This presentation from Jesse Courtier, MD, chief of pediatric radiology at UCSF Benioff Children's Hospitals, provides an update on X-ray and CT risks for kids and how protocols have been shaped to minimize harm and maximize diagnostic detail. Courtier explains algorithms for deciding which imaging studies to order, provides graphics that place radiation doses in context for anxious parents, and displays images that show how machine learning is being used to enhance quality. He also discusses the new guidelines that omit gonadal shielding for patients getting radiographs and describes the shielding pitfalls that led to this change.
All right. Um So, yeah, again, thank you for the opportunity to chat today. And what I wanted to go over is a little bit about pediatric radiation exposure. A little bit about where we're coming from and where we are today. And uh it's a bit of a broad topic, but I wanted to touch on really, I think the important highlights of this. Uh and at the end, finish up a little bit about uh some policy changes that we've had regarding uh go gonadal shielding and pediatric patients. Uh here at U CS F and about uh what we're doing uh in that particular area. So we'll talk a little bit about what we know as far as pediatric radiation exposure, we'll talk about where we are, what we're doing now regarding minimizing and optimizing use of our medical radiation imaging and then we'll finally finish on future directions. So a little bit about what we know. So radiation exposure, there's a couple ways that we think about and uh few models that is thought to be used for identifying uh radiation exposure when it relates to the human body. And those are two different mechanisms. Those are stochastic effects and deterministic effects. Stochastic effects. Meaning that there's not really a clear line or a clear point at which we can say X amount of dose leads to this type of a result. This type of cancer say, for instance, um for instance, a radiation exposure, ionizing radiation beam hits a cell and the cell can repair itself and maintain and become a healthy cell or it can lead to a mutation. And this repair mechanism and this ability to repair is quite variable. It's gonna variable uh be variable between individual and individual, that individual's ability and robustness of their uh cell mechanism repairs. Uh their uh genetic susceptibility to radiation effects. So, there's quite a broad spectrum of how each one of these effects uh this particular result. So, again, in the mutated cell, this proliferates and can become a malignant tumor. But there's not again a clear line or a point where we can say that this effect happens. And so this is what we refer to as a stochastic effect at higher dose. In particular, there's something we call deterministic effects. And these are when using radiation, a radiation source delivers this uh dose to the skin and it results in cell death. And in this particular instance, we're talking about necrosis or ulceration of the skin. So um this is what we can say at this particular level, at this level and above will lead to X finding. So this is much more uh clear cut and we call this a deterministic effect. So we have a clear threshold as far as the sources of radiation. What are the various sources of radiation that we have uh here? Um Just being a human being living on the planet Earth, uh we have background radiation. Uh So for instance, we're exposed to background radiation from space, from cosmic rays um from terrestrial sources to consumer sources of radiation. Actually of the background radiation, the largest dose that we see is from radon. So particularly uh homes with basements and particularly in the Midwest where I'm originally from. Uh this is a high amount of background radiation that can be found uh just as being exposed to this type of uh of radiation here in terms of medical radiation, which is another source of, of the types of imaging modalities that we have. So x-rays fluoroscopy intervention, nuclear medicine, CT accounts for the largest portion of that. And we'll talk about how we've made a lot of strides in reducing the dose of uh administered by CT. And then finally, there are additional ones like occupational industrial and consumer sources of radiation. We'll talk a little bit about uh some specifics of those. So we can talk about effective dose and that is the uh dose that is delivered to an individual organ, for instance, um in terms of how this, how these various things relate and how they stack up. So interestingly, at 0.001 millisieverts eating a banana will give you that amount. So, um really, that's sort of a starting point or a baseline and we'll talk about often how we can contextualize these with other things that expose us to radiation. Uh So for instance, uh a chest radiograph being 0.05 millisieverts comparing that to things like uh dose received by flying a round trip to New York. So uh that being somewhere in the neighborhood of 0.1 millisieverts or a little bit 0.019 millisieverts here. So again, all of these being relative as we go uh a little bit forward here. So this is our dose limit to the public of of 1.0 millisieverts and that's excluding natural background radiation. Um If we see here, the worldwide average dose being about 2.4 millisieverts. So again, just anywhere from 2.4 to 3 millisieverts depending on where you live. Interestingly, the altitude that you live uh will affect the amount of radiation uh that you're exposed to just being alive on planet