Transcribed by Atiya Bahmanyar July 31, 2014Double Exposure- [Dr. Stabulos] Good morning everyone, good morning. Its still morning. Its not still morning? Okay, um, I have a lot to cover so Im going to get started. So the last thing we spoke about the other day and were still talking about the paralleling technique, for those of you who are trying to keep track. Um, so we began our discussion about errors and how to solve the errors, and as I mentioned the other day you can find an appendix in the book that gives you all the errors, the remedies, what it looks like, all in a nice composite table. It works to learn them and go over them. So the last error that we spoke about is double exposure. Just to repeat, double exposure is using the same film twice. Um, or more than twice, Ive actually seen that as well. The best way is to safe guard against it again, we have at the college films that are wrapped in barrier envelopes, so if you remove the barrier envelope after youve used it, you can tell right away that youve already used it. Those that you havent used will still have the barrier envelope on them. So double exposure is the worst possible error you can make in terms of patient exposure. Because for every retake, you have to start with two. Because there are two films that you missed that are on the same film and not diagnostic. So, for every double exposed films you have to retakes to start and if one of them doesnt come out right, then it just keeps snowballing.

Blurred Image[Dr. Stabulos] The next thing we want to talk about is a blurred image, and it really does look like a blurry image- like if youre eyes arent in focus. The cause for a blurry image, is movement, in general. Okay? But it will include any kind of movement- patient movement, film movement, PID movement, tube head movement in its entirety, or just the PID moving and being loose. But, something that you need to know is that the movement has to occur during exposure. If it doesnt move during exposure then its probably going to end up in collimator cut off because if a patient moves after you place the PID at the patients face and the patient moves, it will be off the film and it will probably be in collimator cut off. But if it moves during exposure, then youll get a blurred image. Okay? So whats the remedy? Make sure theres no movement during exposure, keep your eye on the patient. I always have a tendency to back out of the room, so I keep the eye on my patient. That doesnt go for the mannequin we use in preclinical- but for real patients you want to keep your eye on the patient. Once you press it and the time that you need to expose todays films and digital sensors is not a lot of time. So the movement has to be quick and at the right time or the wrong time, depending on how you look at it in order for you to get a blurred image.

Failure to Remove metallic objects-[Dr. Stabulos] If the patient doesnt remove metallic objects then you already know that metal will show more radiopaque than pretty much anything. This is a nose ring that wasnt removed. This is a partial denture that wasnt removed. Let me just bring up the point that you can leave partial dentures in the opposing arch. So lets say youre taking- and this does not go for panoramic- Dr. Friedman gives the lecture on panoramic- everything needs to be removed. Thats a whole different scene. But for intraoral films any thing that is in the way of the primary beam getting into to film will be superimposed over the film. So if youre taking a mandibular PA film for example, and you have the maxillary partial denture in- that can actually help you. You dont want to have the mandibular partial denture in- but you can have the maxillary partial in because it will help you stabilize the bite piece. Okay? So you can leave metallic intraoral objects in- obviously the ones that cant be removed, like a porcelain infused metal crown- haha- you dont remove those, but any thing that can be removed thats in the way of the primary beam will be super imposed. The worst case scenario like here will be that its super imposed right over the tooth surface. The nose ring here doesnt really get in the way, but I usually ask patients to remove any metallic objects that are in the way of the primary beam getting to the film, if they can be removed just to be on the safe side. Were talking intra oral only now- this does not move over easy to panoramic, panoramic is a whole different issue when it comes to metallic objects like facial jewelry and such. A tongue ring doesnt have to be removed for intraoral radiography, why? Wh y do you think? Anybody? Yeah because its usually behind the film. Im going a little ahead- to get you thinking. What intraoral film do you think that youd need to remove a tongue ring for? An occlusal, exactly. It would most likely be a mandibular occlusal, the maxillary occlusal wont matter. The mandibular occlusal it will because the film goes in like a sandwich and it sits right on top of the tongue. So yeah, and its below the tongue in terms of the central rays beam directed from.

