Thermal camera for body application

[KonradF]

Hello everybody !

This is my first post on this forum  . I spent the last 2 days looking for informations about thermal cameras here and it has been very very helpful. Thanks a lot !

I'm currently looking for a thermal camera to a body application. I can't really say a medical use because it won't be for pathology diagnosis. I know that the brands advertising for medical applications are often very very pricy and I cannot afford more than 2k €.

I never owned a thermal camera so I don't know what kind of spec it needs to be able to see interesting things on a human body. For exemple heat differences on the back or on the arm.
One year ago I thought that I needed to invest at least 5k € to get something but recently I saw someone getting some good informations for clinical use with a seek reveal pro.
I was quit skeptical, the image was quit blurry but I could see some heat differences in the same area.

So I looked for other cameras to see if they are better options. I end up with:

-Seek- shot pro: 880€
-Opgal-Therm-app Hz: 1550€
-Thermal Expert-Q1 plus: 780€

Prices I found for Europe

I read also about the xInfrared TS3 and HT 301 but I can't find any store or a lots of informations are missing.

- Are these "good" cameras ? Or on what specs I have to focus on ?
- Are there other cameras more suitable to use on human body ?
(- Do you have some pictures of your hands for exemple to see the differences ?)
- Is thermviewer a must have ? Are native apps so bad ?

The Q1 seems to be more apealing to me because it seems to have the better spec for the price but I read it's not compatbile with thermviewer
The Shot Pro is too expensive for the quality according to what I read on this forum.
Therm-app is 2 times more expensive but it seems to have more third part apps like thermviewer.


Thanks for help 

cordially,

Konrad

[Max Planck]

Hello Konrad,
if I were you, I would start reading as much as possible about medical thermography protocols. In many application there is need for subject temperature stabilisation, i.e. a patient has to spend about 15-20 minutes in a room with more or less controlled temperature, without any physical effort. There are also many other problems.
I think that your description of your intended application is too vague to be able to give you a precise answer.

Max
 

[Fraser]

There are some excellent books on medical and veterinary thermography. If not already fully investigated, it would be worth reading them. There is a good reason why such applications sometimes need quite expensive thermal cameras. Temperature differences in tissues can be subtle but significant. There are many challenges in medical thermography and the user needs to be able to trust the information provided by the equipment used.

Now that I have got that out of the way. It would be worth describing your application of thermography in more detail. There have been many studies involving thermography examination and imaging of animals and humans. There are some areas where it is useful, and others where it can be misleading. As with many diagnostic tools, it is often just part of a wider diagnostic ‘tool kit’. I understand that your use is not for pathology, but it would really help to know the application. This will dictate the quality of radiometric data that you need from a thermal camera. Some of the simpler, lower cost cameras offer little by way of a guarantee of accuracy and where imaging humans is concerned that can be an issue as even a 1C difference beyond nominal can be significant in some scenarios. Most thermal cameras have an accuracy specification of +-2C and this is to be considered when taking measurements. In any sort of study involving measurements, repeatability accuracy is important.

The more expensive thermal imaging cameras usually, but not always, provide superior measurement accuracy, repeatability (important in a study) and resolution. Image quality can be degraded by noise content, poor video processing and other factors that could cause a study problems.

When imaging a human, it is common practice to use a temperature reference black body within the field of view. This provides a known temperature for use when interpreting measurements. Such a black body reference would normally cost more than the budget that you have for your thermal camera.

Fraser

[KonradF]

Thanks for the answers.

I read about some protocols but I didn't know about the black body.
Actually it's not for high level research or for specific diagnostics. It's more to start in the field and discover interesting things to see on living things  .

The thing is that the specs don't seem to be representative of the quality of the camera and it's quit disturbing.

I looked at some cameras used in research or to help in diagnosis:

-Some veterinary research used the Flir ThermaCAM® P25 (http://alacron.com/clientuploads/directory/Cameras/FLIR/P25-Datasheet.pdf) which thermal sensitivity is 80mk, accuracy +-2°C, 320 x 240 pixels.

