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Thermal Imager Fundamentals
Published in James Stewart Campbell, M. Nathaniel Mead, Human Medical Thermography, 2023
James Stewart Campbell, M. Nathaniel Mead
One of the key metrics for assessing an imager's sensitivity is the Noise Equivalent Temperature Difference (NETD). This is a measure of how well the detector is able to distinguish between very small differences in infrared radiation represented within the image. More specifically, NETD is the difference between two temperatures needed to generate a variation of the thermal imager signal equal to its quantum noise level. It can be understood as the imager's thermal resolution and is typically expressed in milli-Kelvins (mK) or degrees centigrade (oC), with 100 mK equaling 0.1°C NETD.
Investigative Duties on Scene
Published in Kevin L. Erskine, Erica J. Armstrong, Water-Related Death Investigation, 2021
Everything on the earth gives off thermal energy, even ice. The hotter something is the more thermal energy it emits. Temperature also affects wavelength and frequency. Objects at room temperature radiate energy as infrared waves. Energy radiating from objects is a range of wavelengths. As an object temperature increases, the wavelength decreases. Hot objects emit shorter wavelengths and higher frequency radiation. Thermal camera specifications list technical details as Noise Equivalent Temperature Differences (NETD), which is a measure for how well a thermal camera can detect thermal differences. NETD are typically expressed in milli-Kelvin or mk. The scientific details of thermal imaging can be very complex, yet the equipment is very easy to use with little training, and the color-coded images are easy to understand and interpret.
Quality Assurance Procedures and Infrared Equipment Operation
Published in Kurt Ammer, Francis Ring, The Thermal Human Body, 2019
Thermal resolution is often described in terms of the NETD (noise equivalent temperature difference), or the MRTD (minimum resolvable temperature difference). Both of these criteria refer to the ability of the system to detect a small change in temperature of an object in the field of view. A simple way of testing for thermal resolution is by imaging the surface of a container of heated water to a known temperature. A mask of rigid material is placed near to the water surface, with varying size apertures. From the thermal image, the aperture size that yields temperature readings close to the known water temperature will indicate the approximate thermal resolution of the system at the distance set, and with the optical settings used.
Dynamic thermal imaging for pigmented basal cell carcinoma and seborrheic keratosis
Published in International Journal of Hyperthermia, 2021
Yoo Sang Baek, Anna Kim, Ji Yun Seo, Jiehyun Jeon, Chil Hwan Oh, Jaeyoung Kim
We used a modified version of the DTI system used in previous studies [11,12]. Thermal images were obtained using a thermal imaging camera (FLIR® A615, FLIR Systems, Wilsonville, OR), which has an infrared resolution of 640 × 480 pixels. This camera measures the temperature variation of the subject with a frame rate of 50 Hz, a noise equivalent temperature difference (NETD) <0.05 °C × at 30 °C and accuracy of ± 2% of the overall temperature reading. For thermal provocation (heat and cold stimuli), we used a thermoelectric cooler (TECH3S, Thorlabs, Newton, NJ) and a resistance temperature detector (TH100PT, Thorlabs). In addition, we used a heater controller (TC200-EC, Thorlabs) to ensure that the stabilized heat and cold stimuli were applied to the target. The size of the heating and cooling regions was approximately 2.0 × 2.5 cm. This was sufficient to cover the target lesion (pigmented BCC or SK, typically about 1.0 cm in diameter) with 0.5–1.0 cm beyond the target’s clinical margin.
Noninvasive intratumoral thermal dose determination during in vivo magnetic nanoparticle hyperthermia: combining surface temperature measurements and computer simulations
Published in International Journal of Hyperthermia, 2020
Gustavo Capistrano, Harley F. Rodrigues, Nicholas Zufelato, Cristhiane Gonçalves, Clever G. Cardoso, Elisangela P. Silveira-Lacerda, Andris F. Bakuzis
The IR Cam spectral bandwidth of acquisition is in the long-wave infrared range (7.5–13 μm), with a temperature measurement ranging from –40 °C to 500 °C and uncertainty of ±2% (an uncooled vanadium oxide-based microbolometer detector). Noise-equivalent temperature difference is less than 40 mK at 30 °C. The objective lens has a focal length equal to 19.31 mm and when IR Cam is placed at a distance d = 50 cm and a resolution of 640 2: a horizontal size of 410 mm and a vertical size of 310 mm, since each pixel has the physical squared dimension of (0.65 2. The commercial software used for IR imaging analysis was the FLIR ResearchIR® (version 1.2.10173.1002). During the MNH treatment, the objective lens of the IR Cam is maintained parallel to the normal direction of the animals tumor to avoid curved object error effects on the surface temperature determination. The temperature error with IR Cam in the in vivo MNH studies is estimated to be 27].
Thermal Imaging of the Ocular Surface in Thyroid Eye Disease: A Comparison between Active, Inactive and Healthy Eyes
Published in Current Eye Research, 2021
Tarjani Vivek Dave, Palash Patodi, Ashutosh Richhariya, Vivek Pravin Dave
The thermal imaging was performed using an infrared thermal camera (Python 640, Analinear technologies, Hyderabad, India). The array type of the camera was 640 × 480 – aSi Micro bolometer with a spectral band of 8–12 µm long wavelength infrared beam. The NETD (Noise equivalent temperature difference) of the camera was <40mK. The infrared (IR) lens used had a focal length of 50 mm and an aperture size of f/1.2. To ensure that the camera is not affected by external atmospheric factors, it was placed inside a controlled environmental chamber. The temperature and humidity were maintained at 25°C and 50%, respectively.