Balancing Infectious Disease Control and Radiotherapy Risk Management Using a Novel Analytic Approach

Purpose/Objective(s)

To develop an analytic risk management method that uses mathematical models in Failure Modes and Effects Analysis (FMEA) to design mitigation efforts to control pandemic infection, while ensuring safe delivery of radiotherapy.

Materials/Methods

A two-stage FMEA approach is proposed to modify radiotherapy workflow during a pandemic. In stage 1, an Infection Control FMEA (IC-FMEA) is conducted, where risks are evaluated based on environmental parameters, clinical interactions, and modeling of the pandemic infection risk. Occupancy` Risk Index (ORI) is defined as a metric of infection risk probability in each room, based on the degree of occupancy during clinical operations. ORI, in combination with ventilation rate per person (R_p), is used to provide a broad infection risk assessment of workspaces. For detailed IC-FMEA of clinical processes, Infection containment failure mode (ICFM) is defined to be any instance of disease transmission within the clinic. Infection risk priority number (IRPN) has been formulated as a function of time, distance, and degree of protective measures. Infection control measures are then systematically integrated into the workflow. In stage 2, a conventional radiotherapy FMEA (RT-FMEA) can be performed on the adjusted workflow. A number of different clinical processes within radiotherapy workflow have been evaluated with this approach.

Results

The COVID-19 pandemic was used to illustrate stage 1 IC-FMEA. ORI and R_p values were calculated for various workspaces within a radiotherapy clinic. A deep inspiration breath hold (DIBH) CT simulation was used as an example to demonstrate detailed IC-FMEA with ICFM identification and IRPN evaluation. A total of 90 ICFMs were identified in the DIBH process. For minimal protective measures the IRPN values ranged from 2 – 1200, while for increasing degrees of infection control the values decreased to 2-530 and 1-189 corresponding to moderate and enhanced measures respectively.

Conclusion

The framework developed in this work provides tools for radiotherapy clinics to analytically assess risks and adjust workflows during a pandemic.