 So I'm going to talk about brachytherapy planning and quality assurance. I'll start off with planning and then we'll go into quality assurance. And I'm going to spend a little bit of time, not much, on classical implant systems. And then I'll talk about modern computerized planning. We used to do planning for brachytherapy without computers, because we didn't have computers, and gradually computers came in. But the classical implant systems didn't need computers. So we could do it that way. And they still kind of exist. And then I'm going to look at the most common clinical applications of brachytherapy today. And then I'll spend some time talking about quality assurance. So let's look at classical implant systems. Well, the most famous is the Manchester system, the so-called Patterson Parker system. Not used very much today, and I'll talk a bit about it. The Quimby system, or sometimes called the Memorial system, because she worked at Memorial Hospital in New York City. And then the Paris system, basically developed in Paris. These are all used all over the world. I've never used the Paris system, but many hospitals in the United States. And it depends where the doctors trained. If the doctors trained in Paris, they'll use the Paris systems. Doctors trained in Britain, they use the Manchester system. And with the advent of computerized treatment planning, most of this is now gone, except maybe the Manchester system for the treatment of cervix cancer. And I'm sure some of you are still using some of these other systems. But with computerized systems, they've kind of gone away now. And we found the computer could do a better job. And it does a lot of work for us, because I can remember doing planning for brachytherapy. It would take me all day to do a plan for a brachytherapy patient. It was very intensive on the work of the physicist to do a good plan. Let's talk then a little bit about the Manchester system. The Manchester system aimed at producing a uniform dose within the treatment volume. Did you find a treatment volume? You put needles or tubes in the patient and try to get as uniform dose distribution as you can. And they had variable strength sources, so they weren't all the same source. You could put different strength on the outside than you put on the inside, for instance, to get a fairly uniform dose. And there were rules applied to the placement of the sources. So you had rules, place the sources, the activity of the sources to get as uniform dose distribution as possible. Now we can do all that with a computer with optimized treatment planning, much easier. And then they produced tables and you could calculate how long to leave the implant in the patient. Most of this, in fact all of this, pretty much in the old days, was for low dose rate brachytherapy. We didn't have high dose rate when most of this was done. It was originally devised for radium, but as I mentioned radium kind of disappeared. It was too dangerous, too hard to shield, and then it took over with cesium. And you get a new table produced with cesium, by the way. I hadn't thought of benching it, but the new tables that turned radium into cesium, Bob Shalik. Remember? Did you know he just died yesterday? Bob Shalik, the person who did all that work to convert the radium tables into cesium tables, unfortunately passed away yesterday. I just heard it by email this morning. I wasn't planning to mention that, but we should thank him for converting all those tables. He and Marilyn Stovall did all that work at EMD Anderson Hospital. The Quimby system, now we're talking Memorial Hospital in New York, another big center for physics. Some of the very early physicists in medicine started at the Memorial Hospital. We did Quimby was one of those pioneers. She was a lovely lady. You knew Edith Quimby, didn't you? Did you know Edith C? She had already died, okay. Edith Quimby, when I first knew her, exactly. Edith Quimby, she was a grey-haired lady, a lot older than I am now. She was probably in her 80s, late 80s, and she would still come to all the chapter meetings and sit there and ask questions and be available to talk to the younger physicists like me coming into the field. She was a wonderful lady. I always remember Edith Quimby. I haven't got time to tell you a story about Edith because you want to talk next. I don't want to take your time. It required a uniform distribution of seeds of all the same strength. So you didn't get a uniform dose distribution. You got uniform seed distribution, all the same strength. Much hotter in the middle than it was on the outside, which may be okay for most cancers because that's probably where most of the cancer cells are near the middle of the volume that you're treating. So they produced a non-uniform dose distribution. And then again, just the same as Patterson Park, you got tables that you could use and I used to use these tables all the time to calculate the treatment times and the dose distributions around the sources. They were originally devised for radium and radon seeds, but eventually extended to iridium and I-125. Lowell Anderson did a lot of work on these developing nomograms. You could use nomograms instead of tables to do the same thing. I'm not going to show that. But not many people I think are using those anymore because everything's computerized. But the nomograms can certainly still use. Yeah, I used to use them. In this system, they were designed for iridium wires and extended later to iridium seeds in a strand. So they looked like wires in terms of the distribution of the radioactivity. The sources were