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Introduction to Radiology - Basics of CT Scan 1



This session will provide an introduction to CT scans, delving into the history of the modality and its various uses in medical applications. It will explore topics such as radiation exposure risks, contrast allergy, and kidney failure in relation to CT scans. It will also cover the advantages and disadvantages of CT scanning, as well as the principles of Radiation Protection. The session will be relevant to medical professionals and invite them to ask questions and benefit from the discussion and knowledge shared during the session.
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As future Surgeons in training, it is very important to understand imaging as throughout your careers, this skill will be required to interpret images and make decisions.

This series will involve the basics of different forms of imaging and how to identify common conditions; thereby giving a solid and useful background for our various careers.

Learning objectives

Learning Objectives: 1. Identify the purpose and history of CT scans. 2. Describe the benefits and drawbacks of CT scans compared to other imaging modalities. 3. Explain the principles of radiation risk and how to minimize radiation exposure. 4. Outline the UK-based principles for radiation protection. 5. Recognise the stochastic effects of radiation and how exposure levels can result in cancer.
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Computer generated transcript

The following transcript was generated automatically from the content and has not been checked or corrected manually.

Um um uh I just share my screen now. Um oh, doing this weird stuff. Can you get some ice cream? Yeah. Ok. So hi guys. Um I'm AA or Emmanuel. You that you're comfortable with? I'm one of the registrars in Northwest England. Um So I I'll be talking, oh, just do like basic session on CT scanning. Um It might be a bit too bus but uh it's going to be bus. So I went a bit bus and if it is too bus for you, apologies, but some bit to be bus, some bit to be likely um not bus. Hopefully you gain something from the session in general. Um I'm happy to, I can't really see um I can't really see the chart box. So if anybody ask questions, I'm happy to um stop and pause for um to answer your questions. Ok. I'll do. And um if anyone would like to ask your questions physically um through the video, I can invite them on the stage. Ok. That's fine. Uh So um basics or c um just introduction on the left is a CT CT scanner. So most probably seen one typical CT scanner I think that's G and on the right is A, I think it's one of the most common CT images is the slide of CT head. Um I think this is level of the basal ganglia. Um So we, we talking about CT scans and images in general. So today, we'll just do a bit of introduction, basic uh history, introduction. Why we do CT why we don't do CT or when should we do CT when should we need to do CT? Uh Of course, we're talking about CT scans and radiology. It's quite important to talk about um radiation risk and risk due to radiation in general. Then the basic principle of how a CT scan works, how the images come out, how we interpret, then we just recap. OK. Um So CT computed tomography like we all know. So what, what it means is you just use x-rays to develop um 3d images of the body of an object. Um tomography basically means um x-rays in a 3 60 degree fashion around the patient to generate the 3D image. Um So there's actually tomography, diagno C based x-ray tomography used in breast imaging. But that's by the way, but CT computed tomography is you fire CT around the patient. Then the computer which is the perfect computer uses advanced um mathematical models to generate the images. So the basic principle the same UT uh applies with um basic radiograph. Um We, we fire an x-ray through a body to through an object to a patient. The patient consist of different um tissues and each tissue has different density. Through this, we can calculate the coefficient and the images appears differently on the detector. Um But the difference is the x-ray tube of the CT scan has a higher energy than conventional radiograph. Um Like, you know, CT CT has become very popular. This was a data from 2020. I think I didn't see any latest when assigned one in 2020. And he said about 6 million were done in the NHS in a year. I'm sure it's more than that now. And since since city was invented, had lots of development and improvement in how the city works, how it was designed and it's, it's, it's an amazing modality to really, um, personally, I'm sure you guys can sense already. I love City a lot. Um So a bit of history. So this famous man is Gregory Hunts Field. He is, was a British physicist. He was, I think was an electrical engineer, com physicist. He invented City City in 1967. Funny enough. He was working with Emi, I don't know if you get an Emiemi a music record Libel and the, the record li be which the beats were on. I don't know how he got his hand away from music tech and develop City, but the first clinical scan was in 1971 in Saint George's in London. And since then the CT scan