Fourier-based dose calculation in radiation brachytherapy

Proposes an accurate and computationally-efficient method for dose calculation in three-dimensional brachytherapy. The proposed method incorporates the nonideal radiation pattern of a source in the spatial domain. When a radiating source transmits energy into a medium, the distribution of the resultant energy in the spatial domain is called the source´s radiation pattern. The radiation pattern of a nonideal source can be accurately determined by integrating an infinite number of differential ideal sources (point sources) which make up the nonideal source. This approach also yields an analytical solution for the Fourier spectrum of a nonideal source´s radiation pattern. Unlike the current Fourier-based convolution methods which are used for dose calculation in brachytherapy, the proposed method exploits the Fourier decomposition of the source´s radiation pattern to avoid the calculation of the nonideal dose function in the spatial domain. For this purpose, the source-patient interaction is modeled as a multidimensional convolution. Then, the Fourier theorem for convolution is applied to accelerate the computation of the dose distribution