my name is Kevin Kennedy I'm a medical physicist at Austin Cancer Centers I thank you for your time to attend this short presentation and I apologize for the technical issues we had at the very beginning if during my presentation you have any issues please don't hesitate to interrupt and suppose your question so as the title of my presentation implies we'll be talking about accepting an HDR source for electron micro solectron and very briefly I worked at Austin Cancer Centers we employ six Linux and have a fairly active brachytherapy program which entails both LDR prostate sitting plant as well as HDR covering the spectrum of GYN skin breast so the first slide shows the workflow for delivery of an HDR source I chose that in a nuclear reactor iridium 191 is bombarded with neutrons uranium 192 gets generated and then it gets transported using different means of transportation to its destination which in this case could be your country and then of course under the watchful eyes of the proper government agency it gets transferred from the port to your hospital you use it for about three months or so and then by that time the source has decayed considerably let's say we typically receive our sources or our source in activity of about eleven to twelve carry by the time that it has decayed to high-fives or well actually high for theories or low five theories then we would consider that source spent and then we return that spent source to the bender through proper channels so that's the workflow of how the source HDR source gets to our destination and it sends back to the vendor regarding some safety issues the hot link that appears at the bottom of the slide could help different participants in different parts of the country to look at IAEA safety standards and see if they have any question about the details of this process which I just described the second slide shows a brief summary of what I just said and the reason I included that in my slide and I'll be more than happy to share this upgraded PowerPoint presentation is that sometimes colleagues patients physicians asks us you know where is it this iridium Y 92 for HDR is coming from and this is a short description of great actually coming from namely bombardment of iridium 191 as I briefly explained how it's manufactured and then what's the decay pattern for that so I won't go through this but you were more than welcome to study this and share that with the interested colleagues so I work in Austin Texas and I wanted to briefly explain to you what happens when we are preparing to receive an HDR source and then if you want we can open this discussion to your clinic and see how you can prepare the workflow in the state of Texas we typically receive an email from the vendor that hey this radiation source is coming your way it's called a reciprocity request so state of Texas knows this source is coming me we know that we are coming but the source is coming and then step two explains that when we should be expected expecting the source again we exchange the sources about every three months or so in this second email we are given the exact date we should be expecting the source plus or minus one day the step number three shows that what we do when the source actually reaches our clinic so what we typically do is as soon as the source reaches our clinic we secure that in the hot lab and we looked at the shippers declaration make sure that the proper source has been sent to us and we measure the transport index which is the dose rate at one meter from the at Ford cardinal angles from the source container which is usually a white bucket in our case and lead-lined so the service engineer usually shows up a day or two after the source arrives here goes through the source exchange namely removes the old source puts in the new source there's all the proper radiation safety issues about leakage part all the tests that's necessary physics follows up by reviewing some of those measurements that the engineer did and we do our own tests and then we declare okay great your job is done engineer thanks very much and the source is now prepared to be sent back to the vendor and that's what step number four here explains when we send the source back with all the proper documentation on the container of course we receive an email from the vendor that we received a spent source and that's great because that closes the loop and it makes sure that the source is back to where it is to get namely the vendor we at stage at step number five I have outlined some of the guidelines we followed task group 56 and 59 here in u.s. that may or may not exactly apply to your site but this also offers it could idea as to why we do the things we do here for the colleagues for outside of USA I have indicated a couple of links here and by referring to these two links you will see the code of conduct on safety and security every year sources i specially encourage you to look at page 15 and table 1 and match that against your local requirements and you can do that after the presentation and i also like to mention that if you have any question during the presentation or afterwards please do contact me and I'd be more than happy to share what I know so I've organized a presentation in two different sections are you sure the correct source has been sent to us not iodine 125 but Erie um 192 once you receive this source and we want to do our tests our dual position dual time source air carry my strength timer errors and all of those things are in place or not so let's go over each one of them through these slides that's coming up so section a refers to we want to make