27 Radiation Therapy Planning

Radiation Therapy Planning with Prostate MRI

A coming application that we're gonna hear about is radiation therapy planning, and that's gonna be presented by Dr. Margolis and Dr. Ani.

I'm going to talk to you about the use of prostate MRI and friends for radiation therapy planning.

How does radiation planning differ from surgical planning?

As we mentioned earlier, extracapsular extension and semi vesical invasion are important to identify, and often the reason that surgery is deferred and a comment was made earlier, and I think it deserves repeating, the presence of T three disease does not preclude surgery.

And in fact, surgery has shown improved outcomes, in at least one series for patients with cancer spread outside of the prostate.

However, because of the recommendation for pro radiation therapy in these patients, some patients will opt for radiation therapy alone.

So again, it's important that we try to accurately stage our patients as possible, so that they can make the best informed choice.

We also want to delineate adjacent structures.

This is probably even more important for radiation therapy planning.

This includes urethra and the bladder, the rectum and the pelvic floor muscles and neurovascular bundles.

And we also want to evaluate lymph nodes and bones.

Localization of cancer in the prostate is import is less important, than in the other modalities, but it can guide a boost.

And because the in recal coil distorts anatomy, this can complicate the image fusion, radiation therapy planning.

And so we generally defer it, but that also means that we would defer, spectroscopic imaging.

So, there is a trade off there as well.

I apologize, this is not in your handout.

I realize I omitted a couple slides, before I sent this off.

I think it's useful to think about what are the common radiation therapy modalities that we encounter for prostate cancer.

So, imrt iss, intensity modulated radiotherapy, IGRT, image guided radiotherapy, SBRT or SRS stereotactic body radiation therapy and stereotactic radiosurgery.

And I'll go into a little bit of detail about these in just a moment.

And then there's brachytherapy, conventional brachytherapy as well as high dose rate brachytherapy.

Radiation Therapy Modalities

In terms of I-M-R-T-I-G-R-T-S-B-R-T and SBS, these are all, all external beam modalities.

They generally will treat the entire prostate, but as I mentioned before, the, dose painting, like you see here, can actually be used to, give a boost to a certain area in the prostate.

We can also treat bones and lymph nodes, if we identify metastatic disease.

And, the radiation oncologist will use a dose painting, algorithm, so he or she will try to optimize as much of the radiation for the, prostate, and as little to the surrounding structures as possible.

And we often use fiducial markers to localize a prostate.

So depending on the platform that your radiation oncologist is using, he or she may want small metallic markers placed in the prostate.

These aren't seeds, you could call them seeds, but that would be confusing because they're not radioactive.

They're simply metallic markers such that if the radiation oncologist is using x-ray to identify the location of the prostate, you can use, a standard, projectional X-ray, brachytherapy, conventionally uses multiple tiny radioactive seeds that are ideally placed uniformly throughout the prostate high dose rate brachytherapy places, catheters in the prostate.

So, here's an example I just cribbed from the UCLA website.

And it shows all of these lines in the prostate.

So they're, placed perineal just like you would for standard brachytherapy.

But rather than placing seeds and leaving them in the prostate, a robot will take a very highly radioactive seed, place it through these catheters, to a location that's, mathematically determined to optimize the dose to the prostate and, not the surrounding tissues based on the dose painting algorithm, and leave it there for the amount of time needed in order to achieve the optimal dose to the prostate.

And, here's what the planning software looks like, for the, high dose rate brachytherapy.

Literature Support for Prostate MRI in Radiation Therapy

So, there is literature support for the use of radiation therapy planning, with prostate MRI.

So, it, 2012 at is MRM.

There was a presentation, looking at target, tumor control probability, which showed, excellent tumor control probability, especially in the prostate by giving a boost to the, target area.

And then the, tumor, control target volume, was shown to improve, by, giving a, a higher dose, especially to the prostate, using the, the boost phenomenon.

And then, in 2012, and in 2011, there were a couple of publications, looking at the, simultaneous, integrated boost, using biometric modulated arc therapy without, which allowed the radiation oncologist to provide more treatment without violating rectal or bladder dose limits.

So obviously I'm not an expert in this field, but what I think that we can bring to our radiation oncology colleagues is a sense that they can actually give more dose to the cancer and simultaneously less dose to the surrounding tissues.

