“To determine the technical parameters and the most suitable methodology to achieve accurate non-contact vital signs including human body temperature measurement”
Since international travel restrictions were imposed by the 2003 SARS epidemic, the science of infrared temperature measurement has been widely adopted as a “first line of defence” for detection of “fever” in individuals at key public locations (airports, train stations etc.). However, whilst thermographic camera systems and software have evolved, the criteria for public temperature screening remains “crude” usually working to a set-point that identifies when a human body temperature is at + 2°C above normal.
Despite the recent widespread adoption of “fever-detection” for mass public screening due to Covid-19 which relies on measurement of the inner eye temperature, there has been very little medical research carried-out in the UK based on the latest technological developments in infrared hardware and software.
It is now recognised that quantification of a person’s “vital signs”, offers a greater degree of reliability in detecting those who may be infectious, when compared to the single measurement of body temperature (via infrared). There is therefore a need to develop a methodology, which captures accurate non-contact measurement data for all three “vital signs” (temperature, pulse and respiration rate).
Vital Signs: Measurement of temperature, pulse, respiration-rate and blood-oxygen levels is the standard technique adopted by clinicians, to initially determine the state of a person’s health. The methodology and equipment used to obtain the measurement data, includes a range of sensors being attached to the patient, which involves direct physical contact with healthcare staff.
In a normal scenario, this physical contact can be accommodated however, whenever clinical staff are faced with assessing a patient who may be suffering from a very dangerous infection (such as Covid 19), there is a need to undertake the initial appraisal in a safe space, with healthcare workers wearing specialised (disposable) PPE in an effort to minimise the risk of infection.
A number of technological advances have been made in non-contact measurement of “vital sign indicators” in clinical health appraisals. In addition to infrared thermography, researchers across the world have adopted innovative techniques, such as monochrome video cameras, terahertz radar and radio frequency to capture data on body temperature, heart rate (pulse) and respiration rate.
Our project will also appraise the potential and accuracy of non-contact measurement techniques, to capture data on other physiological parameters, such as arterial blood oxygen saturation levels.
By comparing the results achieved from all of the non-contact methods, against measurements taken in the traditional manner, we can determine which approach offers the best solution, taking into account the need for an end-product to be functional, reliable and practical in terms of clinical operation.
Heart Rate (Pulse) Measurement:
There are a few locations around the head area, where pulse can be measured e.g.:-
Heart rate variability (HRV) is a reliable indicator of a person’s health and provides a sensitive index of autonomic stress reactivity. The practicalities involved in non-contact measurement of a person’s HRV, present a number of challengers that have led to differences in the methodologies and technologies that have been trialled by researchers in various parts of the world.
We will test the most recent technologies including digital colour video, in order to define their accuracy and suitability for adoption as a key part of our array of vital sign measurement tools.
Respiration Rate: Our research programme will work through trialling the various technologies and methodologies In order to establish whichever one of those non-contacts vital sign measurement techniques provides the most accurate measurement data to determine a person’s respiration rate.
Terahertz Radar has been adopted, using various signal processing techniques, as a way of measuring the displacement of a subject’s chest wall, due to respiration and heartbeat.
Another innovative non-contact system, which uses radio-frequency signals and microchip tags, is described as Near Field Coherent Sensing. This (NFCS) methodology directs electromagnetic signals into body tissue, allowing the tags to measure internal body movement such as a heart-beat. The tags are powered by electromagnetic energy and transmit a unique signal back to a reader to gather blood pressure, heart rate and respiration rate.
Thermography has also been used (in combination with a patient wearing a mask), to measure breathing with the inhalation / exhalation of the lungs being acquired in real time image sequencing, from which the respiration rate can be determined.
Thermography: By being able to accurately quantify (for the first time) very small increments of temperature in an individual, there is the potential for clinicians to identify new “thermal signatures” from 360° data, that could lead to early-stage diagnosis of a range of illness or even in asymptomatic Covid-19 patients who do not display “fever.” Other areas (e.g. wrist & hands) would be included.
