Potential Clinical Ramifications of Dose Alert on CT-Guided Interventional Procedures

Abstract

INTRODUCTION In an effort to protect patients from inadvertent radiation overexposure during CT exams, a new feature, called “dose check,” has been implemented by all CT scanner manufacturers [1-3]. Dose check is designed in accordance with the National Electrical Manufacturers Association (NEMA) XR-25 national standard [4]. Dose check initiates a procedural pause during the examination to indicate that the prescribed image acquisition may yield an “abnormally” large dose to the patient; the upper limit of “normal” patient dose values (threshold CT dose index [CTDIvol] or dose length product [DLP] values) are predetermined by the institution. These thresholds are referred to as “notification values” and “alert values.” Dose check is comprised of two components: dose notification and dose alert. Through dose notification, the estimated CTDIvol or DLP value from each acquisition is compared with the notification value. If the estimated CTDIvol or DLP exceeds the notification value, the technologist is notified, questioned if the acquisition(s) should continue as prescribed, and prompted to record justification for the unusually large CTDIvol or DLP value. The notification value can be configured by the institution and set for each individual scan acquisition. Through dose alert, the cumulative