To learn more about radiation from CTs and other procedures, go to:
http://well.blogs.nytimes.com/2012/08/20/medical-radiation-soars-with-risks-often-overlooked/

For radiation dose from CT/PET scan and subsequent risk, see:
http://radiology.rsna.org/content/251/1/166.full

For increased cancers in children who have had CT scans, go to:
http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(12)60815-0/abstract

For additional information on the life and work of Allan Cormack see: , “The Nobel Prize in Physiology or Medicine 1979: Allan M. Cormack, Godfrey N. Hounsfield,” at: www.Nobelprize.org

For more on the life of Godrey Hounsfield see:
http://www.nobelprize.org/nobel_prizes/medicine/laureates/1979/hounsfield-autobio.html