Quantitative megavoltage radiation therapy dosimetry using the storage phosphor KCl: Eu2+

Area of Science:

• Medical Physics
• Radiation Dosimetry
• Materials Science

Background:

• Europium-doped potassium chloride (KCl:Eu2+) is explored as a storage phosphor for radiation dosimetry.
• It operates via photostimulated luminescence (PSL), similar to existing computed radiography (CR) materials.
• KCl:Eu2+ possesses a lower effective atomic number, suggesting near tissue equivalence.

Purpose of the Study:

• To evaluate KCl:Eu2+ storage phosphors for quantitative megavoltage radiation therapy dosimetry.
• To assess key dosimetric properties of fabricated KCl:Eu2+ dosimeters.

Main Methods:

• Fabrication of cylindrical KCl:Eu2+ dosimeters (7 mm diameter, 1 mm thick).
• Irradiation using a linear accelerator.
• Measurement of dosimetric properties using a laboratory optical reader.
• Evaluation of radiation hardness, linearity, fading, dose rate, and energy dependence.

Main Results:

• KCl:Eu2+ demonstrated satisfactory radiation hardness, reusable over 100 times (assuming 2 Gy/use).
• A supralinear dose response was observed from 0 to 800 cGy.
• PSL signal fading was approximately 0.1%/h after 12 hours.
• Dosimeter sensitivity was independent of dose rate (15-1000 cGy/min) and beam energy.
• Over-response to low-energy photons was reduced using lead foil filters.

Conclusions:

• KCl:Eu2+ storage phosphors exhibit desirable characteristics for radiation therapy dosimetry.
• Potential for development into reusable, quantitative, high-resolution 2D dosimeters with minimal energy dependence.