Dose reconstruction for intensity-modulated radiation therapy using a non-iterative method and portal dose image

Area of Science:

• Medical Physics
• Radiation Oncology
• Computational Imaging

Background:

• Intensity-modulated radiation therapy (IMRT) requires accurate dose verification.
• Existing dose reconstruction methods can be complex and iterative.
• Electronic portal imaging devices (EPIDs) offer a means for in-vivo dosimetry.

Purpose of the Study:

• To develop and validate a straightforward, non-iterative computational method for IMRT dose verification and reconstruction.
• To establish a method utilizing dose response functions derived from Monte Carlo simulations and EPID measurements.
• To experimentally validate the developed algorithm for open and IMRT fields.

Main Methods:

• A computational algorithm was developed based on the linear relationship between beamlets and dose-scoring voxels.
• Dose response functions were quantified using Monte Carlo (MC) particle transport techniques.
• In-phantom and exit film dosimetry were performed, with the algorithm used to reconstruct in-phantom dose from EPID measurements.

Main Results:

• The algorithm successfully reconstructed in-phantom doses from EPID measurements.
• Experimental validation demonstrated a dose comparison pass rate exceeding 90% for all fields, within 3% dose difference and 3 mm distance to agreement.
• The non-iterative nature of the algorithm simplifies the dose reconstruction process.

Conclusions:

• The developed computational method provides a straightforward and accurate approach for IMRT dose verification and reconstruction.
• This non-iterative algorithm, validated experimentally, shows significant promise for clinical application in radiation therapy quality assurance.
• The use of MC-derived dose response functions combined with EPID measurements offers a robust solution for patient-specific dose assessment.