let's do a recap on oral radiology so we're going to zoom into radiation and we're going to start with the basics so when we look at what radiation is in simple words it is an energy it's a form of energy that is transmitted in waves okay so there's waves happening we can't see those waves and that those waves are creating radiation there is radiation all around us think about the sun the sun has radiation that's why we wear sunscreen to prevent us from getting cancer from those radiation when we're listening to music when we turn on the station there are radio waves happening when we take x-rays there's radiation happening as well so things to keep in mind is when you're looking at the wavelength um there could be long wavelengths so this is an example of a long wavelength and reason why it's long is because if you measure from one side of the wavelength to the other side it's long right so the distance is long so wavelength is the distance of the wave and then if you look at this one you can see it's a lot more shorter because if i measure from this end to this end it's short so this is an example of short wavelet now when you have a long wavelength so these are examples of long wavelengths it's low frequency and when they see low frequency what that means is there's less energy so see how all the l's come together long wavelength low frequency less energy so there's less energy here but when we look at x-ray machines what do we see we see short frequency because the distance from one wavelength to the other it's short right so we see short wavelength which means high frequency so i meant short wavelength we see short wavelength which means high frequency high frequency means there's like so many waves like if there's so many waves all you know clustered together that's high frequency and so when we have high frequency there's like a lot more energy needed to create these radiation waves okay so again x-ray what is it it's just a form of energy that comes in these streams of waves it travels really fast like a speed of light and it can cause damage right it can create something called ionization which i'll go over what that means soon and the way we measure the um radiation is through frequency which is if you see lots of waves it's like high frequency we measure it through wavelength so if you see a big gap between the waves then it's low frequency long wavelength less energy and we also look at the term velocity velocity is speed how fast is it coming that's another way to measure radiation so when we're looking at the physics this is an atom and an atom has oops sorry so this is an atom and an atom is basically just um the smallest thing that exists and it's like a building block and you need a small particle and then um you combine so many particles and it becomes something so our human body is made up of so many gazillion atoms so atom is the smallest thing that's out there um and what's interesting about the atom is that it is neutral so you can see here the positive and minus cancelled out the positive and minus uh charge cancelled out so it's neutral there's no charge on this atom but in an ion there is a charge so this is positively charged because we see more positive compared to negative so this is a charge and when we have radiation there is ionization happening where there is a charge and to measure radiation again we look at wavelengths which we talked about before wavelength is like the distance from one wave to the other right from the wave of the crest from one wave to the next wave velocity is how fast this waves are coming frequency is how many crests do we see so this is an example of low frequency high frequency would be like this because we can see so many more crests so that's frequency photon proton and quantum this is like a bundle of energy so when i am you know pushing the x-ray button and we're getting radiation happening it's it's the photon that's creating is the bundle of energy or photon or energy that's helping me create the radiation so here's an example of an electromagnetic energy spectrum and we can see here that it is a spectrum sometimes you can get really high frequencies sometimes you can get low frequency so there is a spectrum and then there's some in between so we look at radiography which is right here it is the you know high frequency you need a lot more energy when we're looking at the x-ray machine there is the control panel which is typically where the on and off switch might be this is also where they would have settings to regulate the exposure factor so for example they would have a setting called for m a which is called milliamperage and they would also have a setting for kb p which stands for killer voltage peak and so may you can adjust this and what emily does is it is it if you have increased m a so if you up the number of m a you're gonna get a darker image okay so it's to do with density and so the higher the ma the more dark the lower the ma the less dark and we'll go over this in another slide kbp looks at contrast and what that means is that if you increase the kvp you're going to get lots and lots of shades of grey in your images in your radiograph but if you decrease kvp then you're just going to see black and white like you probably won't see many shades of grey so you'll just see black and white so kbp looks at contrast if you increase the kvp you're going to see lots and lots of shades of um gray and if you decrease the kvp you're going to see more black and white just simply black and white not that many shades of gray and we'll look at that later on too now in an x-ray machine actually let's go back over here this over here is the extension arm okay so this is the extension arm that can extend and this is the tube head and the tube it is where it was where all the magic happens what i want to point out over here is this circle thing that we're looking at is your pid position position indicating device and uh this is great because it's this is exactly where you know to aim right which tooth you want to aim it at is where you position the pid it helps the pid if you have a long pid there's like 16 inch pid and there's also like eight inch pid for example so the longer the pid the more um better the better because it decreases the radiation so we don't get that much radiation to the patient and there's also less image magnification as well so it doesn't that when you take when the x-rays come out it's not as magnified so let's see what happens in the tube head in the tube head what happens is when you push the x-ray button what's happening is you're getting a bundle of heat um right here so for the cathode this is the cathode this is the anode cathode is where the negative part is anode is