Dynamic wedge factors for a comprehensive range of fields

Area of Science:

• Medical Physics
• Radiation Oncology
• Radiotherapy Physics

Background:

• Accurate modeling of wedge factors is crucial for precise dose delivery in radiotherapy.
• Dynamic wedges offer flexibility but require careful characterization, especially for non-standard field shapes.

Purpose of the Study:

• To assess methods for modeling wedge factors for dynamic wedges across various field elongations.
• To evaluate the accuracy of equivalent square methods (Worthley, Arthur) for dynamic wedge factor calculation in rectangular fields.

Main Methods:

• Experimental measurements of dynamic wedge factors using a Varian 600C linear accelerator.
• Investigation of dynamic wedge angles (15°, 30°, 45°, 60°) for square and rectangular fields.
• Comparison of measured factors with those derived from Worthley and Arthur equivalent square models.

Main Results:

• Dynamic wedge factors are predominantly dependent on field size along the wedged direction.
• Field elongation in the non-wedged axis showed negligible impact on dynamic wedge factors.
• The Worthley and Arthur models resulted in significantly less accurate wedge factors for most elongated fields.

Conclusions:

• The most reliable method for deriving dynamic wedge factors for rectangular fields is based on a square field with a side equal to the dimension in the wedged axis.
• Equivalent square modeling approaches (Worthley, Arthur) are not suitable for improving dynamic wedge factor accuracy in elongated fields.