Risk V/S Benefit – CT Scans and Radiation

Thomas L. Presson, MD, is a radiologist with Wake Radiology and serves as the Radiologist and Radiation Safety Officer for WakeMed Health & Hospitals.

Recently, two studies published in the Archives of Internal Medicine evaluate trends in CT radiation doses and the associated risks of cancer induction. These studies – one sponsored through the U.S. National Institutes of Health (NIH) and the other led by the University of California, San Francisco (UCSF) suggest a possible increased risk of cancer to our population due to the radiation dose delivered by diagnostic CT exams. (Archives of Internal Medicine, December 14-18, 2009, Vol. 169:22, pp. 2072-2078).

One point not made in the articles is the high baseline risk of cancer inherent in our population.  As referenced in the articles, the BEIR study published by the National Academies Press demonstrates a baseline lifetime risk of cancer in our population of 42%.  This means that 42 out of 100 persons will develop some form of cancer in their lifetime unrelated to radiation exposure.  While it is true that radiation received from CT exams over a lifetime likely increases this risk, the tremendous value of CT in diagnosing and treating many life-threatening diseases must not be overlooked.

Without CT, many of these 42% of patients may go undiscovered or under treated much longer.  Wake Radiology and WakeMed have always assumed a proactive role in protecting our patients from unnecessary radiation exposure. We continuously monitor our scan protocols and work with equipment manufacturers to minimize the radiation dose to each patient. The goal is to tailor each exam so that patients are exposed to the least amount of radiation possible to get accurate images.

We want to reassure patients in our community that they are getting the least amount of radiation possible when they come to any WakeMed or Wake Radiology location. Our current scan protocols deliver doses which are well below the published acceptable levels used by the American College of Radiology in their CT accreditation program.  In addition, we employ the following methods to optimize safety.

• Dynamic Dose modulation on CT scanners (lowers radiation according to the density of the body part currently being scanned), resulting in a reduction of radiation to the patient.
• Patient Dose Warning for ED patients – WakeMed warns ED physicians when patients who have had multiple CT exams register in the ED.
• Lowered pediatric radiation dosages.
• Ongoing research using radiation phantoms to improve test results using even lesser amounts of radiation. We actively consult with our medical physicists to adjust radiation dosage at the appropriate levels to get an accurate diagnostic test.
• Monitoring of radiation dosing in real time for each patient by the radiologists and technologists.
• Staff technologists registered in CT by the American Registry of Radiologic Technologists.
• Recommendation of alternative imaging studies – such as ultrasound or MRI – when deemed more appropriate for patients, and especially with our pediatric patients.