Linac-integrated kV-cone beam CT polymer gel dosimetry

Area of Science:

• Medical Physics
• Radiation Oncology
• Dosimetry

Background:

• X-ray CT polymer gel dosimetry (PGD) is a key technology for 3D verification of high-dose radiation deliveries.
• Linac-integrated cone beam CT (LI-CBCT) imaging of PGDs has emerged as a promising advancement.
• LI-CBCT offers real-time imaging and eliminates spatial errors from dosimeter repositioning.

Purpose of the Study:

• To establish the dosimetric properties and critical parameters for cone beam PGD using LI-CBCT.
• To evaluate the feasibility of LI-CBCT PGD for complex, high-dose radiation delivery verification.

Main Methods:

• Investigated dosimetric characteristics and critical parameters for LI-CBCT PGD.
• Analyzed polymerization yield recovery at 20-30 min post-irradiation.
• Assessed gamma pass rates using image averaging and outlier elimination techniques.

Main Results:

• Imaging 20-30 min post-irradiation achieved >90% recovery of maximum polymerization yield.
• Approximately 10 image averages yielded ~90% gamma pass rates (3%, 3 mm) compared to treatment planning.
• Eliminating outlier averaging points improved image precision and signal-to-noise ratio.

Conclusions:

• LI-CBCT PGD, with appropriate methodology, can accurately verify complex 3D high-dose radiation deliveries.
• This technique shows potential for commissioning and validating novel, complex radiation treatments.
• LI-CBCT PGD provides a robust tool for ensuring the accuracy and safety of advanced radiotherapy.