Earth. Um Here, this number of one ct scan, we're gonna show that how U CS F we've actually have significantly reduced this number. Um And uh many of the strides that have been made by manufacturers, by pediatric radiologists, by folks who have advocated for optimal use of radiation have really uh worked in stride to decrease doses like this. So where do we get this information from and this is a bit of a graphic slide here. But I think it's important to help contextualize where the information that we know things about uh cancer, about cancer risks, about deterministic effects. Uh Really a a good majority of this comes from the Hiroshima atomic bomb survivors and where each survivor was in relation to their initial exposure. Um and how much radiation they were exposed, calculating based on this. And then this allows us to know what are some of the risks uh depending on the amount of radiation you were exposed to located um relative to this map. What they found was a number of interesting things from this. Um This particular uh study was that exposure at a higher at a younger age uh is overall riskier. So the younger the individual was at the time of the bombings, the greater the risk of developing cancer was, but the risk does decrease over survivors lifetime. So, uh this is one I think important fact to know specific to pediatric patients. The question is though how similar is this data? Uh because many reports emphasize that credible evidence of carcinogenic risk of imaging related low dose, which is all below 100 mg, it's really non-existent or if it does exist, it's too small to demonstrate, meaning that trying to extrapolate information from refined uranium exposure from an atomic bomb, how well does that really translate to the type of exposure that we use from medical radiation uh using much lower doses in a much different context, different types of radiation exposure. Um How well can we translate that? It's challenging to know exactly that it's likely not going to be a 1 to 1 translation for this. And really the idea though is that we want to be very cognizant knowing that there are some risks inherent likely that we're gonna try to reduce as best we can radiation exposure for our pediatric patients because we know that Children, again, they're different in a number of ways, not only are they smaller but they're growing, they have increased metabolism and so um different parts of their body in particular are more or less susceptible and they have longer remaining lifespan. So it's for this re uh this reason that we know that lifetime risk for cancer from medical imaging were more marked when looking at it over a period of time. So again, we wanna make sure that we are very cognizant of using radiation and using it in an appropriate manner and using it sparingly when needed. So to this effect, for CT, the early CTS, they were higher dose. Uh the uh scans were not child size, they were not adopted with child size parameters. Uh The initial studies back in the 19 nineties showing some really striking data that uh some of the doses in pediatric patients were up to six times higher than really necessary. Uh for diagnostic examinations. Again, centers using uh more adult style protocols on pediatric patients. And a number of factors showing that really there is uh a much higher dose administered to our pediatric patients than needed. And this really spurred uh the image gently campaign in the early two thousands. So this was a really effective campaign talking about medical radiation, providing images and information both for patient facing provider facing information about medical radiation, About what are the reasons uh and necessities for using CT how this this information, how CT protocols can be optimized for centers who aren't doing pediatrics on a routine basis. So really helpful in spurring a lot of things and particularly uh lowering doses by providing standardized approach to CTS. So rather than a very heterogeneous national approach to uh an institution by institution approach, using a more standardized approach for protocols and CTS for pediatric patients. But I think also very importantly, emphasizing use of alternate modalities, increasing access to uh alternate modalities that are non radiation, non ionizing radiation utilizing such as ultrasound such as MRI. So for instance, uh things that we do overnight now where we would have previously done ac T of the abdomen and pelvis for acute appendicitis. Now we have an Mr appendicitis rapid protocol. So I think uh this campaign uh really uh did a lot of positive things not only in terms of education, in terms of standardization, but also an increased utilization of non ionizing radiation modalities. So this is a little bit about historical context of radiation, about what we know why we're taking certain approaches. Talk a little bit about how we're some of the things and the approaches that we're using here uh now at U CS F. So um newer technologies now take account for not only the weight of the patient, the age of the patient, um but also the overall size of the patient in terms of front to back, side, to side their overall girth and their overall individual size. So, again, very, not only child size but individual uh size and optimized dosing. So, uh with newer technologies now, since we're using here, uh we're able to optimize dose for giving higher doses for only the thickest part of the patient, lowering the doses for the thinnest part of the patient in particular