Protons are blowing Rad Onc's boat out the CMS water

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Lamount said:
does not quite have infinite degrees of freedom
Click to expand...
The degrees of freedom is a little bit of a red herring and an unartful description by me.

The point I was trying to make is that the dosimetry of photon treatment is sound enough that you can quickly run through a nearly infinite number of permutations to find optimal dosimetric solutions utilizing many gantry positions (quite a few if arc based plans) and dynamic and complicated modulation of the beam.

This is because the energy deposition and biologic impact of the beam is pretty well defined as is the impact of physical beam modulation. (Not to say there aren't little bits of magic that can happen with photon treatment, including out of beam effects).

While I understand that there is another degree of modulation along the beam axis for protons, the fact that the biologic effect of simple beam arrangements is not readily calculable in year 2020 is shocking. In the paper I referenced, the dose profile would seem close to identical to the physician reviewing a dose only representation of the plans made by flat vs downslope opposed fields, however the LET profile across those fields is very different and the LET-RBE relationship is not well modeled by contemporary methods.

There is no doubt that the physics of protons is cool. But when LET profiles varying as much as 150% in some places are giving you the same dose representation, somethings not right IMO. Then add to it that the LET to cell kill numbers in vitro are not well understood and I'm getting nervous.

Unless it can be better explained to me, I stick by the suspicion that the clinical benefit of the proton approach will be limited to those scenarios where one is far away from catastrophic dose ceilings for small hotspots (the hot spot in the serial organ scenario) and where the long term consequences of low dose scatter are clinically meaningful.
 
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communitydoc13 said:
The degrees of freedom is a little bit of a red herring and an unartful description by me.

The point I was trying to make is that the dosimetry of photon treatment is sound enough that you can quickly run through a nearly infinite number of permutations quickly to find optimal dosimetric solutions utilizing many gantry positions (quite a few if arc based plans) and dynamic and complicated modulation of the beam.

This is because the energy deposition and biologic impact of the beam is pretty well defined as is the impact of physical beam modulation. (Not to say there aren't little bits of magic that can happen with photon treatment, including out of beam effects).

While I understand that there is another degree of modulation along the beam axis for photons, the fact that the biologic effect of simple beam arrangements is not readily calculable in year 2020 is shocking. In the paper I referenced, the dose profile would seem close to identical to the physician reviewing a dose only representation of the plans made by flat vs downslope opposed fields, however the LET profile across those fields is very different and the LET-RBE relationship is not well modeled by contemporary methods.

There is no doubt that the physics of protons is cool. But when LET profiles varying as much as 150% in some places are giving you the same dose representation, somethings not right IMO. Then add to it that the LET to cell kill numbers in vitro are not well understood and I'm getting nervous.

Unless it can be better explained to me, I stick by the suspicion that the clinical benefit of the proton approach will be limited to those scenarios where one is far away from catastrophic dose ceilings for small hotspots (the hot spot in the serial organ scenario) and where the long term consequences of low dose scatter are clinically meaningful.
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If you think thoughts as deeply as this, and have a very patient-first (and skeptical) attitude, it’s like, regarding protons…

“Something is rotten in the State of Florida.”
- Ben Smith (if he were anti proton)
 
There are certainly questions and uncertainties that need to be worked out for protons. I think this is only a matter of time with improved modeling of both physical and biological uncertainties. Protons have inherent advantages to photons, but the modeling is not as accurate in my opinion compared to photons due to the increased complexity. I think the days of photons are numbered, but for now, they are the way to go for most scenarios due to better modeling of dose distribution. Carbon and high rbe particles pose a more interesting philosophical question regarding their future given the possibility of increased toxicity with higher rbe.

Nonetheless, I disagree with the rapid proliferation and application of protons. Protons remain experimental for most sites.
 
medgator said:
Sounds like you're using protons appropriately, unlike what i imagine is happening at the majority of proton centers in the country. There simply aren't enough "appropriate" patients to go around to keep those centers financially viable
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There are plenty of proton appropriate patients to go around, but a maldistribution of 3 and 4 room freestanding proton centers relative to the population in need.