has developed tremendously. Um we have efficient CT angio c colonography for people who can tolerate um endoscopy. Lots of amazing stuff with City Pet CT was the invention of the year and the time the year 2000, I think in invention of the year slash decade, I just put that there as a as another. OK. Moving on. So why do we do CT um do CT for various reasons. You can do CT for almost anything really. Um investigate, confirm lots of diagnosis. Almost all ed now has a CT scan. We do CT to try lots of surgical patients to confirm various conditions from the head down to the toe. Um review CT for surgical planning. I know the surgeons like that also, orthopedics, surgical planning. Um and why, why, why, why, why, why CT really CT gives a very well detailed cross section of you that with plain x-ray radiograph can give and CT scan is relatively quick. You can have a CT scan done in as fast as 3 to 5 minutes. Um It has very good resolution. You can see each um organ is structure clearly. Uh you can use it in very acute settings in very poorly patients. Um And that's why it's, it's used in emergency situations most really and CT scan is actually the best modality to investigate the bones. It's better than MRI by far, it's better than x-ray obviously by far. Um That's what really like it. Um And for cancer staging cancer investigation, we've confirmed uh malignancy, but you want to stage the cancer. It is, it's, it's the best modality to stage cancer and to investigate further. Um why not CT um if, if, if you, if, if you're looking for better tissue resolution, soft tissue, I mean, um MRI is obviously better. Um and the image on the right the down be just MRI scan of the brain and CT and MRI scan of the brain think that's also basal ganglia level. You can see obviously you can see the ja and so, so I clearly and the soft tissue is well more defined in the MRI image. But you can see we can't really see the bones clearly. That's the cranial bone. The CT scan, the bone is is clear and better. Uh on top is ultrasound image of um gallbladder showing gallstones. Ultrasound is the the gold standard for uh investigating and confirming gallstones called UTC. So even though the CT is good, there some cases where x-ray is better, actually there some cases where ultrasound is better and lots of cases where MRI is better. Um Also you think about pregnancy patient is pregnant, you want to expose this patient to so much radiation, think of is there something else I can do um in young patients? Um You think of something else you don't, you think of other things you can do instead of doing a CT scan. Um There's always the concern of excessive radiation to the patients. Uh If the patient has contrast allergy, um we have to think of something else. Kidney failure slash I put in a because uh in emergency cases, I think the guideline has changed. Now, even if the patient has fr less than the guideline is less than 2025 states depend on the insurance rate you work, but now nationwide, they said benefits outweigh the risk. So you you do the scan first, then you start the kidney failure later. So even in some cases with low, you can still use a CT scan if there's no other thing you can do. And the CT scan is the best to be to be used in this in this scenario. Um I saw this uh table online. It's quite good, very good detail difference between a CT scan and MRI and talking about the principle. So like I explained, um CT scan is just x-rays taken at different angles and its 60 degree to get cross section. Uh 3D image is while MRI use this magnetic fields. So obviously because it's magnetic field, CT scan gives radiation, MRI gives no radiation at all. Um CT scan is good for bones, um soft tissue and contrast, but MRI obviously is much better in soft tissue than CT scan. Um CT scan is relatively cheaper, it's faster. Uh Mr more expensive, most departments have at least three CT scans. OK? Maybe I say one CT scan, 23 CT scans, most, not all department does as much as three, maybe just three MRI scans. Um um So just differences. Um CT scan amp for kids, um radiation contrast allergy Y MRI. The risk is um just reaction to implants, the loud noise from the MRI machine. Um There's this increase in body temperature, I don't think it's that significant about one degree if you in an MRI scan for more than 30 minutes or an hour, and there's always a risk of claustrophobia with the scan. So that's that. So I, I talk a bit more with, with additional risk. Um This additional risk is quite good. Uh So as a radiologist will, will, we're quite um I wouldn't say you, you have the final but you mean you are the doctor there and the doctor face do no harm. So you are like the gate keeper to ensure patient isn't getting unnecessary insignificant, excessive radiation. So just as a comprising a CT CT scan of the chest exposes the patient. So about 400 times the radiation, a simple chest x-ray gives. So that's why sometimes we ask for a CT scan, ask, have you done any chest x-ray first? That might just pick up what you're looking for. Uh You need a CT scan in some scenarios like um gallstone, why doing a CT scan I can do to send instead if it's available. Uh and generally radiation