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2.5. Recording five. Yeah. One good one now. Ok. Yeah. Ok. Mhm. Hello everyone. My name is I am one of the educational officer of UI MS team today. I'll be hosting the event today. Um This uh we will have our next radiology series. Um Please feel free to ask your question to the chat box. Questions will be discussed at the end of the seminar and certificates will be provided to everyone who fo uh films the feedback form. So that's all from me doctor. Please share your screen and start the events for us, please. Hello. Thank you so much for having me. I'll share my screen now. One second. Can everybody see my screens? Is that still? Ok. Yes, we can see it. Perfect. So good evening everybody. I hope you are having a wonderful evening. Uh Bear with me if the light is a bit low, it's quite dark here. Welcome back to other uh in the series Interaction to radiology. Today we are discussing CT scans. Our aim obviously is to help you understand the basics of each radio ra radiology uh imaging modalities uh that are out there. And from that base, help you to build your own knowledge as you see more and more scans and develop the ability to pick up pathologies as you work later on in your professional life. So today we go into CT scans before we start CT scans, basically work in the same principle as that of X rays. So we'll just quickly go through that principle. Again, obviously, that is x rays are absorbed to different degrees by different tissues. I've put a good image there that shows that whenever x-rays are passing through air, obviously nothing is absorbed, which will result in a complete black image that you can see. But as the density goes up, there is more and more lighter images that is being formed with the bone or metal having the most light or white test images uh on the gray scale. But then why if we have X rays, did we go and find out its next imaging modality or a new imaging modality called CT scan that basically comes from the shortcomings of X ray. So what are those shortcomings x-ray as you know is a two dimensional uh picture of three dimensional structures. So 3d structures are all superimposed to form a two D picture which will obviously cause the certain tissues to overlap other tissues. And if those tissues are denser than those they overlap, this will result in obscuring the image that is being overlapped. So in order to try and get around this problem. We went for different views. So we discussed last time about ap views, lateral views, basically trying to look at tissues from different sites, hoping to make a diagnosis. But then again, in certain areas of the body, that is not very easy, what else is the problem? And so whenever we have tissues with similar densities, it is difficult to differentiate between those tissues. For example, if you think about water and soft tissue, it is almost very similar density. So which means that if you say, for example, in an X ray, we say that pleural effusion is diagnosed by the blunting of the costophrenic angle. So that basically means that the diaphragm and the the the fluid there are almost similar density. So we see no difference between these two because there's no air over there. But as in this case, it is ok. But in other certain other situations, it is difficult to differentiate certain tissues which won't help us reach the uh diagnosis of whatever pathology is going on there, coming to certain specific areas. For example, a skull X ray, if you look at skull x-ray skull is basically covering the brain has a bony covering. It's extremely more dense compared to the brain. That means that we see only skull, we don't see anything behind that skull. Also covering. If you look closely covering the skull, there is a bit of CSF lining there. So CSF and tissues are very, very similar in density. So it's difficult for us to differentiate the brain from the CSF as well. So even if you try different views, we are not getting a good view of the brain. And this started making healthcare professionals and scientists in older age, start thinking, how can we see the brain, how what can we do to visualize brain inside the skull? And in comes our heroes, sir Godfrey Hounsfield. So Hounsfield is basically an electrical engineer by profession, but he was very much interested in computing and as well as imaging modalities. So he worked with Alan mclear Cormack who is a physiologist. And they together brought about CT scans and they shared a Nobel Prize in 1979 for this particular achievement. How did they end up doing it? Obviously, we know that by bringing on CT, we are able to see a three dimensional view of all the organs which will help us see things that we will otherwise have missed in x rays. So how did they do it? We can look at the CT scanner which will help us to understand a lot more about how they actually end up doing it. So I'm sure all of you have seen a CT scanner uh where you can see uh a motorized bed which has the patient in there which goes in and out of this large donut like structure. This large donut like structure is called as the gry. And this gantry is containing all the missionaries that makes the ct possible. So obviously, it has the motor that helps to move the things inside the gentry as well as the motorized bed. Most importantly, it has the X ray tube and the detector which is situated 180 degrees to each other, basically opposite to each other. And this X ray tube is continuously sending thin X ray beams that is being picked up by this detector. And the bed goes in between this space bed which has the patient or the tissue or the body part that we need to