The Efficacy of Thermal Imaging Scanners in the Detection of SARS

INTRODUCTION

In May 2003, Health Canada implemented a pilot project to assess the efficacy of thermal imaging scanners in the detection of Severe Acute Respiratory Syndrome (SARS). Thermal imaging scanners were set up in Pearson and Vancouver International Airports to monitor the temperature of arriving and departing passengers.

Through an RFP process, Health Canada selected thermal imaging scanners from four different suppliers, for a total of 12 machines. The thermal imaging scanners were selected on the basis of technical specifications developed by Health Canada. As this was a pilot project, all suppliers who met the technical specifications were selected to participate in the project, in order to enable Health Canada to assess a broad range of machines.

The machines selected to participate in the pilot project included the following:

• Five FLIR ThermaCAM® E2 Infrared Cameras – 3 in Toronto & 2 in Vancouver;
• Three CTI Thermo Image Processor System – all in Toronto;
• Three MiKronScan 7302 Thermo Imaging System – all in Vancouver;
• One Cantronic FeverScan M3000 – in Vancouver.

As a result of technical malfunctioning, the supplier collected the Cantronic FeverScan M3000 early in the pilot project, and it was not replaced. Accordingly, the total number of machines in the pilot project was reduced to 11, with Vancouver International Airport having 5 thermal imaging scanners and Pearson International Airport had 6.

PURPOSE

The purpose of this report is to determine whether one machine is superior to another. This report does not address the efficacy of the machines in detecting SARS. The focus of this report is on whether the machines provided a reliable means of measuring temperature, and whether elements in one machine render it more viable than the others should Health Canada decide to use thermal imaging scanners on a long-term basis.

The Canadian Coordinating Office for Health Technology Assessment (CCOHTA) conducted a pre-assessment on the use of thermal imaging devices used in screening for elevated temperature, as requested by Health Canada. The concluding concerns raised by the review were as follows:

1. temperature measurement is but one diagnostic tool in determining the presence of disease;
2. further examination by a qualified medical professional is required to provide an accurate diagnosis;
3. appropriate and accurate application of this technology is needed to prevent waste of resources and protect public safety.

ANALYSIS AND RESULTS

The following data were collected from each machine during the evaluation period:

• number of persons screened;
• number of persons detected with an elevated temperature;
• number of persons referred for medical assessment;
• number of persons referred by a Quarantine Officer as suspected SARS;
• number of persons released;
• number of persons hospitalized.

The FLIR machines screened the most number of passengers – 275,047 – which is not surprising since 5 of the 11 machines were FLIR. The CTI followed closely, with 224,988 passengers screened during the evaluation period. MiKron screened 56,509 passengers, although it should be noted that the MiKron machines were only set up in Vancouver, which had less volume.

Of the passengers screened using the FLIR machines, 171 were sent for medical assessment as a result of an elevated temperature. Forty-seven passengers screened by the CTI machines, and 2 passengers screened by the MiKron machines were sent for medical assessment as a result of elevated temperatures. There were no passengers referred by a Quarantine Officer as suspected SARS cases, and there were no passengers hospitalized.

An assessment of the technical specifications of the 3 machines yielded no conclusive data with respect to differences among the machines. The technical specifications included the following elements:

• temperature range;
• accuracy;
• power source;
• battery operating time;
• battery operating temperature range;
• shock
• vibration;
• weight;
• dimensions.

CONCLUSIONS

On the basis of the data gathered for this assessment, the machines performed according to the specifications of the project to varying degrees. One machine produced a higher number of false positives than the others, but the differences were minimal.

The findings of the Standards, Productivity and Innovation Board of Singapore (SPRING) should be taken into consideration in any future decisions regarding thermal imaging scanners. On May 30, 2003, SPRING convened a national conference on thermal imagers for fever screening and their selection, usage and testing. As the country which first introduced the application of this technology for health screening, Singapore is at the forefront of assessing the effectiveness of the wide range of temperature gauges, including thermal imaging scanners. Their first finding was the inappropriate use of industrial infrared thermometers for body temperature measurements.

Based on this pilot project and a study conducted by Singapore on thermal imaging scanners, it is recommended that Health Canada increase the technical specification requirements should long-term use be desired. Health Canada will have to engage in another RFP process in order to select thermal imaging scanners for future use. Until such a process is embarked upon, Health Canada must continue with the current machines until the agreements are terminated. Health Canada currently has contracts in place with the 3 thermal imaging scanner suppliers until the second week of the next fiscal year – April 15, 2004.