A correction method for diamond detector signal dependence with proton energy

Area of Science:

• Medical Physics
• Radiation Oncology
• Detector Physics

Background:

• Solid-state detectors are crucial for radiotherapy proton beam dosimetry and quality control.
• A significant challenge is the calibration of these detectors, particularly for ophthalmologic proton beams, due to their Linear Energy Transfer (LET)-dependent signal.

Purpose of the Study:

• To develop and validate a method for calibrating a PTW diamond detector for 62 MeV proton beams, accounting for LET dependence.
• To establish the diamond detector as a reliable on-line reference dosimeter for quality control procedures where ionization chambers are less practical.

Main Methods:

• Selected a PTW diamond detector for its signal reproducibility and dose stability.
• Developed an empirical correction factor, kDD(Eo) (Rres), based on the residual range quality index to correct the LET-dependent signal.
• Utilized dedicated software for on-line dosimetry applications.
• Compared the proton energy response of silicon, diamond, and radiochromic film detectors.

Main Results:

• An empirical correction factor was determined to accurately correct the diamond detector signal for LET dependence at 62 MeV.
• The PTW diamond detector demonstrated good signal reproducibility (0.3%) and stable response.
• A comparison revealed differences in signal dependence on proton energy among silicon, diamond, and radiochromic film detectors.

Conclusions:

• The proposed method effectively addresses the LET dependence of diamond detectors in proton beam dosimetry.
• The calibrated diamond detector can serve as a valuable on-line reference dosimeter for quality control in radiotherapy.
• This work contributes to improved accuracy and reliability in proton beam dosimetry, especially for specialized applications.