scan. The second intelligent or smart thing that's happening here is this entire structure keeps rotating or evolving around the patient in 360 degrees. So just like this, it keeps, it keeps rotating around the patient continuously sending the beam which is being picked up by the detector and which is producing thin slices of that tissue that we need to see. And unlike x-rays, this detector is not producing x-ray images. Instead, it is sending all this data to this computer that is attached to the, to the, to the scanner. And the rest of the work is done by the computer. So what is the computer doing? So basically the computer is looking at something called as Voxel. It's a new term that I want to bring to your attention. So what is Voxel? I'm sure all of you have heard of pixels, pixels are the smallest unit of a picture or a two D picture. I know that when you buy T VS or monitors, you think about the more pixel you have, the more contrast, the better the image quality. The same way in a three dimensional world, the smallest unit is called as a volume pixel. That is a pixel with a volume, a cube. So a volume pixel a short tend to form voxel. So what is the computer doing? Computer is looking at each voxel. So each image is formed by millions of voxel. Each tissue is formed by millions of voxel. And they look at each voxel and try to de deduce the the density of that voxel. And how do they do it? Basically, it's coming back to the technology of X ray where each tissue has inability to absorb radiation, which we call as attenuation and each tissue's ability to attenuate has pretty much constant. And we put a term for it called attenuation coefficient. So the scanner computer is using this information to try and understand the density of each of this voxel. Now, Hansel, what he did was he made a unit called HSD unit to basically measure this attenuation coefficient. So what he did was he said, you know what? We're gonna put zero HU or zero Hounsfield unit for water. So that was his arbitrary measurement zero for water and minus 1000 for every other tissue will have a HOFI unit relating to these two numbers these zero and minus 1000. And with this, he made a scale called as the HOFI scale. Now, you can see at one end, the air with minus 1003 unit is the blackest or the, the which which lets through the, all the radiation. So it's black and in the middle you have water which is quite gray, which has zero houn unit. And on the other extreme, almost white or white is bone and metal. Now it's not exactly 1000 it's almost near 2000 HO W units for cortical bone and every tissue in between has one portion of the gray scale assigned to them. For example, fat is about 60 minus 60 to minus 100 ounce field units. So it comes around here, simple fluid has 10 to 20 ounce field units. So it is just adjacent to water. But when you add globin molecules to this simple fluid, which forms blood, it is becoming way more denser. And that is why blood is about 60 to 90 ho W units in between. You can see soft tissues having 30 to 45 ho W units. So even bone, we can see a difference between the trabecular bone and the cortical bone, which is thicker than the trabecular bone because of Harfield unit. So this has given us this amazing potential to differentiate all these tissues, which is earlier, not possible with xray. So now we are starting to see all those different things separately what's more now, how does a radiologist use house field units or how can you use house field unit to pick up various things in a CT scan image? So say you have a CT scan image in your computer, you're looking at it and you your computer, uh lets you select a small portion of that scan. Say if I'm selecting the small portion, this is considered as a region of interest and the computer tells you the mean house field unit or mean at coefficient of that particular region of interest. Now, here, if I collect, select here, the computer says, you know what, this is 300 units. I know that that is the trabecular part of the bone, the vertebrae. Now, this may not feel very uh like groundbreaking. But if I come a bit to here, I see that this is quite black and this is also black. If I select here, the computer says that it is around 1000 houseful units. So now I know that this is air within the stomach. And here the, the the computer says that it's say it's minus 50 or minus 100. I know that it is the subcutaneous fat and on liver, soft tissue. Again, it has a different number. And what you see here, almost white is the contrast. This is an oral contrast CT scan. That's why it's all white inside the stomach. But this is a groundbreaking discovery which is helping us to see different tissues and not just see them in a two D picture in a 3D picture. So you are seeing different uh views together. Now, how is that happening? So I told you that when we are taking say a limb x-ray, we look at different views. So we need to see the knee, we can do ap view and lateral view of the knee. But for each view, a separate radiation dosage is going into that patient. But in a CT scan, what's happening is all the images are always started off as an axial image. So the the scanner basically takes small axial slices of the body part is in question and then feeds in the computer. The computer then uses this data to create sagittal plain views as well as coronal plain views, thereby limiting technically limiting the amount of radiation that goes into the patient to help us to see different views. We don't have to do scans over and over. Now, looking at this head of this uh patient, obviously axial slices are taken first, this is the axial slice that helps us to