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CT Dose Metrics: What Are We Tracking


J Guild

J Guild*, G Arbique, T Blackburn, J Gallet, J Anderson, UT Southwestern Medical Ctr at Dallas, Dallas, TX

SU-E-I-57 Sunday 3:00:00 PM - 6:00:00 PM Room: Exhibit Hall

Purpose: Recent guidance by The Joint Commission and CRCPD recommendations require establishing CT reference dose levels (RDLs) for clinical protocols and recording CT dose metrics in the patient's medical record. This presentation addresses which dose values in the CT report should be recorded for the purposes of monitoring patient dose and determining RDLs effectively.

Methods: CT dose reports are commonly recorded in the PACS as screen captures, although structured reporting is becoming available on current CT scanners and PACS systems. The goal is to obtain data that correctly reflects the patient's dose, but the dose information captured is not standardized across vendors and can be difficult to compare. Multi-phase studies, deviations from established protocols and dynamic scanning present problems when recording numbers to establish RDLs because of the lack of information on the anatomy scanned. The cumulative DLP and CTDIvol manually entered by radiologic technologists into the electronic medical record were compared with more detailed dose metrics compiled from PACS images.

Results: Analysis of this data showed that simple cumulative metrics are a poor indicator of patient dose. Major problems are 1) the inclusion of dynamic scan doses associated with bolus tracking, which can skew protocol CTDIvol values by a factor of up to 20, and 2) add-on scans of non-overlapping anatomy which can inaccurately increase apparent patient dose.

Conclusions: Recording CTDIvol to monitor patient doses is not straightforward, since details of the actual anatomy scanned are lacking without image-based review. More granular dose reporting which identifies individual acquisitions is required; however, current RIS systems do not provide the flexibility necessary to capture all this information.

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