And then there was another, article that, also showed that the boost to the target, was, sort of, correlated to the distance to the rectum.

Anatomic Features for Radiation Therapy Planning

And before I get into showing some cases about how this might be used, I'd like to, remind you all that.

There are, specific anatomic features that the radiation oncologists, tend to focus on, for their radiation therapy planning.

So, here on this axial T two 80 image, these white arrows, are, identifying dease fascia that separates the prostate from the rectum.

And we can see, the level of the urethra here.

And then on this sagittal image, we again see de ofs fascia separating the prostate, which is behind the arrows from the rectum, as well as this sort of triangular low signal, structure here that identifies the level of the urogenital diaphragm.

Case Examples

And now I'd like to show you a few case examples.

The first is actually not, a case of, radiation therapy planning itself, but what you may see on the MRI when, you have a patient that's had fiduciary markers placed,

so you can see here on a, T two 80 image, these being metal will show up as low signal.

And you can see these very small signal voids on the T two 80 image.

They're often a little more conspicuous, with, a, larger field of view image because of the larger voxels.

So you, because of the image blurring, you actually see them a little better.

But I've found that, either a 2D or 3D uh, post contrast gradient, recalled echo image is very nice because the delayed images, tend to show near uniform enhancements, so very high signal in the prostate, and you see a little bit of signal void wherever these, fiduciary markers are.

Similarly, on your B zero diffusion weighted image, this is effectively a T two weighted image with a lot of susceptibility artifact, and they will show up as susceptibility signal voids on your B zero image.

So, we generally don't look at this too often because it doesn't add a lot of value, for general diagnosis, but can be useful for identify, identifying the location of the fiducial markers.

Case 1: Radiation Therapy with Follow-Up

So I'm going to show a case of radiation therapy with follow up.

This is a 69-year-old where the, with, benign prostatic, hyperplasia with a gradual rise in the PSA from 1.6 to 4.8.

There's an abnormal DRE as you can imagine from this tumor.

And, the biopsies revealed a very high grade tumor.

So, this is an axial T two weighted image and def, dynamic contrast image from, December, 2009.

You'll notice I'm not talking about, diffusion weighted image, just dynamic contrast in T two.

As you'll notice from the DCE, there's a lot of image noise here.

We're not getting a great image here.

The diffusion weighted image was basically uninterpretable in this case.

And so this is a good example of how we use the, new PY rads algorithm when one of our key sequences is not available.

So there's a large low signal area, which is basically the entire right gland, so peripheral gland and transition zone, and probably crossing midline.

And you can see on the diffuse, sorry, perfusion map that you've got abnormal, perfusion that crosses midline if you use a lot of imagination.

And then when you look here, you can see that the capsule is a little irregular suggesting extra prostatic extension.

And again, there's abnormal blood flow on the DCE map.

So, how, do we image this on follow up?

We use basically the same protocol.

And what's interesting in this case is, here you can see that the transition zone and the peripheral gland are now quite distinct from each other, and that we see that normal low signal line, dividing the, the two.

So, the patient underwent, hormone therapy and external beam radiation therapy.

And this is a, a year later.

We also see that the blood flow has also normalized.

So now there's, decreased blood flow and normalization of the low, signal mass, which suggests a response to therapy.

Now, we would still follow the PSA, but what the radiation oncologist will tell us is that they can, perceive a response.

It's unclear exactly how useful it is on imaging far in advance of a change in PSA.

The change in PSA can be, relatively slow.

Reporting for Radiation Therapy Planning

So here's an example of how we might report this out.

This is for the first study where the, DWI was compromised.

So here we see that we want to mention, whether or not there are any, abnormal lymph nodes or bone lesions that would deserve external beam radiation therapy.

We want to give, give 'em the size of the prostate again, and, the degree of prostatic hyperplasia.

And then, there was one abnormal, lesion here.

You'll notice that the location is rather general, bilateral anterior and right posterior, prostate gland.

There's two reasons why, this is a little more general.

One, it's, it's encompassing a number of different, sections in the prostate, diagram that we would need to include.

So, basically I got lazy and didn't include them all, but also because we're doing radiation therapy, they're a little less, preoccupied with exactly what level the, prostate needs to be treated.

