Miniature scintillating detector for small field radiation therapy.

Area of Science:

• Medical Physics
• Radiotherapy Physics
• Radiation Detection

Background:

• Conventional detectors struggle with accurate measurements for stereotactic radiosurgery (SRS) due to lateral electronic disequilibrium and volume averaging.
• Obtaining precise depth dose curves and beam profiles is critical for effective SRS treatment planning.

Purpose of the Study:

• To develop and evaluate a novel miniature scintillating detector for improved SRS dosimetry.
• To overcome the limitations of conventional detectors in measuring SRS beam characteristics.

Main Methods:

• A miniature dosimeter was designed using radiation-resistant silica optical fibers, silicon photodiodes, and a polystyrene scintillator.
• A reference fiber without scintillator was used to subtract Cerenkov light contributions.
• The detector's sensitive volume was designed to be nearly water-equivalent to minimize dose perturbation.

Main Results:

• The scintillating detector demonstrated high spatial resolution comparable to film-densitometry systems.
• Measurements of a 6 MV photon beam profile showed excellent agreement with film-densitometry.
• The detector achieved a nearly water-equivalent sensitive volume, minimizing perturbation in dose distributions.

Conclusions:

• The developed miniature scintillating detector is a reliable and accurate tool for SRS dosimetry.
• It overcomes key limitations of conventional detectors, enabling precise measurement of beam profiles and depth dose curves.
• The use of photodiodes enhances stability and allows for absolute dosimetry, advancing SRS treatment planning.