A sector-integration method for dose/MU calculation in a uniform scanning proton beam.

Area of Science:

• Medical Physics
• Radiation Oncology
• Proton Therapy

Background:

• Accurate dose calculation is crucial for effective proton therapy.
• Existing methods may be time-consuming or lack precision.
• Proton therapy utilizes unique beam characteristics for precise dose delivery.

Purpose of the Study:

• To develop and validate a simple, time-saving sector integration method for calculating proton dose per monitor unit (MU).
• To assess the accuracy and stability of the proposed calculation model across various clinical parameters.

Main Methods:

• A sector integration model was developed using treatment field parameters: aperture shape, size, measuring position, beam range, and modulation.
• The model was validated against 431 previously measured dose/MU values in a uniform scanning proton beam.
• Measurements were performed in a water phantom using a parallel plate ionization chamber at various depths and spread-out Bragg peak (SOBP) extents.

Main Results:

• The developed model demonstrated high accuracy, with calculation errors ranging from -2.4% to 3.3%.
• 99% of the calculated dose/MU values had errors less than +/-2%.
• Accuracy improved with higher energy, larger SOBP, and bigger aperture sizes, with an average error of 0.31 +/- 0.96% for small fields.

Conclusions:

• The proposed sector integration method provides an accurate, simple, and time-saving approach for proton dose/MU calculations.
• The model's performance is reliable across a range of clinical scenarios, enhancing treatment planning efficiency.
• This method has the potential to improve the precision and efficiency of proton therapy delivery.