Multi-parametric Improvements in the CCD Camera-based EPID for Portal Dosimetry

Area of Science:

• Medical Physics
• Radiation Oncology
• Imaging Technology

Background:

• Electronic portal imaging devices (EPIDs) are advancing radiation therapy verification.
• Thorough dosimetric characterization of EPIDs is crucial before clinical implementation.

Purpose of the Study:

• To evaluate the dosimetric properties of the Theraview camera-based EPID with a cooled CCD.
• To assess its suitability for portal dosimetry applications.

Main Methods:

• Investigated dose response, warm-up behavior, and short/long-term stability.
• Measured field size dependency and compared with ion chamber data.
• Evaluated performance for 6 and 15 MV photon beams.

Main Results:

• Linear dose response up to 2 Gy for both beam qualities.
• No significant warm-up effect observed.
• Excellent short-term stability (SD 0.38%) and negligible long-term decline (0.01%/day).

Conclusions:

• The cooled CCD camera-based EPID demonstrates promising dosimetric capabilities.
• It can be utilized for portal dosimetry after applying corrections for field size dependency and sensitivity loss.