Clinic based transfer of the N(D,W)(60Co) calibration coefficient using a linear accelerator

Area of Science:

• Medical Physics
• Radiation Dosimetry
• Radiotherapy Physics

Background:

• Reference dosimetry relies on secondary standard ionization chambers with traceable calibration coefficients.
• Traditionally, 60Co beams were used for transferring these coefficients, but access is declining.
• Clinic-based physicists need alternative methods for accurate dosimetry calibration.

Purpose of the Study:

• To investigate the accuracy of transferring the absorbed dose to water calibration coefficient N(D,W)(60Co) using 6 and 18 MV photon beams from a linear accelerator.
• To assess the feasibility of these alternative methods as a replacement for 60Co beams in clinical settings.

Main Methods:

• Investigated five different experimental setups for calibration coefficient transfer.
• Utilized four commonly used ionization chamber types for the study.
• Employed 6 and 18 MV photon beams from a linear accelerator for cross-calibration.

Main Results:

• The study evaluated the accuracy of alternative calibration transfer methods.
• Results indicate the viability of using linear accelerator photon beams for coefficient transfer.
• Performance was assessed across various setups and chamber types.

Conclusions:

• Alternative methods using linear accelerator photon beams are accurate for transferring N(D,W)(60Co) calibration coefficients.
• These methods offer a practical solution for clinic-based physicists facing limited access to 60Co sources.
• The findings support the adoption of these techniques for maintaining high standards in medical dosimetry.