Common Bitewing Errors[Dr. Stabulos] Okay, so the common errors that are related to bitewing films as opposed to PA films can be also applied to PA films as well. The first one that you should avoid at all cost is overlapping. And thats because bitewing films are used to see the interproximal areas. So anything that obliterates the interproximal areas is going to be trouble on the bitewing. So that overlapping. Umm, if a collimator cut off, and this is done with a cylindrical cone, and you can tell because its curved and it follows the same trail as a circular colum n would. If it involves the teeth that youre looking at in this case, if it was a premolar that you wanted to see the premolar is pretty much, actually, yeah this a premolar this side, its cut off. Yeah you wouldnt see it. So if it involves the tooth that you want to see- the collimator cut off can be a problem on any film, not just bite wings. Now what do you think about this bitewing here. First of all when we look at films the first thing that I want you to do is say- if the film is a bitewing of the patients left or right side and its a premolar or molar film. So who can do that for me with this film? Which side of the patient is this on? Patients left. Is it a premolar or a molar film? Premolar? Molar? The point is, you dont know what it is. Why do you not know that? Because the film placement is off. So thats a film placement error, common with not only bitewings, but with PAs as well.

ACCESSORY RADIOGRAPHIC TECHNIQUES: BISECTING TECHNIQUE[Dr. Stabulos] Now were going to go on to the next item on the agenda, which is accessory techniques, and youll get a chance to experience some of the accessory techniques when you get to the lab as well. The two that Im going to talk about today are bisecting and occlusals. So the principles of the bisecting technique that weve discussed before are that the first principle of any technique, even parallel, talks about the film placement. So in terms of the bisecting angle technique, the film should be placed as close to the tooth as possible. Thats it. Its a very easy film placement. The second principle is a little bit more complicated and I might sound like the teacher on the peanuts episode, you know Charlie brown? Wah wah wah wah. Because its very confusing. Bare with me. So the central ray is going to be directed so that its perpendicular to an imaginary bisector that bisects the angle between the film and the tooth. Because what it basically means is that heres the long axis of the tooth, heres the long axis of the film. So where do I direct the beam? So its easier with the paralleling because theyre both parallel. But where do I direct the beam when Im talking about bisecting? I direct the beam at the happy medium. We cant decide where to go, we find some place that we both like to go to. So the central ray says, Im going to go half way between both options and be perpendicular to the imaginary bisector. Okay?

Edentulous Series

[Dr. Stabulos] Now most edentulous series you probably, not most, lets say some, edentulous series if you have to take PA films you dont take bitewings on edentulous patients because there are no teeth to occlude. So the PAs would need to be taking in the absence of another option, either occlusals or panoramics- but lets say that it has to be taken. Sometimes the ridge is not, does not have the length for you to place the film parallel. So you may need to use the bisecting angle technique.

COMMON BISECTING ERRORS ELONGATION, FORESHORTENING & POOR SAGITTAL PLANE ORIENTATION[Dr. Stabulos] also, small mouths like in the case of pediatric patients. If films are prescribed for that pediatric patient, you may need to use the bisecting angle technique. So those are indications for use. Also if you have the patient who has anatomic constraints that stop you from placing the film parallel to the tooth. Usually what I do is decrease the size of the film first- Ill use 1, not a 0 because you cant even fit a whole adult tooth on the film anyway. But if that still doesnt work we resort to using the bisecting angle technique because for us its an accessory technique. We use it here as an accessory because of its disadvantages, like dimensional distortion and more exposure to the patient in terms of the lens of the eye and the thyroid gland.

ACCESSORY RADIOGRAPHICTECHNIQUES: OCCLUSAL PROJECTIONS[Dr. Stabulos] As far as the bisecting angle technique if the patient has a narrow palate, if the patient has a very high steepled palate, if the patient has very large tori, whether it be palatal or on the mandible. Those will be indications for use in every day life in the clinic. And then you would use the bisecting. As I mentioned the other day, the two most common errors that youll find with the bisecting technique, because its very dependent upon vertical angulation, are foreshortening and elongation. Okay? And again, foreshortening is caused by either poor film placement, if the film is not as close to the tooth as possible, that can cause foreshortening or elongation depending on which arch youre at. But more likely it would be incorrect vertical angulation. So if youre vertical angulation is too much, too much vertical angulation- would cause foreshortening. The other day we talked about the sun in the sky, did I mention that the other day. When the sun is high in the sky you have a short shadow, when the sun is low in the sky you have a long shadow. This would be an elongated film and this would be a foreshortened film, and this would be a poor sagittal orientation. Lets look at these two films. If the tooth is shorter than it should be as opposed to longer than it should be, you actually see the entire tooth, which makes, and this sounds quite ironic, it makes that error more acceptable- because errors are not acceptable, especially if youre doing root canal therapy- but I would rather foreshortening over elongation because with elongation you dont even see the whole tooth. But were going to teach you a technique in the lab that I kind of eliminate the need to choose foreshortening or elongation.