see the brain pan primer. And then the computer uses this information to basically produce this coronal image as well as this sagittal image, giving us all the information that we need to find out that pathology in there. Now, next term that I want to introduce is windowing. OK. So we have found out a way to like get more information than X ray by introducing a gray scale ranging from minus 1000 to plus 1000. But the problem is our eyes are not as good human eyes has maybe the capability to differentiate between 16 to 30 different shades of gray. So when you have around 2000 shades of gray, a lot of pathologies are still not picked up by your eyes. It's basically your problem. So then how do the computer help you with your eyes to pick up these these pathologies? So that is that is why windowing comes up. So c is kind of helps you to basically focus on a single tissue and thereby providing the whole of the gray scale to that tissue alone and thereby not looking at other parts of the same scan. How is that, how, how is that happening? So if you look at this particular image here. So uh let me just explain with this this particular thing first. Now the gray scale is starting from minus 1000 in air to plus 1000 which is almost a bone, but I only want to see this small section. Therefore, head and neck. So I am gonna use two new data points to the computer. I'm gonna say about width and level. So what is width and what is level? So width is basically the the section that I want to see the range that I want to see and level is the midpoint of that range. So say if I give up arbitrary point of a width of 600 at level of zero means the computer, what it does is you show me images between. So from zero midpoint of 600 will go to minus 300 on one side and plus 300 on the other side. So it will utilize all of the gray scale from black till till white. All the ranges of the gray scale in that region alone and everything below will be black above will be white and you won't be able to see it properly. So coming back to this image say I am initially giving uh a like a width of 2000, that is the full gray scale range from minus 1000 to plus 1000 at the level of 350. I am able to see the bones really well. I can see the air within the sinuses but everything else seems to be quite obscured. But if I narrow it down to a level of 40 at the level of 40 midpoint with a width of 350 on either side. Now, the same image I'm starting to see the eyeballs more clearly, the muscles more clearly. So this has helped me to visualize the orbital fo are much the the orbit, much better and thereby seeing if there's any blood in there, if there is any other pathology in there much, much better. Now, this particular concept is called as windowing. Now it is difficult for us to learn every single window for every point. But there are certain preset window levels available in the city. So if you want to see bone, there will be a bone window which will be a as I saw earlier at a level of 500 with a width of 2000. Just like that. If you want to see soft tissues, it will be a level of 50 width of 350 like that. There are different different preset sections available within the CT scanner. Just trying to make you understand how awesome it is one more time. This is a slice of a CT chest. Now, in this particular window, a soft tissue window, we have put the soft tissue parameters in there. You can see the soft tissues around the chest, the chest wall much better, but the lungs are not very clear. The the heart is ok. We can see a lot of the, the the mediastinum quite well, but the lungs and the bones are not as clear as you would want it to. So you say you want to rule out a rib fracture if you put a bone window, now, the lungs are not very clear, the soft tissue is not very clear, but you start seeing the bones much better. Now, if you want to see the lung, you put the lung window in, you can see the bones have become obscured. You can see that the soft tissue has become obscured, but the lungs has come into full view and you are able to pick up all the pathologies from that lung window. Again, coming to CT head. If you look at this particular in the middle, this is a like a normal CT head view where they are focusing on the parenchyma, the soft tissues. So all the soft tissues are well seen, but the bone is not very clear. But if you put a bone window, you can see the bones all clear, but the parenchyma is quite obscure. But this helps us to pick up if there is any fracture or in any fracture in those skull bones or facial bones. Now, this is called a blood window. Now, here you can see that the soft tissue is not very clear, not the contrast is not very good over there and even the bone is not very clear, but you can start to pick up blood inside the parenchyma. Now, in this window, this is like a very wide window where you are seeing very well, but rest of it is very obscured. So this basically this adjustment basically helps you to focus on individual tissues that you're looking at to catch pathologies that you are otherwise going to miss with a wide range of gray scale. Once again, looking at this image, this is a ct abdomen, looking at the liver. When a soft tissue window is picked up, you can see some pathologies in there. But it's not very clear because we're not able to differentiate all the tissue parts as clear as we would want to. And if you go wider, what happens is it becomes even more obscured, you are not able to differentiate at all. So you go for a liver window and you're starting to see the pathologies more clearly and even the the individual pathologies are more accurately seen in that particular window. So