I think of a proton vault like a Cyberknife, GammaKnife, or dedicated SRS/SBRT linac. It's a great addition to your existing busy 2-3 room center looking to subspecialize or expand into something new However, nobody in their right mind would build a 4-room Cyberknife-only center in the middle of a sleepy suburb that is unattached and unaffiliated with any local doctors, and expect to succeed.

"Real change, lasting change, happens one step at a time." RBG
 
IonsAreOurFuture said:
There are plenty of proton appropriate patients to go around,
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Like? Prostate? I recently had a head and neck/oropharynx pt seen by the local quasi academic center with protons and the interesting thing is they decided against protons because the pt would require bilateral neck RT (???)
 
TheWallnerus said:
When palliative proton therapy becomes a thing I will know my days are numbered. And I am afraid rad onc’s days will be numbered.
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The issue is, when protons become "widespread" (are we there yet?), they won't/can't continue to reimburse at the current "special interest" rate. Reimbursement will drop to, or below, current photon rates. But the startup will cost 25(?) times more.

Yes, that's the death of the field.

The arms race for reimbursement/marketing with dubious clinical benefit in rad onc is one of the more embarrassing parts of being in this career.
 
medgator said:
Like? Prostate? I recently had a head and neck/oropharynx pt seen by the local quasi academic center with protons and the interesting thing is they decided against protons because the pt would require bilateral neck RT (???)
Click to expand...

I think unilateral neck is likely where proton gives most bang for buck in head and neck.
 
IonsAreOurFuture said:
There are plenty of proton appropriate patients to go around
Click to expand...
medgator said:
Like? Prostate?
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Yeah I wonder this too. What is "plenty" and what is "proton appropriate." There are 1 million XRT patients per year. Let us assume this number continues to be very stable year to year, which it has shown itself to be. What % should be proton? Do proton users have a number in mind. Every proton appropriate patient treated with proton is a patient that was photon inappropriate. I don't see any way past the fact that photon users "steal" from proton users, and proton users steal from photon users. Wasn't it this kind of agita that drove e.g. the outrage against excess use of IMRT in prostate cancer. I mean what prevents a headline like "Study sees jump in self-referring radiation oncologists promoting proton treatment." Here's what I feel like is true: if proton machine price and logistics were accessible in the community, and I put in a proton center and started treating everything with it (because let's face it, proton use far outweighs the robustness of available data... its use is based on feeling and emotion and not data), I would be pilloried. But it seems just fine for the places that have proton to be using it on all the patients they treat.

In summary, ASTRO spent years being pissed that urologists who bought IMRT machines used the IMRT machines to treat prostate patients, because money. But ASTRO, and maybe our whole field, seems wholly unbothered that radiation centers that buy proton machines use proton machines to the hilt on this that and the other, and the money is way bigger w/ proton vs IMRT.
 
jondunn said:
I don’t think lack of training is anything to be worried about. Many people take proton jobs with no prior experience. It’s easy
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I have not found that to be case.
IonsAreOurFuture said:
There are plenty of proton appropriate patients to go around, but a maldistribution of 3 and 4 room freestanding proton centers relative to the population in need.

I think of a proton vault like a Cyberknife, GammaKnife, or dedicated SRS/SBRT linac. It's a great addition to your existing busy 2-3 room center looking to subspecialize or expand into something new However, nobody in their right mind would build a 4-room Cyberknife-only center in the middle of a sleepy suburb that is unattached and unaffiliated with any local doctors, and expect to succeed.

"Real change, lasting change, happens one step at a time." RBG
Click to expand...
Quoting RBG wrt to proton proliferation. Wow. That’s… something. Maybe Gandhi when talking about SBRT?
 
medgator said:
For the proportional increase in cost? Data?
Click to expand...

Im just saying that a unilateral neck treatment has more appeal for proton over bilateral neck, as you seemed confused why the proton place cited the bilateral neck as a reason not to do proton.
 
RickyScott said:
why? They do great with IMRT
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I agree. I’m not advocating for proton. Just saying with a unilateral neck you can actually get awesome contralateral sparing, and bilateral neck doesn’t get you a lot with proton.