Now as far as bisecting is concerned, what you need to know is the biggest disadvantage is dimensional distortion. Second to, or uh probably almost equal to the increase in um exposure to the patient. And um, the principles of the bisecting technique. Okay? And youll learn how to use it clinically when you get to lab.

Occlusal film packet[Dr. Stabulos] As far as the occlusal projections are concerned- occlusal radiographs are used to show the buccal lingual perspective. So youll hear us say a million times before you leave this building, when you look at radiographs- that youre seeing the length, and the width of your teeth, of the oral cavity, but youre not seeing the depth. SO youre seeing a 3D object in only 2D. Well show you all 3 dimensions on 1 film if its a CT scan of whatever youre looking at. If its not that an occlusal does fine in giving you the buccal lingual projection. So the indications of use for an occlusal is anything that you want to be seeing in a buccal lingual dimension. So if you have a um growth thats causing buccal bone expansion. You want to see that- how much buccal bone is expanding, seeing if its infiltrating the bone if its not infiltrating the bone. You can do that with an occlusal film. A cleft palate, impacted canine, a vertical fracture in a tooth. A vertical fracture is very hard to see in a PA because a vertical fracture doesnt have to do a buccal to lingual all the way through. So if it has normal structures super imposed, its not going to be very useful. So a vertical fracture will probably be better seen in an occlusal film. So those are the basic indications for use. The most common one Ive used here, not to say that its the most common over all- but the submandibular salivary gland stone. So in the submandibular gland, not the parotid gland, which is a whole different scene. For parotid gland you need a soft tissue film inside the cheek. Now we have to talk about the two types. So when you see a person come to you they either present with signs and symptoms of something in the buccal lingual perspective- or you see something superimposed on those films that are showing you 2D. Okay? So whether it be that submandibular salivary gland stone, or the buccal bone expansion, or whatever, the first decision is I need to take an occlusal of this.

The second decision is what type of occlusal should I take. So there are two different types of occlusal. You know that the occlusal film is the number 4 size. What do you think would be an exception to using the #4 size film which is nicknamed the sandwich film because of the way it goes into the mouth- but dont let the patient bite into it like a sandwich or youll get bite registration that you dont need. We have wax for that. Bite registration is black marks all over the film. So what would be the exception to the rule of using a large film like this for an occlusal film? What do you think? Child. Who said that? So yes, pediatric patients. So what do you think you can do? Use a #2 size film and just hold it like a sandwich- and thats what we usually do. SO the occlusal size film packet it is still the highest film here that we use- F speed film. I personally havent seen a digital sensor in #4 but that doesnt mean it doesnt exist. We still use conventional film for occlusal. It has a front and back side. F speed is designated purple. There is still an orientation dot on the film. Whether youre holding the film horizontally or vertically you need to make sure the orientation dot is seen outside of the oral cavity or else its going to be round and radioluscent and rounder and bigger than the orientation dot on a #2 size film because its number 4.

Maxillary right- angle project[Dr. Stabulos]So if youre taking maxillary right angle film- now here are the 2 types of films of occlusals the topographic occlusal is less than 90 degrees. Youre basically looking at a birds eye view or angular subway view. The right angle, topographic, used for large areas of pathology- an indication of use. Anything that affects the tooth like a vertical fracture, depth of PA pathology. Because on a topographic youre still going to be able to see the teeth, youd use that topographic projection to see the teeth and the surrounding area and the surrounding pathology because its larger. Now as far as the 90 degree is concerned, also called cross sectional- so nay of those terms will apply to the film youre looking at now. Youre seeing the extreme buccal lingual perspective. If youre looking at an impacted canine and to see if its closer to the buccal or the lingual- youd look at a right angle. If looking at a cleft palate- youd take a 90 degree. For that mandibular, submandibular gland stone- youd take a right angle- because what youd see more in that case is the surrounding area and not the teeth. Okay? So that would be for the maxillary. The topographic from the maxilla is set anywhere from the positive angle. Positive angulation comes down from heaven- dont need to believe in it just know where they are. Postiive used for the maxilla- negative is not good, but just the angulation you use for the mandible. Positive angulation for maxillary topographic film- from +65 to +75. If you want to see more of a length on a tooth what angle do you use? Lower angle or higher angle? Think foreshortening and angulation. Lower angle will give you more tooth length that the higher will. Dpeends what youre looking for and what you want to see as to where you want to set it. All occlusal radiographs are set on the highest intraoral setting which is usually equated with maxiallarmolar and thats for max and mand occlusals. Because when you do an occlusal youre coming in from here and theres a lot of bone to get through so you want the highest penetration that will allow to get the beam through. The same goes for gthe mandible. So this is what a topographic will look like . This is an anterior topographic. You need to know that occlusals can be taken anywhere on the arches. What doesnt change is the angles that youre using. Its 90 for 90 degree cross sectional right angle. Its 65-75 on the maxilla, but you can do that in the area of the maxillary sinus. What does change is the point of entry for the central ray is directed. Okay? The angle stays the same.