protection, it's is based on three principles. So justification, optimization and those limits, justification is um you have to justify why you're doing this scan or in any investigation generally in radiation, you have to justify why you're doing it. Then you optimize is there a way you can make it better? I think that to adjust those and those limits also uh all principle which is all that stands for as low as achievable is the worldwide principle that guides protection in the UK, the CP CD. Um And this different countries have different that this. But what all means is actually there's no absolute contraindication to CT scan. If you, if you can argue that the benefit, the risk, you can always do this for anybody. So even in Children in pregnancy, if you see patients really need to scan patients, going to have this scan done. Um But obviously, there are always contraindications in kids. You don't want to expose them to due radiation, pregnant people, obviously, because of pregnancy and people with um high risk patients who have exposed to lots of additional people with childhood malignancy, they've had lots of CT scans during the years. Uh If you're asking for a CT scan, you see there's something else I can do the deal and this can at this point, can you move it on to something else? Uh I'm talking about radiation is what do radiation to the body? It usually affects the um from the edge of the, to really the common one everybody talks about is cancer but really cancer is when you have about, I, I don't know if you can my or I I to about 1000 mills, but it's actually stochastic um effects, meaning you can have less than 1000 MT and to get cancer from exposure or common ones have been documented, um, cataracts in the eye, affect the thyroid bones and the skin um for stability and lots of um various risk radiation gives to the patient. So, um that one common one we usually talk about is bone marrow. That's why in kids we don't like it. You get it there because of they have lots of red marrow and um radiation can lead to leukemia in them. So, radiation risk is quite important. So most, um but actually with newer CT CT scanners, I think modifications have been done but still with new CT scanners, we do most scan. So additional risk is still quite. But um ok, I think that's a bit about uh that let's just go through how, how a CT scan works. Um So I'm trying not to get too deep into the physics. Um So this is a typical CT scan. He has a tree which is the ground, do not. And there's a trolley, the table patient slides on the table um into the gun tree. Um This gun tree has thousands of detect tiny detectors on one side and the x-ray tube on the other side. So the x-ray tube fires the radiation, the gun tree spins around. So it just fires on the detector. I spin around and patient goes in and out the the detector spins and patient comes out. Um So the detectors get the x-ray images, then the computer workstation actually does most of the work and that uses um complex mathematical models to process the imaging information is gotten and generate the image. Um I think that the same place where I can explain it. So the thousands of um it's not 3 60 degrees detector, those des on one side, x-ray trip on site and they will spin around why the patient was in and out of it. Um Then we give contrast sometimes not every time just do eye, eye light vessels and organs, we speak more about contrast and how contrast work later on in the talk. OK. Um So this, this just talking more about how it works. So um x-rays as uh x-ray is directed towards the patients from various angles, the detectors and the scanner measures the difference between the x-ray that absorbed in the body and the ones that are transmitted through the body. And this will require attenuation. So x-ray is coming from the point A to point B um body in the middle difference between the energy of the x-ray from 0.10 point B is what gives the attenuation. And if we can calculate the attenuation, we we can calculate the physical density of the tissue. So physical density of tissue is, is proportion directly proportional to the absorption of attenuation of the beam. Um From this attenuation coefficient or absorption coefficient, we can from that calculate what we, what we, what we call the um age unit or the C number. And is this age unit or C number that we used to know what particular tissue is um we seen on the CT scan machine. Uh So every x-ray that I show you if it's not blocked by anything, it goes in um lens on detector and comes out black. So a is least density, it just comes in, comes out the same way. So that's the same similar to the lung. So in the CT scan, it comes out as like as black cos coon is the most dense, it stops and absorbs most of the x-ray and none of the x-rays gets the detector at all. So it shows up as white cos coupon is about 1000 ounces units. Uh And based on different density, we can calculate what's uh based on what we're looking at on the um detector. What what comes out and you can calculate what tissue is was actually there. What tissue was between the um x-ray from when you left the x-ray tube to when you got to the det. So fat is less dense than