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Intro

Human Dynamics Thermography
About Medical Infrared Thermography
Exploring Thermography?
Discussion of Specifications
Camera Specifications
Choosing a Thermography Company




 
 
Discussion of Specifications

If you are investigating thermography, the technology is a major consideration, and is typically the most difficult to assess. The following discussion of the specifications attributed to infrared technology in relative layman’s terms, along with the benefits will assist you in understanding this highly technical device. If you are gathering information for someone else to review, you will want to copy this page.

Technology/Detector: Today, the un-cooled Focal Plane Array (FPA) Microbolometer is based on an infrared thermal detection mechanism which is particularly suited to operate at ambient clinical temperature. This technology has created the opportunity to achieve high performance temperature capture at a more affordable cost. In addition, it has the advantages of long life, light-weight and near instant-on operation. You will find that all current medical infrared technology has adopted the FPA technology.
Material: Vanadium Oxide is one of the most widely known and used material for the microbolometer technology. It is a material that optimizes the image quality specifically for the medical application. It facilitates the ability to achieve a more desirable thermal sensitivity (see below). In the quality vs. cost analysis, vanadium oxide is the undeniable material of choice. Because of these two major benefits, it has set the newest medical infrared industry standard.
Spectral Response: The spectral response is essentially the camera sensors' ability to capture incoming radiation within specific EMF (electro magnetic frequencies’) bands and wavelengths. In the case of medical imaging, the goal is to capture accurate image(s) of infrared data that accurately differentiates the variant surface temperatures of human tissue.
Thermal Sensitivity: This is probably one of the most important technical considerations when assessing camera performance. The camera’s thermal sensitivity refers to its sensors' ability to distinguish differentiation in energy impinging on the sensor from the target being imaged (or infrared data). The lower the number, the better for the analysis of temperature variance in human tissue.
Data Output: The most fundamental difference between the data output hardware of the analog video data and the digital data is not functionally significant when taking into account the device’s end functions and responsibilities in the medical environment. The primary goal of each device is to simply display to its user, in a static image or live video, accurate temperature data of human surface tissue for analysis. However, a camera system that outputs it’s data in a digital format better preserves the dynamic range of the image and therefore provides a more robust effective thermal resolution relative to the raw data generation by the sensor.
Refresh Rate/Frames Per Second: This is a measure of the rate at which an image is collected within the camera and at what subsequent rate that image is sent to a display device. This becomes important when imaging of a high speed event is taking place, or in the unavoidable movement of the patient while imaging. An increase in the Frame Per Second (FPS) will also allow for the capture of rapid temperature change.
Optics: The differentiation in lens optics are purely visual preferences of the user. In the medical environment, practitioner users prefer the angle and depth of the 25mm or 18mm lens, however this is not a specification that will make a significant difference in the over-all performance. All else being equal, the device’s primary function is to provide the capturing agent with accurately rendered images and video representational of a patient’s surface temperature.
Array Resolution: A major consideration when considering camera performance. Most commercially available modern imagers use a sensor technology called focal plane array (FPA). This means that the sensor in the camera is, in fact, an array of sensors, not just one. There are two array sizes that are standard in today’s medical cameras; 160x120 and 320x240. The 160x120 array for example has a two dimensional configuration that posts 160 sensors in the horizontal direction and 120 sensors in the vertical direction, or 19,200 individual sensors. In contrast the 320x240 has a comparative 76,800 sensors, or 4 times more sensors. It is intuitively obvious that the more sensors you employ towards a target the higher spatial quality the resultant image will be (referred to as spatial resolution). While the 160x120 camera will provide a high quality image, the 320x240 camera will provide 4 times the ability to detect and present spatial detail of the target being imaged.