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Establishing Reference Values for All CT Exams and Monitoring Them: The Texas Experience

J Clements

J Clements*, J Moirano , R Lindsey , Texas Health Presbyterian Hospital Dallas, Dallas, TX


MO-F-19A-7 Monday 2:45PM - 3:45PM Room: 19A

Purpose: To establish reference levels (RLs) in terms of standard dose metrics (CTDIvol and DLP) for all CT exams performed in a community hospital and monitor clinical exams performed against RLs.

Methods: Clinical CT exams already performed were categorized by body region and CTDIvol and DLP values were analyzed. RLs for the dose metrics were established at either the ACR RL or at approximately the 75th percentile for the patient population performed at the facility. Once RLs were set, all patient exams performed were compared to the RLs. Monthly summaries were completed which include the exam type, applicable RL, actual dose metric, and initials of the technologist performing the exam. Performance summaries are posted in the department and discussed quarterly at CT dose committee meetings.

Results: Initially, significant overages were observed for abdomen/pelvis exams that used the CTDIvol RL established by the ACR (25 mGy). This RL is for 70 kg patients while a disproportionate number of the patients in our patient population exceed this weight. As a result, a separate RL was established for abdomen pelvis exams for patients greater than 90kg. After adjusting the abdomen/pelvis RL for patient weight, the total number of exams exceeding RLs has dropped by 50% over a period of 6 months.

Conclusion: This work indicates the potential for optimizing CT exams with respect to patient exposure by establishing region-specific RLs, monitoring values, publishing results, and providing education to staff performing exams. Reasonable RLs have been set for body region and modified based on patient size. This illustrates the need for considering more than an absolute maximum value as a RL and the process of continuous quality improvement. Commercial software has been purchased and will allow for the establishment of more refined RLs and more comprehensive analysis.

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