sure that the actual source has been sent to us it's very unusual if a mistake is committed by the vendor in sending us the wrong source or wrong activity but it can happen so as medical physicists and to do due diligence we look at the shipping declaration and we go over the details indicated there to make sure that uranium 192 let me see if I can March this iridium 192 is sent to us it's a type 2 package what the expected transport index could be and this is one of the discrepancies I briefly wanted to point to here it says transport index should be point 7 that's dose rate at 1 meter the vendor booklet says point 6 and we try to say with point 6 so some minor discrepancies might occur I encourage you to open a discussion with the vendor and trying to resolve this we haven't been able to do to resolve this issue maybe you could and then making sure that it's coming from the vendor and it's coming to us here at Austin so just a cursory review of the documents on the container that holds the radiation source would be very helpful okay as far as one of the first tests that we do after the sources exchanged is dual position accuracy this is a very important test that we do immediately after the source exchange and every day that we want to do an HDR so essentially we want to make sure that the source goes to where we want it to go if I ask it to travel to certain dual position and stay there for a certain period of time then jump two millimeters or five millimeters or one centimeters it'll do that so I've posed a question and the rest of my presentation is also formed in the in the form of questions and answers and a few suggestions so if I may if I may I quickly ask just read the question I post here so the question we're trying to answer is that after an HDR source exchange does the source travel to designated points and the tolerance is one millimeter and the answer for those of us who use treatment control system and the Elektra system is that we program the treatment control system to have the HDR source travel to for dual positions one centimeter apart so for for example I start at 1500 and I say go to 1500 1490 1480 and 1470 and if I want to repeat that test next day I usually skip one dual position and a start at 1450 so again for dual positions are marked and you can see the marks here - let me enlarge the screen so you can see here that in this film strip that's placed into the source position check ruler we ask the source to go to 1500 and then jump 1 centimeters for dwell for burnt marks are made here and then next day I skip this and I say let's start at 1450 do it for 4 - all positions then next day I say start at 1400 so this way we can separate the burns marks and we can mark them the date of the measurement now the film strips are provided by the bender and we find it to be somewhat expensive they are laser-cut very nicely marked but we came up with a more cost-effective solution in that we purchased large EBT - films we marked them manually granted there's there could be up to half a millimeter of error in marking them then we cut the film into strips here so it's a homemade film strip if you will and that's a dimension one and a half centimeters in width and about 20 centimeters long and then we use that in the source position check ruler and we go through this tool position check on regular basis each film takes about five of these so one week if you will and then we marked them we remove it and replace it with the next homemade film strip so it's as I said this is a relatively cost-effective solution in using film straight for draw position trip ruler so we look at these burnt marks and we want to make sure that the source has gone to where we want it and is it within plus or minus one millimeter and we want to make sure that I know you will refer to this again in the future slides that because of the heat that's built up in the HDR housing we want to make sure that thermal equilibrium has reached before we made this measurement how we do that I'll explain that later on so transfer tube needs to be as straight as possible and some of those subtleties that we'll explain as we get to more detail of the measurements that we do on a daily basis before each HDR treatment so one good way that we can develop confidence in making sure the radiation source goes to where we want it to go is by simply using your iPhone or smartphone here I've used a source position check ruler and then I place two LED blocks or any type of blots and then I put my smart smartphone on top of that and as I have explained here we can capture a video of where the source actually goes we can for example program our trigger control system to have the source go to 1514 90/14 ATM 14 70 and then just before the process starts we start the video capture in our smartphone we leave the vault and then we start the process and so we get a video clip of where everything how everything is taking place so this is something that might be of interest to you and you can show that to your colleagues and I think as I said it develops confidence in making sure we understand where the source goes and where's the exact center of the source and if it is off more than one millimeter or so which entails calling the engineer to make to return here and adjust it adjust the position any questions so far okay let's move on to dwell time accuracy the question asked is after an HDR source exchange is a dwell time of the HDR source accurate within plus or minus one second for we have a live demonstration of dwell time measurements I have provided you with a link here one of our colleagues has gone through