Medgator was confused, I was answering his question
 
jondunn said:
Im just saying that a unilateral neck treatment has more appeal for proton over bilateral neck, as you seemed confused why the proton place cited the bilateral neck as a reason not to do proton.
Click to expand...
What does proton therapy offer over IMRT for unilateral neck and primary treatment, given the increased cost? Pretty straightforward question imo
 
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medgator said:
What does proton therapy offer over IMRT for unilateral neck and primary treatment, given the increased cost? Pretty straightforward question imo
Click to expand...


Dude re-read your post that I was replying to.

I can ask you - what does proton offer over photon for bilateral neck? Probably just oral cavity, maybe
 
jondunn said:
Dude re-read your post that I was replying to.

I can ask you - what does proton offer over photon for bilateral neck? Probably just oral cavity, maybe
Click to expand...
over your head GIF by ABC Network
 
jondunn said:
I agree. I’m not advocating for proton. Just saying with a unilateral neck you can actually get awesome contralateral sparing, and bilateral neck doesn’t get you a lot with proton.

Medgator was confused, I was answering his question
Click to expand...
You get awesome sparing with well done imrt
 
‘they decided against protons because the pt would require bilateral neck RT (???)’

Would advise that you revise your post so no one reading this wonders what you mean- maybe remove the question marks.

Have a good one!
 
RickyScott said:
You get awesome sparing with well done imrt
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Yes you do. Dosimetricsly better with proton. Whether this matters or not remains to be seen.

I state again- the incremental benefit seems to be more present with unilateral than bilateral.
 
RealSimulD said:
But "bang for the buck" ?
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Bad choice of words haha. Definitely not meaning to say anything about cost.


Just saying there’s something there with unilateral and I think that was a good steward choice for that center to use photons instead of proton because they didn’t think it would help in a bilateral case. That’s how it should be.
 
communitydoc13 said:
The degrees of freedom is a little bit of a red herring and an unartful description by me.

The point I was trying to make is that the dosimetry of photon treatment is sound enough that you can quickly run through a nearly infinite number of permutations to find optimal dosimetric solutions utilizing many gantry positions (quite a few if arc based plans) and dynamic and complicated modulation of the beam.

This is because the energy deposition and biologic impact of the beam is pretty well defined as is the impact of physical beam modulation. (Not to say there aren't little bits of magic that can happen with photon treatment, including out of beam effects).

While I understand that there is another degree of modulation along the beam axis for protons, the fact that the biologic effect of simple beam arrangements is not readily calculable in year 2020 is shocking. In the paper I referenced, the dose profile would seem close to identical to the physician reviewing a dose only representation of the plans made by flat vs downslope opposed fields, however the LET profile across those fields is very different and the LET-RBE relationship is not well modeled by contemporary methods.

There is no doubt that the physics of protons is cool. But when LET profiles varying as much as 150% in some places are giving you the same dose representation, somethings not right IMO. Then add to it that the LET to cell kill numbers in vitro are not well understood and I'm getting nervous.

Unless it can be better explained to me, I stick by the suspicion that the clinical benefit of the proton approach will be limited to those scenarios where one is far away from catastrophic dose ceilings for small hotspots (the hot spot in the serial organ scenario) and where the long term consequences of low dose scatter are clinically meaningful.
Click to expand...

Fully agree. One of my main beefs with protons is that what one sees on the computer has tremendous variability to what the patient may get, and I am not seeing QA efforts and progress being made to account for that properly. Imagine your physicist QA'd a photon IMRT plan and an area was getting 125-150% more dose than it was supposed to get. The plan would fail and you wouldn't treat the patient. Not sure why this basic concept is lost on all proton supporters.

You want me to be impressed about the pretty picture on the screen? Get the modeling of that as (or nearly as) accurate as how we do photon treatments, then maybe.

Or, show me clinical toxicity benefits.
 
jondunn said:
Bad choice of words haha. Definitely not meaning to say anything about cost.


Just saying there’s something there with unilateral and I think that was a good steward choice for that center to use photons instead of proton because they didn’t think it would help in a bilateral case. That’s how it should be.
Click to expand...