Posterior Maxillary Topographic projection[Dr. Stabulos]Thats what I was saying for the posterior

Mandibular right angle projection[Dr. Stabulos]For the mandibular it would be 90 degrees for taking a cross sectional. And anything for a topographic will be 35 and 45 degrees. Thats usually what works for us clinically. Um sometimes it will say 40-50 degrees, it depends. 35-45 is a good image. You need to know what youre looking for in order to determine how that angle should be. And again the range remains the same for the angle, what changes is where the central ray is directed. So for the mandible its negative angulation.

Digital Imaging[Dr. Stabulos] Okay now were going to talk about digital radiography. So I think youve all probably gotten the message that the school is turning over to digital by the end of this year. Well be using this on a regular basic. Youll be taught both digital and conventional in the lab. At this point, you know digital just means that youre digitizing the image.

Digital Imaging[Dr. Stabulos] In order to digitize the image you need a receptor inside the mouth directly connected by wire or wifi to a computer. The image is projected onto the computer whether direct or indirect digital radiography will tell you if its instantaneous or if theres a halfway point. Uses digital sensors to record the X-ray photons. So the x ray is still hitting the sensor with a chip inside that will read it and project onto the computer. First introduced in 1987. Its taken a while. In a university this side it will take some time.

You can use the same radiographic unit- you dont have to replace the unit- tube head machine, etc- the time will have to be re-adjusted depending. The one we use here you just push the button that says digital on it. Much less time is needed to expose, for the sensor to show that image then for conventional film. Much less time. One of the advantages is that it gives less exposure radiation to the patient. One thing you can use to decrease radiation is digital radiography and rectangular collimation. Best combination to reduce exposure to the patient. So when you take a digital image, and we dont call it a radiograph because its nolong film. You are taking that image and converting it to electrical impulses. The pixels together will produce the image- they arent in color- but we still have pixels because using a digital sensor.

Digital Imaging [Dr. Stabulos] digital imaging refers to the numeric format of the image content and the numbers are encased as little pixels. The digital images are numeric and discrete. From each other they hold the numbers but they are discrete one from the other. Um what takes into consideration as far as the digital images are concerned are the spatial distribution of the pixels, where are they, how many are they in one spot, and the shades of gray. So were still talking about shades of gray. Although, one of the options once you get it on a digital screen, is to colorize the image- you can actually colorize the image. Another advantage is that you can adjust the image. Which is a wonderful gift. You can change the color on it- zoom in, change whites to blacks and blacks to white. You can say I want to see caries in green, bone loss in red, etc. Being able to manipulate the image is a huge advantage of digital imaging.

X-ray unit[Dr. Stabulos] The elements that you need to acquire digital image is the conventional unit- change the itme to coordinate with sensor. Theres a sensor for direct and indirect. There needs to be a converter in between. A convertor and a monitor.

This is the unit we use here- on this side of this gray shaded area you have a film and you have a computer. All you have to do is press the computer and it transfers over to the times that are needed for digital imaging.

Sensors[Dr. Stabulos] There are three types of sensors . The most common type is the CCD- the charge coupled device. The CCD and the CMOS senosrs are the most common sensors used for direct digital radiography. What do I mean by direct? Theres a wire thats attached to the sensor and attached on the other side to the computer. There is a visibile wire that you should be aware of. Direct digital because there is a direct relationship between the sensor and the computer. Now the indirect digital radiography will use the sensor thats called the PSP. Now this sensor is not directly connected to the computer. Let me just go back and say the CCD and CMOS can be connected to WIFI- no direct wire but the image is still instantaneous. Okay? The PSP are actually senosrs that can be used but youre not using the same sensor for every one of your projections. Different sensor for each one. Then placed in a laser scanning disc that gives you the image. There is a processing in between but not like conventional film. Will take 10-15 seconds.

Different Digital Imaging Systems[Dr. Stabulos] With digital images you can actually have the images go up on computer- you can have them printed out on hard copy- you can send it to a remote site- you have to be aware of protecting patient though when you do that- according to HIPPA. Must be a secure site.

