[Method for estimating 4 MV X-ray irregular field dose using the collimator scatter factor (Sc) and phantom scatter...

Area of Science:

• Medical Physics
• Radiotherapy Physics
• Radiation Dosimetry

Context:

• Accurate dose calculation is crucial for effective radiotherapy.
• Irregular radiation fields, often generated by multi-leaf collimators (MLCs), pose challenges in dose calculation.
• Existing methods require precise evaluation of scatter factors.

Purpose:

• To investigate accurate methods for calculating in-air and in-water doses for 4 MV X-ray irregular fields.
• To evaluate the effectiveness of the collimator scatter factor (S(c)) and phantom scatter factor (S(p)) concepts for irregular fields.
• To refine dose calculation algorithms using the S(c)-Clarkson and S(p)-Clarkson integration methods.

Summary:

• The S(c)-Clarkson integration method provides a straightforward approach for calculating equivalent square fields of MLC-defined irregular fields.
• Introduction of a small segment correction (SSC) factor improves the accuracy of S(c) evaluation for smaller MLC fields.
• The F(MLC) factor enables precise evaluation of S(p) and tissue-phantom ratio (TPR) when the MLC field size is significantly smaller than the main collimator field.

Impact:

• Enhances the accuracy of radiation dose calculations in radiotherapy, particularly for complex irregular fields.
• Provides a more robust and simpler method for physicists to determine dose distributions.
• Contributes to improved treatment planning and delivery, potentially leading to better patient outcomes.