conclusions:

• The developed dosimeter provides high-resolution, quasi-real-time dose mapping.
• It is suitable for quality assurance in IMRT, effectively inspecting multileaf positions and dose delivery accuracy.