Israeli startup Convergent RNR has developed MercyBeam, to improve radiation therapy for patients. A patented lens collects most of the X-rays from any standard X-ray generator and focuses them at the tumor. It increases the therapeutic dose where it’s needed and not at surrounding tissue.
http://www.israel21c.org/headlines/radiation-therapy-is-about-to-get-much-kinder/
https://www.youtube.com/watch?v=xltOvraGxCM