the details of men during the dual time accuracy based on my experience dual time accuracy is always spot-on of course if you take on transit transition time of the source and some people use stopwatches I use the computer real-time clock to see if the accurate if the you time accuracy is intact and as I have indicated here it's highly unusual to find time in accuracy everything is digital and so if you during your observation of this video or if you use your rock salt watch if you measure your time accuracy to be larger than two seconds there is something unusual either something unusual in our process or something has gone awry in the TCS you suggest that you repeat that or ask a colleague to take a look at pardon me take a look at the process and make sure that everything is being done properly but again one easy way to do this test is also program your trick and control system to go to a certain position for five seconds and you can start your stopwatch and see if that source actually stays there for five seconds or 10 seconds before jumping to the next dual position ok measuring the activity of the source the question has been posed that after the source exchange is the measurement of the source strength similar to that reported by the certificate provided by the vendor and the typical agreement is two percent based on our measurements of the last ten years it's less than one percent and of course the threshold is it should be less than five percent but again if your measurement comes anywhere close gets to be more than one percent or even closer two percent I suggest that we you the whole process make sure that temperature pressure correction has been said properly the source strength has been entered properly in the Excel spreadsheet and number of items that we'll go over in our Excel spreadsheet to make sure all of those things are interred properly because as I said we expected to be less than 1% difference compared to what the bender has suggested so here I've indicated that I will share an Excel spreadsheet which I will go to you at the very end there's also an Express each offered in this web link I strongly suggest you to pay visit to it one item I wanted to mention before I go to next slide about measuring the source strength and before I actually we go over some of the nitty-gritty clinical aspects of measurement is the use of Curie for the source strength it's a good idea to start developing the idea of using Eric Irma strengths to indicate what the strength of the source activity is rather than Curie it's good to know both of them many of the physicians or our colleagues are accustomed to Curie but more and more centers are defining source strength in terms of Eric Irma strength any questions so far please let me know if I'm speeding through it or if I'm too slow so I can adjust my presentation timer error is what we discussed earlier namely the dwell time accuracy should be better than two seconds okay so let's say the sources exchanged by the engineer and we want to make sure that we reflect that change properly in all the pertinent documents so after the sources exchanged we want to make sure that in the treatment planning system which in this case could be on Sentra that is in turn the decay sheet that we placed next to the TCS it also shows the source activity correctly and lastly we want to make sure that all of those match with what the treatment control systems print out of the system overview is intact so in the case of on Sentra there is a file called Rd Rd store which I'm sure you know where it's located in your work station you go there and you enter the reference error memo rate according to what's what appears in the system overview which comes from your tribute control system so in this case looking at system overview which is a printout of the source information in the treatment control system it shows that the current activity is ten point nine one five Curie it's very important that equal to certain air chroma strengths it's very important that we put this information here and I will briefly explain to you why the error my rate here is different than that so treatment planning system the Excel spreadsheet that we placed next to the computer treatment control system let me change this to this is B actually and this is C and of course this is some overview so let's go over some of these subtleties this of course is a simple exercise which I'm sure all of you guys already do in your practice namely you have an Excel spreadsheet that shows what the source activity according to this certificate was and what the source activity when this source actually got installed in your clinic is and based on the exponential source decay you you know what the expected source activity is so any day that you want to treat your patient by referring to the date and the source activity and matching it against the trigger control system you can do a sanity check to make sure that there are no discrepancy but once done properly in the first step we shouldn't see any discrepancy of more than maybe 0.5% if that much so here I've indicated there are some rounding errors of course depending on number of significant significant figures that you want to use so let's go into some more detail about some of these items so I indicated that the certificate for the sealed source comes with the bucket that contains the radiation source you want what we have observed is a discrepancy in our certificate for the sealed sources and I will explain to you shortly here so we want to make sure that the serial number of the after loader is correctly recorded here I have indicated