Viewray‘s Demise

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Mandelin Rain said:
Continuing with the "knife" analogy, If we say linac based photon radiation is open surgery, if feels like platforms such as MR adaptive and protons are the rough equivalent of robotic surgery. Been around forever but still "feels" "high-tech" and "cutting-edge." Seems intuitively like it "should" be better and more "precise", but very little evidence indicating that clinically. And the evidence that does support is mainly tortured statistics of endpoints of dubious relevance. Some evidence pointing to the exact opposite, that it may do more harm than good, particularly in certain hands is roundly ignored. Certainly much more expensive and nice to market directly to patients, so the beat goes on.

FWIW: there's MUCH more evidence supporting the use of robotic surgery than protons.
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Agree with your analogy but would postulate maybe laparoscopic vs robotic would be a better comparison? The slices of pie are getting very, very thin.
 
I've had one patient who post 68/25 is struggling with cystitis. Every other patient sailed through treatment the past 2 years. He didn't have a a severe AUA beforehand, nothing unusual about his anatomy, plan, CBCT, or bladder filling from what I could see.

I think this is the kind of case that deserves to get 'marked down' as being different. All the GU grade 2 stuff used to say "this is better then that" is nonsense (I posted a paper previously showing how the GU 1-2 reporting is all over the place between patient, nurse and doctor).

Instant adaptive planning based on CBCT would be great, but I just don't know how they are going to bridge that gap quickly, safely, and consistently.

Unlike "hot, sane, single.. pick 2" getting 2 outta 3 isn't going to be good enough for patient care.
 
sirspamalot said:
Instant adaptive planning based on CBCT would be great, but I just don't know how they are going to bridge that gap quickly, safely, and consistently.

Unlike "hot, sane, single.. pick 2" getting 2 outta 3 isn't going to be good enough for patient care.
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The bolded is literally what Ethos does. Can take as few as 15-20 minutes on table time for a prostate plan.

Having evaluated adaptive RT on Ethos on prostate - the juice is not worth the squeeze (IMO) in vast majority of patients. There is a tiny dosimetric benefit that is unlikely to ever pan out into an actual clinical toxicity benefit.

Adaptive RT for bladder is going to potentially be a big winner, assuming we can ever nationally get enough bladder patients from the urologists to justify it despite like every study ever suggesting equipoise.

MIRAGE did not use the adaptive function of MR-Linac. Some feel comfortable with 3mm all around - I personally do 3mm post, 5mm all others including into bladder, as the prostate/bladder interface can be a bit more mobile with even slight variations in bladder filling. I also prefer doing 40/5 to the PTV with underdosing at bladder interface because that's been shown to be more effective than 36.25/5 (Dose-response with stereotactic body radiotherapy for prostate cancer: A multi-institutional analysis of prostate-specific antigen kinetics and biochemical control - PubMed) . I get that people do 36.25 routinely, but to me that's like doing 70Gy conventional instead of 78Gy conventional. I get there isn't a randomized trial of 36.25 vs 40 (to PTV) prostate SBRT like there was with 70 vs 78, but to me it's the value of dose escalation. Unfortunately, trials like PACE-B (where they call it Rx to 40Gy but it's 40Gy to CTV and 36.25 to PTV) aren't helping us to prospectively determine the dose response curve.

There is an immense amount of variation in practice with prostate SBRT - there is a significant chunk of US ROs who will never do it, and I agree that they probably shouldn't do it. Then there's all the others who feel comfort with it but are (IMO) underdosing patients. Yes 7.25-8Gy x 5 is NCCN supported but so is 1.8-2Gy x 37-45Fx. 1.8 x 39 = 70.2.
 
evilbooyaa said:
There is an immense amount of variation in practice with prostate SBRT - there is a significant chunk of US ROs who will never do it, and I agree that they probably shouldn't do it. Then there's all the others who feel comfort with it but are (IMO) underdosing patients. Yes 7.25-8Gy x 5 is NCCN supported but so is 1.8-2Gy x 37-45Fx. 1.8 x 39 = 70.2.
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Can you elaborate? I am doing 7.25x5. I do not feel that there is enough evidence today to say that this is under dosing, but I also prefer work life balance and mustard on a hot dog... you know, not an expert.

I know some people are big believers that it is, and thats okay, but Im not sure that's really an evidence based belief?

I should add context that I am still pretty selective here, I only offer SBRT really to favorable intermediate risk or the rare low risk where we would treat them.
 
evilbooyaa said:
The bolded is literally what Ethos does. Can take as few as 15-20 minutes on table time for a prostate plan.

Having evaluated adaptive RT on Ethos on prostate - the juice is not worth the squeeze (IMO) in vast majority of patients. There is a tiny dosimetric benefit that is unlikely to ever pan out into an actual clinical toxicity benefit.

Adaptive RT for bladder is going to potentially be a big winner, assuming we can ever nationally get enough bladder patients from the urologists to justify it despite like every study ever suggesting equipoise.

MIRAGE did not use the adaptive function of MR-Linac. Some feel comfortable with 3mm all around - I personally do 3mm post, 5mm all others including into bladder, as the prostate/bladder interface can be a bit more mobile with even slight variations in bladder filling. I also prefer doing 40/5 to the PTV with underdosing at bladder interface because that's been shown to be more effective than 36.25/5 (Dose-response with stereotactic body radiotherapy for prostate cancer: A multi-institutional analysis of prostate-specific antigen kinetics and biochemical control - PubMed) . I get that people do 36.25 routinely, but to me that's like doing 70Gy conventional instead of 78Gy conventional. I get there isn't a randomized trial of 36.25 vs 40 (to PTV) prostate SBRT like there was with 70 vs 78, but to me it's the value of dose escalation. Unfortunately, trials like PACE-B (where they call it Rx to 40Gy but it's 40Gy to CTV and 36.25 to PTV) aren't helping us to prospectively determine the dose response curve.