equidistant apart, arranged in patterns, usually squares or triangles. The dose was called the basal dose. They had this which was the minimum dose, located halfway between the sources in these patterns. So it was kind of a minimum dose in the implant. I never used a parasystem. Do you ever use a parasystem? I know of only two places in the USA that used it. Both they trained in Paris. The doctors changed the parasystem. They wanted to use the parasystem. No, they wouldn't let parasystem there. They had the memorial system. And again, they had tables provided to calculate the treatment times and to work out the dose distributions. That's the old system of dosimetry. We'll talk a little bit later about the computerized system of dosimetry. What are the most common clinical applications of brachytherapy today? I haven't got time to do them all, so I'll just pick a few. Gynecological treatments are probably very common around the world. Prostate implants are very common around the world, particularly in the United States. And breast implants is getting to be more common around the world now. We do a lot of them in the United States. So I'm going to just talk about those three. So let's talk about gynecological brachytherapy. When is it used? When is brachytherapy used? It's used for treating cervix cancer, very extensively. It's used for treating cancer cells that are in and around the vagina. Not necessarily vaginal cancer, but cells that might have spread maybe from the uterus into the vagina and endometrial cancers. So let me talk about cervix cancers first of all. And these are typical applicators that we used to use. They're now more modern, but the same kind of design. You have these tandems that are pushed into the uterine cavity and hopefully nowadays we've got iridium sources so they can be made a little bit smaller. It used to be quite painful for patients to have these pushed in when we had cesium for instance because they were quite big diameter. So these get pushed in and they have different curvatures depending on the curvature of the uterine canal. They also have these things called ovoids. Ovoids fit into the vault of the vagina and they irradiate the cervical arson around the distal end of the vagina. And then we have these so-called caps that fit onto those. Why do you want caps to fit onto those? You want to use the biggest spacing you can away from the tissues to get the best dose distribution. Remember, the further the distance the better the dose distribution. The better the penetration you get into the tissues. So you put the biggest caps on that would comfortably fit into the patient's vagina. And these are modern versions of the same thing. These are just the same thing. And you'll notice that the latest ones are CT and MR compatible. They don't have steel in them. They're made of CT and MR compatible. And notice also instead of just the ovoids, we now have rings and a lot of people use ring applicators so the ring fits into the end of the distal end of the vagina around the uterine canal sources that go into the uterine canal. We found that they were much more easy to input into a patient and the patient didn't need any anesthesia. It wasn't really painful. To put these, the bigger ovoids in could be quite painful. That's why the Hengki applicator fits in a lot easier into the patient's vagina. It's not so uncomfortable. When you're doing high dose rate practice therapy, the patient is going to be coming in maybe six or seven times. You don't want to have to keep and desatizing them every time they come in. That worked very well in our hospital. One of the ones that started with the... Another thing I haven't shown here is we used to put into the uterine canal a stent we called it. Did you use the stent? That stayed there during the maybe seven or eight treatments the patient was going to get. The intrauterine sausage would fit in very easily with no pain to the patient at all. So that worked out really well. We came from Schmitt in South Africa. And Felix made them, but Dr. Schmitt is a radiation oncologist. He basically invented them. In fact, while we're talking about inventing, correct. You didn't need to dilate the uterine canal each time, which is again a problem. If you look at this... I'm losing it. If you look at this one, there's kind of a spacer here. This pushes away the rectum from the sources. And that was invented by Jocelyn in Leeds. And you know what he did? He went to the barber shops and got shoe horns. Did you put your shoes on? Got shoe horns. And he fitted them on and found the best shoe horns. And then he bought up and they couldn't understand why there were no shoe horns in Leeds in England because he had them all in his hospital. He bought them all up and tried them all and eventually... And that's what this is. And the company then started making them to fit onto their applicators. Let's look at the Manchester system. And this is still going on today. With the Manchester system, they would calculate the dose at two points, points A and points B. And we still do it today. Even though we have advanced dosimetry systems, we still use points A and B for cervix cancer and maybe endometrial cancer as well. And point A is 2cm up from the cervical loss, which is right down the entrance point to the cervical canal there. 