Direct Digital Radiography[Dr. Stabulos]So the direct digital radiography will use CCD or CMOS sensor- most of them are wired directly to the computer- some of them can be connected via WIFI. All of these senosrs are extremely sensitive. You can drop it once and may have to replace them. Can range from $8000 to $20000. Image is instantaneous.

Direct digital sensors available in different sizes[Dr. Stabulos] Um these are just some sensors- this is older this is newer that is closer to what well be using but we may be changing that as we go on. These CCD sensor that are used with direct digital radiography are large, thick, and not flexible. A little more difficult to place than flexible film packet. They do come in 0, 1, and 2. I havent seen 4s but they may be out there.

Storage Phosphor sensors[Dr. Stabulos] The phosphor plate- is much thinner, still rigid, easier to place and most of the time youll see in pediatric practices because they are easier on the patient when you place them into the patients mouth. Must be placed in drum and then you have to use a sensor.

Storage Phosphor unit[Dr. Stabulos]You can use the same sensor put it in the patients mouth, get the instantaneous image take the sensor again, do another image, and get another image. With this one you have to get another one and put It in this drum so that it can scan it and get the image. Not as slow as conventional but takes more time than the instantaneous.

The Image[Dr. Stabulos] The image thats been acquired is composed of pixels- the equivalent of silver halide crystals. More sensitive to radiation so takes less time to expose them and is less radiation to the patient. If you compare digital to D speed film- there is a 90% decrease in radiation exposure. 90% if you take that sensor in terms of radiation exposure compared to E speed is 60% decrease in radiation exposure. Still need safety precautions in terms of the lead apron because its not 0 exposure- just less. When compared to F speed film- 50% decrease. Thats a lot. Coupled with rectangular- its the best combo when it comes to exposing patients.

Computer screen showing images[Dr. Stabulos] There are different icons that allow you to do different things- I zoom in because you can see things that much closer. Once you print it out on hard copy it loses contrast and detail. Nothing better than viewing it on the screen. You can adjust the image and its a big advantage.

Optically scanned digital radiography is like scanning a radiograph- scan then digitize- but was taken conventionally. Not used as much recently- was used when we needed to send images to others.

Advantages of ditial that Ive been saying all along are the reduction to radiation exposure, faster image acquisition, can manipulate and adjust image, can store it, can send it to a remote site for consultation, hard copies- are an advantage because you can have it- but interms of contrast- not so good. Patient education, oh yeah. You can teach them whats going on in the cavity. No processing required but will always have conventional to fall back on. Environmentally friendly compared to conventional. Paperless needs to go digital too- happening here as well. Cross contamination still consideration- still need to cover whatever you touch- including key board- needs to be taken into consideration.

Digital imagingThe legal aspects of digital radiography is a consideration I wish for you that you never have a malpractice suit- if you show up with digital images- they can or can not accept them as medical evidence because they can be altered. They can or can not so thats definitely something to consider. They are working on that now to put some kind of stamp or security on the first image.

Errors in intraoral digital radiographyFor instance anything that has to do with the film- doesnt apply- no orientation dot to worry about. No worries about mounting films. If you click on template, once you take the film it will go into that spot- so no mounting. No such thing as reversed film- because you cant reverse it. No double exposure- it eliminates some overexposure. There are some underexposure issues- you can still alter the image

Some that still do apply are collimator cut off, poor film placement, overlapping, light films/dark films, but you can adjust that, blurred images- they could still be moving. Metallic superimposition, foreshortening and elongation. The exceptions would be any processing errors, film reversal, overmending of film packet, and double exposure. Okay?

Sensor with plastic covering for infection control purposes[Dr. Stabulos] The sensors need to be cared for. You need to cover them with barriers. You need to make sure cable is uncoiled. Cant clamp or roll over cable with chair- etc. Phosphor plates should be covered with barrier and you cant submerge them in cold sterilization solutions, and that goes for the sensors as well

Digital imaging technique[Dr. Stabulos]Placing sensor in patients mouth, bring column up to patients face, acquire image, change if you need to- in our case will be an instantaneous image. Which concerns me because we still need to- although its less radiation- have to think about implications of retaking the film. When its that easy to see and retake- I hope we dont disrespect the option to do that, if you know what I mean. I hope there arent more retakes. Okay?

The end[Dr. Stabulos]Haha I applauded myself- any questions come up to the podium. You dont have to applaud because I just applauded myself.