Choose Best Thermal Imaging Cameras for Medical Applications

Are you planning to purchase or use thermal imaging cameras for clinical applications? It's crucial to understand certain specifications before making your decision. In this blog, we'll delve into the crucial factors you need to know about when choosing thermal imaging cameras for medical use.

Thermal imaging cameras are sophisticated devices designed to detect and convert the long-wave infrared radiation emitted by objects into temperature values. While these cameras have long been popular in industrial and military settings due to their ability to visualize heat signatures, its usage in clinical applications is gaining traction. This shift is driven by the recognition of affordable, radiation-free and portable thermal imaging's potential to aid in medical diagnostics and patient care.

Unlike in industrial or military settings, where thermal imaging may serve broader surveillance purposes or identify heat anomalies, the clinical use of these cameras requires precision and accuracy in temperature measurements. In healthcare settings, accurate temperature values play a crucial role in diagnosing medical conditions, monitoring patient progress, and guiding treatment decisions.

When selecting thermal imaging cameras for medical applications, one needs to look at certain key specifications as discussed below:

Spatial Resolution: Spatial resolution refers to the level of detail and clarity in thermal images. Higher spatial resolution allows for better visualization of temperature variations and subtle changes, which is essential for detecting abnormalities or anomalies in medical imaging. Most medical applications require a minimum spatial resolution > 240x320 pixels. 

Thermal Sensitivity: Thermal sensitivity, often measured in millikelvins (mK), indicates the camera's ability to detect small temperature differences. A lower thermal sensitivity value signifies higher sensitivity and the ability to detect minute temperature variations, making it crucial for medical applications where subtle temperature changes may be significant. Most medical applications require thermal cameras that have thermal sensitivity < 60 mK.

Accuracy: The accuracy of temperature measurements is paramount in clinical settings. Look for cameras that offer high accuracy and precision in temperature readings, typically expressed in degrees Celsius or Fahrenheit. A deviation in temperature measurement can significantly impact diagnostic decisions. The current medical applications require thermal cameras that have an accuracy within ± 2°C.

Radiometric Export: Thermal imaging cameras capture the long wave infrared radiation emitted from a body and converts it into raw temperature data. This raw temperature data is called radiometric information. Accessing the radiometric array is essential for obtaining precise temperature values. It's important to note that not all thermal cameras support radiometric export; some only provide color images obtained by converting temperature values using a pseudo-color palette. 

Field of View (FOV): The Field of View refers to the area that the camera can capture in a single image. In clinical settings, the FoV plays a significant role in determining the camera's usability and applicability for specific medical tasks. A wider FoV is beneficial for clinical examinations where a broader area needs to be assessed, such as screening multiple body parts or monitoring large anatomical regions simultaneously. For screening a single body part such as breast or foot, a FoV of 25° X 19° is recommended. 

Focus: Focus plays a critical role in the quality and accuracy of thermal images, impacting diagnostic interpretation and overall visualization. Thermal cameras offer various focus options, including fixed focus, motorized focus, manual focus, and auto focus.

• Manual Focus: Manual focus requires users to physically adjust the focus ring on the camera lens to achieve optimal focus. This method offers precise control but may be time-consuming and requires operator expertise.

• Motorized Focus: Cameras with motorized focus allow for remote adjustment of focus settings, offering convenience and adaptability in capturing images at different distances.

• Auto Focus: Auto focus is automated and adjusts the focus automatically based on the subject's distance, ensuring sharp images without manual intervention. This feature is particularly beneficial in clinical settings where quick and accurate image capture is essential.

• Fixed Focus: This type of focus is set to a specific distance and cannot be adjusted. While it simplifies operation, it may limit flexibility in capturing images at varying distances.

In most clinical applications, auto focus or fixed focus thermal cameras are commonly preferred as they ease the image capture.

Frame Rate: The frame rate of a thermal imaging camera determines how quickly it can capture and display thermal images. A higher frame rate is beneficial for dynamic applications such as monitoring physiological processes or capturing fast-moving subjects during medical procedures. For static imaging, a Frame Rate of 9 Hz suffices, but dynamic thermography may require higher rates such as 30 Hz, 60 Hz, or 100 Hz to capture thermal variations over time. 

Integrated Visual Camera: For many clinical applications, having a visual camera along with thermal camera might benefit tasks such as registration, segmentation etc. This integration also facilitates clearer anatomical reference points, aiding in precise image analysis and interpretation.

Regulatory Compliance: Ensure that the thermal imaging cameras comply with relevant regulatory standards and guidelines for medical devices. Compliance with standards such as ISO 13485 (Medical Devices Quality Management Systems) and FDA regulations (for cameras intended for clinical use in the United States) is essential to ensure safety, reliability, and legal compliance.

Below are some thermal cameras that are widely used for clinical applications:

1. Teledyne FLIR: Teledyne FLIR is a major player in the thermal imaging industry with a significant market share globally. In clinical applications, the FLIR Axxx Series, Exx Series, and Txxx Series are widely utilized. All these devices are FDA cleared with an intended use as an adjunct to other clinical diagnostic procedures in the diagnosis, quantifying, and screening of differences in skin surface temperature changes. It can visualize, document temperature patterns and changes. Additionally, the FLIR One Pro, a mobile attachment, is gaining attention for its potential in low-cost medical imaging applications.

2. SpectronIR: SpectronIR Medical Infrared Imaging offers thermal cameras that are specifically designed for medical applications. TyTron C-500 IR is their flagship FDA cleared product with  an intended use of adjunctive diagnostic screening for the detection of breast cancer and other uses such as: peripheral vascular disease, neuromusculoskeletal disorders, extracranial cerebral facial vascular disease, thyroid gland abnormalities, and various other neoplastic, metabolic, and inflammatory conditions.

Spectron IR

3. Medicore: Medi-core is a leading manufacturer and distributor specializing in medical products, encompassing a range of solutions beyond thermal imaging. Their flagship medical thermal imaging product is called IRIS-XP, which is FDA/CE approved with an intended use for measuring relative skin temperatures generated by the human body in the clinical, hospital, acute care settings, surgery, healthcare practitioner facilities or in any environment where healthcare is provided by a qualified healthcare professional.

IRIS-XP

4. ICI Infrared Cameras: ICI (Infrared Cameras Inc.) also offers a range of advanced thermal imaging solutions for diverse industrial, medical, and scientific applications. In clinical applications, FMX 400 P-Series Medical, IR-Pad 640 S Series Gen 2 Medical and FMX 700 P Series are prominently used.

5. Seek: Seek thermal cameras are mainly used for firefighting and military  applications.  During COVID-19,  Seek Scan™ Kiosk is released for fever screening.

Regular Calibration of Thermal Cameras

It is also important that one need to regularly calibrate thermal cameras for accurate temperature measurements. This is necessary because over time, electronic components within a thermal camera may age, deteriorate, or undergo changes. These changes can lead to a gradual drift, known as calibration shift, in the camera's temperature readings, resulting in inaccurate temperature measurements. Calibration is essential to correct for such drift and ensure that the camera continues to provide accurate measurements. The frequency of calibration may vary based on factors such as camera vendor, camera usage, environmental conditions, and the required level of accuracy for specific applications.