Research Article

Lateral Penumbra Modelling Based Leaf End Shape Optimization for Multileaf Collimator in Radiotherapy

Table 1

Leaf end parameterization and design variables.

TypeParametric curvesDesign variables

Circular arc
R: radius of circular arc 
d: arc centre offset

Elliptical arc
a: semimajor axis 
b: semiminor axis

Bézier curve, 

,

B-spline



, 

Bernstein basis polynomial of Bézier curve is denoted by .
B-spline is a piecewise polynomial function of degree k, which is defined by control points and knots . Coefficient is obtained by recurrence relation.