====== Dose Calculation Algorithms ======

===== Overview =====

The decimal eRT software application uses the Pencil Beam Redefinition Algorithm (PBRA) as primary means of computing electron beam dose. This is a semi-analytical model that combines pencil beam theory with a localized electron transport process to create a fast and accurate dose calculation. Many published references exist in the literature for this algorithm, including:
1. FIXME REFERENCE 1 
2. FIXME REFERENCE 2
3. FIXME REFERENCE 3

While the PBRA is well described in the literature, as shown above, a basic description is also provided herein, to allow users to develop a more complete understanding of the eRT software and the commissioning data it uses.

===== Pencil Beam Redefinition Algorithm =====

FIXME Details of the PBRA here

Include: details regarding (at a minimum): the handling of tissue
heterogeneities, the mathematical equations forming the basis of the calculations, the limits of the variables used in these equations, and a statement of accuracy (with results) for a pre-dened set of dose calculation conditions (with a full description of said conditions).


===== Data Regularization (Interpolation) =====

FIXME Describe the process of moving from the PBRA dose aligned grid to the DICOM regular grid.

===== Out of Bounds (Extrapolation) =====

FIXME Describe when and how eRT extrapolates data in regards to beam models and dose calculations.

===== Dose Volume Histogram (DVH) Calculation =====

FIXME Ensure that the User Guide contains information describing the interpolation and extrapolation techniques and their usage within the context of dose calculation, DVH computation, and data exporting.