here. Actually, we can even further adjust things like this to give and deliver even lower doses here uh on average for for this patient. So we're able to account for the size of the child and optimize their overall um their overall uh dose level and making sure that we're able to get diagnostic quality exams. And uh at the same time, only using the as low as reasonably achievable uh amount of radiation. Uh And so again, um we've, I think early on when this uh image gently campaign was going on uh pediatric radiology as a whole, we're trying to find the the ideal optimal sweet spot between being low dose and diagnostic at the same time. Because if we are going to low dose and you, you have a nondiagnostic examination, uh then you've done the patient a disservice and that you've given them radiation with no benefit. So we now uh use these technologies which I think are very helpful to make sure that we're optimizing the dose. Um And also very, I think excitingly using things like iterative reconstruction. So these are methods such that we can take data that would have in the past been uh a non diagnostic exam and using machine learning techniques and using advanced computer reconstruction techniques, we can take this and reconstructed into a diagnostic quality examination using a much lower dose. Uh So these are some of the exciting things I think we're we're using here. So really this approach is more algorithmic um really now the way that we approach things is starting off with the referring diagnosis and the referring provider. So uh at the point of discussion with uh when we get the referral is CT the best examination to uh answer this question, can we alternatively use a non radiation method such as MRI where we have a lot of other exciting developments uh optimized for pediatric patients uh or ultrasound? Really, and then say if we've decided that CT is our best modality for this, choosing the right type of scan, choosing the right type of contrast, um appropriately child sizing it, using it the level of protocol, it uh appropriately deciding on the timing, the injection, the types of bouse that we have. These are all things that we'll be thinking about. And then our reconstruction. So now, not only using the standard methods of reconstruction, but also also newer methods such as iterative reconstruction where we can take these again, low doses and reconstruct them into higher, more useful examinations. Um And then finally, in uh our rendering, storing and um a visual uh assessment of these. So I'll just touch on a little bit of this uh as well. So here is some of the uh general numbers that we have specific to U CS F. Um We can see a one hour flight being 0.005 millisieverts, a standard chest X ray uh with two views. Uh If you include the frontal and the lateral about 0.08 if we look at our ultra low dose protocol, this is something that is essentially equivalent to a two view chest radiograph. So our ultra low dose protocol is something we will use for assessments of things like Pectus six GATT. We now use this uh routinely for foreign body assessments instead of our uh in in compliments to our uh decubitus views looking for foreign bodies in pediatric emergency cases. So this allows us to get very high quality three dimensional cross sectional imaging. Uh but at the level of the dose of a two view chess radiograph. So I think a really, I think exciting um advance in application here uh at U CS F even our standard CT routinely. Now we've gotten at lower doses one millisievert even lower depending on the patient. Again, these are uh numbers that are uh general to this uh type of scan. Each individual to be able to calculate an individual specific dose uh requires uh much more detailed calculations, the organ, the size of the patient, the um amount of radiation used in the CT scan. So we're not able to provide a individualized if you see our reports, something specific to that patient of their effective dose. Uh because that requires a uh a lot of calculations that are very specific. Um However, you'll see on our reports that we do list the something called the CTD I ball, which is a um an overall general metric of the amount of radiation uh used. We use this information and we track this routinely as part of our quality control in our radiation safety committee so that we're making sure that our doses are consistently across the board being used. We're not seeing any outliers for any reason. Uh It allows us to keep a close eye on our doses and making sure that there are no aberrations, there's no changes in protocols. Um And again, something that we find uh very helpful and again, just to show the overall natural radiation exposure uh for one year anywhere from 2.4 to 3 millisieverts. And so this is some of the data that we can get even from our low dose protocols. So, again, high quality uh 3D renderings that we can get in cases of pectus Exum, uh we can get these uh beautiful renderings of the lung pereny here. And in this patient again, with the pectus Exum, this uh body surface rendering here. So I think again, one of the, the nice things, the advances that we've seen over the last 20 years where 2001 the dose for a pediatric ct test might have been 33 millisieverts somewhere in that neighborhood. Uh Nowadays, 10 years later, that became seven millisieverts nowadays down to 12.4 mill 0.4 miller. So really marked strides. And this has been on a number of fronts from the uh advocacy from pediatric radiologists to make sure that