There has been a recent increase in attention focused on the potential risk of radiationinduced carcinogenesis from diagnostic radiology, with a particular emphasis on computed tomography (CT). After the rapid adoption of multidetector CT (MDCT), radiation doses from CT are now the single largest source of diagnostic radiation exposure to patients, and the carcinogenesis risk from diagnostic CT radiation dose exposure can no longer be ignored by physicians. To understand the exposure risk and monitor radiation dose exposure, an understanding and interest in CT dose reports is necessary. Almost all MDCTs now show and allow storage of the volume CT dose index (CTDIvol), dose length product (DLP), and effective dose estimations on dose reports, which are essential to assess patient radiation exposure and risks. To decrease these radiation exposure risks, the principles of justification and optimization should be followed. Justification means that the examination must be medically indicated and useful. Optimization means that the imaging should be performed using doses that are as low as reasonably achievable (ALARA), consistent with the diagnostic task. Optimization includes understanding and changing CT protocols to perform the same diagnostic task with the minimal amount of radiation exposure while maintaining diagnostic accuracy. Physicians and radiologists must be aware of the radiation risks associated with CT exams, and understand and implement the principles for patient radiation dose reduction.