Protocol for Clinical Thermography

Definition

Clinical thermography is a non-invasive, diagnostic imaging procedure involving the detection and recording of a patient's skin surface thermal patterns, using instruments which can provide visual and quantitative documentation of these temperature measurements. The interpretation of these temperatures and thermal patterns can be important in the development of a diagnostic impression.

Thermography is appropriate and germane to any health care practice whenever the treating physician feels a physiological imaging test is needed for diagnosis or case management. It provides information about acute as well as chronic conditions and can be useful in distinguishing aggravated from residual tissue injury. Thermography is an imaging technology which provides information on the normal and abnormal functioning of the sensory and sympathetic nervous systems, vascular dysfunction, myofascial trauma, and local inflammatory processes. It may contribute to a diagnosis and patient management by aiding in the determination of the site and degree of lesion, the type of functional disorder, and the prognosis for treatment outcomes, as well as assisting the determination of the most effective course of treatment through continual case evaluation.

Thermography is an acceptable analytical procedure which may be performed by a licensed or certified professional or under their direct supervision in specific cases which demonstrate adequate clinical justification. However, only a certified professional, holding appropriate credentials with regard to knowledge, skill and experience in thermography may interpret the results.

Currently there are two recognized methods of thermographic imaging: infrared thermography (IRT) and liquid-crystal thermography (LCT).

Procedures

Clinic: The temperature of the room should be such that the patient is neither perspiring nor shivering. The preferred temperature range is between 18-23^oC (64-74^oF). Room temperature changes during the course of an examination must be gradual, so that all parts of the patient's body can adjust uniformly. The temperature should not vary more than 1^oC (1.8^oF) during the course of a study. The examining room must have an ambient temperature thermometer to monitor the room temperature.

The thermography room should be carpeted and windows should be covered to prevent excess infrared radiation from entering or escaping the room. Shades or blinds may be adequate for this purpose. Windows and doors should be adequately sealed to prevent drafts, especially in the area where the patient is positioned. Standard fluorescent or thoroughly diffused incandescent lighting is adequate, with fluorescent lighting preferred.

Heat and air conditioning sources should be minimized in the room, and must be kept well away from the patient. Vents should be directed away from the patient and should be thoroughly baffled or turned off during any examination.

Patient: The patient should equilibrate with laboratory ambient conditions for sufficient time to approximate a steady state. Further equilibration results in minimal surface temperature changes with little or no effect on clinical impression. The equilibration period should be at least 15-20 minutes. During the equilibration period, and the subsequent examination, the area to be viewed should remain completely uncovered of clothing, jewelry or gowning. A loose gown may be worn, provided that it does not restrict air flow for equilibration and does not constrict or irritate the skin surface in any way which would produce an artifactual result on the thermogram. Special gowning procedures, specific to the clinic or examination, may be required and are permitted, as long as the above stipulations are observed.

The patient may be provided with instructions intended to reduce the likelihood of artifacts or inconclusive thermography. Make-up, vasoactive drugs, and therapy which will produce altered cutaneous blood flow or emissivity are discouraged or restricted for appropriate periods prior to thermography.

Equipment: Liquid-crystal thermography employs a range of interchangeable detector "screens" or "pillows" which are impregnated with cholesteric methylester derivatives and change color as a function of their temperature. The thermal precision of the equipment is generally within 0.2^oC -- adequate for clinical interpretation.

Electronic telethermography equipment scans the field-of-view in two dimensions simultaneously via an infrared detector. Temperature repeatability and precision of 0.1^oC or better is standard for electronic thermography equipment. Absolute temperature measurements are generally not required for a clinical diagnostic impression; relative temperatures and temperature differentials are the relevant parameters.

When multiple views are required for bilateral equivalent areas, the detector selection or equipment settings must not be altered for the two views.

Electronic studies should be performed with the scanner perpendicular to the surface to be viewed. If other than perpendicular views are required, the angle must be kept exactly the same for comparable, bilateral views.

Documentation: Each thermography series should include all or as many body surfaces as possible, which are relevant to the patient's complaint and symptomatology, along with anatomically and physiologically-related areas. These records (views) should contain as much detail as possible for the equipment type used.

Each thermographic image, captured on archival media, should contain an indication of the anatomic view in the image (if not apparent) along with the following minimal information, either included with the original image or immediately traceable to other archived documents:

1. patient's name or identification code
2. clinical facility name and address
3. name of the professional rendering the thermographic service
4. date the service was rendered

If a patient identification code is used, it must be clearly identifiable on each archived document, whether a single view, a series, or the patient records in the clinic files.

Examination protocol: A thermographic series consists of one or more images, captured on archival medium, which permit the evaluation of the body surface area relevant to the purpose of the examination. Typically, the entire face and upper body, or the lower body is examined. Specific or limited views may be appropriate in the diagnosis or evaluation of a particular disease, lesion or injury.

A single thermographic series is considered adequate if performed by the thermographer under appropriate conditions outlined elsewhere in this document, and if the findings are negative with respect to the clinical impression. If the examination is performed by a technician or if findings are questionable or positive with regard to the clinical impression, a second series is required to rule out artifacts and confirm the abnormal findings. The second and subsequent studies may be done on succeeding days or even later. Stress studies involving symptom exacerbation, autonomic challenge or alcohol spray may be performed following a first, baseline, thermographic series.

International Thermographic Society

Editor's Note:

The International Thermographic Society (ITS) was chartered in 1983. The ITS describes itself as a sponsor of "educational symposia and research grants to foster a greater understanding of the theory and use of thermography. It was one of the first organizations to publish a protocol for the clinical performance of thermography, and it was responsible for the establishment of the first thermography certifying agency in chiropractic, the American Board of Clinical Thermology."