the serial number of the after loader here and then the address to which the source is being delivered this is the discrepancy I was referring to earlier they have indicated in this certificate for sealed sources the activity of the source is eleven point six three Curie as I said we want to refer to Eric Irma rate as our standard and they have associated this activity with this error my rate and we have a problem with this why because when I go through my independent check and I put my error my rate constant here I come up with a eleven point seven six five verses eleven point six three and what I've indicated here is that we want to be consistent in our use of constants activities throughout the whole chain of operation here so because we have chosen this as error my rate constant for 0.03 six seven we enter this activity in our treatment planning system and one might say wait a second isn't this the certificate for sealed source in indicating eleven point six three why would you do that well my response to that is that when the engineer from Elektra enters the information in our treatment control system they actually use this error my rate constant in the treatment control system why because well the reason is so they really come up with a an activity 7.65 that we do and one might ask why is there a discrepancy between the constant use here and the constant use there the answer is that elector hasn't based on my experience of course has not reconciled the two separate portions of the operations by elector alpha-omega generates the certificate for sealed source and they have stuck to the reference erica erica a rate constant of a different value which is about one percent higher than this which gives a lower activity here hiring the denominator lowering the net result whereas electra treatment planning system has continues to use the larger air commemorated constant hence the larger activity so we have selected a number of years ago about ten years ago to stay with the higher area rate constant 4.0 three six seven and therefore we want to stay consistent with determining what the shorts activity is and then q8 accordingly so i've indicated here that the source manufacturer and the harf after loader they have usually about one percent difference in value you choose which one you want let's stick with that we've chosen the smaller error my rate constant which yields a higher activity so in the suggestion section i've indicated stick to the error my rate as this standard which can resolve many of these issues and stay consistent with defining the source activity any question okay so we have exchanged the source we've put the information in treatment planning system being generated the excel spreadsheet we have made sure that they match what's the printout from treatment control system offers so we know that we're in harmony among all these different components and now we want to essentially run a test to make sure that the when we do a trick you're planning on on centra we can actually export it to treatment control system and then once we export it to treat the control system great we can bring it up with gosh what happens if there is a network issue and for whatever reason our networks go down you may have a backup system to transfer the treatment parameters from on central treatment planning system to the treatment control system so regarding the network based transfer once the treatment planning is completed in on Sentra we use the proper icon to export the treatment parameters this is an example of the DICOM file to relatively small 55 kilobytes and then once we exported then we have to go to treatment control system and actually import the treatment parameters as I said briefly we have to do a test when we initially install the system we can either pin get or test the exporting data we want to make sure that we have a static IP address if we want to make sure our IT colleagues assign that static IP address so things don't change and as I briefly mentioned if you have a network connectivity issue we want to make sure that we have a back-up plan so we have to go through the process of saving the treatment parameters in a US v and then take the US v and actually go to the treatment control system plug the USB in there and then go and see if you can export the information from the USB information so this way the treatment parameters won't be treatment won't be interrupted now it's very unusual that in the process of export of treatment parameters any of the treatment parameters get corrupted it's a fairly small system but can it happen sure it can happen I'm sure those of us who have worked with external being planning that they have knows noticed some anomalies especially if there are some portion polling vault some rounding up of the error of the monitor units any any funny thing can happen whenever you have different systems or if you push and pull treatment data so it's very important that when you pull the information into your treatment control system you want to make sure everything matches with the treatment planning system namely you're using the same number of catheters the source activity in the treatment planning system and that in treatment control system match the prescription doses match so just a sanity check that when you import everything into control treatment control system nothing has changed this is a display of our workstation where I work here this is the treatment control system or TCS that's a country that's a computer that controls the TCP or treatment control panel this truth me control panel controls the motion of the source in