And then we give the size of the lesion more than 1.5 centimeters.

The capsules involved poster laterally, and we see this asymmetric ill-defined T two signal.

So, it's, suspicious and more than 1.5 centimeters.

So b, based on the new rads, this constitutes a five out of five, T two, assessment, crate, category, and then the perfusion was abnormal.

The diffusion we list as technically compromised.

So this is that X category for rads, so it'd be X out of five.

The overall suspicion in this case is driven by T two.

So we have a highly suspicious lesion on T two, and therefore our overall, assessment category, is also five out five.

And in this case, seminal vesical neurovascular bundles themselves look normal.

So technical quality, well, at least part of it was excellent.

The, large right lesion crosses midline anteriorly.

It extends to the capsule.

It's otherwise organ confined disease, no suspicious lymph nodes or bone lesion.

So is it really fair to say it's excellent? Probably not.

But in fact, we are able to give them all the information they need to treat the patient.

So that's my excuse why I call it excellent.

And then organ confined disease, well, we did mention it involves a capsule, but they're going to treat that.

So their concern for whether or not it's organ confined or not is, is their regional spread and not local spread.

Case 2: High Dose Rate Brachytherapy Effects Over Time

It's also, illustrative to see the effects of the high dose rate brachytherapy over time.

So, here is a, a planning study.

And you can see here this is an indirect coil with Voluma.

We were trying that for a little while to see if that would give us a low enough signal.

Obviously it's not the, the best choice.

But here you can see this low, the, so sorry, normal high signal peripheral gland, and there's a small low signal area here in the transition zone here.

There's another low signal area here, maybe at most three out of five suspicion.

They do correspond to restricted diffusion and abnormal perfusion.

And we had positive biopsies from this area.

So the important thing is we didn't see anything that looked like there was, extracapsular extension.

And we knew that there was, cancer.

So, we, recommended the patient, continue on to the plan treatment, which was high dose rate brachytherapy.

And this is what the patient looks like on follow up.

So now we don't have an indirect coil.

You can see that the T two and the peripheral gland has this sort of shading appearance.

Maybe not exactly like an endometrioma, but again, it's a little lower than you would expect for normal peripheral gland.

We still see the low signal areas here and here.

And, you can see that there's a lot of noise on the, A DC.

So again, we see, catheter defects as well.

So if you look carefully, you can also see that there are a couple, tiny signal voids here.

It's actually very conspicuous if you get just the right angle on your coronal where you can actually see the catheter tracks.

But again, we see normalization of perfusion and that helps us, feel confident that this patient was, adequately treated.

But it does become very difficult to interpret the T two and the A DC because you see this reduction in the A DC, I don't know, I don't, I don't think I would call the shading on the, oh, sorry, reduction signal on the T two and reduced signal on the A DC.

Case 3: High Risk Disease

Here's another example of high risk disease.

So this was a young man with a positive family history.

At age 47, he had his first PSA checked and it was 5.6.

And so there were only two of 12 systematic biopsies that were positive, but they were four plus four equals eight.

So, this is one of the other instances when you might consider a prostate.

MR is this intermediate risk category for extra prostatic disease.

This is someone where you want to determine if they're a good candidate for surgery.

And so we did this MRI, and you can see this very large bulbus, low signal mass extending well up into the seminal vesicles and, parts unknown.

And, so, this is a very locally advanced disease.

And so here's the color perfusion map.

The interesting thing is these bright areas here are the peri prostatic venous plexus.

The tumor itself actually shows low signal.

We occasionally see this with very large tumors.

I think it's because they outstrip their blood supply.

So the absence of DCE abnormality and a large tumor should not be thought of as, comforting.

There was restricted diffusion.

There were no lymph nodes or bone lesions, but, the patient chose radiation therapy based on the size of the tumor.

Cases with High Risk Disease and Lymphadenopathy

And now a couple cases showing high risk disease with lymphadenopathy, 69-year-old PSA of 40, multiple cores, four plus four equals eight.

Here we see that there's this low signal mass with a little extra prostatic extension and probably seminal vesicle invasion here and here, we see that there's restricted diffusion.

So here's the A DC map and here's the DWI.

And you can see here there's a little lymph node.

So here's the, full field of view post contrast image, and you can see the lymph node here.