This element of the research would involve carrying-out a range of thermographic assessments of individuals, followed by a detailed scientific analysis of the temperature data, including the nature and location of any potentially meaningful anomalies found. A clinical review of the data-set analysis would then feed into the vital scan algorithm, to produce a medical diagnosis (healthy or possible infection).
Over the research period, we would define a clear set of technical parameters and best-practice methodology in order to ensure “repeatability and accuracy” of the thermographic patient assessments.
Combined Data-Set: The individual measurements captured by the various non-contact assessment methods, will be compared with vital sign data obtained in the traditional manner (i.e. involving physical contact). We can then determine which combination of technologies offers the best solution, taking into account the need for any end-product to be functional, reliable and practical in use.
Once the technical parameters and a suitable methodology have been selected for the thermographic body temperature scan, the other measurements (captured via other technologies) of the individual’s respiration and heart rates, would be undertaken, to complement the infrared data. All of the data would then be processed, analysed and fed into an algorithm to produce an indicative clinical diagnosis.
Over the research period, we will have arrived at a stage where a clear set of technical specifications and best-practice methodology can be determined for the infrared thermographic temperature measurement, together with each of the other non-contact technologies that have proven to deliver “repeatability and accuracy” when capturing the heart and respiration rates i.e. vital signs measurements.
The combined data-output generated from each of the measurements systems, will be processed via the software and will form the basis for a clinical diagnosis of that person’s state of health to be made.
Further non-contact assessments and clinical analysis of the data produced, will be undertaken on a number of individuals within a control group, in order to ensure accuracy and to inform improvements to the custom-designed software programme, that produces a diagnostic analysis of the data.
It is feasible to project that; with confidence in the data, the Alba Vital Scan software could produce a “Healthy or Infection” diagnosis independent of clinical intervention. By combining the data from the three elements in a software programme, with algorithms that will process the sensor input and produce an accurate data-set from which a detailed analysis and medical diagnosis can be made.
In the initial stages of the project, when research into sensor accuracy is being undertaken, all of the measurement hardware will be housed in a prototype mobile workstation, adapted around existing NHS standard units and with adjustments in height, sensor focus, direction and distance from the person. e.g.:
Prototype Mobile Workstation
The Basic design of the prototype unit will allow various types of sensor systems to be mounted and installed. Adjustment of height and distance will be a built-in feature. All of the sensor output data will be linked into the PC for processing. An indicative result on the patient assessment will be delivered by the Alba Vital Scan.
Following-on from that functional prototype, we will develop a custom-designed robotic unit that has the data-capture hardware mounted on a remote control mobile platform. A computer system, complete with Alba Vital Scan diagnostic software and an integrated iPad to facilitate control of all functions and remote communication between clinician and patient will also be housed in this unit.
Development of the Robotic platform is based on the premise that, wherever possible, clinician’s should be protected from direct contact with any individual who may be suffering from an illness which is highly contagious, at least until an initial state of health assessment, has been undertaken remotely.
The data obtained from a remote facetime interview between doctor and patient, together with the output from the Alba Vital Scan diagnostic programme would allow a clinical assessment to be made on the level of risk associated with that person and what steps (e.g. isolation) were necessary in the management and treatment of the patient’s condition going forward.
It is envisaged that design and engineering of the integrated Alba Vital Scan unit can be further developed and that sensor technology will improve alongside continuous update of the diagnostic software. On that basis, we would expect costs to be brought-down to a level where the unit would be affordable for adoption across all of the NHS and in general practice in the future.
In particular, the advances being made in the capabilities of infrared thermographic systems have led to a wider uptake of applications in the marketplace, resulting in cost reductions at the lower-end of camera specifications. The new scientific-grade thermographic imagers will have many valid applications across a number of areas of medicine, both in clinical diagnosis and monitoring.