Principles and Test Methods of Non-contact Body Thermometry

Investigation of the Effect of Environmental Temperatures on Non-contact Thermal Imaging for Core Body Temperature Measurement

Long-wavelength infrared (IR) detectors have a more than 20-year history in medical thermometry and have been used widely for febrile screening. However, over the past year and a half, public health entities, medical professionals, and the general public have begun to question the claimed accuracy of non-contact body thermometry. The standard assessment of a device's performance relies on clinical testing with febrile individuals, yet this practice may have inadvertently allowed the approval of IR systems that are unable to detect moderate fevers. The ability to test device performance without relying on febrile test participants would have important ramifications for public health, especially if this test discovered undisclosed differences in accuracy in widely used devices.

The aim is to examine the effect of the local environment and the physiology of the human body on the relationship between core body temperature and inner canthi (region near tear duct) skin temperature measured using non-contact thermal imaging and to use of this relationship to test actual device performance at detecting simulated elevated temperatures, without requiring volunteers having actual elevated temperatures. The overall goal of this research study is to validate and improve the science of non-contact core body temperature measurement.

Study Overview

• Status: Active, not recruiting
• Conditions: Thermometry
• Intervention / Treatment: Diagnostic test: Infrared Thermography

Detailed Description

It is difficult to assess the performance of non-contact thermometry at detection of febrile subjects unless febrile subjects are included in the test, which severely limits development and independent testing of such devices. The underlying mechanisms of non-contact thermometry might be used to develop a test without requiring the inclusion of febrile subjects, and the development and demonstration of such a test is the object of this study.

Literature review and pilot study revealed the offset between skin temperature and core (oral) body temperature is dependent on air temperature by a linear relationship. In a 70F room, the inner canthi temperature of a human with core (oral-reference) body temperature of 98.6F is 94.4F, a difference of 4.2F. This same individual in an 87F room (after waiting several minutes) will have an inner canthi temperature of 97.0F, a difference of only 1.6F (the actual values may depend on sensor confounds not addressed here). Therefore, one could use a several-minutes exposure to elevated air temperatures (equilibration environment) to simulate an elevated body temperature, by continuing to operate the device under test from a non-elevated air temperature environment (test environment), while taking care to limit the effects of temperature changes and gradients due to the mixing of these two environments.

Subjects will be recruited from a college campus via a recruitment protocol to participate in an up to 2 hour study session. The study session will involve collection of demographic information on a non-identifiable form, five collections of oral thermometry, four 10 minute periods of equilibration inside 4 elevated temperature environments during repeat continuous non-contact thermometry, and measurements via several non-contact test devices operated from within a non-elevated environment through a window into each elevated environment.

• Study Type: Observational
• Enrollment (Anticipated): 110

Contacts and Locations

Study Locations

• United States
  • Minnesota
    • Northfield, Minnesota, United States, 55057
      • St. Olaf College

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (ADULT, OLDER_ADULT)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: All

• Sampling Method: Non-Probability Sample

Study Population

Participants will be selected from those responding to electronic advertisement on St Olaf College internal email lists and message boards. It is expected that the majority of the study population will be students, with a small proportion of Staff and Faculty.

Description

Inclusion Criteria:

• Age > 18.
• Have received a clinical oral thermometry measurement in the past.

Exclusion Criteria:

• Contraindication to oral temperature measurement.
• Inability to follow instructions.
• Any diagnosis associated with abnormal core thermoregulation, e.g. autonomic dysfunction.
• Obvious signs of tissue damage present in either inner canthus.
• Facial artery abnormality if previously diagnosed.
• Experienced discomfort while receiving most recent clinical oral thermometry measurement.

Study Plan

How is the study designed?

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Clinical Bias (CB)	Average difference between device measurement and reference measurement as per ASTM E1965-98	10 months
Limits of Acceptability (LA)	Two times standard deviation of device measurement as per ASTM E1965-98	10 months
Bland-Altman (BA) Plot	Plot of device minus reference output versus reference output (or versus average of reference and device outputs)	10 months

Collaborators and Investigators

• Sponsor: Thermal Diagnostics LLC

Study record dates

Study Major Dates

• Study Start (ACTUAL): July 22, 2021
• Primary Completion (ANTICIPATED): May 15, 2022
• Study Completion (ANTICIPATED): May 15, 2022

Study Registration Dates

• First Submitted: January 26, 2022
• First Submitted That Met QC Criteria: February 15, 2022
• First Posted (ACTUAL): February 21, 2022

Study Record Updates

• Last Update Posted (ACTUAL): February 21, 2022
• Last Update Submitted That Met QC Criteria: February 15, 2022
• Last Verified: February 1, 2022

More Information

Terms related to this study

• Keywords: thermal imaging; febrile; non-contact infrared thermometry; elevated body temperature
• Other Study ID Numbers: ClinicalStudyAugust2021

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: No identifying information was collected except for thermal images of faces, which were extracted to only numeric inner canthi temperature values per subject. This data is being shared via a github repository.
• IPD Sharing Time Frame: The first set of 28 subjects' data is available as of Jan 24, 2022
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ICF

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: Yes
• product manufactured in and exported from the U.S.: Yes