2cm up from there and 2cm across. And we all use that, rightly or wrongly, to represent the tumour dose. You can't have a tumour dose because this is a three-dimensional object. But that's what we represent, certainly the prescription dose. And we all think of it as a tumour dose. And then they have this other point, B, further out over here, 5cm out from the centre. Manchester had a reason for that point, but we kind of always thought that that has been the normal tissue dose. You're outside the tumour now, and that's where some normal tissues are. Well, that's easy, except most patients aren't designed like that. Most patients have a tilt to their uterine canal, their uterus, particularly if there's cancer in it. Cancer is pushing you off to one side. So most patients aren't really like that. And so what you do is you measure 2cm up along the tandem, and then 2cm at right angles to the tandem to represent point A if you like the tumour dose. Because the tumour moves. The tumour moves. The area you want to treat, the target volume, moves as the uterus moves. So that's why point A moves with the uterus, whereas point B represents the anatomy of the patient, the pelvis of the patient. So point B stays the same. Point B, you move straight up along the axis of the patient and 5cm out. So that's often an exam question. We had that so many times in our exam. I should put it in an exam, but I didn't put it in. I should have done it. I gave... All the answers in the test... Did you all know you were going to have a test? You were going to have a test? All the answers in the test we've already talked about. So you can read that. I don't intend you to read it. These are some recommended doses for low-dose rate brachytherapy for cervix cancer. And all I want you to see is that as the tumour stage goes up, the amount of external whole-pelvis dose goes up. Why? Because now you expect that some of the cells, the cancer cells might have got into the rest of the pelvis. So you treat the whole pelvis and the higher the stage of the disease, the more pelvis you treat. When you're doing that, you can't keep giving the same amount of dose to the intracavitree. You're going to have to reduce the intracavitree dose. So the intracavitree dose is decreased somewhat. The total dose actually increases because now you've got more advanced disease, you need more dose. So that's how that works. And the same thing applies to high-dose rate. This is an example for early-stage disease. Probably you don't need as much high-dose rate, some much external beam. Although I notice this table goes out to 54-gray. I just did something. Here it is. It goes all the way out to 50.4-gray. Early-stage service cancer probably doesn't need that much external beam. You're probably better off treating it mainly with high-dose rate. And the brachytherapy is the most efficient way to deliver radiation. You're putting it inside the cancer. So brachytherapy is a very conformal type of therapy. So the more brachytherapy you can use, the better. So my department would never have treated very high doses to the external beam, oh, this is now advanced disease. I've moved on. Advanced disease now, you need the external beam. And so you've got a lot of external beam. And as you increase the external beam, you decrease the dose or the dose per fraction accordingly to get a constant dose. I've got strange things happening here, okay? Now let's talk about irradiating the vagina. It can be treated low-dose rate. But probably nowadays mostly it's treated with high-dose rate. Low-dose rate is a problem because the patient is lying in bed, the nursing staff has a problem coming in and seeing the patient. Although pulse-dose rate is often used here. So I should have said you can't do it with pulse-dose rate. But most times we use high-dose rate for vaginal brachytherapy. We usually use a cylindrical applicator of an appropriate diameter and I'll explain that in a minute what's appropriate, okay? And then you have this stepping pattern with a high-dose rate remover afterloader or a pulse-dose rate remover afterloader that can design a dose distribution around it to get a uniform dose distribution in the tissue around the vaginal vault. And typically we define the dose as half a centimeter outside. Okay, remember inverse square law again. So this is what these applicators look like, these cylinders and you use the largest diameter applicator that will fit comfortably into the patient's vagina because you want a better dose distribution. You get a better depth dose with a larger applicator. And then finally, endometrial brachytherapy and this can be treated low-dose rate again, most commonly nowadays high-dose rate. For patients who have lost their uterus, so post-historectomy patients, we just treat the vagina, the upper end of the vaginal cuff because maybe before they removed the uterus, some of the cancer cells are gone down into the vaginal walls. For patients who have an intact uterus, then we treat both the vagina and the uterine cavity. And this will give you a picture of what we're talking about here. This is a picture of a patient's uterus, this is the uterus here and this is the vagina down here. And the endometrium is all this tissue surrounding the uterine cavity and it can spread down into the vagina. So we want a system that will actually open up in the uterine cavity up here. So this is what the system looked like. What did we used to call this? Not Hensky. Is that it loudly? The type of applicator that spreads out, what was it called? See, we've both forgotten. We used to have to do this and we've forgotten what it's called now. It's not Hensky. Correct. So what happens is you push this in through the uterine canal and then you push a little trigger and the bottom bit opens out to push against the walls so that you can treat the vaginal vault, the far