Dosimetric validation for multileaf collimator-based intensity-modulated radiotherapy: a review.

Area of Science:

• Medical Physics
• Radiation Oncology
• Radiotherapy Technology

Background:

• Intensity-modulated radiotherapy (IMRT) enables complex dose distributions.
• Accurate dose delivery relies on precise planning systems and mechanical devices.
• Ensuring agreement between calculated and delivered doses is critical due to potential inaccuracies.

Purpose of the Study:

• To review the current status of validating IMRT dose predictions against measurements.
• To emphasize multileaf collimator (MLC)-based IMRT validation.
• To discuss factors influencing dosimetry and achievable accuracy.

Main Methods:

• Comparison of calculated dose distributions with measurements.
• Analysis of discrepancies arising from dose calculation algorithms, measurement uncertainties, or beam delivery errors.
• Evaluation of various dosimeters (film, ion chambers, TLD, EPID) and measurement techniques.

Main Results:

• Discrepancies can stem from calculation algorithms, measurement errors, or MLC/accelerator delivery inaccuracies.
• Factors like fluence modulation technique, MLC characteristics (leakage, leaf shape), and dosimeter choice significantly impact results.
• Validation involves specific field measurements, phantom use, and defined measurement techniques.

Conclusions:

• Rigorous dosimetric validation of IMRT planning systems is essential.
• Understanding and mitigating sources of error in calculation, measurement, and delivery are key to achieving accurate IMRT.
• The review outlines practical steps and considerations for comprehensive IMRT dosimetry validation.