There is quite a bit of data out there on the effects of medical ionizing radiation, in both adults and children. While a lot of data were collected from the survivors of the atomic blasts and other radiation accidents, there have also been many controlled studies specifically on medical ionizing radiation.
The National Cancer Institute, which is part of the National Institutes of Health, put out an article about CT scans and kids called: “Radiation Risks and Pediatric Computed Tomography (CT): A Guide for Health Care Providers.”
The following is the reference section from that article. You might find some articles of interest in it.
Amis ES, Jr., Butler PF, Applegate KE, et al. American College of Radiology white paper on radiation dose in medicine. Journal of the American College of Radiology 2007; 4:272-284.
Arch ME, Frush DP. Pediatric body MDCT: A 5-year follow-up survey of scanning parameters used by pediatric radiologists. American Journal of Roentgenology 2008:191;611-617.
Brenner DJ, Doll R, Goodhead DT, et al. Cancer risks attributable to low doses of ionizing radiation: Assessing what we really know. Proceedings of the National Academy of Sciences of the United States of America 2003; 100:13761-13766.
Brenner DJ, Elliston CD, Hall EJ, Berdon WE. Estimated risks of radiation-induced fatal cancer from pediatric CT. American Journal of Roentgenology 2001; 176:289-296.
Brenner DJ, Hall EJ. Current concepts - Computed tomography - An increasing source of radiation exposure. New England Journal of Medicine 2007; 357:2277-2284.
Brody AS, Frush DP, Huda W, Brent RL, Radiology AAoPSo. Radiation risk to children from computed tomography. Pediatrics 2007; 120:677-682.
Cardis E, Vrijheid M, Blettner M, et al. The 15-country collaborative study of cancer risk among radiation workers in the nuclear industry: Estimates of radiation-related cancer risks. Radiation Research 2007; 167:396-416.
Chodick G, Ronckers C, Ron E, Shalev V. The utilization of pediatric computed tomography in a large Israeli Health Maintenance Organization. Pediatric Radiology 2006; 36:485-490.
Chodick G, Ronckers CM, Shalev V, Ron E. Excess lifetime cancer mortality risk attributable to radiation exposure from computed tomography examinations in children. Israel Medical Association Journal 2007; 9:584-587.
da Costa e Silva EJ, da Silva GA. Eliminating unenhanced CT when evaluating abdominal neoplasms in children. American Journal of Roentgenology 2007; 189:1211-1214.
Donnelly LF, Emery KH, Brody AS, et al. Minimizing radiation dose for pediatric body applications of single-detector helical CT: Strategies at a large children's hospital. American Journal of Roentgenology 2001; 176:303-306.
Frush DP, Applegate K. Computed tomography and radiation: understanding the issues. Journal of the American College of Radiology 2004; 1:113-119.
Frush DP, Donnelly LF, Rosen NS. Computed tomography and radiation risks: What pediatric health care providers should know. Pediatrics 2003; 112:951-957.
Garcia Pea BM, Cook EF, Mandl KD. Selective imaging strategies for the diagnosis of appendicitis in children. Pediatrics 2004; 113:24-28.
Goske MJ, Applegate KE, Boylan J, et al. The 'Image Gently' campaign: increasing CT radiation dose awareness through a national education and awareness program. Pediatric Radiology 2008; 38:265-269.
Huda W, Vance A. Patient radiation doses from adult and pediatric CT. American Journal of Roentgenology 2007; 188:540-546.
Larson DB, Rader SB, Forman HP, Fenton LZ. Informing parents about CT radiation exposure in children: It's OK to tell them. American Journal of Roentgenology 2007; 189:271-275.
McNitt-Gray MF. AAPM/RSNA physics tutorial for residents: Topics in CT - Radiation dose in CT1. Radiographics 2002; 22:1541-1553.
Mettler FA, Jr., Wiest PW, Locken JA, Kelsey CA. CT scanning: patterns of use and dose. Journal of Radiological Protection 2000; 20:353-359.
NAS. Health risks from exposure to low levels of ionizing radiation: BEIR VII phase 2. Washington D.C.: National Academy of Sciences, 2005.
Paterson A, Frush DP, Donnelly LF. Helical CT of the body: Are settings adjusted for pediatric patients? American Journal of Roentgenology 2001; 176:297-301.
Pierce DA, Preston DL. Radiation-related cancer risks at low doses among atomic bomb survivors. Radiation Research 2000; 154:178-186.
Preston DL, Ron E, Tokuoka S, et al. Solid cancer incidence in atomic bomb survivors: 1958-1998. Radiation Research 2007; 168:1-64.
Rogers LF. Taking care of children: Check out the parameters used for helical CT. American Journal of Roentgenology 2001; 176:287-287.
Slovis TL. The ALARA (as low as reasonably achievable) concept in pediatric CT intelligent dose reduction. Multidisciplinary conference organized by the Society of Pediatric Radiology. August 18-19, 2001. Pediatric Radiology 2002; 32:217-317.
Thomas KE, Wang BB. Age-specific effective doses for pediatric MSCT examinations at a large children's hospital using DLP conversion coefficients: a simple estimation method. Pediatric Radiology 2008; 38:645-656.