end. And I think I've got a picture of the dose distribution. Here's the dose distribution that you'll get from a typical and you can see it's spreading out at the far end. So this is the far end, this is the vaginal, this is the vault of the uterus and you've got these sources spread out here. Typically we would define the dose two centimetres lateral to the middle of the uterine applicators. So that would be a typical point to define. You might want to give 500 centigrade per fraction there or something, that would be how you define it. And what are the guidelines? Guidelines published everywhere. I'm just quoting American Brachytherapy because I can get hold of them very easily. So if you don't add any external beam to these patients, these are the number of high dose rate fractions of different doses that people are using and that the American Brachytherapy Society say are appropriate for these patients. Remember it's half a centimetre away from this centre, sorry, two centimetres away from the centre of the uterine canal in the middle. So these are typical views. So that's gynecological Brachytherapy. Very common, I would say one of the most common applications of Brachytherapy. Maybe the most common now is prostate because we found certainly in North America prostate is correct. So we're now using a lot of prostate cancer because prostate cancer is very common in North America partly because it's overdiagnosed and we treat a lot of prostate cancer patients that would never die of prostate cancer because these are usually older gentlemen and they would probably die of older age or heart attack or something before there because prostate cancer is a very slow-growing cancer but we treat a lot of them because their PSA goes up and then they get frightened that they've got cancer, treat me and they go in for treatment and one of the most common treatments prostate cancer is Brachytherapy. So there are two major alternatives, a Brachytherapy. We can treat with permanent implants with either iodine or palladium or we can treat with temporary high-dose rate implants. You can do it high-dose rate or you can do electronic Brachytherapy which is basically high-dose rate as we mentioned before. And how do we do it? Well, the most common method is ultrasound-guided trans-perineal prostate Brachytherapy. Sounds very complicated. All you do is you put an ultrasound device into the patient's rectum and you look at the ultrasound outline of the prostate at different points in the rectum and then you design your treatment accordingly and put in, you have a template like this that you push up against the perineum of the patient so it's trans-perineal. You push it up against the perineal and under ultrasound guidance you put needles in to where you want the sources to go. Drop the sources off if you're doing a permanent implant or leave the catheters in to see if you're going to do a high-dose rate treatment. And this is what the ultrasound pictures will look like when you get them at different points along the rectum and you see that. And then you can use this to plan where you put the seeds. You can use it for planning. In fact, here we go. This is used for planning and you can put seeds to get the distribution that you want. You have an optimization program that would do this for you to tell you where to drop off. If you're doing a permanent implant you're going to drop off seeds. They're going to stay there for the rest of the life of the patient. So you just drop them off where the planning system tells you to drop off the seeds. And this is just a, I won't spend a lot of time doing this because we haven't got a lot of time, but basically what we start off with is we have the ultrasound scan of the prostate. We do the contouring of the prostate, all this in the treatment planning computer. And then you develop a plan. You look at the dosimetry. If the dosimetry is what you wanted, okay. If it's not, then you go back and plan again. But let's just say it's okay. And then you record all that data. You're going to have to go in and implant the seeds with real-time dosimetry. So you can do this real-time or not real-time, but most of the time nowadays it's done real-time. So you have the ultrasound system there in the patient's rectum showing you where you're actually dumping the seeds. So you can see where they go, okay. Then you review this, see if it's okay. Maybe use some fluoroscopy, see if the seeds are in the right place. If the dosimetry is acceptable, you record all the data and then send the patient home because you can't do anything about it now because the seeds are there permanently. So it's the way it's done in practice. And medical physicists get involved all the time with this. They're in the room with the patient. One of the few times that the physicist actually gets in with the patient and sees the patient. We did the ultrasound with the intravascular and brachytherapy. Yes, we used to do intravascular brachytherapy and the physicist would always have to be there to do it. But that's died out because the vascular experts have found a better way to treat the patients rather than radiation, so we don't... Anybody doing intravascular, putting radioactive sources into blood vessels to open them up? Nobody does it anymore. They were so exciting when we first... About 20 years ago. It was great. Very exciting. It's close to 20 years ago because we stopped doing it 15 years ago. I think we pretty much stopped. It lasted for about five years. Right. They came up with stents that they could put in that had a chemotherapy on them and it