Experimental validation of a kilovoltage x-ray source model for computing imaging dose.

Area of Science:

• Medical Physics
• Radiological Imaging
• Radiation Dosimetry

Background:

• Accurate absorbed dose calculation is crucial for kilovoltage (kV) x-ray imaging and therapy.
• Existing methods for kV x-ray source characterization may require complex modeling.
• A simplified and validated approach is needed for reliable dose computation.

Purpose of the Study:

• To introduce and validate a simplified virtual point source model for kV x-ray sources.
• To develop a characterization method for computing absorbed dose from kV x-rays.
• To validate the accuracy of the proposed model and method using dose measurements.

Main Methods:

• A virtual point source model was created by characterizing spatial, spectral, and fluence distributions at the isocenter.
• In-air relative dose measurements and half-value layer measurements were used for characterization.
• The model was validated by comparing computed doses from the kVDoseCalc software to measurements in homogeneous and heterogeneous phantoms.

Main Results:

• The characterized beam qualities and spatial photon distributions align with literature values.
• Computed percent depth-dose curves showed agreement within 2% in homogeneous and 2.5% in heterogeneous phantoms.
• Transverse axis dose profiles demonstrated agreement within 2.5%-8% across different materials and beam qualities.

Conclusions:

• The proposed virtual point source model and characterization method accurately compute absorbed dose in phantoms.
• The method achieves dose computation within 2%-8% of measured values, depending on phantom and beam quality.
• Experimental validation supports the accuracy of the kVDoseCalc software for kV dose computation.