There's another lymph node here.

And as Andy said earlier, the DWI can be very useful for finding these lymph nodes, but it's unfortunately not borne out to be discriminatory.

But anything that big you've have, you've got to consider is suspicious.

And finally, an example of lymphadenopathy and C 11 acetate pet.

So, this patient, has this low signal mass with bulging of the capsule there, broad base of contact and low signal that extends into the seminal vesicles.

We do see the, contralateral hemorrhage exclusion sign, so low signal here, but hemorrhage, so probably no cancer, although in this case, I don't know, all bets are off.

What we do see is on the DWI, and this is actually a B 1000 image.

This was, on a somewhat older, study.

We do see restricted diffusion corresponding to the seminal vesicles and, the, tumor here in the prostate.

And we also see abnormal lymph nodes.

So here's a full field of view post contrast, fats at T one, and we see a lymph node here, along the pelvic sidewall.

And here an external iliac lymph node.

They also show up as restricted diffusion on our DWI.

Because this, there is extensive disease and we wanted to completely stage the patient.

This patient had a C 11 acetate pet, which is analogous to C 11 choline, acetate being a metabolic analog choline being a cell turnover analog.

And what we see is a very nice correlation where we have, radiotracer uptake in the, pelvic sidewall and external iliac lymph node and in the tumor in the semial vesicles and in, the prostate.

So, I think that, prostate MRI can add a lot of value in terms of not only determining which patients would be appropriate for, radiation therapy, or surgery, but also helping plan, the, radiation therapy.

And now I'd like to turn it over to, Dr. Ani.

Dr. Ani's Perspective on Radiation Therapy Planning

Well, Dan did a fabulous job and I won't have a whole lot extra to add.

Maybe just a slightly different perspective and different images maybe.

But basically I think you've really got a really good message on that.

And what is it that the radiation oncologist and the medical physics, colleagues need from us?

And I think they are very excited about PI rads.

I will tell you that, I have the nurses from radiation oncology emailing me and asking me why did I not put the PI RAD score in a given report?

Where is the number? What is the A DC?

Is there restricted diffusion?

Their quantitative metrically driven people in radiation oncology, they love numbers and they're gonna really be so happy when you all start talking to them in their numerical format.

And they've been incredible supporters of MRI over the years, as Kasha mentioned, we've had this love hate thing with the surgeons.

We love you all now, but, we always have.

But with the radiation oncologist, it's been a continuously wonderful dialogue.

I have learned so much from my radiation on colleagues Anthony Dko, who interestingly, anecdotally was trained in MRI by Mitch Schnall at University of Pennsylvania before he came to the Brigham, sort of walked in on the second day, I think first day he found his office.

Second day he came, found me and said, Claire, we're gonna work together and here's a pile of films.

I'd like you to read them. Now, that was in the day, oh my God.

Anyway, so we embarked on, on a big huge C-A-L-G-B study, and we've been studying, all aspects of imaging and its role in care of men with advanced prostate cancer ever since.

And, you know, I think they really appreciate imaging.

Many, and I don't wanna sort of go on forever here, but many radiation oncology departments are installing MRI scanners to do MR simulations instead of CT simulations for all pelvic malignancies.

As we know, CT for GYN malignancies for, uterine cancer for prostate cancer is not good.

You get this gray area, you know, no matter what you do with the IV contrast on ct, which radiation oncology people don't use themselves, no use, you can't discriminate.

So they're really moving and many of their departments where they can afford it are installing a pet mr.

It's not a pet mr. That's probably the next step.

An MR scanner for simulation and truly a better investment, many would say over proton beam, which is a system and a divisive radiation therapy that will break the bank and take up so much real estate, particularly those of us in landlocked urban areas.

A very challenging thing to do.

So that's my sort of little editorial introduction.

So again, you know, the really the role, our role is as we've looked at so many times here, is to delineate the tumor and the adjacent normal structures really carefully.

For the radiation oncologists, they have a choice of imaging modalities and, and they use ultrasound to guide brachytherapy.

Most of them, it will always have an MRI beforehand.

But the real time image placement of the guided placement of the sources is under ultrasound guidance, which will show them the prostate gland and, and better and better ultrasound techniques will certainly be better at delineating the outer capsules.