would open up the blood vessels with chemotherapy rather than with radiation. You know why they stopped it? Because they didn't need the radiation oncologist or the physicist. So in America, that means that they get all the reimbursement. They get all the money from that procedure. They don't have to share it with other people. Which is another logistic issue. Another logistic issue. In neurosurgeons, which we used to do that because of the brain, the seed implants in the brain. They didn't want anybody to tell them what to do. We were telling them what to do. Well, it was the law in America in most states, probably all states that the radiation oncologist had to actually do the procedure. So reimbursement for them was great because that's all they did. They didn't have to worry about the patient from then on. That was after the patient. Which is kind of nice. Let's talk about prostate permanent implants with I-125, half-life is 60 days. The dose is delivered over many months. The dose is delivered over the lifetime of the source, which is forever. A little bit. Forever, because it's exponential. But the useful dose is delivered over many months. With palladium, the useful dose is delivered over many weeks. If you have a more rapidly growing prostate cancer, you would use palladium, slower growing, most of them are slower growing, use I-125. The total dose delivered to infinity is very simple. It's the initial dose rate times the mean life. Makes it very easy for a physicist to calculate the dose. But it gets very complicated when you've got a tumor that's repopulating while you're treating it. Because then you have to calculate what effective dose is. So, examples. If the initial dose rate of I-125 is seven centigrade per hour, then the total dose is initial dose rate times the mean life is 145 grade, which is what we mentioned before is what we now use. And the same thing with palladium. The initial dose rate is 21 centigrade per hour. You get about 123 grade. When prostate cancer treatments first began with palladium, nobody knew what dose to give. I calculated with the linear quadratic model and came up with exactly the dose that we give today. So the LQ model sometimes works really well. And it's still used today, right? And then these are some recommendations. Let's not go over them in detail of what kind of doses to give if you're just giving the seeds or if you're combining seeds with some external beam radiation. You won't use external beam radiation at all unless you think that the cancer spread outside the prostate. If you think it spread outside the prostate they need some external beam too because you're only putting the seeds into the prostate. They won't irradiate anything outside. So HDR for monotherapy there are a variety of different fractionation schemes that you could use. And the American Bracket Therapies published these in case people don't know what to use and they haven't done much. HDR therapy for prostate cancer then they can use these these doses. So this is a task group of the American Bracket Therapies side. He said, what do you do if you're going to have to give some external beam because of the spread outside of the prostate and these are some of the numbers that they give you depending on what external beam that you've had. So I'll just show you that. These are all published and you don't even need to know. That's the physician who's going to prescribe these doses. They need to know this. They need to know where to get this information. And I'm sure other organizations, Europeans have different publications to do this. Now I'm going to talk about accelerated partial breast irradiation APBI as we call it in the United States is Bracket Therapy for breast cancer and it's used after a lumpectomy. Now we've discovered that we don't need to irradiate the whole breast in probably the majority of breast cancer patients. Just take out the tumor and it leaves a cavity inside and treat the walls of the cavity in case the surgeon has left some cancer cells in the walls of the cavity. The two major techniques one is to put needles in and I'll show you that interstitial bracket therapy or the other is to put a special applicator that actually makes the cavity into roughly spherical shape which is very convenient in terms of dosimetry because if it's roughly a spherical shape and you put a source in the middle you pretty much get a spherical dose distribution and so the dose distribution in the cavity is pretty much uniform around. So I'm very interesting and I don't know how wide that spread this is outside of the USA we use it a lot in the USA. Balloons. Well I'm going to show you some examples. So let's look at the technique for interstitial and this is just one example. You have a template that you attach to the breast and compress the breast and then you put the needles in through that template must be very painful for the patient. Presumably they get enough sedation. We'll never go through this. Well no, we do it in the transperineum. Come on. Prostate. And you can see the distribution of the needles in here and then if you're doing high dose rate for instance it would be easy to optimize the dose distribution to irradiate around the cavity. Here the cavity is an irregular shape you haven't made the cavity into a sphere here so it's an irregular shape. I see the templates in the superior view. Yes, this is Bob Kusky in Wisconsin. He used to be in New Orleans that's when I first knew him and he invented this method and took it with him to Wisconsin. Actually my son's a medical physicist used to work with