A pencil beam model for photon dose calculation

Area of Science:

• Medical Physics
• Radiation Oncology
• Computational Biology

Background:

• Accurate photon dose calculation is crucial for effective 3D radiotherapy planning.
• Existing methods may face limitations with complex radiation fields and heterogeneous patient tissues.

Purpose of the Study:

• To present a novel, efficient method for photon dose calculation in 3D radiotherapy planning.
• To develop an algorithm capable of handling irregularly shaped radiation fields and heterogeneous patient anatomy.
• To ensure the method's accuracy by comparing it with established techniques and experimental data.

Main Methods:

• Utilized pencil beam energy deposition kernels for dose calculation.
• Developed a point-oriented, semianalytical integration method based on field triangulation.
• Derived analytical pencil beam kernels from Monte Carlo simulations and water phantom measurements.
• Incorporated a scatter correction factor for heterogeneous media using monodirectional convolution.

Main Results:

• The proposed method is faster than full 3D convolution algorithms.
• Photon therapy beams were characterized with high accuracy.
• Dose calculations were validated against measurements in homogeneous media and Monte Carlo/Batho methods in heterogeneous media.
• The method facilitates output factor calculation by normalizing dose to incident energy fluence.

Conclusions:

• The presented method offers an accurate and efficient approach for photon dose calculation in 3D radiotherapy.
• It effectively addresses the challenges posed by irregular radiation fields and heterogeneous patient tissues.
• This technique holds significant potential for enhancing the precision and speed of radiotherapy treatment planning.