Dose distribution depending on the number of control points in forward-planned intensity-modulated radiation therapy for breast cancer

Abstract

Dose uniformity was estimated depending on the number of control points in forward-planned intensity-modulated radiation therapy for breast cancer. Data were obtained from four patients who had undergone left-sided breast conserving surgery. Five plans for each patient were designed depending on the size of dose clouds to be blocked. To evaluate the effect of the technique on dose uniformity maximum dose, conformity index, and percent volume of the breast more than 95% of the prescription dose were calculated. Although there is no clinical difference between segmented field-in-field technique and control points field-in-field technique, dose distribution in a plan did not depend on the only number of control points, but also depend on the breast size and the shape after the breast surgery. To acquire simple and reasonable monitor units for each control point, minimum 3 MUs are needed. © 2009 Springer-Verlag.