water. So uh fat is minus 1000 is middle zero and then simply fluid, soft tissue blood, everything just takes the beats between zero and 1000. OK. That's clear. Any questions in the chart? No, I think I'll just continue. So um so am I still uh just to be sure I'm still talking. Can you guys still hear me? Uh Yes, yes. There's the no question that OK. I was scheduled for, I need that. I thought that was OK. Um um So still on principle. So that is just basically how we know what it is on the CT image. How do we know this is point? This is plus, this is soft tissue. Um So another good um prop of the computer is it construct and can produce 3d images. So we can get the um film out and search it out the film that comes out. But the computer we of gene different um the image three different plane. So we, we, we give contrast to really highlight first class structure and organs. So thinking why this patient needs to ct with contrast or c without contrast? What thats that? Um So it, if you want to look at the vessels or you want to look at um organs properly, you give contrast um you don't give contrast to when you know what you're looking for is of some of um of I or IC number because the contrast is always going to mask what you're looking at. So, in the case of um bleed or hemorrhage in the brain, you don't give contrast cause if you give contrast, there's going to be lots of contrast in the brain. And you don't know if this is a blood, if this is a bleed or it's just the contrast you've given. Uh then the contrast scan and we tie the contrast contrast to scan time based on the history to get different physics. We'll talk about that also. Uh so we give you contrast now through the vein, it goes through the vein, it goes into the, it goes into the arteries first, then into the organs then comes into the veins back. So it depends on what you want to do the first time when they want to do this scan. After the contrast have been given to get um different phys, that's why the clinical history is very important because without history, uh we give contrasted scan, but you may not really get the best information from the scan. Um And we all know um CT images always produce, we look at the patients from the foot like your clinically examined, the patient or the patient is facing you and the patients right is your left and the always scan is always from top to down, always from top to down um windowing. So windowing is, I think this is, I know this is just when you are interpreting. So I know that you can always, you can always adjust this number this year. So you can always adjust it that you want to just see between minus 100 0. So that attenuates all the um structures between that number and the rest is just going to be like that. So looking back here, so this is soft tissue window. So everything below um let's see, 10 to 20 comes out as black, everything above comes out well gray and everything, everything within that comes out well gray and everything above that just is just white. So the soft tissue windows, this is the bone window. Everything below that is that than normal and everything between the number. So bone is really between I think 100 to 1000. Everything below that is just very dark is gray, very black in case of a and the bone shows well. So it just helps us to look at different structures very well. And this is long window. So this is minus long window is minus 400 or by 1000. So you can see the lungs properly. But everything above that is white, see the soft tissue is just white. The when the heart is white, the bones are extra white because it's just now this is number to look at various um structures properly. Ok. So we can take a breath there. Um So that was just a bit about um the basic basic, I think that is the most basic way I could explain the basic principle. Of our CT works, how the images are and how we interpret uh so about interpretation. Cause cause what, what, what we are calculating is the density, the density of the structure that blocks the x-ray from reaching the. So the terminology will usually use this density. So yes, stuff like uh is an hypodense or dense lesion somewhere. It's just density and x-ray risk opacity or is in MRI is intensity in um CT which is density hyperdense ISOS hypodense. So, bone is obviously white is always hypodense. A is black, hypodense blood is white. So blood is also going to be dense uh so and so on and so forth. So the gray matter is hyperdense to the white matter cause it's lighter is whiter than the white, is whiter than the uh is whiter than the white matter. OK. Uh So I just wanted to, I think we're going to be very quick. We going on a very good pa just use what length the basic principles to talk a bit about some common um scans. So I think I choose CT eight CT P and CT abdomen. I will just take it 11 at a time. Um So, CT eight generally uh technique most times is always non contrast. CT eight. The only time we do contrast which is CT eight, you looking to check the blood vessels and geographic to look for any aneurysm, um AVMs or if you're looking for um venous sinus thrombosis, look at the um venous CYO. Otherwise most times CT eight is always non contrast to check