So, now we're ready to dive into the actual course material. What you are going to learn here in the first module is what is tomography and what can we use it for? When you're making radiographs, that is, shadow images of materials using for example X-rays, you get a shadow projection of your sample as the X-rays pass through and is partially absorbed by the different parts inside. You get this shadow image but just from the shadow image itself, you may not be able to tell exactly what is inside this surprise egg. You will get a projection of it which can be somewhat misleading as to what it really is. To that end, we need tomography. Jakob Sauer J�rgensen from the University of Manchester will tell you a little bit more about how this works in practice. Let's hear a few words from him. So, tomographic reconstruction is what helps us find out what's inside things we can't look inside. So, for example you could take a chocolate egg and find out what toy is inside. So, what would you do? You would put it in a scanner and you would take X-ray pictures of it like the one shown at the bottom left here, then you take a number of those from all around the egg and then you'll use tomographic reconstruction to form a 3D model of what's inside. This 3D model can then be visualized and you can see different components, you can see the chocolate, you can see the plastic container, and you can actually see the little toy that's inside. So, tomography is the process of taking projections and putting them together to form a 3D interior model. So, in principle, X-ray tomography in a non-destructive way allow us to see what is inside our objects. So, we can without opening the wrapping of the surprise egg, we can see the chocolate egg inside. Without breaking the chocolate egg, we can see the capsule in there, and without opening the capsule we can see the actual toy inside the capsule, in a complete 3D model. That's a neat way to find your favourite toy inside the surprise egg. But of course there's a lot more to it and we're going to hear more from Jakob in week two of the course where he will go in much more detail with the tomographic method. As scientists though, we are often interested in much more impressive capabilities of tomography. Rajmund Mokso, from the Max IV laboratory in Sweden will show you a state of the art example, where the finest details are imaged at a very high time resolution that far exceeds what is possible with the naked eye to allow you to see the live action of a fly in flight. As it rotates, we have several thousands of frames while it rotates a 180 degrees and then we get a three-dimensional reconstruction. When we get this three-dimensional reconstruction, we get real 3D movie. So, it's a movie that actually shows how inside the fly the flight engine works when it's flying. So, in this movie you can follow now how the fly flips his wings. You see here the head of the fly is virtually cut off, the fly is alive but the head is virtually cut off and now you are going deep inside the fly body, you see the big power muscles now. These are painted, each group of the power muscles is painted a different color and that you see now is the airways that are bringing the air into these power muscles. These power muscles are going at 150 Hertz without knowing anything about the environment. What really makes now the flight controlled is what we're after and these are what you just see now the very small, what we call control muscles. Steering muscles or control muscles, they are extremely small compared to the big power muscles, but they are connected to the sensors of the fly. Sensors could be the eyes or it could be the pressure sensors in the wings and then they suddenly damp the big power muscles and by this damping of the big power muscles the fly is changing its direction. So, this rapid change in direction is because of this brilliant way how very small force which are exercised by the steering muscles can just act as a damper for these big powerful muscles and then for example on one side and then it changes the direction. So, this can only be looked into with X-ray imaging because there is no other way we can look through a living organisms during it's doing the movement which we are interested in for example. Did you notice the coloring that Rajmund mentioned and also showed in his slides? This represents actually the segmentation that I have mentioned for you earlier on, where we identify various parts of our 3D volume and then add for example coloring to it to make it easier to visualize but also to make the physical analysis of the 3D volume easier for us. In fact X-ray methods can be used to cover size scales all over the relevant scales for life science from Atomic scale, to macroscopic objects like bones and whole bodies as you know it from clinical CT. As Rajmund mentioned, this method is actually the only method that will allow you to look inside a living organism while it is functioning. So, you can actually also use computed tomography CT scanning on living people to study for example the function of their lungs as they are breathing. The scales that I just mentioned is something that Rajmund has a few more words to you about. So, let's hear from him again. X-rays can be used in various manners with various techniques. So, here what you see is a large scale of spatial resolutions and the length scales you see adopted on the images to a different way we will want look into material going all the way from atoms through molecules, which are macro molecular crystallography which is important in drug research for example, through cells and all the way to the small animal imaging which are pre-clinical methods important for having in the clinics and the appropriate knowledge when we go and treat humans. So, we can cover a very wide range of size resolutions. But as you remember from the example of the fly in flight, time resolution may be equally important. This is also very true for many of the applications in materials science where we may want to follow a rapid change or a reaction in the material as it happens. The speed with which we can record the tomograms have increased tremendously in recent years, allowing us to follow changes in materials as they happen in real-time. Rajmund has more on this. So, I want to show you that in the last about 10 years we have made enormous progress in how fast we can do X-ray imaging. Here you see if I take the last years, starting in 2005, we have something that synchrotron tomographic microscopy could make three-dimensional images in a few tens of seconds. We can then five years later record images for a full 3D scan in about one second, and five years later we do that in a fraction of a second. So, we can today record routinely images, 20 tomographic scans per seconds. So, we have a almost a video rate 3D image that we are able to record and that helps a lot. Here you see another movie where we are pulling on a sample, on an aluminum sample. You see the whole rig that pulls is rotating very fast, it rotates at 10 Hertz and during this rotation we are recording at a speed of about 3,000 frames per second images and like this we can get the three-dimensional image during a crack happens in this aluminum alloy. Now, this can then be visualized in 3D and you can follow the path of the cracks. To get to these impressive time resolutions, we need X-rays from a really high power source, the synchrotrons that Rajmund mentioned. You're going to hear more about what a synchrotron actually is a little bit later in this week's modules, but I just wanted to mention it now so that you know that there's a difference between what you can do in terms of both resolution in space and in time, in the laboratory, at your home laboratory, and at these large-scale synchrotron facilities where the X-ray intensity is many orders of magnitude higher. You have also now heard a few examples of what can be done with tomography. Throughout the course, we will work with two specific cases of tomography applications. If you follow the honors track, you're going to work with the actual real data representing these application cases and you will do the reconstructions, the segmentation's, and also work a little bit with the ideas for modelling of the materials cases. If you follow just the basic course track, you will hear about the scientific background for the application cases and the conclusions that we draw based on the tomography experiments that we make on these cases. The two material cases are a composite material for wind turbine blades, and natural chalk from the North Sea. They will be introduced in the next week's lectures but I would just like to mention them now already so that you know what we have in store for you.