-Some thermal centers use the Meditherm camera, which is built for medical application (https://meditherm.com/iris_450.html). It has a 40mk thermal sensitivity, accuracy +-2°C,380 x 280 pixels. The meditherm spec displays other information like "Temperature measurement sensitivity (comparative Δ)" : 0.01℃.

When I look for exemple at a Q1 with the following spec:
-array format : 384 x 288
-NETD : < 50mK
-accuracy +-2°C
It seems quite near the specs of the pro cameras.

So are Q1 lying about the specs ? Or is it for specific temperature range ? or do I have to look at other specs like comparative delta  ?

If you can give me some references for the books, I'll be grateful .

Konrad.
 

[Vipitis]

the cameras you mentioned are older, and today we have newer sensor design. the pixel pitch is reduced but other improvements in the ROIC and processing can still allow these modern phone dongle to have the specs they stated. There is a whole argument about those claims and that they have no common protocols. Lenses are also way different. my suggestion is to look at examples for the exact thing you want to see.

[Fraser]

https://books.google.co.uk/books/about/Medical_Infrared_Imaging.html?id=5BrXeG3XkKoC&printsec=frontcover&source=kp_read_button&redir_esc=y


https://books.google.co.uk/books/about/Equine_Thermography_in_Practice.html?id=A5-rDAAAQBAJ&printsec=frontcover&source=kp_read_button&redir_esc=y

[Bill W]

When I look for example at a Q1 with the following spec:
-array format : 384 x 288
-NETD : < 50mK
-accuracy +-2°C
It seems quite near the specs of the pro cameras.

So are Q1 lying about the specs ? Or is it for specific temperature range ? or do I have to look at other specs like comparative delta  ?

Konrad.

The Q1 is using a good sensor, and the NETD spec belongs to the sensor.
NETD = <50mK (with f/1 lens, in ideal conditions)
Q1 has lens: 6,8mm f1.3, so NETD in system is <85mK
Q1 may, not unreasonably, have compromised electronics compared the the 19" rack unit used to test sensors.
Q1 may not even be running the sensor as per the <50mK test, again for good reasons if they do.
Q1 do not know about the display you will connect, so cannot give a system 'visible difference' number like MDTD or 'comparative Δ'

An MDTD or 'comparative Δ' of 10mK is really very good on the Meditherm, and suggests a lot of added value processing to get that from a <40mK sensor.

Bill

[bap2703]

Do you know if you require a thermographic camera?
Ie do you want to retrieve the actual temperature (that pixel is at that temperature) or just see temperature variations (that pixel is hotter than this one).

Then you can dig further: do you want the surface temperature or the inside body temperature? For example think of a non contact thermometer: it reads your surface temperature and translate that measurement to the equivalent internal temperature you are used to analyse --> your surface temperature is never near 37°C.

[KonradF]

Thanks for the answers and for the books .

I think I just want the temperature variations. For me it's not important to have the exact temperature. If I can see differences between the right and left hands, it will be good ^^. The main goal is to find asymetries, regions that are too cold or too hot.


According to one of Frasers book reference page 1-13, the therm-app and Q1 are good for informal application.

I think I'll go for the Q1, my colleague will try the therm app th .

[Fraser]

KonradF,

I am pleased that my book reference helped you in your decision making process. It is an excellent book that I purchased from a nurse who was studying thermography of the human body as extended training. Though an expensive book to purchase in hard format, it is worth it for those wishing to better understand what thermal imaging can offer in the human body imaging scenario.

The first chapter is full of information that, as you have seen, is invaluable for understanding the type and quality of thermal imaging camera needed for working on the human body.

I hope you enjoy your journey into thermal imaging and the world that it reveals to us with its interesting and revealing images.

Fraser

[Vipitis]

Having a student ID card now allows me to access a giant library of our University. I did a quick search for "thermography" and found a few dozen entries. I found the isle for introduction into physics and already a handful of old but very detailed textbooks on the thermography. There were some entries for medical thermography as well, but turns out all medical books are in a different buildings I haven#t been to yet.