him and he was very unhappy with my son left because he was the one physicist that really understood this method. He worked with him a lot. So this is what it looks like when you finish putting the needles into the patient. Look how they've shaped it around the cavity. Your right hand diagram there is a round cavity so you get a fairly uniform distribution around the cavity and then you do this high dose rate with maybe five fractions in a week, something like that. And the American Brachytherapist Society again has come up with some examples. Now the blue method that Jakov was discussing is relatively new probably the last six or seven years and at the time of surgery when the patients just had the lump removed you insert a deflated balloon into the cavity. Then you sticks the patient up and a week later the patient comes back after the wound has started to heal the patient comes back and then you inflate the balloon and then that makes the cavity nice and spherical so you can treat it. This is the mammocyte system used to just be one source or done high dose rate and then they've changed it now and you've got various catheters that spread out inside there and it's very similar actually to this system which is called the Contura system which has four different catheters that are spread out inside the balloon and a central one and you can get a dose distribution that you designed for that cavity. It's not quite spherical but you can get it spherical. Right. So the Contura displaces the shape of the tissue more or less spherical doesn't have to be spherical because you can do optimization of the dose distribution you've got lots of potential source positions. There's another method called the Savvy that doesn't use a balloon but uses this system that you can expand inside the cavity. You expand it and it pushes the cavity up to be roughly spherical again and get it and again it doesn't have to be exactly spherical because you have different source positions you can optimize the dose distribution very easily and it finally is another one that I haven't actually used called the Clear Path and it's very similar to that again it's something you can expand inside to create something that looks like a cylinder a spherical system and you've got this little pink thing there which actually protects the tubes when the patient because this is going to be probably a weak treatment come in once a day for a treatment you want to protect it and it's not so ugly because it kind of covers up the tubes that are in the patient but that's about all that's for Yeah this looks like a big incision as I said I haven't got any experience of using that because that's a but remember this is all done in surgery this is when the patient's having surgery you insert it and then you wait a week and eventually when it's taken out the doctor will stitch it back up again so you haven't got a hole left in the patient typical doses that are used typically if you do it low dose rate not many people are doing it low dose rate but you can and high dose rate everybody almost in the United States is using 34 gray one centimeter outside the cavity okay think about it that means closer to the cavity wall you get a much higher dose maybe as high as 50 or 60 gray closer and that's very clever because you expect the higher density of cancer cells to be closer to the cavity because that's where they might have been left by the surgeon so it's very clever that you actually have this dose distribution and it works very well so I'm going to finish very little on quality assurance because some of you are coming to the demonstration this afternoon we do quite a bit of quality assurance in the demonstration this afternoon so it's needed to ensure the safety of the patient the public and the staff positional accuracy of the sources temporal accuracy so they've got to be in place for a certain time temporal accuracy of the sources and then dose delivery accuracy in general so there are guidelines to do this Astro has some guidelines you can find these free online similarly AAPM has a task group report and you can get all those online and they look at daily or quarterly and so on quality assurance safety of the public and staff you're taught next I should stop now because error avoidance is very important to avoid errors and make errors in brachytherapy as you didn't present them in that but a lot of big errors have been made in brachytherapy patients have actually died because they left the source in the patient and sent the patient home bad news clear prescriptions and you've heard all about this for external beam the same thing applies to brachytherapy emergency, got to have emergency procedures to make sure you know what to do if the source gets stuck which it does I usually send in my junior staff into the room to get the source out of the patient I don't want to do it he's quicker than me too and he's got longer arms, Gary is hell has very long arms because you get a lot of radiation there with a high dose rate source you have to do it fast and you have to train the staff to do it radiation safety in general room shielding and so on additional accuracy you've got to make sure that the machine is programmed properly and you've got to check it that the sources go to the right place, lots of systems for doing that the catheters are all the correct lengths errors made because of that and then all the applications are in the correct place and you have to do this per patient, not just per week or per day, you have to do it for every patient and make sure that each patient gets the right