A method to relate StarTrack(®) measurements to R50 variations in clinical linacs.

Area of Science:

• Medical Physics
• Radiation Oncology
• Quality Assurance

Background:

• The relationship between daily clinical linear accelerator (linac) monitoring data and reference magnitudes can be unclear.
• Accurate monitoring of beam quality indices, such as R50, is crucial for patient safety and treatment efficacy.

Purpose of the Study:

• To develop an experimental method correlating StarTrack® output data with the R50 beam quality index.
• To establish a reliable approach for monitoring R50 using daily quality control data from StarTrack®.

Main Methods:

• Electron beam energy stability was experimentally linked to the R50 index by varying the bending magnet current.
• StarTrack® output and R50 values (from water phantom depth dose measurements) were recorded for different magnet currents.
• Linear regression analysis was used to identify the optimal StarTrack® output for R50 estimation at specific beam energies.

Main Results:

• A good linear correlation was observed between StarTrack® output data and R50 values.
• The developed method allows for the direct monitoring of R50 using daily quality control data from the StarTrack® device.
• The methodology is applicable to similar devices where the control variable lacks linear behavior with R50.

Conclusions:

• A practical methodology has been established for monitoring the R50 beam quality index during daily linac quality control.
• This approach enhances the reliability of quality assurance by directly utilizing routine StarTrack® measurements.
• The findings support the adaptation of this method for similar quality control devices.