A dose texture plot in a moving frame as a new planning tool for single-plane implants in HDR brachytherapy

A dose-texture plot is a print of dose values on the points of interest in a super-plane. The super-plane is a moving frame across the treatment depth-surface(s) with a fixed distance from surgical bed. The moving frame has an axis tangent to the midline of two neighboring catheters and the other axis perpendicular to the midline. By setting the scales of the two axes in units of the dwell step-size and the local distance between the two catheters, we can easily locate the basal-dose points with pairs of integers. A dose-texture plot on the basal-dose points in the super-plane provides the dose and location information in one picture. Such a picture can concisely represent the dose distribution in the treatment depth and allows us to quickly and quantitatively evaluate the effect of the source-dwell times and positions. This treatment-planning-evaluation tool has been used for development of an iteration optimization algorithm. The results of the iteration optimization on clinical cases demonstrated significant improvements over the optimization algorithms used in a commercial planning system.