The only thing I'll say about unilateral neck treatment is that most people still get oral mucositis. Doesn't affect the patient in any significant way. Pain managed with lidocaine as necessary, can frequently get by without narcotics.

Proton folks will swear that these patients get ZERO oral mucositis (I'd be interested to see peer-reviewed research compared to a contemporarily treated cohort), which I cannot easily refute.
 
evilbooyaa said:
Fully agree. One of my main beefs with protons is that what one sees on the computer has tremendous variability to what the patient may get, and I am not seeing QA efforts and progress being made to account for that properly. Imagine your physicist QA'd a photon IMRT plan and an area was getting 125-150% more dose than it was supposed to get. The plan would fail and you wouldn't treat the patient. Not sure why this basic concept is lost on all proton supporters.
Click to expand...
Cue evergreen Upton SInclair quote

“It is difficult to get a man to understand something, when his salary depends upon his not understanding it!”

That is the answer why the basic concept is lost
 
communitydoc13 said:
The degrees of freedom is a little bit of a red herring and an unartful description by me.

The point I was trying to make is that the dosimetry of photon treatment is sound enough that you can quickly run through a nearly infinite number of permutations to find optimal dosimetric solutions utilizing many gantry positions (quite a few if arc based plans) and dynamic and complicated modulation of the beam.

This is because the energy deposition and biologic impact of the beam is pretty well defined as is the impact of physical beam modulation. (Not to say there aren't little bits of magic that can happen with photon treatment, including out of beam effects).

While I understand that there is another degree of modulation along the beam axis for protons, the fact that the biologic effect of simple beam arrangements is not readily calculable in year 2020 is shocking. In the paper I referenced, the dose profile would seem close to identical to the physician reviewing a dose only representation of the plans made by flat vs downslope opposed fields, however the LET profile across those fields is very different and the LET-RBE relationship is not well modeled by contemporary methods.

There is no doubt that the physics of protons is cool. But when LET profiles varying as much as 150% in some places are giving you the same dose representation, somethings not right IMO. Then add to it that the LET to cell kill numbers in vitro are not well understood and I'm getting nervous.

Unless it can be better explained to me, I stick by the suspicion that the clinical benefit of the proton approach will be limited to those scenarios where one is far away from catastrophic dose ceilings for small hotspots (the hot spot in the serial organ scenario) and where the long term consequences of low dose scatter are clinically meaningful.
Click to expand...
Your skepticism is more than reasonable. There are many points that I can make to refute each specific concern (and I will link some papers when I have some time at my work computer)… but the moral of the story is that, although the highest uncertainty in RBE happens in the falloff region where there is almost no dose, there is still a fair amount of uncertainty in the distal high dose region… and this uncertainty must be respected. However, it doesn’t take much to mitigate risk with the following approaches

1) not having too many beams where there is a sensitive OAR immediately beyond the target
2) using non coplanar beams
3) robust optimization (the same principles mitigate LET hot spots in OARs)
4) LETd optimization. While the relationship between LET and RBE is dependent on many variables, one can easily calculate LET. Avoiding LET hot spots in OARs is not hard and clinical Monte Carlo optimization algorithms will be doing this soon
 
communitydoc13 said:
The degrees of freedom is a little bit of a red herring and an unartful description by me.

The point I was trying to make is that the dosimetry of photon treatment is sound enough that you can quickly run through a nearly infinite number of permutations to find optimal dosimetric solutions utilizing many gantry positions (quite a few if arc based plans) and dynamic and complicated modulation of the beam.

This is because the energy deposition and biologic impact of the beam is pretty well defined as is the impact of physical beam modulation. (Not to say there aren't little bits of magic that can happen with photon treatment, including out of beam effects).

While I understand that there is another degree of modulation along the beam axis for protons, the fact that the biologic effect of simple beam arrangements is not readily calculable in year 2020 is shocking. In the paper I referenced, the dose profile would seem close to identical to the physician reviewing a dose only representation of the plans made by flat vs downslope opposed fields, however the LET profile across those fields is very different and the LET-RBE relationship is not well modeled by contemporary methods.

There is no doubt that the physics of protons is cool. But when LET profiles varying as much as 150% in some places are giving you the same dose representation, somethings not right IMO. Then add to it that the LET to cell kill numbers in vitro are not well understood and I'm getting nervous.