for ischemia and stroke check for he bleed, post trauma, always non contrast. You really get the contrast CT eight. Even now having to do a CT with contrast for to check for masses or tumors is frowned upon because most times it just to get an MRI scan because it's a better resolution. So most people would just rejected from you. We just expose it to patients on DU radiation and just do an MRI scan after a non contrast CT scan and different people have different ways which they look at the city at. Um I'm sure, but this is my own way. I don't think it's, I don't know if it's the best way but how I look at it just look at the brain came um go down to the brain stem and the posterior fa the ventricles, blood vessels, bones sinuses space orbits and just correlated between the clinical history. Uh What I was saying about the uh um gray and white matter, we can just appreciate it here. So, so you see the um gray white matter tracks here, so you can see lines uh of lightness and blackness. I have your playlist on your P I got, I think that's actually better. OK. Uh So um you can always, so how, how I go is uh top to bottom follow white trac trac look at the brain came, generally looking for any bleed, um any abnormality generally. Um It's not come out. Uh I don't know, it's not come out. Um And it's really then after that, look at the ventricles, um go down and look at the blood vessels, the heart tree, um M CS um um sorry. Um This is not a very good scan but look at the orbits sinuses and all uh so different, different people, different ways to look at it. But this is, this is a normal CT scan of the head. Um And that's just how I look at it. Um follow the brain point camera down to the posterior fossa with the brain stem, um ventricles for any um on due dilation, uh early dilation of the ventricles will show up in the temporal S yeah, just see the temporal of the lateral ventricles showing up as hydrocephalus. Um When I'm done with that, um look at the blood vessels, follow the blood vessels up to the circular which we should be somewhere, but it's, it's cutting off somehow. I don't know why it's cut off. Um Then look at the bones sinuses and you don't. OK. Let go back slight. So that's generally, it's about c maintenance technique. Why do we do contrast and why do we do noncontrast and interpretation? We um then uh that's it. So we'll go to the next one which is CT PA. So I picked, I pick a CT P just to explain. Um um the bit I was saying, talking about about contrast and timing of the contrast. So CCCCP it's a CT pulmonary angiogram. So done for P is to look at the pulmonary arteries. So the the scan time is time to it is is ted to a time where the contrast is in the pulmonary vessels. So imagine your history is not good the greatest or you don't discuss well, patient, well, to be honest, patients present differently. But if you can see the aorta is as the aorta and the aorta, they are know well pa for because the contrast is not there. Uh if it's a very large aortic dissection, you see it. But the way the scan is tied or primed for aortic is different for my CP uh I mean aortic, they do we uh non contrast and your face. So it's, it's very different. That's why um clinical history is quite important in interpreting uh CT CT scans. Um So this just to highlight to what I was explain about contrast and how they give contrast when they give contrast, why, why they don't just give contrast and take this scan? It is usually targeted to specified various structures based on what the history is generally. Um So yeah, I was just trying to say how personally how I look at um AC P scans because the main role is A P uh just follow the vessels go down to the subsegmental branches and look at the lung field to see if there's something in the lung cause it. And see if we can, you can actually see something massive in the aorta going on. Look at that. Uh If you slide down, you see the, as we see, usually not the arteries might just be um an M I going on if you can see any calcification and the A DS, if we take the A for evidence of that strain, um the bones, the rest of the soft tissue, um check for any lymph nodes. If there's malignancy, then upper abdomen, that is also there. Um See, I think I have a playlist also of a normal CT P scan. Um Yeah, I think I put this here. So this just uh so you can see the CT we just on the pulmonary artery, just follow it down to subsegmental branches. It better on the PA system. We can always follow it down, up and down. Same on the other side for it up and down. What you're looking for is any filling defect and an evidence of a um thrombus formation, any filling defects um in this point after I've traced it down, change it to long window, I can't do this because it's just a play list. So, apologies for that, then look at the lungs properly. Um So the long window like we explained earlier, blow out everything and just show the lungs properly. Um the more we done with that check the a any evidence of any hi strain check for any lymph nodes. Um before that to check the aorta to see if there's anything in the aorta. Um I was if, if it's difficult to see the, the coronary artist, OK. See coronary check for