But again, fusion technology I think will change that.

And then they've also, we've worked, for many years on an MR guided brachytherapy program.

IMRT, of course uses MRI for dose distribution and dis and the so-called dose painting where you can vocally increase the delivery and dose of radiation.

CT is used for external beam radiation therapy a lot, particularly with those gold fiducials in place.

And you can see a big prostate cancer here.

It's at five o'clock extending out of the capsule, but you can't tell at all where that cancer is inside the prostate.

And I, I'm not sure if I have more slides in this case later, but I've shown you this case already, which was the patient who had the rectal wall invasion, the T four lesion that we saw before and the prostate cancer within the, the gland cannot be seen here at all, but was a very significant tumor burden as you can imagine on MRI.

So really looking at the comparison of these images, there's no doubt why they would choose MRI as the imaging modality to plan their therapy off, if not, use it in real time.

Clearly you can see the prostate here, you really can see nothing almost, except the sources on this patient post brachytherapy implantation.

And the relationship at the back of the prostate and the pubic bone and the sidewalls, it, you really can't tell where it is.

And this is the one that they've been using for years to plan external beam radiation delivery.

So when the, the operator is not confident as to where to place the boundaries, what do they do?

They certainly don't go smaller.

They go bigger in the area that has to be treated.

So you overestimate the volume to be treated.

And unfortunately that then leads to an increased pro increased post-radiation toxicity profile.

So you're going to see a lot more proctitis and rectal inflammation and your arthritis and then even if it's very aggressive and they're pushing the dose of radiation up all the time.

It used to be in the mid sixties now the seventies and high 70 gray just delivered to the prostate, which leads to more and more complications in these areas.

And it's not unusual to see fistulization and urethral fistulas developing in these areas and all kinds of tragic situations.

So it is a toxic substance radiation options of localized prostate cancer.

Dan did a very nice job on this already.

We had the 3D con conform, the IMRT dose implantation.

So our role and our reports fit perfectly into the RADS classification, but develop a nice standardized templated report.

And we talked a little bit on this, you need to make sure that your colleagues and you are reporting the scans in exactly the same way.

The emphasis for radiation oncology is certainly on the primary index tumor, but it's all the other stuff as well.

So don't leave out the discussion about capsule, neurovascular bundle, seminal vesicle, lymph nodes and bones, and then any other ancillary findings.

So really, very, very important so that they can try to deliver the tightest dose possible sparing the area of the bladder and the rectum.

Hormonal Therapy and Imaging

So one of the, the things that's really on the table at the moment with radiation oncologists is how much of the hormonal replacement to do before or after the radiation therapy.

And I think I touched on this already, but in more and more unfavorable risk or intermediate risk patients, they're seeing more and more benefit from longer courses of androgen deprivation therapy.

They're looking to us to identify occult high grade disease.

Now I don't know that I can really tell the difference.

I don't think any of us have discussed this.

Really the difference between a Gleason seven and a Gleason eight on MRI, except you've seen the box plots and the trends in the A DC as it goes down lower, we feel like we're more likely with a lower lower A DC to have a higher, higher Gleason.

But this is something that they're going to be pushing on us for, is to try to get out and find these gle higher higher risk patients with the Gleason eight and 10.

This will still be PY RADS four and fives.

They'll still be revealed after biopsy as you've seen.

So beyond that, I'm not sure that there's anything we can add in our imaging to distinguish seven from the eight and tens at this point.

And even out to 18 months of, of hormonal therapy as being seen.

Most of the patients hate this.

It introduces male menopause symptoms and they're very unhappy with it.

But it is helpful and it does show a prolonged survival benefit, and something to be considered.

Dose Volume Histograms and Techniques

Now, when we were doing the MR guided brachytherapy, one of the concepts that I learned to understand a lot were the so-called dose volume histograms that are generated by the medical physicist, which show the target area.

That's your clinical target volume, your CTV.

So that is typically in whole gland therapy, just the entire prostate of course.

But as already mentioned, in some areas where subtotal volume treatments are done, you will see areas where the CTV will be increased and you wanna see those go red, which will be a higher dose.

And then the, the green area is really the corresponds to the yellow here.

And then the blue is of course the outer peripheral area that's getting almost nothing.