the after loader that's where all the emergency buttons or interrupt buttons are located this treatment control system that you see on the top that's just a display monitor and this is the tower we have a UPS here just in case we lose power so let's say if for whatever reason our Cancer Center loses power using this UPS we can finish the delivery at least for that channel we have a printer that we rarely use but Elektra insists that we need to have it then we finish our treatment treatment deliveries we usually save the treatment summary as a PDF and then we pull that PDF file into our electronic medical record so we rarely do anything with paper and of course our survey meters we have a I have a digital survey meter here so I can turn it on and immediately use it rather than gas based one which I'll have to be typically about five minutes or so until it stabilizes this is a display of what you see here on the top here treatment control system when you turn on your computer here it runs through a self-test just to make sure that all the connectivities are intact it checks the status of the treatment control system treatment control panel and the status of the after loader is it is treatment control panel communicating with the after loader so here I've indicated is our system functional so we run the self-test we have to run the self test otherwise we really cannot deliver the treatment it prevents us from doing that then we do this source position accuracy the ruler test I showed earlier to make sure that all of these burns marks are within one millimeter of the marked destinations then we check the functionality of the interrupt button namely if the for whatever reason if patient is uncomfortable or for whatever reason we have to stop their treatment does this system work properly by depressing drop button and then we'll see that the sources actually gets drawn back to the after loader we can press it again to resume the treatment where it stopped okay so see daily QA so this is just a display of what I had shown earlier but let me enlarge this so you can see that better mmm so I've indicated that every day expose four to all positions one centimeter apart each for one second so for burnt marks are made we skip a day to leave a gap pardon me and then repeat that same test the next day I've indicated here what kind of film we use you can use either a BT 2 films or a BT 3 films having a film and cutting it and we will allow you to run many many tests and stay stay within budgets so in the daily QA I've indicated what I just described one thing about the thermal equilibrium and which I briefly mentioned earlier is this but you notice that this is the housing for our after loader this is the pig that we have to always have available for radiation safety purposes we have drilled couple of holes here around the housing and we keep the telescope here open why because that radiation source as its decaying it generates heat and it can adversely affect the precision of the dual position so this will help keep inside of the housing fairly cool so here for the describe why we use the bell Chamber frequency of calibration it's cross calibration do we use current or charge and the sweet spot clearly all of you have some of these equipment I'd be more than happy to go over this I hate to read over the things that you can't read yourself I simply want to point to the salient and important points for each one of these items so if I'm skipping too many things please stop me and let me know but in short regarding this very slight we use well chambers which I briefly described in here that's a well chamber we use an HDR well chamber from standard imaging and we use max 4000 electrometer we usually send a well chamber and the electrometer in tandem to the calibration laboratory and we ask the calibration laboratory to calibrate the electrometer both for high and low current values we do that every other year in us we have to calibrate this every year survey meters we have to calibrate it every year but electrometer and well chamber every other year when these returned from calibration he typically used a different electrometer to essentially repeat my QA making sure both of these electrometers this electrometer and the secondary electron mer read the same values this helps as a cross calibration and backup if something goes haywire with the first unit I always have the second unit to refer to we use current measurement of the activity and of course every time we send the source to the well chamber we have to determine where the sweet spot is and send it there and I will explain to you in an Excel spreadsheet how do we determine where the sweet spot is a couple of interesting points which I had not mentioned in the PowerPoint I have shared with you earlier and my good colleague Adam my attention which I need to emphasize is that these are some of the of course temperature pressure correction all of us are familiar with even for external treatment planning but for key ion and polarity it's not to use them in the case of HDR measurement why because whenever you look at the calibration certificate that comes from the accredited dosimetry calibration certificate they don't use cobalt-60 for measurement they use HDR system and unlike the external beam planning system that we have to go through this for the HDR system we don't do this so here I've indicated use P ion and P polarity only if needed which I will explain to you then that might be needed this is the Excel spreadsheet oops sorry this is the formula rather that we use to determine the error my rate of the Iridium source which later