this is optimized from the advocacy of the technologists and also at the level of the uh national manufacturers working in collaboration with them and researchers to be able to find these algorithms, to be able to uh optimize this use so that we can get the best high quality information using the lowest amount of radiation uh possible. And just to touch a little bit on future directions and then we'll talk about gonadal shielding and how we utilize uh that here at U CS F as well. Um So the traditional method uh was a more of a black box math mathematical calculation to be able to take AC T scan raw data and convert it into a usable image. And while that was very effective, it also required a higher dose. So uh and this was something that was really only possible at the time because the computing methods that we have now were not available at the time. So uh this was essentially the best it could be done uh back in those days before uh really high power computing was routinely available. The next step was iterative reconstruction. Uh This is what we're using now routinely. And the step beyond that is things like deep learning imaging, uh deep learning image reconstructions using things like machine learning convolutional neural networks using uh new methods to be able to even further take this into uh the next level of low dose high quality information. Um And so this is the direction that we see uh things heading both even CT and even MRI uh usable uh information that can be gathered from very low uh low signal uh source data. So yeah, I think these are very exciting directions again, taking information that would have otherwise been diagnostic nondiagnostic previously and turning it into these high quality precise images where in this particular case, we can see now uh within this stint that it is patent where before again, very blurry, very difficult to see. I'm not sure if this is quantum model or if this is actually real data here. Again, the ability to take this using machine learning technologies is using it to apply this to be able to reconstruct into a very high quality uh usable data. Uh Now I wanted to touch on uh radiation exposure as it relates to our radiographs and some of the things that we've incorporated here and some of the new ideas that you may see um about radiation exposure relating to pediatrics and gona shielding. And we'll specifically talk a little bit about what we thought previously, what we know now and again, some current guidelines. So shielding uh back when this was originally uh implemented, this actually comes from uh 1976 code at the f federal regulations um which addressed really only gonadal shielding specifically. And at the time, uh this was thought to be based on a hereditary risk uh rather than a stochastic model. The uh thought that perhaps this could result, radiation could result from um a dose to the gonads and this could be uh propagated to uh future offspring. But it was really found that uh this doesn't occur at doses lower than 250 mg. So, again, quite a high dose, uh female fertility isn't affected at doses less than 3000 mg. And so really the regulation cited only concerted, concerned a theoretical hereditary risk. Um and that's, that was the thinking behind it, but it was found that really, this has not been the case after many, many years of using uh radiation. Um So what do we know? Well, uh we know that we've actually dramatically reduced dose even in radiographs. When we talk about CT reducing dose, we've also done the same with radiographs. Uh So for instance, a uh abdominal radiograph in 1959 the dose delivered to the testes of 2.5 mg and to the ovaries of 1.2 mg. Even in 2012, we can see that we reduced this by more than 98%. So uh to 0.6 mg and 0.1 mg uh in 2012. And so, even now, even further advances beyond this, uh but we can see that we've dramatically reduced the dose uh to the testes. Now, based on using computerized techniques rather than standard film, which required a much higher dose. Uh We've been able to markedly reduce the amount of dose used uh in radiographs. The idea behind sh uh shielding was that you are trying to prevent direct exposure of things uh by placing a lead shield over it, such that the photons won't, won't hit, it won't cause some of these effects. However, uh really, this is thought mostly to be something that is off the focal beam. However, a radiograph nowadays, they are much more precise in being able to provide the focal beam really only to the necessary area. So we can use calm to really focus this beam. So the outside scatter is really less of a concern now. And really the majority of any kind of radiation to the gonads actually occurs from internal scatter. That means that the radiation beams are hitting things like the bones and bouncing around. And that internal scatter actually is getting and accounting for the majority of the dose to things like the gonads, the ovaries of the testicles. So really external shielding doesn't do any good to prevent any of that. And the other thing is the automatic exposure control. So remember I showed you the diagram of the chest and how we can modulate the dose depending on where the thinnest or thickest portions of the patient are with a radiograph, it's a similar idea in that uh if it sees something that's very dense, it is going to adjust the amount of dose to uh account for the very densest structure so that it will make sure that it gets a very perfectly exposed picture. However, if you place some lead