The system of radiation protection assumes a linear dose–response relationship with no threshold for low doses and dose rate exposures. This is based on epidemiological evidence at higher doses.
Hence there is a small theoretical risk of carcinogenesis attributable to low doses of ionising radiation. This risk is associated with any diagnostic imaging procedure involving radiation.
Radiosensitivity declines with age, so children are more susceptible to radiation risks than adults. Females are more radiosensitive than males.
The radiation protection system is based on the assumption that radiation risk is cumulative over a lifetime.
For an individual, a justified, optimised computed tomography (CT) scan will result in more benefit than harm. A doctor must justify the necessity for a CT scan before referring an individual for imaging.
- 1. Royal Australian and New Zealand College of Radiologists. Computed Tomography and Radiation Risks. Position statement. Sydney: RANZCR, 2010. http://www.ranzcr.edu.au/resources/professional-documents/position-statements (accessed Jun 2012).
- 2. de Gelder R, Draisma G, Heijnsdijk EA, de Koning HJ. Population-based mammography screening below age 50: balancing radiation-induced vs prevented breast cancer deaths. Br J Cancer 2011; 104: 1214-1220.
- 3. Yaffe MJ, Mainprize JG. Risk of radiation-induced breast cancer from mammographic screening. Radiology 2011; 258: 98-105.
- 4. Brenner DJ, Elliston CD. Estimated radiation risks potentially associated with full-body CT screening. Radiology 2004; 232: 735-738.
- 5. Royal Australian and New Zealand College of Radiologists. The use of diagnostic imaging for screening purposes and non-referred investigations. Statement of principles. Sydney: RANZCR, 2005. http://www.ranzcr.edu.au/resources/professional-documents/policies (accessed Jun 2012).
- 6. Blecher CM. Alarm about computed tomography scans is unjustified [letter]. Med J Aust 2010; 192: 723-734. <MJA full text>
- 7. Mendelson RM, Fox RA, de Klerk NH. Alarm about computed tomography scans is unjustified [letter]. Med J Aust 2010; 193: 246. <MJA full text>
- 8. Heggie JC, Goergen SK, Fallon MJ. Alarm about computed tomography scans is unjustified [letter]. Med J Aust 2011; 194: 150-151. <MJA full text>
- 9. International Commission on Radiological Protection. The 2007 recommendations of the International Commission on Radiological Protection. ICRP Publication 103. Ann ICRP 2007; 37: 1-332.
- 10. International Commission on Radiological Protection. Low-dose extrapolation of radiation-related cancer risk. ICRP Publication 99. Ann ICRP 2005; 35: 1-140.
- 11. National Research Council. Health risks from exposure to low levels of ionizing radiation: BEIR VII Phase 2. Washington, DC: The National Academies Press, 2006. http://www.nap.edu/catalog.php?record_id=11340 (accessed Jun 2012).
- 12. de Campo JF, de Campo MP. Is informed consent necessary for computed tomography in children and young adults? [letter]. Med J Aust 2010; 192: 423. <MJA full text>
- 13. Preston DL, Shimizu Y, Pierce DA, et al. Studies of mortality of atomic bomb survivors. Report 13: Solid cancer and noncancer disease mortality: 1950-1997. Radiat Res 2003; 160: 381-407.
- 14. Brenner DJ, Doll R, Goodhead DT, et al. Cancer risks attributable to low doses of ionizing radiation: assessing what we really know. Proc Natl Acad Sci U S A 2003; 100: 13761-13766.
- 15. United Nations Scientific Committee on the Effects of Atomic Radiation. Sources and effects of ionizing radiation. Vol I: Sources. Vol II: Effects. UNSCEAR 2000 Report to the General Assembly, with scientific annexes. New York: United Nations, 2000. http://www.unscear.org/unscear/en/publications.html (accessed Jun 2012).
- 16. Tubiana M, Feinendegen LE, Yang C, Kaminski JM. The linear no-threshold relationship is inconsistent with radiation biologic and experimental data. Radiology 2009; 251: 13-22.
- 17. Sykes PJ, Day TK. Requirements for identification of low dose and non-linear mutagenic responses to ionising radiation. Dose Response 2007; 5: 308-314.
- 18. Nair RR, Rajan B, Akiba S, et al. Background radiation and cancer incidence in Kerala, India — Karanagappally cohort study. Health Phys 2009; 96: 55-66.
- 19. Pearce MS, Salotti JA, Little MP, et al. Radiation exposure from CT scans in childhood and subsequent risk of leukaemia and brain tumours: a retrospective cohort study. Lancet 2012; 7 Jun. [Epub ahead of print.] doi: 10.1016/S0140-6736(12)60815-0.
- 20. Shuryak I, Sachs RK, Brenner DJ. Cancer risks after radiation exposure in middle age. J Natl Cancer Inst 2010; 102: 1628-1636.
- 21. Picano E. Informed consent and communication of risk from radiological and nuclear medicine examinations: how to escape from a communication inferno. BMJ 2004; 329: 849-851.
- 22. United Nations Scientific Committee on the Effects of Atomic Radiation. Sources and effects of ionizing radiation. Vol I. UNSCEAR 2008 Report to the UN General Assembly. Annex A: Medical Radiation Exposures. New York: United Nations, 2010. http://www.unscear.org/unscear/en/publications.html (accessed Jun 2012).
- 23. Brady Z, Cain TM, Johnston PN. Paediatric CT imaging trends in Australia. J Med Imaging Radiat Oncol 2011; 55: 132-142.
- 24. Paterson A, Frush DP, Donnelly LF. Helical CT of the body: are settings adjusted for pediatric patients? AJR Am J Roentgenol 2001; 176: 297-301.
- 25. Brenner D, Elliston C, Hall E, Berdon W. Estimated risks of radiation-induced fatal cancer from pediatric CT. AJR Am J Roentgenol 2001; 176: 289-296.
- 26. 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. AJR Am J Roentgenol 2001; 176: 303-306.
- 27. Goske MJ, Applegate KE, Boylan J, et al. The Image Gently campaign: working together to change practice. AJR Am J Roentgenol 2008; 190: 273-274.
- 28. Image Gently. The Alliance for Radiation Safety in Pediatric Imaging. http://www.pedrad.org/associations/5364/ig/ (accessed Jun 2012).
- 29. International Commission on Radiological Protection. Radiation protection in medicine. ICRP Publication 105. Ann ICRP 2007; 37: 1-63.
- 30. Donnelly LF. Reducing radiation dose associated with pediatric CT by decreasing unnecessary examinations. AJR Am J Roentgenol 2005; 184: 655-657.
- 31. Hendee WR, Becker GJ, Borgstede JP, et al. Addressing overutilization in medical imaging. Radiology 2010; 257: 240-245.
- 32. Professional Services Review. PSR report to the professions 2008-09. Canberra: Commonwealth of Australia, 2010. http://www.psr.gov.au/publications-and-resources/other-publications (accessed Jun 2012).
- 33. Goske MJ, Bulas D. Improving health literacy: informed decision-making rather than informed consent for CT scans in children. Pediatr Radiol 2009; 39: 901-903.
- 34. Karsli T, Kalra MK, Self JL, et al. What physicians think about the need for informed consent for communicating the risk of cancer from low-dose radiation. Pediatr Radiol 2009; 39: 917-925.
- 35. Larson DB, Rader SB, Forman HP, Fenton LZ. Informing parents about CT radiation exposure in children: it’s OK to tell them. AJR Am J Roentgenol 2007; 189: 271-275.
Publication of your online response is subject to the Medical Journal of Australia's editorial discretion. You will be notified by email within five working days should your response be accepted.