From Columbia: Regarding patients' appropriate radiation doses

http://www.ncbi.nlm.nih.gov/pubmed/21771956

Radiology. 2011 Jul 19. [Epub ahead of print]
Impact of Reduced Patient Life Expectancy on Potential Cancer Risks from Radiologic Imaging.
Brenner DJ, Shuryak I, Einstein AJ.
Source
Center for Radiological Research and Departments of Medicine and Radiology, College of Physicians and Surgeons, Columbia University Medical Center, 630 W 168th St, VC-11-235, New York, NY 10032.

Abstract
Purpose: To quantify the effect of reduced life expectancy on cancer risk by comparing estimated lifetime risks of lung cancer attributable to radiation from commonly used computed tomographic (CT) examinations in patients with and those without cancer or cardiac disease. Materials and Methods: With the use of clinically determined life tables, reductions in radiation-attributable lung cancer risks were estimated for coronary CT angiographic examinations in patients with multivessel coronary artery disease who underwent coronary artery bypass graft (CABG) surgery and for surveillance CT examinations in patients treated for colon cancer. Statistical uncertainties were estimated for the risk ratios in patients who underwent CABG surgery and patients with colon cancer versus the general population. Results: Patients with decreased life expectancy had decreased radiation-associated cancer risks. For example, for a 70-year-old patient with colon cancer, the estimated reduction in lifetime radiation-associated lung cancer risk was approximately 92% for stage IV disease, versus 8% for stage 0 or I disease. For a patient who had been treated with CABG surgery, the estimated reduction in lifetime radiation-associated lung cancer risk was approximately 57% for a 55-year-old patient, versus 12% for a 75-year-old patient. Conclusion: The importance of radiation exposure in determining optimal imaging usage is much reduced for patients with markedly reduced life expectancies: Imaging justification and optimization criteria for patients with substantially reduced life expectancies should not necessarily be the same as for those with normal life expectancies. © RSNA, 2011.