always remember house field units windowing. Next thing is contrast. Now we have come a long way from X ray. We initially started uh developing the ability to see different tissues, then we brought in windowing and that why we are able to focus on specific tissues to pick up pathologies. But we are still lacking something, we are still not able to look at the vessels as well as we would want to comes contrast, which is another game changer in the equation. So contrast in C is usually an iodinated solution that is used and most common route of entry is either orally or in intravenous injection. And this helps to further improve the differentiations that we previously achieved with windowing. The most important terms that I want you to keep in mind with regards to contrast is the faces, the arterial face and portal venous face. What is it basically, it it it's very simple. It all it means is when the time that you take the scan after injecting the contrast will determine what phase of scan you have. So imagine these two are the phases, as I said, arterial face and portal venous face. So say what is happening when you inject the dye into the vein, it first goes into the right side of the heart, from there to the lungs, from there to the left side of the heart and from there to the arteries. So it takes about 30 seconds for that. So when you take a scan, after 30 seconds of injecting the dye, you're able to see the arterial system, the aorta all very like brightly lit up showing you if there is any dissection in there. If there is any, if there is any uh aneurysm, any rupture, all those things are easily picked up, even Iogramma are easily picked up at that point. But when you go a bit later, what happens from the iota, it goes into the organs, the arteries, the organs from the organs, some of the organs like lever it go into the portal venous system from the, the, the GI T and all it's going to the portal venous system and from the portal venous system. After all, it, it then from through the veins, it is going into the kidneys and from the kidneys, it is excreted out. So if you wait about 70 to 80 seconds, all the contrast is in the portal venous system. And when you take a scan at that time, the portal venous system is lit up and helping you to see all the pathologies in there. Say, if you want to assess the kidneys, you wait for 6 to 10 minutes. That's a delayed CT which will help us to see the caliceal system of the kidneys. Uh I'll explain the same with this image. Now, now the first one is the arterial face. How do you know it's an arterial face? Obviously, this is the aorta and you can see that in the abdominal aorta, it is brightly lit because of the contrast in there. But compared to the liver, you can't see the hepatic veins very well. And if you look at the spleen, it looks quite heterogeneous like it has some some abnormalities in there or no when you, when you wait for 75 so 70 to 80 seconds and then do a CT scan again. Now the iota is not as bright, but you start seeing the hepatic veins more prominently compared to the scan. You can see them more prominently as well as if you look at the spleen. Compared to this image, it is slowly starting to become more homogeneous, but this is a portal venous phase helping us to pick up more pathologies in the abdomen. Now, once again, the same thing, if you look at this before contrast image, you can see a lot of soft tissues but they are not well demarcated, not giving you the proper differentiation to come to a conclusion as to what's going on there. But when you give the arterial face, you can see the abdominal aorta being very prominent, but the hepatic veins not as much. And the heterogeneous appearance of the spleen. And in the portal face, you can see that the abdominal aorta is not as bright, but the hepatic venous system starts to be more prominent showing us all the veins in there and also the the spleen is becoming more homogeneous. Next thing that is usually difficult for a lot of people is when they look at CT scans, how do you orient yourself, which is left, which is right. So by convention, you can see that there is a little one lying on uh sorry, there is, there is a patient lying on the bed and you can see the eye here. So you are always imagining yourself looking at the patient from the foot end. So if you're looking at the patient from the food end, your left is going to be patient's right and your right is going to be patient's left just like that. Always in every single CT scan, the right will be on your left and the left will be on your right. So that is the convention. So it's always right here and left on this side. And I've also mentioned front and back here. It feels kind of like why do we need to know front and back in c always they are gonna be supine. But in, in, during COVID time, we have used prone CT sa lot to look at lungs. So you need to know whether you're looking at a supine CT or a prone CT. And what helps you to do that is this small line here. Now, this is the Gantry line and you can see that the vertebra is over the gantry line. So this patient is actually lying on his, on his back. So this is Zine CT. But imagine if the gantry line was away or gantry line was here and the vertebra was on this side. Now, you know that this is a prone CT. Now, uh we have quickly went through the basic things that we need to know about CT scans. Most important x-rays are absorbed differently by different tissues. And that is why we have the Hounsfield unit. Remember Hounsfield unit helps us to differentiate different tissues. Remember about windowing, which helps us to narrow and focus on a single window, single, same