Response corrections for solid-state detectors in megavoltage photon dosimetry.

Area of Science:

• Medical Physics
• Radiation Dosimetry
• Solid-State Detectors

Background:

• Solid-state detectors (diodes, MOSFETs) are crucial for on-line dosimetry and stereotactic radiosurgery due to their sensitivity and stability.
• Departures from tissue equivalence in solid-state devices are significant at lower energies and with Compton scattered radiation, impacting accuracy.
• The Z-dependent photoelectric effect is a key factor influencing detector response in these scenarios.

Purpose of the Study:

• To develop a modified Burlin cavity theory for accurate dosimetry with solid-state detectors.
• To determine correction factors for diode detector measurements in 6 and 15 MV linear accelerator beams.
• To provide a basis for correcting diode measurements in routine dosimetry applications.

Main Methods:

• A modified Burlin cavity theory was developed, treating primary and scatter photon spectra separately.
• The modified theory was applied to calculate correction factors for diode detectors.
• Measurements were performed using 6 and 15 MV linear accelerator beams.

Main Results:

• Uncorrected diode measurements can overestimate dose at depth by up to 15% for a 6 MV beam.
• The proposed model predicts the dose measurement effects with an accuracy of within 1% for both 6 and 15 MV beams.
• The study quantifies the necessary corrections for diode detectors in specific clinical scenarios.

Conclusions:

• The modified Burlin cavity theory provides accurate corrections for solid-state diode dosimetry.
• This approach enhances the reliability of diode detectors in clinical radiation dosimetry, particularly for small field therapies.
• The findings support the routine use of corrected diode measurements for improved patient safety and treatment efficacy.