Direct and indirect action of free electrons created by ionizing radiation. (Reproduced, with permission, from Hall EJ, Giaccia AJ. Radiobiology for the Radiologist. 7th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2012:9, Figure 1.8.) Source: Principles of Radiation Therapy, Gynecologic Oncology: Clinical Practice and Surgical Atlas Citation: Karlan BY, Bristow RE, Li AJ. Gynecologic Oncology: Clinical Practice and Surgical Atlas; 2015 Available at: http://obgyn.mhmedical.com/DownloadImage.aspx?image=/data/Books/1381/kar_ch19_fg002.png&sec=75545066&BookID=1381&ChapterSecID=75545015&imagename= Accessed: October 26, 2017 Copyright © 2017 McGraw-Hill Education. All rights reserved