bone window or lung window, which helps us to focus on that tissue alone to help us get more information. And remember about contrast and different faces, the arterial face, the portal venous face, and also the orientation about your left being the patient's right and your right being patient's left. Whenever you're looking at a scan, I also want to briefly mention about an interaction and approach to CT head because obviously CT S were initially found out for this exact purpose. So CT head is actually quite complicated, to be honest. And the best person to look at a CT head will be a neuroradiologist. But working in a hospital, working in emergencies, you need to have a basic idea about CT head so that you can pick up some of the common presentations, common life threating presentations that can come to your uh hospital and you, it, it is beneficial if you can get an idea of what you're dealing with before you get the actual report in your hands. That is why I want to tell you some brief introduction about CT head. Obviously, more in detail will be discussed in the next session, but some basics first. So obviously, for any major pathology, the basic thing that you need to know is the anatomy of that particular region. Now, Ct's head is taken as axial slices from neck above throughout to get the whole part of the head. So let's divide it into different levels to understand the anatomy. So the lowermost level is the posterior fossa level. And if you look at the posterior fossa level, what you can see is you can see the foramen magnum and inside you can see the medulla and two small cerebellar tonsils on either side. And when you go to the next level, that is a low cerebellum level, we can start seeing the cerebellum. Most importantly, we can see a bit of the temporal lobe on each sides. We start seeing the mastoid air cells, we start seeing the sinuses, the sphenoid sinus and the ethmoid sinuses as well. Next section that we go up high one another level is the high pons level. Now, important structures are starting to show up. One is suprasellar cistern and the circum mesencephalic cistern that is around the pons or the Ambien system. These two systems keep in mind we'll come back to them later. They are very important and we start to see a bit of frontal lobe at the fourth ventricle as well. Next level is at the cerebral cerebral ping where another important structure comes into view. It is the sylvian system between the frontal lobe and the temporal lobe. The small space here. And the next stage, we are going into the high midbrain level where we start to see the ventricles, the frontal horn of the ventricles, the third ventricle and another important structure here in the form of a W the quadrigeminal system, the W shaped structure of a quadrigeminal cistern. Next level is the basal ganglia. Now, here there are some important structures that you can find. You can see the chordate nucleus, you can see the marking here. So this is the chordate nucleus below that we have the anterior limb of the internal capsule, posterior limb of the internal capsule and the lentiform nucleus is visible here. And also you can see the quadrigeminal system in the W shaped system that we mentioned earlier. And coming to the next one is the lateral ventricles have become more, more prominent with the occipital horns, as well as the calcified fox and the central sulcus and the topmost portion showing you all the gyri and Sulci. Now these are the different levels II and I know that it's difficult to remember all of it when I quickly go through them like that. But the point is there are so many things that you can see in a plain CT head, there was no contrast, used, a plain ct head can give you so much data. Let's so at the same time with so much data in there, how do you get to read this? How do we go about reading it? The simplest pneumonic for an emergency physician will be blood can be very bad, so blood can be very bad. What does it stand for? B obviously stands for blood, C stands for assistance, B for brain pattern trimer V for ventricles and B for bone. So this is the order in which you're going to read the CT head. Obviously, when you look at blood, the most important thing is where is the blood located? How much bleeding is there? So let's look at the different types of bleeding that you can see in intracranial bleeding that you can see. So the first one here is a very nicely con cave uh sorry, nicely convex uh lens shaped uh structure lens shaped bleeding that you can see. The important point is it is not passing the suture line. So this is uh extradural hemorrhage uh that is above the dura matter. And in this case, but it is actually crossing the suture line. It is looking convex. This is a subdural hemorrhage. And here you can see that there is bleeding into the cell side and gyra that you can see. So this is a subarachnoid hemorrhage. You can see the cisterns being involved as well. This case, the bleeding is within the parent came. And how do we differentiate between soft tissues and bleeding? Obviously, we have your house unit. So you place a small circle there and the computer is showing you that it is about 68.6 house units, which is quite high for tissue. So this can be blood. So this is intraparenteral hemorrhage and in this case, there is bleeding into the ventricles as such. So there's a name of ventricular hemorrhage. So the first thing that you look for when you have a CT head is obviously the patient's name details. And then you look for if you can see any blood anywhere. So if you are in a system, you can always go for the blood window which will help you to figure it out faster. But