I don't see the need yet to read physics textbooks, as I feel I understand enough for now. But a book in your hand is sometimes better than 20 chrome tabs.

[Spectron IR]

Hello Konrad!

There can be lots of misleading information when discerning differences in IR camera technology. Many factors have to be taken into account in order to understand. Fraser has provided some great information and references. It pretty much boils down to what your application is and how accurate do you want to be? The cheaper the unit, the less accurate and repeatable the imaging will be. If you are imaging a person for ANY clinical application, you would really want a much higher quality system. Thermal sensitivity can be a difficult spec to understand. At first, you may think a more sensitive camera the better the camera. This is not always the case. In fact, if a camera is very sensitive (20 mk) it can be very susceptible to "drift" internally in the camera body itself and environmentally from the surrounding atmosphere. This drift can lead to scene changes and level differences in the images being captured. To assist in reducing this, Some medical IR camera manufacturers have placed TEC's (thermoelectric cooler)inside their cameras to stabilize internal camera temperature after a warm up period. The warm up period on the camera can vary on the mass of the camera. Generally, a larger mass takes longer to stabilize but is also less susceptible to drastic changes in temperature due to its mass. The warm up period on an IR camera could be 10 minutes to an hour. This is the time it takes for the temperature to stabilize after the camera has been turned on and from the working electronics producing heat. Small cameras that have little mass, no TEC and high sensitivity can vary in the temperature level you see from image to image. This is the camera drifting. IR cameras due have a NUC (non uniform correction) that they perform, some perform this automatically and it adjusts the camera back to a previous setting before the drifting occurred. This NUC is not a calibration but a correction of the FOV (Field of View). In IR, there is a concern with the uniformity of the detector and the output data. non uniformity can be really any shape and can be unnoticed really changing the data readout. This is common concern with lower quality detectors. Also, cameras can have dead pixels, smoothing out effect, to much "noise", columns of pixels averaging temperature, or even be out of calibration producing non uniformity. My suggestion would be to think about your application, your budget and what you want to sacrifice. You will either have to provide more payment for a higher quality system or understand that the data itself may be compromised due the lower quality components in the camera. There are many other specs to understand: Focal length, spatial resolution, array size (resolution), angle of lens, size of lens, even regulatory clearance on the device itself. If you would more information, please feel free to send a reply to info@spectronir.com. At Spectron IR, we are a medical specific IR camera manufacturer averaging 0.08 variance in the FOV with a spatial resolution of 0.50mRad on a 640x480 array with built in calibration and TEC. Also, we are medical and do not deal with any lower quality components as such, the systems are $20K+. Best of Luck!!!    Here are some other reference materials: https://spectronir.com/reference-materials/

[KonradF]

Thanks for this detailed answer !

I'm gonna look for the reference materials.

Yeah, that's the price I imagined for medical IR. But for now I'm going for cheapier ones. I'm not going to buy a Ferrari if I don't even have a driver licence .

And for this kind of camera, due to the price, you "have" to make the patient pay for the image. That's what I'm seeing when I look for person making IR imagery. I don't know what kind of training I'll need and what kind of profession is allow to do this legally in my country. That's something I will have to check if I'm going for a true medical IR camera.

Konrad.

[Spectron IR]

Hi Konrad,
You are obviously free to do whatever you desire! This is a class I device so there is little regulatory on the device itself. Just remember that the data you receive can be very different from the true data if you are using a less expensive camera for medical applications. Those less expensive devices are really designed for seeing color (temp) differences in a scene and not really accurate temp readings for medical. I would also encourage you to get lots of experience with the camera BEFORE attempting to use it in ANY clinical setting. This way you can potentially start to spot non uniformity, drift, etc and understand the quality of the device. Try looking at something that has a pretty uniform temp, such as a piece of paper that is hanging in a room. The paper is thin and can acclimate to a room temp fairly quickly. Just don't touch it (give it time to acclimate to the room temp) or have it near a vent blowing heat/cold or have a fan on. You can also hang streamers in a room to see the airflow of the room and get an idea of how that might affect your device (drift). Best of luck and when you are ready to step the game up, feel free to contact www.spectronir.com