where the positive part is to remember this think of c minus and then a plus you want your grade to go from c minus to a plus right we all want that we have a c minus right now we want our grade to to become an a plus so what's happening over here is we start with the c minus and what happens is this is a filament and this filament is creating so much energy so much um heat sorry so much heat and it's um electrons i just come up so you can see electrons have come out and the electrons need to go to the anode how does the electron go there well the kvp the voltage will take it there so depending on your kvp if you have a high kvp the voltage will just you know smack it onto the anode and the anode will catch it and you know slow down the radiation and take the radiation out this way it comes out into the pid and it goes to the tooth and it takes a picture or takes the x-ray of that toot so the radiation the way it happens is it goes from the cathode goes to the anode remember positive attracts i mean uh negative always attracts opposites attract that's what i want to say so negative will always be attracted to positive so opposites attract that's why they're going to the positive side the kvp is forcing them to go and touch the target it's called the tungsten target on the anode and the anode releases the energy or releases the heat and the radiation rather and the radiation cost allows for the x-ray of this tooth so here we have the molybdenum cup which is right here this is like a focusing cup it allows all the electrons to stay within that area when you get so much heat here electrons come out gets shooted into the tungsten target which is where the anode is and then the anode releases these um radiation and heat what's important is only one percent of that radiation is all that is needed to create that image the other 99 is just useless it's just um you know radiation that we don't really need it's not useful but the one percent is all you need to get that image and so the cathode or the cathode releases that one percent of radiation that comes out over here so here's a question for you um which exposure factor has a direct effect on image contrast contrast remember we looked at this before when we're looking at contrast it is kvp and again i just highlighted this so that you can remember that contrast and kvp they step out start with the cassand so that's how you can remember that kvp and contrast go hand in hand m a or milli amperage that is for density it's um you know if you want a dark image you need to increase the ima if you want a light image then you want to decrease the um ma a good trick hashtag to remember the ma is think about like you know you're baking a cake so if you're baking a um a cake for example this is my horrible attempt of uh drawing a cake but let's say this is a cake right here um if you increase the oven temperature so if you increase the oven temperature the cake will get burnt right it will get dark if you increase the temperature the cake will get dark if you decrease the temperature the cake will be light so same thing with m a okay so if you decrease the m a you're gonna get a light image if you increase the ma you're going to get a darker image now with radiation we have primary primary radiation and secondary radiation the radiation that we need to get our image is the useful one is the primary one so that's the useful radiation the useful beam that we want but secondary radiation are the ones that we don't need those are radiation that are harmful to us that don't matter and so that a type of secondary radiation is actually scatter radiation it's a type as a form of secondary radiation where instead of the x-ray going to or the radiation going to where we want it to go it's going elsewhere and this is why we wear like a lead apron so that it protects the rest of our body so when we're looking at scatter radiation there are different types of scatter radiation there's the compton scatter and the coherence scatter and then there's also the photoelectric effect which is um the radiation that happens i'm going to go over all of these compton scatter is when you have this photon this bundle of energy this radiation going and it finds a electron on the outer shell and it kicks it out and when it kicks it out this is ionization so when the electron comes out of the shell of this is the atom if the electron comes out of the atom we get ionization and so what's happening now is the photon the bundle of energy the x-ray came looked at you know knocked this electron out and then the rest of the x-ray and the rest of the photon went elsewhere that's a scatter it went to an area we don't want it to go so that's why it's known as the compton scatter ionization happened because this electron was kicked out this is very common 60 of the time this is what happens you get a lot of scatter radiation you get a lot of constant scatter radiation so compton sounds like common so this is the most common type of radiation we see the coherence scatter okay is you push the x-ray button there's photon there's that energy the x-ray comes hits the atom and nothing happens and and then it just and then like no electron comes out then the photon the rest of the photon just goes and gets scattered somewhere else not in an area you're interested in so no ionization happened here no electron got out so this is coherent scatter happens eight percent of the time where it's you know not harmful because no ionization happened so there's no biologic harm here but there is scatter so the image the x-ray radiation didn't go to where we wanted to go but um no ionization happened therefore no harm happened photoelectric effect this is what happens 30 of the time and here what's happening is you push the x-ray button the photons are coming it's going to an inner shell it finds an electron in the inner shell and it kicks it out and when it kicks it out we get ionization notice the difference between these two is that there's no scatter there's no other photon that comes out and goes elsewhere there's no other radiation that goes elsewhere so compton scatter is when you get photon in photon out and electron out photoelectric effect is when you get a photon in electron out with no proton out right nothing else has come out coherent scatters when you get photon in photon out but no electrons so no ionization over here so here's a question ionization occurs in which two interactions of x-ray photons and matter i'll let you have a look you can pause it the answer is b photoelectric effect and compton scatter this is where ionization happens let's look again photoelectric effect we can see the electron has been bounced out kicked out ionization happens compton scatter the