on some of us may want to also convert that to activity theory I've indicated what each one of these items are and how to measure them again I will share this updated PowerPoint with you it has a little more detailed which you might find useful this is the air camera rate constant I was referring to which Elektra uses what the source manufacturer uses a different value which is slightly higher than that about 1% higher than that so here I've indicated that for one over AI on don't use it if ad ad CL certificate doesn't show that again I will explain to you what I mean in that Excel spreadsheet that we'll go over the actual calculation of the activity of the source next slide shows that if you have to use P polarity and P ion this is the procedure that you have to go through but again I've indicated only if you're if it is used by a DCR okay this essentially completes my presentation about accepting in you HD or source we have gone through the process of making sure that iridium 192 is actually delivered to us it's in the activity that we expect and once we once the Elector engineer has exchanged the source a number of tests that we go through for position and timing to make sure that it meets our standards so if you have no question I'll be more than happy to bring up an Excel spreadsheet and go over the procedure that we go through when this source is actually given to the physicist to validate what electra claims to be the source activity kevin has any questions like can you hear me yes yes go ahead please okay I just wanted to comment regarding source position accuracy I see the system you're using your elector micro solectron older variant systems for instance the very source has I think a camera system built into the after loader itself where the dummy wires force position as well as the active wire source position this checked via an image taken during the morning QA check so just an FYI you may have that and other users that have perhaps the plexidrone from electron they usually install a camera in the room that looks directly at a Czech ruler that's mounted to a wall underneath the camera and you can hook up your transfer guide tube to that Czech ruler and ask the source to go out say to 1200 millimeters and visually also capture an image so some sites may not require film on a daily basis and but that's definitely good how you showed it and how you can make your homemade film strips on gas comic film and thereby be you know fiscally very responsible instead of spending a lot of money on that so I just wanted to make everyone aware that some sites may not require film thanks I agree with you I think that's a great solution that Darian has come up with namely the camera and being able to capture the image of the camera that will do do away with all of these physical inventory any other question or comments colleagues if anyone has question you can just type it in the chat okay allow me to show you an excel spreadsheet that we use here Oh Kevin I think you just typed in a question yes it says does the 12th position accuracy affected with the temperature of the room yes it does one of the reasons I suggested the this configuration in which two at least two holes are drilled in the HDR after loader housing is because of that namely as the source decays it generates heat and based on our observation it can adversely affect the positional accuracy of the source so what we've done is we've drilled a pair of holes and also there is a telescope window here that we keep open so this kind of helps the air ventilation and we have seen that improve the positional accuracy namely let's say we come one day after two days of weekends in a closed system of after lower housing we've noticed that the positional accuracy didn't match what we had measured on Thursday and Friday prior and of course it takes some time for it to reach its thermal equilibrium and after a number of observations be came up with this solution so the short answer is yes but there is a simple solution for that and as my colleague mentioned many of these things that's well all the things that I'm discussing is really pointed towards my crystal ektron electa by Alexa many of these overlapped with variants but clearly some of these system approaches that vary in users part of me employed are a bit different than that so if you are using a variant system please ask questions and one colleagues can address them okay so let's take a look at the process flow for Excel spreadsheet using the Excel spreadsheet I the first thing that we use when we receive a radiation source or HDR radiation source is for measure transport index and according to local laws we have to do that within three hours after arrival of the source so I wanted to part of me I wanted to share this rare case with you in which T I actually failed in overwhelming majority of the cases 95 96 now I mean higher percentages TI passes but at times it does fail so in this case one of my colleagues measured the transport index at different card at four cardinal angles for me and recorded them and came up with a with an average transport index of 0.65 our threshold is 0.6 and therefore it failed what that means is that in the container that's holding the HD or source is not attenuating the radiation as much as one would have expected having said that to be contacted pardon me Alexa explained the situation and only I think the last year or so they increase the transport index threshold from point 6 to point 7 in in our locality it used to be point six now it's point seven having said that the Elector user's manual still warns the user to make sure