Unless it can be better explained to me, I stick by the suspicion that the clinical benefit of the proton approach will be limited to those scenarios where one is far away from catastrophic dose ceilings for small hotspots (the hot spot in the serial organ scenario) and where the long term consequences of low dose scatter are clinically meaningful.
Click to expand...
You would think photon planning would be solved by now, but no:

1639616234611.png
 
Lamount said:
Your skepticism is more than reasonable. There are many points that I can make to refute each specific concern (and I will link some papers when I have some time at my work computer)… but the moral of the story is that, although the highest uncertainty in RBE happens in the falloff region where there is almost no dose, there is still a fair amount of uncertainty in the distal high dose region… and this uncertainty must be respected. However, it doesn’t take much to mitigate risk with the following approaches

1) not having too many beams where there is a sensitive OAR immediately beyond the target
2) using non coplanar beams
3) robust optimization (the same principles mitigate LET hot spots in OARs)
4) LETd optimization. While the relationship between LET and RBE is dependent on many variables, one can easily calculate LET. Avoiding LET hot spots in OARs is not hard and clinical Monte Carlo optimization algorithms will be doing this soon
Click to expand...
In aggregate, all of these optimizations "cost" more PTV than you would have in a photon plan. I wish someone would an analysis where you compared volume of normal tissue getting the PTV dose in protons and volume on normal tissue getting the PTV dose in photons, its almost always going to be higher in protons
 
radiation said:
In aggregate, all of these optimizations "cost" more PTV than you would have in a photon plan. I wish someone would an analysis where you compared volume of normal tissue getting the PTV dose in protons and volume on normal tissue getting the PTV dose in photons, its almost always going to be higher in protons
Click to expand...
It depends up the goal and the uncertainties. There are certainly a lot of cases where photons would win out…

If low-intermediate is driving morbidity, protons may have an advantage
 
Lamount said:
It depends up the goal and the uncertainties. There are certainly a lot of cases where photons would win out…

If low-intermediate is driving morbidity, protons may have an advantage
Click to expand...

Ideally we would treat protons like we do electrons. We never see editorials on photons vs electrons. We never see billboards or commercials for electrons. Sometimes electrons clearly work better and we use them logically. But nobody tries to sweep the limitations of electrons under the rug like they do for protons.
 
radiation said:
Ideally we would treat protons like we do electrons. We never see editorials on photons vs electrons. We never see billboards or commercials for electrons. Sometimes electrons clearly work better and we use them logically. But nobody tries to sweep the limitations of electrons under the rug like they do for protons.
Click to expand...
Electrons are not sexy. Electrons are not limited to the elite. Electrons are not administered only by the smartest rad oncs in America because if you do not have electrons obviously you are neither smart enough nor can be trusted to wield the electron beam.
 
radiation said:
Ideally we would treat protons like we do electrons. We never see editorials on photons vs electrons. We never see billboards or commercials for electrons. Sometimes electrons clearly work better and we use them logically. But nobody tries to sweep the limitations of electrons under the rug like they do for protons.
Click to expand...
On an aside, some of the research being done into robust inverse optimized mixed beam RT I think is incredible. As I understand, MLC shielded electron + photon + modulated energies for each can arrive at some proton-like distribution without the need for bolus placement, either. If that ever gets to commercial license I think that would be another step up in plan quality, and available on the standard linac setups.

edit: obviously still some exit dose but yet another improvement in the optimization kit.
 
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radiation said:
Ideally we would treat protons like we do electrons. We never see editorials on photons vs electrons. We never see billboards or commercials for electrons. Sometimes electrons clearly work better and we use them logically. But nobody tries to sweep the limitations of electrons under the rug like they do for protons.
Click to expand...
I agree with that. Protons, carbon ion, I-131, radium, photons, electrons are all just modalities that we should have access to and understand the best way to use them for different scenarios. Protons aren't designed to replace all uses of a linac and probably won't in our lifetimes, at least until cost parity arrives. Just another modality. A good one for many uses but not the only one.