treatment that you're planning and there's a tool for doing this I think you've probably seen one like this this afternoon, those of you who go over to the hospital very similar to this using gaff chromic film for instance you can see where the source stopped and you know where you meant it to stop and you can check is it within a millimeter of where you meant it to go the same thing with time, low dose rate this is important make sure that you take the sources out low dose rate when they're supposed to be taken out you don't leave them in the patient for an extra day or two because you forgot to tell somebody to take them out and we did that once and I had to go in and take them out myself instead of the doctor because the doctor was on vacation and he forgot so I had to do it that doesn't happen very often fortunately I had good records remote afterloading everything has to be has to be checked for quality assurance program and transit dose is the dose that the patient gets as the source is moving in the patient, not when it's stationary when the source stops, but when it's moving to the stop positions, there's some dose and we need to know what that is it's an added dose to the patient and then accurate transfer of the data from the treatment planning computer and in dose delivery accuracy, physical aspects make sure everything's right source strength for that particular patient and all the data's in there and if you're taking account of the attenuation in the applicators, that should all be a part of your quality assurance program and then clinical aspects every patient, you've got to know how accurate that data is if you're using imaging data and you're transferring it to the treatment planning computer make sure that it's all right and then source strength calibration I already talked about source strength primary standards lab or secondary standards lab has the ability to do this accurately, you don't in your department, they do it and then they calibrate your equipment that you're using to do it so typically this is done by the primary lab and then you have dosimeters like these well-typed sanitization chambers that you can put the sources in they have been calibrated by the standards lab to represent the dose that they measure equivalent to measuring at one meter from the source to get the source strength and these are just three of the I don't know what one I'm sure you can see one this afternoon if you come to the demonstration the calibration lab surprise you with lots of data and I'll just show you one of them the sweet spot localization location inside your chamber there's a sweet spot a spot where it doesn't change much with position which is where you want to work and they'll tell you about that and you should measure that too moving your source in and out until you get the maximum and that's where it's more like you've got less error in positioning and then for each patient you need to check everything make sure you've got the right patient as we heard before everything has to be as it was prescribed so the patient gets the right dose everything that you check you need double check by an independent expert and if you can do a manual check and I mentioned how you might do that at one point just to manually check that it's giving you the right information for that patient and then make sure everything gets signed at the end we have to do that in the United States because it's a law I don't know about other countries but we always make sure everything's signed the other reason we make sure everything's signed is you can't get reimbursed unless you've signed it the law in the United States says you didn't do it unless you signed it so they apply for reimbursement and if they get reimbursed then that's against the law and then they get into trouble and this has been happening a lot in the USA a lot of people the tax man has been catching up with them for getting reimbursed and then kind of hiding it, not very good and then imaging I won't go into any details but there are lots of papers on imaging for various reasons you use imaging for planning use imaging for guiding the applications like we did ultrasound earlier and then you define the final treatment plan using your images and then finally you can do some quality assurance using the imaging system that you have so the general flow of a treatment is you prepare the patient, if the patient needs anesthesia you give them anesthesia you do some QA on the equipment make sure it's working right and then you apply it with or without image guidance you might be localizing while you're doing it it might be foroscopy, it might be ultrasound for instance, some people now have CT scans when they can do it while actively while the patient is being treated and then define the target and the organs at risk with the imaging system do your planning, validate the plan, make sure it's what you intended to use and then give the treatment and then document everything so let me summarize quickly so that you can get on with your talk about how to avoid errors classical systems are relatively little used today except maybe the digestive system for cervix cancer computerized planning is pretty much taken over you buy a high dose rate unit you buy the computerized planning system with it for instance and then you need a really good QA program for the individual patient and for all the patients so that's got to be done regularly by the physicist and we have daily checks, monthly checks checks per patient, annual checks on the plans and this is all published by Astro and published by the AAPM