any calcifications. Yeah, let's see. The left led there, right. Yeah. Um then go down this. Oh, sorry, apologies. But down upper abdomen, see it not the greatest because the contrast has not got into the aorta to go into the organs to light them up or you can see a few stuff um cut the upper abdominal organs up to where you can pick up something um soft tissue bones. Then there's always the construction from that which is so cool and you can see the bones properly, you can see the aorta properly. You can see the pulmonary vessels very well. Yeah. So go in and out and following it up and it out completely. Usually you don't. So this is just a normal CT P nothing in there. I just put this up to explain uh Patan of contrast and just talk a bit more about how I look at the CTP. We do, we do more of um acute cases and check on pa of vascular. Guess next week, I'm just talking about normal scans today to explain um to explain how I how uh to explain the basic principles really. So let's continue. Um So the next is one of the most common CT abdomen. So, ct abdomen is slightly more different. So you do mostly the most common technique in ct abdomen and pelvis or ct chest abdomen and always a contrast scan. Um because you want contrast and the face, the common phase is also the post venous phase cause you want contrast to have gone into the aorta into the organs to light them up like this. This is more lit up compared to the um CT P we saw earlier cause that was that we couldn't really see the organs properly. Then the the blood we have left the organs and will be in the portal vein. So you can actually look at the portal vein, check for any venous thrombosis also. So the common, that's the common is really uh CT abdomen and usually contrast venous face. Both different pieces are also and different types are also present. We can do a non contrast scan in CT Kub, which is oh sorry, which is CT scan to check for kidney stones or renal stones, stones. Why you don't want contrast is because the calculus is hyperdensity. But if you give contrast, it's just going to mask, you don't know what you're looking at. But if everything is dark and you're just looking for the dense stone, you can easily pick it up and check it. Uh and on the opposite scenario where they do a non control scan, it's in um create bleeding, but that has always done it as a triple phase where you do a, a non contrast scan first and do a contrast scan. So if you see a bleed in the contrast scan, you have to confirm in a noncontrast scan that what you're seeing is not just a calcification or a random bullet somewhere. So you are confirming that what you're seeing in the contrast phase is actually blood and not just calcification. Um So ct abdomen, there, there are a lot of other techniques too, but these are the, but these are the common ones, non contrast. Um contrast. Um IV or, or contrast, we do oral contrast also um in CT abdomen in for different purposes, uh checking for uh ischemia or um what's this ti cards from? I forgotten if it just, it's just to line up the bowel. Really. Um We do oral contrast to check that uh to line up the bowel and give you could sate between the and the uh the darkness and the fat of the abdomen and the power. OK. Um And how, how I personally look at ct abdomen and pelvis is follow the abdominal organs like I'm examining the patient's liver spleen, stomach, both kidneys, adrenals on top, the pancreas come down to follow the bowel from the large bowel, from the rectum to the sigmoid, descending, transverse, ascending small bowel. I look at the vessels starting with the aorta for any aneurysms, um, check the vessels, follow it down to the iliac, check all the main branches, the vein for any thrombosis and check the gallbladder. I didn't put the gallbladder, gallbladder and the bio dot uh, for any distension, uh, pancreatic dot For any distension, then there's always the edges of the film, the lung disease, the bones and the correlated clinical history, really. Um, so I think I have a playlist here also of the ct abdomen and venous face. Uh So you can see the, I think this is still open. So you can just compare this is the CCP with the contrast in the um pulmonary vessels, see how the liver and the spleen is there. It's not well lit up but yeah, in the part of his no face, it just lights up beautifully and you can um investigate the abdominal structures properly. Um So this is part of venous phase with the blood. Blood is going into the aorta, is going into the organs and it come out through the port of vein. Um Generally because I, I don't want to forget I start on top the long basis. Any long window check the lungs for any basal consolidation then deliver. Uh if anything catches your eye, check it, the spleen, both kidneys, right and left. Um This is just the baggy, um not really ID as such. Um The adrenals are me be uh me be shaped organs on top of both kidneys. Um, stomach could be dis food content need, um, from the esophagus, checking for any viruses and liver disease. Um, pancreas, pancreatic dot is not distended. You, you just slightly see it but it's not distended. Um, gallbladder, just, uh, the CBD coming here to go in the second part