And the goal is to keep the rectum and the urethra as pure as possible and not damaged.

And so that's really the trade off here.

Now what happens sometimes in some of these high dose patients and others I've seen doing this in focal therapy is the injection of so-called spacers into the gap between the prostate and the rectum.

And I don't have an image to illustrate this, but if you see this on an image of a CT or something and you see a strange fluid collection in the Dun Nvi fascial plane right there, or a side of falling off to the side here, ask the radiation oncologist, have they injected something?

'cause many times now they're pushing the space wider to allow for higher and higher doses of radiation to that prostate at the back wall there.

And trying in an effort to spare the rectum, they're also doing things to the bladder, like keeping it constantly full or empty, whichever, but one of the attempts to try to stabilize it and motion and reduce the amount of motion, the precision of placement of these brachy therapy sources as already mentioned too, is very important to get it right.

Each of these little sources, have only radiation out for three millimeters.

So we would be asked to reposition needles like that under the guidance of the medical physics team that are trying to ensure the maximal coverage based on this DVH planning program.

And this is just to illustrate the fall off of the various high dose rate and the very low, low dose dose rate seeds, which are quite different.

And these are the techniques that the radiation oncologist will choose from when you see the sources.

Ideally this is a good implant and of how well that's projecting, but you can see nice uniform placement and relatively good separation of these on the plain film, obviously a few extraneous sources where you may not think there's a prostate, these get ha what happens is when the needle, it's preloaded with four or five sources within it and they pull the needle and inject it the trocar in at the same time and the sources are falling out at the tip.

But because of that particular technique, what happens is that everything generally ends up a little bit lower down towards the perineum than you might like.

And so you do tend to see lower seeds.

They often try to overcome that by going into high and into the, the trade off is do you go into the bladder and stop there and then start pulling back.

So there are a lot of manipulative techniques that have been favored and disfavored and go in and outta popularity on how to ensure a nice uniform placement of these sources.

In the whole gland approaches the I 1 25 is more forgiving than the palladium.

The palladium is higher dose rate locally, so you have to be even more careful placing that.

We worked mostly with I 1 25 and there's not much shielding needed.

There's usually a recommendation that no small children hang around the patient for, you know, a week or two afterwards.

But really there's very little energy admitted beyond the actual site.

As I've already mentioned, they do a volume scan on everybody before they do an MRI before they do the actual procedure.

I think we've pretty much replaced that by the MRI volumes that we can generate.

As you know, studies way back when PR have shown that the calculation of overall total prostate gland volume on ultrasound MRI and pathology are slightly different with ultrasound and pathology showing the greatest degree of difference in MRIs, particularly if you do the computed contouring techniques, sliced by slice is the most accurate in vivo volumetric assessment.

And this is one thing that I will really, give credit to the dyna CADs and the iCADs of the world.

That segmentation tool that is built into those programs is very helpful and pretty uniformly accurate on estimating total gland volume.

And so if you're working in those on the workstations like that, use the volumetric measurement that's acquired automatically.

If you just click on that prostate volume icon, put that in your reports.

What it tells the radiation oncologist is how many seeds to order.

If it's 120 cc prostate versus a 30 cc prostate.

You know, there's clearly a big difference in numbers of seeds, that need to go into that gland.

These sources are expensive.

The doses of probably on average five to $7,000 per patient just for the sources alone.

And again, that varies according to the volume of the prostate so that we don't actually charge big prostate men more, I don't think, I don't think they actually parse it out that way and itemize the bill that much.

But there is a, obviously a significant cost consideration here.

And as discussed earlier, this is really one of the reasons why permanent implants are becoming a little less popular.

So the volume scans are going away, but those are typically done a couple of weeks before the procedure, then the planning, then the implant, and then afterwards post-implant dosimetry either with MRI or CT and excuse me, yeah, MRI or ct.

So we've tried a lot of, tricks with the MRI to identify each and every source.

We did this for a while and then we sort of eventually have sort of given up, but because again, we're not doing such a high volume of this procedure anymore, but it is possible to do seed based total dosimetry.

And I think that's the most accurate thing that should be done, but isn't typically done in clinical practice.

What's done is the whole gland dosimetry is calculated, so that eventual amount of radiation that went to the entire prostate, but really a purist would want to know each source and how much it's emitting and then of course correlate that with the three dimensional volume of the prostate on top of that.