Indications are still emerging for all newer drugs and modalities. I think protons currently are where IMRT was in 2004 or so - larger academic facilities and entrepreneurial private facilities. There were 2 IMRT uses then: prostate and head and neck. Not due to randomized trial results with 3D, but because of documented organ sparing. With further use, we learned it also looks good for treating pelvic nodes, and brain, and esophagus, and lung, and liver, and anal, and can do SRS and SBRT.

The same is true of any new skill or technology, the more you use it, the more uses appear. Only an experienced IMRT user would look at a 3D plan for a long span of esophagus cancer in 2004 and say "we could do better with IMRT for this one" maybe due to exceeding lung V20. Cardiac sparing wouldn't have entered into it though, because the Darby paper came out in 2013 and cardiac V5 was an unknown concept in 2004, so that is a new indication, cardiac sparing.
 
IonsAreOurFuture said:
I agree with that. Protons, carbon ion, I-131, radium, photons, electrons are all just modalities that we should have access to and understand the best way to use them for different scenarios. Protons aren't designed to replace all uses of a linac and probably won't in our lifetimes, at least until cost parity arrives. Just another modality. A good one for many uses but not the only one.

Indications are still emerging for all newer drugs and modalities. I think protons currently are where IMRT was in 2004 or so - larger academic facilities and entrepreneurial private facilities. There were 2 IMRT uses then: prostate and head and neck. Not due to randomized trial results with 3D, but because of documented organ sparing. With further use, we learned it also looks good for treating pelvic nodes, and brain, and esophagus, and lung, and liver, and anal, and can do SRS and SBRT.

The same is true of any new skill or technology, the more you use it, the more uses appear. Only an experienced IMRT user would look at a 3D plan for a long span of esophagus cancer in 2004 and say "we could do better with IMRT for this one" maybe due to exceeding lung V20. Cardiac sparing wouldn't have entered into it though, because the Darby paper came out in 2013 and cardiac V5 was an unknown concept in 2004, so that is a new indication, cardiac sparing.
Click to expand...
Cardiac sparing was definitely a thing in 2004. The cox textbook showed the relation of lad coronary to chest wall and discussed avoiding it to spare atherosclerosis and we sometimes put in heart blocks in residency. Data was not a solid, but no one thought treating the heart was a good idea. Specifically I remember a back and forth in the red journal (Larry marks? or breast guy at duke ) about a recurrence under a heart block.
 
IonsAreOurFuture said:
I agree with that. Protons, carbon ion, I-131, radium, photons, electrons are all just modalities that we should have access to and understand the best way to use them for different scenarios. Protons aren't designed to replace all uses of a linac and probably won't in our lifetimes, at least until cost parity arrives. Just another modality. A good one for many uses but not the only one.

Indications are still emerging for all newer drugs and modalities. I think protons currently are where IMRT was in 2004 or so - larger academic facilities and entrepreneurial private facilities. There were 2 IMRT uses then: prostate and head and neck. Not due to randomized trial results with 3D, but because of documented organ sparing. With further use, we learned it also looks good for treating pelvic nodes, and brain, and esophagus, and lung, and liver, and anal, and can do SRS and SBRT.

The same is true of any new skill or technology, the more you use it, the more uses appear. Only an experienced IMRT user would look at a 3D plan for a long span of esophagus cancer in 2004 and say "we could do better with IMRT for this one" maybe due to exceeding lung V20. Cardiac sparing wouldn't have entered into it though, because the Darby paper came out in 2013 and cardiac V5 was an unknown concept in 2004, so that is a new indication, cardiac sparing.
Click to expand...
My main argument is protons centers existed in 2004. They existed well before that.

Why don't we know more about when proton therapy is beneficial?

There's been time. There's been studies. There's been no benefit. That's the issue. The pretty picture has no clothes.
 
Mandelin Rain said:
My main argument is protons centers existed in 2004. They existed well before that.

Why don't we know more about when proton therapy is beneficial?

There's been time. There's been studies. There's been no benefit. That's the issue. The pretty picture has no clothes.
Click to expand...
We are coming up on like 50 years with no benefit.
 
In the first post in this thread, ProVision Knoxville was home to the highest-reimbursed-by-Medicare rad onc in the United States.

