Highly conformal nature of prostate CyberKnife treatment

This figure illustrates the highly conformal nature of the prostate CyberKnife treatment approach, with the yellow prescription dose line wrapping tightly around the intended target volume (illustrated by the outer green line), while sparing the rectum directly behind the prostate (illustrated by the outer orange line). Additional CyberKnife customization features shown here include "hyperdosage" within the white dose lines, designed to further increase the dose to suspicious areas indicated on prostate MRI (semi-transparent red areas inside the light blue lines), with a small "hole" in the presctiption dose line centrally (yellow), to limit the urethra dose (inner small green circle is the urethra). The principles illustrated in this figure are similar to the principles illustrated in the prostate IGRT/IMRT section, but the dose gradients are sharper and the treatment is delivered with sub-millimeter precision, making this an appropriate method for patients with the highest probability of prostate-confined disease.