So I think there's room for further growth and development in this area should brachytherapy come back into, into place and be utilized.

Fiducial Markers and Advanced Techniques

This is again what Dan nicely showed, the, the imaging findings for the gold seeds that are placed or the fiducial markers that are used by the external systems.

And there's one called Calypso and others that use electromagnetic tracking to try to determine where is the prostate at all times during the delivery of radiation.

They're not great, they, but they do work and they do slightly anyway, I guess.

And they give a, they give an approximate estimate of to as to where the gland is.

But again, as shown earlier, the prostate gland moves considerably.

Anthony DCO as well in, in his enthusiasm for using the endorectal coil has actually pioneered using it during radiation delivery.

So we're really nuts about this coil in Boston.

But, they were using it every day for six weeks in patients who are getting repeated radiation doses because of the fact that the coil freezes the motion.

It literally because of the balloon locking it into place there behind the pubic ramus, it, the pubic synthesis, it helps enormously during radiation.

So there isn't that free fall of the prostate bouncing around between the rectum, and with the rectal peristalsis.

So the coil was used a lot for that as well.

And it still is in the external beam program.

But again, big pros, big big cancers are the ones that seem to present to radiation oncologists quite frequently because they tend to be, of course, the profile of the patients they're seeing are the older men with the higher grade, higher stage disease and more advanced tumor.

This one is actually a T four blading the bladder wall here as well.

And you can see again, nice disorganized chaos in this one.

As opposed to the normal BPH, you can really see the crisp boundary between the normal and the other one here.

We'll come back, I'll just contoured it there for you so you can get an estimate roughly on the total cancer volume burden in this man.

Very significant disease.

But again, keep looking at these transition zones every prostate you can and try to get a good handle on what's normal and what's abnormal.

And here's a very advanced and abnormal, entirely replaced prostate with cancer in this very young man.

It's like breast cancer. Kesh and I were talking about this earlier, when young men get prostate cancer, it is unfortunately often a very bad player.

And this was clearly evidence from his biopsy bilaterally, a Gleason eight completely replaced with disorganized chaos and, and charcoal smudge signs.

And then again, lots and lots of areas of extra prostatic extension with tongues of tissue going out into the seminal vesicle area here.

And he had lymph node disease and bone disease.

Bone Metastasis Detection

Now, bone metastasis we haven't spoken very much about.

We've talked a little bit about it, but one of the techniques that allows us to pick it up best is to do your delayed scans at the end when you're doing that lymph node survey, be it to the aortic bifurcation or kidneys or whatever retroperitoneal imaging you do.

Do it with the gadolinium.

And of course, as you typically do with gadolinium fat suppress sequences.

So when you suppress the marrow, you really should have nothing in there except black marrow.

And if you see these little white arrows, now they're gonna point out to you all those tiny little white spots of metastatic disease in the bones in this young man.

And your sensitivity for picking it up will be higher using this.

And this is again, going to Pete's discussion earlier today on whole body diffusion techniques that Anwar and others are using.

This is, you know, generally a great this is, this is simply just post gadolinium fat suppressed T one imaging, but diffusion imaging as well will pick up these bone metastasis and whole body imaging is I think something we will do eventually.

This man's bone scan is there and with the corresponding areas of increased upstate of Technetium 99 and again, more advanced disease with seminal vesicle invasion, we are repeating ourselves a little bit here.

And I'll just get to the end now in one second.

Role in Treatment Planning and Monitoring

The role in treatment planning, again with diffusion showing a seminal vesicle invasion, it's a very useful, if it's abnormal there, it'll go all the way up into the Seminole vesicles as well.

Here's a nice case where there's a lot of abutment on the capsule and that focal thickening of the capsule showing the invasion and advanced disease with clearly a significant amount of tumor burden in the seminal vesicles there.

And again, the diffusion and the subtraction concurring.

So our role is to really monitor these patients during and after the radiation.

Again, our protocol is the same as always, and it now is standard to use all three sequences.

Typically again, we will use the three Tesla with an indirect coil.

We still follow up with nodal survey and imaging, and we really have a major role to play in all of the radiation treatment planning.

Thank you for your attention.