electron has been kicked out ionization happens here no electron has been kicked out therefore no ionization has happened so therefore the answer for here is indeed b let's um recap some things we have learned earlier which term describes the speed the speed of wave it is velocity velocity looks at how fast the waves are coming so the speed of wave is velocity frequency is how many wavelengths the number of wavelengths so this is could be high frequency and this could be low frequency lots of energy here not so much energy over here wavelength is the distance from one end of the wave to the other end of the wave that's wavelength and quantum is also known as photon which is like that bundle of energy that happens when you hit the x-ray button the energy the photon the quantum comes out and gets passed through the useful beam is also referred to as which type of radiation useful beam it is primary radiation primary radiation is when the beam is produced at the a node um it's also referred to as the useful beam secondary and scatter radiation those are um radiation that the x-ray is when the x-ray beam has been altered has gone a different route here is um kbp so we're gonna look at kvp right now and what i want you guys to know is that with kbp when you have a high kbp so 90 for example is considered high you have a low contrast and i'll explain this in a bit but when you have a low kvp so 40 is considered low you have a high contrast what does that mean what does contrast means the conscious means what is the difference from this color to the next color and here there is not much of a difference there's a low difference so hence low contrast but high contrast is when you see a significant difference from the black to the gray you can see that significant difference that's a high contrast so sometimes when you have high kbp or not sometimes all the time whenever you have high kbp you have low contrast because the difference from this band to the next band is very low it's very little so you have low contrast but when you have a huge difference between the two colors that is considered a high contrast and so typically what happens is when you see many many shades of grey this is increased kvp this is a high kvp that's good to check for bone abnormalities so if you want to check for bone conditions bone abnormalities this a low contrast or high kbp would be good but when you just want to check for cavities so carries then a low kbp which should do it because now you want to see the really the difference between where the cavity is or the black compared to the other shades right so high contrast or low kvp is good for carries high kvp low contrast is good to see um a grocery check for bone abnormalities all right this is m a so when we look at increasing the m a the milli amperage you're gonna get a darker image think about like you know cooking in the oven when you're cooking a cake in the oven when you want a dark cake you're gonna put it in more you're gonna increase the temperature when you want a lighter cake you're gonna decrease the temperature and you're gonna get a lighter image now what we're going to do is look at some images and figure out what the error is so when we look at this image you can tell that there is it looks gray and there's not much of a contrast right as so it's like a fogged film and this can happen if um you know the lightning the lighting was off in the dark room it could happen because of scatter radiation so these are excess radiation um it could happen so many reasons can happen because of heat the humidity was off the chemicals were contaminated or it could have been an old image so this is an example of a fogged filament that is grey it doesn't have that much contrast many reasons why this could happen let's look at a dark image so this is a dark radiograph why do you think this could have happened this is an over developed film and it an overdue developed film happens to show up as dark and this could be because of the developer solution if the temperature is too high this can happen um if you developed it for too long so the time for developing was to this for you know was too long this can happen so again we don't really um see this as much because we don't use the developer solution or the fixer solution we don't use a dark room as much because we're now digital using more digital um types of radiographs but this could happen look at this light radiograph this is an underdeveloped film and again temperature of the solution was off it was too cold so when we look at this one if the temperature is too high this dark image can happen if the temperature is too low if it's cool um you can get a light image okay so low temperature light image ll right low temperature light image dark temperature um sorry high temperature dark image now what can cause a clear radiograph well that can happen because it wasn't exposed to radiation you didn't push the x-ray button um or you know this film didn't actually get exposed in the mouth and that's probably the main reason why you get a clear radiograph um sometimes you can get a completely black radiograph and that's because you when you opened up the film it got exposed to light and then you process it so when you expose it to light it will become black here we see spots and these are fixer spots okay so when you're going to the dark room to develop the films and you got fixers splashing the solutions splashed on the film before it got processed it creates these dots okay so radiograph with dots is because of it's known as fixer spots they appear light or white as we see here let's look at angulation so angulation of the x-ray beam vertical angulation is when it goes up and down so vertical angulation you can get positive which is on top where you're aiming the pid up negative is when you're aiming the pid like this so at the from downwards um so the pid is pointing upwards here the pid is pointing downwards so this is positive this is negative look at the numbers and this right here straight on is zero angulation this is horizontal so when you aim the pids dead on like this onto the occlusal plane which is like where the occlusal teeth are like right there that is horizontal angulation but when you aim it up or down that is considered vertical angulation and negative vertical angulation is when you aim the pid like this and positive angulation vertical english when you aim the pid from above now in terms of technique we have the paralleling technique and we also have the bisecting technique so let's look at the difference between the two paralleling is when you take this pid and you literally aim it right at the um [Music] detute and if you look at the film when you put the film and you