transport index stays below point six so what do we actually do if it fails we really can't do anything what we in this case we did was we made our colleagues aware that this bucket that holds the radioactive source is secured in our hot lab but we typically put it behind the shield again we brought to their attention that transport index is a little higher and we also brought it up to the attention of the engineer from Elektra that paid a visit together later to install this and we also let the radiation safety officer in Elektra know about this thing if it were me I would make the bucket a little thicker and as far as lead shielding is concerned to make sure it falls below point six and also make sure that the personnel involved in transport of this in this case FedEx would be aware that transport index is a little higher but again this is a rare occurrence but we typically measure about 0.7 I mean sorry point five seven point five eight point five six just below the point six threshold in this case was a little higher and look at the heterogeneity in measurements so that means they're not using a the source or the shielding is not uniform throughout the bucket or the position of the source here we have explained you know where to place the radiation survey meters and we make sure that the calibration of the radiation survey meters up-to-date when we received it when we measured it okay this Excel spreadsheet which I will share with you through my colleagues in rays of hope is essentially similar to what I had mentioned earlier there were a couple of minor improvements that's been done in it which I will explain to you here we've indicated to enter data in colored cells only namely the green ones so what kind of electrometer are you using what kind of bell chamber are you using what's the source activity according to the printout from treatment control system the date associated with that activity what the temperature and pressure are and then of course a series of measurements the rest of these are calculated automatically and you can of course click on any of these and learn what the equation is used in calculating these values we want to make sure that the calibration time and date are entered especially very carefully very accurately we have to find out the time difference for example in netherland relative to texas and just make sure that everything is properly entered now you know as far as calibration of the activity of the source we don't know where the sweet spot is well we have a general idea but depending on the setup the sweet spot could be a little different so what we do is we send the source in to all positions of five millimeters to different parts of the well chamber and what I had shown earlier it's actually a setup like this so we have the after loader we have the proper transfer tube for source activity measurement so we send the source to the most distal position and then we step it every five millimeters so we send it here most distal position have it stay there for 10 seconds we measure the charge we see what the charge is being displayed here and we record it then in the treatment control system we see the source jumps one centimeter or ten millimeter to the next roll position and stays there for ten seconds we recorded charge and we do that for a number of steps as shown here and clearly by looking at this we see that the source is reaching the sweet spot which gives us the which gives us the largest current value so and then of course beyond the sweet spot the value decreases then this Excel spreadsheet finds the maximum reading and goes to the charge to current conversion but I coven hi hi sorry are we supposed to be looking at an excel sheet with you yes can you not see the Excel spreadsheet no oh okay sorry now I can now I can see it okay great thank you sure sure of course all right so very briefly this excel spreadsheet we put the information about the electrometer use well chamber use the source activity that comes from treatment control system not from the source certificate because treatment control system holds the source information that we also interned in TPS earlier of course temperature and pressure correction and then once we put all these information again a ion is zero no correction for ion or P polarity and then we step the radiation source through the transfer tube and we record the charge collected the Excel spreadsheet finds the maximum value and then converts the charge to current we record when we actually took these measurements as I said we enter data in colored cells and then we see what the difference is between the measured value of activity and the reported value of the activity and we report here if the measure in the measurement is within 5% again we based on our measure our 10 plus years of using the system premier I would say overwhelming majority of the time 95 97 percent of the time within well within 1% at times going to be a extreme temperature pressure it might go a little beyond 1% but I definitely know we're closer to percent so even though the threshold is 5% be aware if your measurement comes out to be too different than the expected measurement so my colleague measured it I double checked it and that's the date that the measurement took place so transport index was measured source activity was was measured and then and validated then we go through the quarterly check of the system have you measured the source strength interlocks are operational the control unit time accuracy and positional accuracy have been verified different control a different systems treatment planning system treatment panel