A method for patient-specific DVH verification using a high-sampling-rate log file in an Elekta linac

Area of Science:

• Medical Physics
• Radiation Oncology
• Radiotherapy Quality Assurance

Background:

• Patient-specific quality assurance is crucial in radiotherapy.
• Verifying dose-volume histogram (DVH) parameters ensures treatment accuracy.
• Current methods can be complex and time-consuming.

Purpose of the Study:

• To propose and validate a novel method for patient-specific DVH verification.
• To utilize high-sampling-rate log files (HLF) from Elekta linacs for this purpose.
• To assess the accuracy and sensitivity of the proposed method in detecting systematic leaf position errors.

Main Methods:

• Ten prostate volumetric-modulated arc therapy plans were modified with systematic leaf position errors (±0.2 to ±0.8 mm).
• A high-sampling-rate log file (HLF) was used to create a treatment planning system-compatible file.
• HLF-based isocenter dose calculations were compared to phantom measurements; PTV D95 was compared between HLF-based and theory-based plans.

Main Results:

• The relative difference in isocenter doses between HLF-based calculations and measurements was 0.21% ± 0.67%.
• Maximum relative differences in PTV D95 between HLF-based and theory-based plans were 0.11%.
• The method detected target DVH parameter changes <1% with a ±0.2 mm systematic leaf position error.

Conclusions:

• The proposed HLF-based DVH verification method is accurate and sensitive.
• It simplifies patient-specific dose quality assurance procedures.
• This method offers a potential improvement for radiotherapy quality assurance without compromising accuracy.