Institutional experience with implanted cardiac device risk level assessment: Comparing calculation and measurement.

Background: The use of in-vivo dosimetry is a long-standing but also labor-intensive component of risk-level assessment for patients with implanted devices. A calculation-only approach, using treatment planning system (TPS)-calculated doses along with imaging doses estimates when relevant, has the potential to streamline the physics workflow without negatively impacting patient safety.

Purpose: To evaluate the feasibility of using a calculation-only approach for risk level assessment for patients with implanted electronic medical devices.

Methods: A total of 86 patients were included in this retrospective study. For each patient, in-vivo dosimetry measurements using optically stimulated luminescent dosimeter (OSLD) were compared to calculated doses (based on TPS calculated doses and an estimate of imaging doses when relevant). The comparison of OSLD doses and estimated predicted doses was structured in the following manner: (1) direct comparison of both absolute dose difference and percent difference for measured and calculated doses, (2) risk level assessment comparison using measured and estimated doses, and (3) sensitivity and positive predictive value assessment of each method for TG-203 risk level assessment.

Results: For all cases, the calculation-based approach yielded a risk level that was equivalent to or more conservative than the risk level from OSLD measurement. For 79 of 86 patients (91.9%), the calculated and measured doses provided the same risk level. For 7 of 86 patients (8.1%), the calculated dose yielded the more conservative risk level. The calculation-based dose estimate provided a sensitivity of 1.00 with a positive predictive value of 0.92.

Conclusions: The use of a calculation-only approach has the potential to reduce workload while maintaining the efficacy of risk-level assessment for patients with implanted devices.