Preparing for a "dirty bomb" attack: the optimum mix of medical countermeasure resources

Abstract

Background: In radiological emergencies with radionuclide incorporation, decorporation treatment is particularly effective if started early. Treating all people potentially contaminated ("urgent treatment") may require large antidote stockpiles. An efficacious way to reduce antidote requirements is by using radioactivity screening equipment. We analyzed the suitability of such equipment for triage purposes and determined the most efficient mix of screening units and antidote daily doses.

Methods: The committed effective doses corresponding to activities within the detection limits of monitoring portals and mobile whole-body counters were used to assess their usefulness as triage tools. To determine the optimal resource mix, we departed from a large-scale scenario (60,000 victims) and based on purchase prices of antidotes and screening equipment in Germany, we calculated efficiencies of different combinations of medical countermeasure resources by data envelopment analysis. Cost-effectiveness was expressed as the costs per life year saved and compared to risk reduction opportunities in other sectors of society as well as the values of a statistical life.

Results: Monitoring portals are adequate instruments for a sensitive triage after cesium-137 exposure with a high screening throughput. For the detection of americium-241 whole-body counters with a lower daily screening capacity per unit are needed. Assuming that 1% of the potentially contaminated patients actually need decorporation treatment, an efficient resource mix includes 6 monitoring portals and 25 mobile whole-body counters. The optimum mix depends on price discounts and in particular the fraction of victims actually needing treatment. The cost-effectiveness of preparedness for a "dirty bomb" attack is less than for common health care, but costs for a life year saved are less than for many risk-reduction interventions in the environmental sector.

Conclusion: To achieve economic efficiency a high daily screening capacity is of major importance to substantially decrease the required amount of antidote doses. Among the determinants of the number of equipment units needed, the fraction of the potentially contaminated victims that actually needs treatment is the most difficult to assess. Judging cost-effectiveness of the preparedness for "dirty bomb" attacks is an issue of principle that must be dealt with by political leaders.

Keywords: Data envelopment analysis; Decorporation treatment; Dirty bomb; Efficiency; Medical countermeasures; Radiological emergency; Radionuclide incorporation; Screening.

Fig. 1

The monitoring portal used at the Bundeswehr Institute of Radiobiology (CheckPoint: Gate™ FastTrack-Fibre™ Mobile) with technical specifications. Detection limits are given for different measurement modes and times [32]. Lead shielding 15 mm: cesium-137 [wait in (5 s): 1.35 kBq; walkthrough (0.57 s): 4.8 kBq], americium-241 [wait in (5 s): 29 kBq; walkthrough (0.57 s): 105 kBq]. Lead shielding 30 mm: cesium-137 [wait in (5 s): 1.25 kBq; walkthrough (0.57 s): 4.5 kBq], americium-241 [wait in (5 s): 28 kBq; walkthrough (0.57 s): 100 kBq]

Fig. 2

Number of antidote daily doses needed for an “urgent approach” treatment strategy and a large-scale scenario with 60,000 potentially internally contaminated victims depending on the screening capacities (monitoring portals or whole-body counters). Assumption: 1% of the potentially contaminated victims actually need treatment. Treatment duration 90 days. Figures are independent on the radionuclide(s) involved. Computations according to the algorithm described in [23]

Fig. 3

Efficiency of combinations involving various numbers of screening equipment units to detect cesium-137 or americium-241. Decorporation treatment is started according to the “urgent treatment” approach 12 h after acute radioactivity incorporation with Prussian Blue for cesium-137 or Ca(DTPA) for americium-241. Inputs are measured in monetary units based on prices in Germany and statistical life time saved as output. Efficiency values for americium-241 and portal monitors are shown for completeness, but portal monitors are not an acceptable option for that purpose because of their limited technical detection limits

Fig. 4

Costs to save a statistical life year in different age groups after the acute inhalative incorporation of cesium-137 or americium-241 if implementing an “urgent approach” treatment strategy with decorporation starting 12 h after radioactivity exposure. Assumptions: Decorporation treatment threshold level 200 mSv; 1% of the potentially contaminated victims actually need treatment; purchase costs of equipment and antidotes: see method section without discounts

Fig. 5

Costs of a statistical life year depending on the threshold level fixed for the indication of decorporation treatment and a resource mix corresponding to optimum efficiency (1.000). Assumptions: Scenario with 60,000 potentially contaminated people and 1% of them actually needing treatment; purchasing cost of a monitoring portal 100,000 € and screening capacity of 10,000 people/day and unit; purchasing cost of a whole-body counter 500,000 € and screening capacity of 100 people/day and unit

Fig. 6

Costs per life year saved in various sectors of society (columns, logarithmic scale) (data from [56]) and values achieved by preparedness for a dirty bomb attack with cesium-137 or americium-241. Exchange rates 1 € = 1.1 US-$; monit. Port.: Monitoring portal; WBC: Whole body counter