Standardized environmental and laboratory conditions for clinical infrared thermography (IACT, 2015) [32, 33].
| Standardized environmental and laboratory conditions | |
|---|---|
| Environment and laboratory | |
| Ambient temperature | The room should be maintained between 18°C and 23°C. |
| Temperature stability | The room temperature should not vary by more than 1.0°C during the examination. |
| Humidity control | Humidity should be controlled to avoid moisture accumulation on the skin, perspiration, or vapor. |
| Airflow | The room should be free of drafts. Doors and windows should be sealed. |
| Infrared (IR) radiation sources | Windows should be covered or shielded to prevent entry of external IR radiation. Heating or air-conditioning ducts should be kept away from the patient or turned off. |
| Lighting | Incandescent lighting (which produces IR radiation) should not be used during the examination. Standard fluorescent lighting is adequate. |
| Patient preparation | |
| Acclimatization (equilibration) | The patient should undergo a minimum acclimatization period of 15 minutes in the examination room environment. |
| Skin exposure | The area to be imaged must remain completely uncovered by clothing or jewelry. For breast examinations, the breasts must remain uncovered throughout the entire acclimatization and imaging period. |
| Sun exposure | The area to be analyzed should not be exposed to sunbathing/tanning in the 5 days prior to the examination. |
| Topical products | Do not use lotions, oils, creams, powders, makeup, deodorants, or antiperspirants (for trunk/breast examinations) on the day of the exam. |
| Physical stimuli | Do not undergo physical therapy, EMS, TENS, ultrasound, acupuncture, chiropractic treatment, sauna, or use hot/cold packs within 24 hours before the examination. |
| Physical exercise | Do not exercise on the day of the examination. |
| Bathing | If showering, it must be at least 1 hour before the exam. Immersion baths (bathtub) are prohibited in the 24 hours prior to the exam. |
| Minimum equipment requirements | |
| Spectral range | Detector response must be greater than 5 µm and less than 15 µm, encompassing the 8–10 µm region. |
| Emissivity setting | Emissivity must be set to 0.98 (human skin). |
| Absolute resolution | At least 19,200 temperature measurement points per image frame. |
| Spatial resolution | 1 mm2 at 40 cm (2.5 mrad IFOV). |
| Thermal sensitivity (NETD) | Less than 80 mK. |
| Precision (repeatability) | Ability to detect a temperature difference of 0.1°C. |
| Absolute accuracy | ± 2°C or ± 2% of the reading, whichever is smaller. |
| Image acquisition protocol | |
| Personnel qualification | Image acquisition should be performed only by personnel credentialed as a certified clinical thermography technician or certified clinical thermologist. |
| Positioning (angle) | The detector(s) should be as perpendicular as possible to the surface being imaged. |
| Positioning (bilateral views) | If non-perpendicular views are necessary, the angle must be kept exactly the same for comparable bilateral views. |
| Settings (bilateral views) | Equipment settings (color scale and temperature range) must not be changed between the two views. |
| Field of view (FOV) | The body region of interest should be brought close enough to the detector to fill the visible image area. |
This table summarizes minimum environmental control variables, acclimation and participant preparation requirements, operational specifications for the acquisition environment, and restrictions required to ensure repeatability and comparability of thermal image acquisition in clinical and research settings [32, 52]. IACT: International Academy of Clinical Thermology; EMS: electrical muscle stimulation; IFOV: instantaneous FOV.