of the, you know, it's not good scan but CBD. A comma enter, uh, really go down, start from this for contrast in it also rectum, go up, sigmoid, go up decent descending, descending, descending splenic fracture, child, not school long, um descending, ascending colon. Then the sitcom, you know, the come because there's a blind ending structure coming out from it, which is, which should be the appendix and the small bowel, which is the ileum. Um Then you go follow the small bowel. OK. Te take usually look at the small vol in segments because it's very long and always up together. So this is not really an interpretation session. I just got carried with it looking at the scan. Then um you have three things like I said, now you can always look at it again. Go now and gi um so it's just to really explain the basic principles of um why we do the scan, how the scan comes out and how we look at the scan really um uh um just see if I can use this to explain honest speech and its um so because explain oxygen needs the fats, I'm just trying to compare fat and fluid. Yeah. Yeah. So there's fluid in the gallbladder, which should be better. So it's slightly more hyperdense than fats cause fat is less dense than uh the fluid. Uh bone is the uh most structures that comes out very bright. Um The soft tissue, it's just in the middle blood in the vessels is also but not as good as the soft tissue or it's not as bright as the soft tissue. Um So if you see something, yeah, you're not sure where it is. You can always compare, you cannot, if it looks like this, you know, it looks like blood, it's blood, if it looks like this or it looks like fluid, it's a cyst, I think it's a small liver cyst. Common cyst is to know, OK. That's a simple cyst. We're not worried about that. They just compare the answer. So you need to a similar structure that contains fluid or water and you know, this, the fluid uh um soft air outside is always black and dark and there's always air in the lung to compare with. Really? Ok. So I think I've got it on a while there. Um So that I, I hope, I hope that was helpful, just explaining technique of common um CT scans and or uh why we do them, the reason behind doing them and how they come out really? Um So just a bit of a cop. Um So CT is quick, it's cheap. It's very good, good resolution. You can see the structures very well. You can see very tiny stuff very well. Um It's amazing for bone and skeletal structures. The orthopedist like it, they use, I think almost everybody that needs an ankle, ankle surge or elective orthopedic surgeon now needs a CT scan for surgical planning, but we most most always remember and think about um radiation safety. Um don't patient if you don't need to do something else. Um Answer you need is just C number which is given to tissues based on the scale and it helps us to know what the lesion you're looking at is and to differentiate and investigate properly. Um knowledge of normal anatom is important really. If you don't know what the number looks like, then you will not show which is abnormal, you looking at like anything and clinical history is, is very important. It's, it determines not just interpreting the scan, it determines how the scan has been performed in the first instance. That's why some uh are quite uh I don't use what they are quite an know when the C history is not. It's not, it's not given. Um I think that that's it for today. Um My reference is a radioed radio system. UIA is an amazing resource for anybody who is interested in radio, even consultants, everybody, we all use it and it's worldwide resource and it free, there's free membership for, for, for full assets. For different, for people with, but you have to meet certain criteria. But the even the free one that does not have full assets, has lots of stuff on it. And there's also radiology assistance which explains very well how to look at most of the common um CT scans, even x-rays, ultrasound MRI. So these two websites acquired useful, I think that me for today and next week I was planning on bring in uh a few acute cases, the emergency cases, we just go through them together. Um to explain, how do I stop sharing to explain? 00 I, I, I um look at them. I'm I'm not gonna do greatest go when it comes to Liukin A CT scan. We'll look at them together and see if anybody has any question. Um scans you want need to bring, you can put them in the chart box now and I can get them, get them, see if I can get some cases up for next week. OK. Any questions? Thank you. Um a love this session. Um My question when you are talking about the oral contrast. Yeah. In terms of the timing, how, what guides the timing for giving oral contrast for o oral contrast is given Quitely um because you want the contrast to have gone pass the stomach into the small bowel. I don't get into the large bowel is not a, it's not a problem because light bo shows up mostly small bowel. So about an hour before the scan is done, the will just think or they will tell you the time is this time. Can we give her her contrast here? We don't give our contrast when the patient is in the scanning room because they just have to wait for a long period. So we give her contrast