system and TPS are communicating with each other survey results are favorable we input the information in treatment console and also we updated the information in an independent Excel spreadsheet that we've developed to check the TPS we also want to make sure that that's also entered correctly since I mentioned that we use rad calc that's the software that we use so every time we generate a treatment plan for let's say mrs. Jones before we treat mrs. Jones we export the treatment parameters from the treatment planning system to rad calc and make sure that the results are well within 3% we typically see them well within point 5 percent and then proceed to treatment and then we want to make sure that all the documentation czar in place for our own policy and procedures and also for inspection purposes lastly we generate the Excel spreadsheet I briefly mentioned again what we see here should be well within 0.1 0.2 percent of what the treatment control system reports in electa there are some rounding errors but here we have indicated what the location is what the afterload or serial number is so we don't mix up Excel spreadsheets what's the source serial number so this after loader is always associated with this site but the source changes what air caramel rate constants that we use and of course what the half-life of the radioactive source is just to make sure that we were talking about reading these show the exponential decay when this force was actually calibrated in the accelerator and then many many was actually installed and again I'd be more than happy to I think I shared this earlier but if you have any question about any of these Excel spreadsheets please contact you not be more than happy to share it through my colleagues arrays of hope or through directly to you so that the completion of review of the Excel spreadsheet I like to open the discussion to any question that you might have about this topic and sorry about my misspellings so let me open up the ask you a couple of questions if I may could those of you who have already started using HDR program simply raise your hand great and for those of you who have actually started using HDR program using Elektra brand of HDR could you raise your hand okay great great so I'm glad that you had exposure to some of these topics earlier I trust that you will start to use I think somebody might have a question maybe not okay go ahead please sorry I have one question I want to ask you there are three kind of three three three type of measuring an air carelessness air care mistakes in air and in the chamber also we have a another way that we can measure air chemistries in the Phantom this is a German way I think the basic company we have we measured our masters by using formal ionization chamber I want to ask you which one in your opinion which way is better and why I see one of my colleagues Adam Schulman has a great presentation about this very topic that you mentioned which you may or may not have that presentation I like to bring it up but I'll give you the answer and I agree with Adam he discourages using ion chamber and he explains that in his PowerPoint presentation if you have a couple of minutes I can bring it bring it up and actually point you to why he recommends his suggestion is it okay sorry let me open up this XLS so the the short answer to your question is that we highly recommend using your not used not to use the farmer type ion chamber we use the value that's given to us by accredited dosimetry laboratory and if I may I'd like to show you a couple of slides which explains why that's the case but if it goes beyond the scope of this conversation we can follow up this topic after this presentation on a one-to-one basis okay okay so what at least would allow me to show you that Excel spreadsheet that Adam shared earlier it seems that I'm having difficulty finding that PowerPoint presentation this is my email address if you send me an email at the end I'll be more than happy to share that with you and I think it has lots of information about the error memory or strength measurements different ways of doing that and why we think using an ad CL and using an HDR system and unit is the best way of doing that so please send me an e-mail after this presentation and we can continue this conversation after that did you hear me hubby or did you did you did you hear me my internet connection is too slow yes I will I will I will send you the detail of the way that we will measure that we measured the air care masters I will be happy to to share information and to to know your comment about our results sure thank you yeah thank you very much for you thank you for your presentation sure colleagues any other question or comments and I want to mention that we don't have a well chamber so we have to measure in phantom method I see in our department there is no world chamber so if we don't have well chamber so we use this trigger phantom it's a kind of phantom that fight wall inside it so we put the applicator in law in the middle of the hole and iron chamber in another hole in front of the applicator thank you yes I'm fairly familiar with that approach in fact in Adams presentation he emphasizes that you need to really press the hospital administration to purchase you a real chamber I think very very important yes any other question or comments colleagues he bring up that outline of presentation these were the things we talked about okay if there are no questions or comments I like to thank you for your time and I look forward to our next encounter thank you so much Kevin this is great thank you our wonderful day goodbye