That was then (2018). This is now.

As of 2022, Provision Knoxville is being sold to Covenant Health for pennies on the dollar (they are, or were, in bankruptcy) and Provision itself will essentially cease to be as a functioning entity, at least in TN.
 

Relative biological effectiveness in proton beam therapy – Current knowledge and future challenges - PMC

www.ncbi.nlm.nih.gov www.ncbi.nlm.nih.gov

Characterization of relative biological effectiveness for conventional radiation therapy: a comparison of clinical 6 MV X-rays and 137Cs - PMC

Various types of radiation are utilized in the treatment of cancer. Equal physical doses of different radiation types do not always result in the same amount of biological damage. In order to account for these differences, a scaling factor known as ...
www.ncbi.nlm.nih.gov www.ncbi.nlm.nih.gov

I'm just going to leave these links here for anyone interested. I'm not an expert in proton therapy (or photon therapy for that matter). My clinical practice is based of comfort levels regarding areas of uncertainty. I don't believe my Acuros dose engine beyond about 5%. I don't believe in indefinitely segmenting breast plans and extending patient time on the table for incremental dosimetric gains that I have never seen to correlate with clinical outcomes.

But, I do like there to be some sort of relatively robust (a fashionable term I know, I just mean when things get fuzzy they don't get bad) underpinning to what I do.

And, I would like the chair of an academic department with recently commissioned protons, who calls little old me out of the blue to sell me the idea that being part of a consortium where I can send patients two and a half hours away for proton treatment off of protocol with some potential nominal personal involvement is a good idea, to have damn good answers for me when I bring up "where's the data" and they bring up "that's all old passive scattering stuff, this IMPT is the gamechanger".

Of course, I expect nothing from the Procure proton guy in the community.

But if anyone is wondering how you meaningfully optimize a plan when you don't know the RBE (may be factor of 2-3 off), you are in the same boat as me and probably agree that 4-10 academic places only should be studying proton therapy and treating as an experimental therapy except in certain clear cut pediatric/young adult cases.

If anyone wants a shocker, just look at the RBE curves in these two papers.

The photon paper is looking at RBE of Cs 137 (low enough energy that we are seeing some variability in LET with energy for photons) compared to 6MV linac in different cell lines. (yes, there is some small variability is some cell lines, and nobody is using Cs137 in IMRT planning).

The proton paper is looking at RBE in different cell lines for 2 different proton energies including along the beam axis. The spreads in RBE between energies is remarkable.
 
TheWallnerus said:
In the first post in this thread, ProVision Knoxville was home to the highest-reimbursed-by-Medicare rad onc in the United States.

That was then (2018). This is now.

As of 2022, Provision Knoxville is being sold to Covenant Health for pennies on the dollar (they are, or were, in bankruptcy) and Provision itself will essentially cease to be as a functioning entity, at least in TN.
Click to expand...
They got a very good deal. The Knoxville facility has 5 rooms and 2!!! Cyclotrons that can be run simultaneously. It's a beautiful facility centrally located near downtown and freeway close, on a nice campus.

It's also far away from a hospital, too large for the size of its city (larger than the NY proton center), not a major transit or airline hub, and not affiliated with any health system or university.

Unfortunately they over-built on borrowed money at high interest rates; what probably cost $135+ million to build a decade ago now sold for $45 million. It's a beautiful facility and good team of people that should be able to operate in the black now, especially since they are now owned by a major local oncology program that won't have to send patients out of their network to get proton therapy.
 
If the proton money was instead used to help inner city hospitals and to help troubled kids, the society would be better
(better for humanity)...
 
Radonc90 said:
If the proton money was instead used to help inner city hospitals and to help troubled kids, the society would be better
(better for humanity)...
Click to expand...
Same can be said of the billionaire space race money. And lots of other money. But in this world, in 2021, CREAM.
 
Mandelin Rain said:
Same can be said of the billionaire space race money. And lots of other money. But in this world, in 2021, CREAM.
Click to expand...
Considering we will probably need an off world colony fairly soon as things considered with what is happening on this planet, i don't think that's a complete waste of money
 
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