shielding in that area, it's going to think there is a very dense structure there and it's going to dial up the dose to be able to try to account for that. So essentially by placing the shielding, you're actually causing an increase in the dose to the rest of the abdomen or the rest of the patient that is ex that is not exposed, that is not shielded, you're actually giving more dose to those areas. Um And this is another thing that touches on it and that's placement challenges. So we see that we can not be, can be quite challenging to place these lead shield of patients and pediatric patients, they can move between the time that you place the shield and you walk over to take the radiograph. Uh So uh it can be difficult for the patient and for the technologist to accurately place this note that also the ovaries are in a very variable location. This was a study where they assessed the location of the ovaries based on ultrasound and found uh this diagram of how really widely variable the locations of the ovaries are uh finding that when trying to place the goal shielding uh for patients that they are often incorrect, you know, and understandably. So based on how variable this this location can be. So trying to put goal shielding for ovaries can be really essentially a guessing game. And the other part is that um the shielding can obscure pathology. So we have seen uh not infrequently how placement of the shielding while well intentioned obscures the actual area of interest in this radiograph and such that uh we have missed or can have the potential of missing uh things like uh Osteomyelitis fractures. Those types of things, studies have shown that there's uh been a higher repeat rates uh with obscuration of bunny landmarks in shielding and up to 30 43% of uh images. So, again, needing to take a radiograph repeat radiograph uh because of use of shielding um can lead to increased dose and sort of uh is counter to what we're, our initial goal would be uh by trying to place the shielding. So, um again, can obscure pathology as we're seeing uh some of these examples here where really uh the point of the scoliosis radiograph is to assess the scoliosis here. And as we see, we're completely obscuring some of these things again, while well intentioned um are uh not something that uh is able to make this uh useful in this uh diagnostic setting and also obscuring things like the tips of catheters and things like that. So, again, uh resulting in a higher dose because you've got this large amount of shielding overlying the patient here. So because of all these factors, um really, they started to think a little bit about potentially discontinue this practice. Again, a few years back, this was brought up and really uh at first met with skepticism. Again, this really required looking at the data, looking at the practice and uh over subsequent years, uh it was found um a National Committee on Radiation Protection National Council on Radiation Protection currently now recommends that uh goal she not be used routinely during a radiography. And this is uh subsequently since been supported by our A number of our both um regulatory bodies, our certifying bodies, uh our societies here uh really across the spectrum uh with messaging that really, this is not something that is recommended any longer because of these reasons that I stated. Um and this has become really a national standard um through messaging, through endorsement of this positioning. Uh There's really a lot of great information out there about the practice, something useful for patients, patient facing information because we still do get questions from parents. So uh why aren't you using a shield? Uh when you're taking the radiograph uh when you're doing the floo. Um And this is, I think is very helpful this material um to be able to give information. The American Academy of Physicists and Medicine also provides a great website that uh provides information for uh technologists for uh ordering providers about the ideas and use uh behind um this recommendation. And I think it is really helpful for uh messaging because again, um we wanna make sure that pa parents are aware that this is why that this has been very thoughtful uh decision and what's behind this and what uh regulatory bodies are supportive of this as well, that this is this just an individual institution deciding this, this is a a decision and um messaging from a national standpoint. Again, this is our American Society of Radiation Technologists. They've got great information here with uh informational video uh about this. So, again, a new a change that was implemented here that um is now uh and standard across all children's hospitals. Uh member of our Society of Chiefs and Pediatric Radiology and children's hospitals or scorch. And again, this is a, a topic, a nice topic of discussion about implementation of this uh at our last year's meeting. So, um yeah, I think this is really just a one thing that I thought would be good for people to be aware of so that we are no longer using lead shielding for imaging, both in pediatric and adult patients. Uh There's been no change to occupational use of shielding, but this is a new policy as of uh January 1st 2023. And so yes. So we've talked a little bit about what we know about uh pediatric radiation exposure, a little bit about where we are and what we do and some future directions. So, um yeah, thank you very much for your time and opportunity and now I'm happy to answer and field any questions.