look at the tooth they are parallel to each other so you're hitting the beam perpendicular so right a right attitude but if you look at the long axis or the line of the two to the film line it is parallel parallel means when two lines are running uh beside each other okay so this is the this is a really good one because when you do paralleling there's a very little image distortion you won't get for shortening or elongation or any distortion of that sort because paralleling is a good way to get an image bisecting is more challenging you may remember the snap array this is a snapper right here and what you're doing over here with bisecting is you're here you're applying the rule of isometry and this is a little more difficult because here you have to imagine um the bisecting angle so what what are we looking at here this is the the long axis of the tooth this is the line that you can just draw on the tooth and here is the film right here and you have to imagine there is a line a bisector an imaginary line right in the middle in between the receptor and the tube and that is where you're going to shoot it out you're going to shoot it right at the imaginary line and this is called the rule of isometry and actually when you look at this if you look at what we wish to draw um if you wish to look at the imaginary bisecting line there is a 90 degree angle which is right here the reason why it's called isometrics because of that 90 degree angle we have equal triangles on one side and also on the other side so 90 degree angle on both ends two equal angles this one unfortunately produces more distortion than paralleling technique because it is very hard right it's very hard to visualize that bisecting angle and i'm sure some of you guys did struggle with this in radiology so here again is another image you can see here the film and the long axis of the teeth are if you look at this line here the red line it is parallel hence paralleling technique but bisecting technique when you look at the long axis of the tooth and you look at the sensor or the film it's not parallel it's it's you just have to imagine that there's a bisecting angle right here a bisecting line a line right in between those and that is what you're aiming at right at this line so it's a little bit more challenging to do let's look at this image over here this is an example of a bitewing so another actually i should probably start with this one another um type of intra oral imagings is so we looked at paralleling we looked at bisecting then there's also bitewing there's horizontal bitewing and vertical bitewing where you hold the film vertically where you place the foam vertically so why do you need to do white wings why would a dentist prescribe weight rings well maybe there's interproximal cavities maybe the restorations aren't you know proper so it's defective or maybe they're suspecting periodontal disease and if there's expecting periodontal disease or periodontitis to be more specific then they might want to do a vertical bitewing so we can see the bone level a lot better okay so uh vertical vitamins are great for perio so if i were to look at this question here what is one reason that the dentist may have prescribed vertical bitewing images for this patient look at the options and tell me what you think i know the letters aren't there but it is this one it is a because of the increased pocket depth since the last visit so um we're suspecting periodontal disease so we want to see their bone levels which is why we did the vertical bite rings uh when you have a gag reflex we do not you know that's not an indication for vertical vitamins um when they have occlusal decay we're not really going to see the occlusal decay here is not an indication for vertical bitewings um and a broken amalgam on the maxillary molar you could see that with that you know a horizontal bitewing or even a pa you don't need to do vertical bitewing for that because vertical biteworks looks at bone 63 what is the reason for the lightness of this image why was it light okay so i know we didn't necessarily talk much about this but if you can recall from radiology class uh one of the things that happens is if your time is too low okay so if the time is too low um the exposure time you can get light image and think of um this just like m8 we're looking at me and we were like if you're baking a cake and you put like a low temperature you're gonna get a light image same thing with time if you decrease the time and if you don't you know if you use less time to cook if you only put the cake in for 10 minutes versus 20 minutes you're gonna get a lighter cake right so same thing with time same thing with m8 the exposure time setting was too low that is why there is lightness of this image developer solution was too warm if that was the case it would be dark the image would be dark fix this solution was too cool if that was the case the image would be dark kbp setting was too high if that was the case if kvp is high you're going to have a darker image you're going to have many a high or many shades of gray low contrast are low contrast many shades of grey because of the lightness of this image this film can be described as low contrast is the answer when you see many many shades of gray it's low conscious when you just see black and white um that is considered high contrast so low contrast is the answer here this arrow is pointing to a radio opaque structure so radio opaque is something white radio loosen to something like you know black what is this radio opaque structure that we are or that this arrow is pointing to it is the internal oblique ridge so this is a bone that just extends downward from the ramus of the mandible so there's a in the mandible there's a ramus of the mandible and that ridge is the internal oblique mental ridge this is a ridge that you would see near the premolar of the mandibular this is the molar so it can't be the mental ridge zygomatic process that would be at the top is in the maxillary arc median suture that is something you would see between the maxillary central incisors so the best answer here is this internal oblique ridge what is the restorative material used in the occlusal surface i know that the thing has been cut off but if you were to look at the posterior teeth what do you think the material is in the posterior teeth amalgam gold pfms or composite yeah it is composite so composite this is what it looks like you can see it's less radio opaque amalgam would be a lot more rigid opaque gold will also be a lot more rich opaque which we don't see pfms they usually have a would also be a beige opaque and there would also be a porcelain component as well which um we don't see so this is definitely a composite