Physician self-regard benefits patients’ radiation exposure: real-time monitoring of patient and occupational dose
There has been increasing emphasis on quality improvement throughout radiology departments. Radiation exposure to both the patient and the operator is one important aspect of this. This prospective study evaluated the effects of dose to patients and operators when employing real time dose monitoring of both patients and operators during fluoroscopic procedures.
Two experienced operators were enrolled in this study. These operators performed 730 procedures during the study (720 included for analysis) which was subdivided into two discreet periods. In the first period, real time monitoring of patient dose was performed using the DoseWatch (GE Healthcare Systems, Buc, France) program. In the second period, both the patient dose and operator dose were recorded in real time. Operator dose was recorded via four individual wireless devices (Ray-Safe i2; Unfors RaySafe, Inc, Billdal, Sweden). During both periods operator dose was recorded with a thermoluminescent dosimeter. Data was available real time, for the patient dose in the control room with alarms for certain thresholds, and for the operator dose on a touch screen in the procedure room with color coded dose rates and cumulative doses. Comparison of kerma area product (KAP) for each procedure type was then made between the two study periods. Mean KAP was significantly lower in period 2 (37 mGy · cm²) compared to period 1 (47 mGy · cm²), and this held true for 15/19 of the procedure types performed. In addition, a direct correlation was observed between patient dose and occupational dose (r = 0.88). From period 2, it was observed that the mean dose per procedure was 4.6 µSv, with a dose rate of 0.24 mSv/hr.
This study demonstrates real time monitoring of patient and occupational dose results in decreased KAP when compared to monitoring patient dose alone. This study’s most noticeable confounding variable is its susceptibility to the Hawthorne effect, as both operators were aware of the two ongoing study periods. In addition, while there was a direct correlation between KAP and accumulated operator dose, no direct measure of operator dose per procedure was performed during the first study period. Lastly, KAP had a poor correlation with operator dose at low exposure levels. However, given the significant differences observed between the two study periods, the results are noteworthy. It would be interesting to see this tool implemented in our residency and fellowship programs to more effectively teach our trainees the benefits of radiation safety.
Figure 2. Correlation between KAP (Gy ∙ cm2) and dose to operator. Overall, there was a strong correlation of KAP, measured with the patient dose monitoring system, and accumulated equivalent dose per intervention (μSv), registered with the real-time occupational dose monitoring system. However, correlation in low-dose areas (KAP < 10 Gy ∙ cm2) was poor.
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Heilmaier, C. et al. Combined use of a patient dose monitoring system and a real-time occupational dose monitoring system for fluoroscopically guided interventions. J Vasc Interv Radiol 2016; 10.1016/j.jvir.2015.11.033.
Daniel Sheeran, MD
VIR Pathway Resident at University of Virginia