How to reduce CT-related potential increases in lifetime attributable risk of cancer

Abstract

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Learning Objectives: 1. CT-related small, estimated potential increase in lifetime attributable risk of cancer is influenced by the protocol used, age and sex of the patient. 2. This estimated risk is far less that the likely benefit to the patient for indicated examinations, and can be reduced.

Abstract Body: Imaging studies that use ionizing radiation are an essential tool for the evaluation of patients. Utilization of CT increased from 3 million procedures in ’80 to 62 million in 2000, which was implicated for 2% of all cancers in America. PET-SPECT/CT utilization has increased 20% last year. Although the cause-and-effect relationship between low-level radiation, and cancer is still unclear, consensus statements suggest that low-level radiation may have a small risk of causing cancer, which depend on patient's age and size, equipment settings and model, and the duration of procedure. For a given mAs setting, pediatric doses are much larger than adult doses. A reduction in the mAs setting proportionately reduces the dose and the risk. The ways to reduce radiation exposure induced by CT scans will be discussed and include: perform CT scanning only when necessary, keep the imaging field to possible minimum, design specific protocols optimized to reduce radiation exposure, avoid repetitive imaging. Points to consider: Average background radiation from natural and manmade sources is 3 mSv/year per person. Radiation doses from CT scans of chest (3 mSv), head (4 mSv), and abdomen (5 mSv) correlate to 150, 200, and 250 chest x-rays, respectively. Although low-level radiation from CT studies might carry a small risk for cancer, the risk is outweighed by the benefits of indicated CT studies, which can be reduced through technologic advances, adoption of "as low as reasonably achievable" (ALARA) concept, and the use of appropriateness rule.