then if you are just having an image with you like like a printed image, always try and find out if there is blood in any of these locations that we have discussed. Next thing is cisterns most importantly, four cisterns. One is the circum mesencephalic or the ambient around the bones that we saw earlier. And then we have the suprasellar, the quadrigeminal and the Sylvian. Now, if you look at here in this image, we can see that this is the circum mesencephalic cistern which is it has this slightly denser fluid in there that is the blood. And then this is the suprasellar cistern. This is the Sylvian cistern here. And in this image, you can see blood in the quadrigeminal system. The W A structure here, other important use of cistern is to figure out if the intracranial pressure is high or not, especially the circum cph and quadrigeminal cisterns are the first to be attenuated. So they, they become invisible when the intracranial pressure is very high. So you need to see a lot of normal scans to start seeing these structures in and to see how they appear normally for you to know when they are not there. So if you don't know about these structures being actually present there, it's difficult for you to pick up these kind of subtle signs. So whenever you see a CD, next time, look for these things and you will start seeing them and you will feel the confidence rising up. Next thing is, so we have finished the blood part, next is scan. So C is also finished And now BB is for brain parenchyma. Now brain parenchyma is fascinating because you can see the gray white differentiation here. This the outer part is the gray matter and the inner part is the white matter. So white matter appears more dark compared to the gray matter. Keep that in mind it ct scans. What you can see here is there is a bit of tumor there, unlike blood, this is very similar to the tissue density and around there is this darker section because it is edema. So it is tumor with surrounding edema that you're seeing in this particular section also look for gray white differentiation loss. So earliest a sign of a stroke, you know, usually we say that stroke, the best thing to do is MRI. But if you are not having access to MRI and you are having a CT scan done, look for gray white differentiation loss. So you can see that the gray and white matter is very obviously seen there anywhere if you don't see this differentiation. And if you see a darker patch there, that is a sign of stroke, obviously, it comes like quite to date sign compared to MRI because MRI can pick it up way earlier than the gray white differentation is starting to be seen in CT scan. But I'm just saying, keep that in mind, other thing that you need to be keep in mind is the midline if there is any midline shift. So look at this image, you can see the midline being shift quite obviously here because of the S th on this side. OK. Now, so we have finished blood can be next as we very very is for ventricle ventricle, you can see this ventricle obviously looks very much uh distended because of the CSF fluid that is stuck there. This is a case of hydrocephalus will require shunting so that you have picked up And the last thing is bone. So you can see this is a parenchymal view, parenchymal view. Obviously, you can see that there is some something abnormal there, but it the contrast is not very good that you you are not able to differentiate the the fracture properly. So you do a bone window and the bone window is showing the fracture line beautifully there. It's a depressed fracture of the skull and you can see a bit of blood on top as well. It is. So this is a depressed structure. So today, what I want you to keep in mind most importantly is about the house field units that helps you to differentiate different structures, the orientation, your left being patients, your left, being patients right and your right being patients left. Also remember about contrast faces, the arterial and the portal venous faces and also windowing as well. And with regards to CT head, always remember, blood can be very bad with that. I think we can wind up this introduction section Uh Thank you so much. I hope you have some understanding about the basics of CT scan. And hopefully next time you see act scan, you won't be hesitant to take a look and understand what you see in there. Maybe something more will stand out for you. And uh the next section you will be dealing with different pathologies that you can find in CT scans and helping to see them uh with all this in your mind. Thank you so much. Uh If you have any questions, uh please feel free to ask. I'm gonna stop sharing. Thank you very much, doctor. It was a great lecture. Um Thank you. Seems like we do not have any questions right now. We can wait a few more seconds in case if anyone will have a question, of course, of course. And the feedback forms will be sent to the emails. You can get your certificates when you fill the forms, but just in case I'll also share the QR code for you so you can have it. OK? I think there was an issue in people uh getting into the, into the middle. Yeah, hopefully that's sorted. We have sort we started using metal recently and now from now on we will use metal platform for the future events. Thank you. OK. So it seems like we do not have any questions problem. Hopefully it was useful. Yeah, it was great lecture. Thank you very much again for your time and for your lecture, it was really helpful and thank you everyone for attending our lecture. It is the end of our seminar. I wish great day for everyone. And thank you very much again, Doctor. Thank you. Thank you. Have a great day. You too. You too.