Small-field measurements in 3D polymer gel dosimetry using optical computed tomography

Area of Science:

• Medical Physics
• Radiation Dosimetry
• Image Processing

Background:

• Polymer gel dosimetry offers 3D dose measurement capabilities.
• Accurate field output factor calculation is crucial in radiation therapy.

Purpose of the Study:

• To evaluate polymer gel-optical CT for accurate dose-response assessment.
• To validate scatter correction methods for precise field output factor determination.
• To assess the system's suitability for small-field dosimetry.

Main Methods:

• Dose-response characteristics were measured using an optical CT system.
• Scatter correction was applied to polymer gel-optical CT images.
• A four-finger gel phantom was irradiated and scanned.
• Field output factors were calculated and compared with ionization chamber measurements.

Main Results:

• Dose-response was characterized within the 0-10 Gy range using a fitting model.
• Scatter correction improved low-intensity signal detection in optical CT images.
• The polymer gel-optical CT system demonstrated suitability for small-field output factor calculations.

Conclusions:

• Polymer gel-optical CT is a viable method for 3D radiation dosimetry.
• The evaluated system provides accurate field output factors, particularly for small fields.
• This technique enhances precision in radiation therapy dosimetry.