when they do what before they come down? Ok. Thank you. I'm just checking the chart for the problem. Thank you so much. It. Um What I'm seeing on the chart box, you've been very good eye doctor for the Atkins cases next week. Yeah, if you have any, I have a few on my video video playlist and I can get from colleagues also. It's just gonna be common stuff. Um Nothing like that. It's just common stuff that you should see and emergency stuff you should be able to recognize and how, how we talk with them. Um So mostly new have to um few just cases maybe. OK, thank you once again. Um So if he is asking that, do you use? Ok. Can you see it yourself? Um Mostly for CT if the patient is, if the patient will not tolerate it, we don't sed it if we don't where, where I work though, we don't, we don't really sedate the patient is not going to be coming up for uh our contrast. We don't sed it the contrast, the scan itself is quite quick. So we just do, uh, IV contrast instead. Um, so about sedation and, and diazePAM and stuff different, have different guidelines. But usually it's just mostly an MRI because they need to be laid down. Um, for quite a long period. Prophet, not really, um, 10 or two ago. She did them the g at it also because they don't like Ed patient because anything can go to. So it's different if the patient comes in from Ed poorly and then usually come in with the Ed doctors but generally we don't. Um, and the Ed doctors, the different drug guide, uh different, different, different, different guidelines we have. Is that answer your question if you? All right. That's good. Mm. All right. Um Is there any other question or clarification before we end the session? Was I was, I was I speaking a bit too fast. I tend to speak a bit too fast because I think, um complain. No, it was, no, it wasn't, it wasn't too fast. No, at least I was able to, to feel quite well. So II I don't know that for, for me it was ok. I was hoping to finish a bit earlier for questions, bro. I'm happy with no questions, to be honest. Ok. I, I think um it's gonna get, is it gonna be the same time next week or? Yeah, we gonna do it. Yeah. Next week. Oh next week. Um Saturday, Saturday. Ok. 6:06 p.m. Yeah. Ok. It's fine. Yeah. All right. Thank you. Thank you so much for very much for this session, man. Thank you everyone that 10 days, for sure, we meet again next week. Ok. So someone just asked that, what advice do you have for people who are interested in your radio? But I, I know yet. Um it depends on me where you are, really what stage in your career you are. I'm assuming this means you are. Uh because I also opinion me, I'm assuming you are already a doctor working somewhere, but you are just not in radiology training. Um So basically what, what um I will have to talk about just in the NHS because that's why I'm not interested in England. So it's three stages or it's not three stages, it's three parts to um get into individual training. You have to get a portfolio, you have to write the M SI exam, you have to sit for an interview and the portfolio bit takes a while to get your portfolio and the way you can um package your portfolio, you just visit or you arrange it based on the last year's scoring guidance. There's always a scoring guidance that they expect you to have. They also have like a person or job specification. So you can arrange your portio based on that the M SI exam. It's uh an exam which uh um I think GP PS neurosurgery Radiology. I'm not sure which it, yeah, so you have to write the exam, but the cut off is quite high thinking my year was 5 29. This year it was 5 45. So you have to just aim to smash as high as possible if you can. Then the next stage is the stage I tell everybody to my coding advice is you can smash MS, you're gonna get slots because if you have a perfect portfolio, but you don't score I in the MS R, you won't get caught in the. So the MS R is the limiting step. So you have to get a good score in MS R together to get into the interview first. Any interviews, anybody's game really, you just have to like make them, make them like you convince them that what you have in your port is actually what you have and that a very good story. But most times um M si cuts down I think from my stage um interview getting to and getting a job was one in 1.5 I think. And from before MS R was one in eight. So one in 1.5 and one in eight. You um so just to get the I I talk a lot sometimes it's yeah portfolio uh MS R and interview then that's it. If you want more uh advice on how to arrange your portfolio and stuff there guys on this call you can speak to, you can always me, me, I can drop my email address here if you want. Uh Don't send me any spam. So if I see you then we can check it out. Um So, um but the other guys you can link up to um I speak to him what he, he is a advice. Uh So uh that's my middle address. You can just contact me and we can chat. Oh, all right. Thank you so much. Um I think that's the, that's the last question I can see. All right. So, uh please do well to um fill up the feedback. Um and then we will meet the next week. All right. Thank you so much. Once a day. You're welcome. See you guys. I think I'm good. I'm done.