There is an immense amount of variation in practice with prostate SBRT - there is a significant chunk of US ROs who will never do it, and I agree that they probably shouldn't do it. Then there's all the others who feel comfort with it but are (IMO) underdosing patients. Yes 7.25-8Gy x 5 is NCCN supported but so is 1.8-2Gy x 37-45Fx. 1.8 x 39 = 70.2.
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I do 40 in 5

Also, I think mustard on a dog is considered standard:
"Cheaper than a hot dog with no mustard" - Ad Rock
 
drowsy12 said:
just came across this on my feed

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Yes, there is a dosimetric benefit to the rectum.
Do we think a difference of 0.4Gy to rectum per fx, x 5 fractions, so up to 2Gy point dose improvement, is going to be routinely clinically beneficial?

The bladder was HIGHER with adaptive which is, IMO, a failure to adapt properly, but is 0.1Gy increase to bladder per fx going to be noticed?
Also, no.

Regardless, there is a trial ongoing in this space. It is a valuable research question and I support the question being asked. I'm not sure there is such a clear benefit to offer this to prostate patient's off protocol at current time.

Bladder patients? Hell yeah, I'd recommend it for all given how dramatic the differences are.

OTN said:
I do 40 in 5

Also, I think mustard on a dog is considered standard:
"Cheaper than a hot dog with no mustard" - Ad Rock
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You are probably top 5% of ROs nationwide in terms of 'being a good Rad Onc' based on our interactions on SDN so I'm not surprised you do prostate SBRT 'the right way' (AKA, the way I do it).

NotMattSpraker said:
Can you elaborate? I am doing 7.25x5. I do not feel that there is enough evidence today to say that this is under dosing, but I also prefer work life balance and mustard on a hot dog... you know, not an expert.

I know some people are big believers that it is, and thats okay, but Im not sure that's really an evidence based belief?

I should add context that I am still pretty selective here, I only offer SBRT really to favorable intermediate risk or the rare low risk where we would treat them.
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40/5 is the best for bPFS as per the link I sent. I recognize that it's not the highest quality data and I don't think people are 'wrong' to treat 36.25 but 36.25 in 5 was picked because it seemed reasonable based on a/b calculations (which as we learned from all the mod hypo data, our thought that 'a/b of prostate cancer is < 3!!!' is almost guaranteed to be incredibly wrong) and also what people have deemed 'safe'. Maybe one day there will be a prospective comparison of 36.25 vs 40/5 regimens.

People were also doing 'only' 33/5 pancreatic SBRT because that was 'safe' too. We've learned a somewhat painful lession as to the utility of only doing something because it's 'safe'.
 
evilbooyaa said:
Do we think a difference of 0.4Gy to rectum per fx, x 5 fractions, so up to 2Gy point dose improvement, is going to be routinely clinically beneficial?
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agree, just was adding it as relevant to the discussion
 
Ah, the good old MIRAGE debate. It's been a while.

Any trial can get criticism. Fair points were brought up in the accompanying editorial.

However, there are some points I do not think are fair/accurate and warrant a response. In advance, I’ll say I cannot respond individually further, but I do want to leave these notes here in response to what I saw recently posted here.

(1) “Margins are not standard” – Not true. PACE-B, NRG GU-005 all used 5 mm margins, allowing down to 3 posteriorly. MIRAGE used 4 mm in one arm and 2 mm in the other. People can cite their own smaller margins all they want, that doesn’t suddenly make the MIRAGE margins nonstandard.

(2) “Margins were different on the arms” – Yes. That was the point of the trial. 2 mm margins would be considered extremely narrow, and we were comfortable with it only using MRI-guidance. The literal objective of the trial: “To determine whether aggressive margin reduction with MRI guidance significantly reduces acute grade 2 or greater genitourinary (GU) toxic effects after prostate SBRT compared with computed tomography (CT) guidance.”

(3) “Toxicity higher than I see” –
(a) For GU: Yes, GU toxicity on the CT-guided arm of MIRAGE was higher than on PACE-B, which I would consider as providing the gold standard data in this setting. This is expected because the PTV dose is 10% higher--if you believe in EQD2, with an EQD2 that’s an 8 Gy dose escalation. Was acute toxicity higher for example with an LDR boost vs 78 Gy? Yes, it was actually 2 fold higher… So seeing higher toxicity with dose-escalation is actually the expectation. In that regard the low toxicity on the MRI arm would be the major result. In any case we did an interim analysis precisely because we expected higher toxicity.

(b) For GI: Simply not true. Acute grade 2 or higher GI toxicity on the PACE-B trial was higher than on MIRAGE CT arm, and much higher than MIRAGE MRI arm, despite the substantially higher PTV dose.

What makes it OK to say GU toxicity is higher (in one arm), but ignore that GI toxicity was lower (in both arms, much lower in one of the arms) and disregard the results? Seems like a double standard…plus we have an explanation for the higher GU toxicity.

(4) “You adapted in one arm” – Nope. Not sure where this even comes from, and the full text is open access.

(5) “Trial was designed to be positive” – Well…it’s a superiority trial, those are typically designed to detect a benefit. Why would anyone run a superiority trial with no hypothesis or precedence to determine superiority? If you are implying that the trial was “rigged” because the margins were different, that is just showcasing that you don’t understand the design/rationale of the trial. Please refer to (1) and (2).

(6) “Endpoint is physician-scored which can be subjective” – Yes, grade 2 GU toxicity is not the best endpoint in the world. For the sake of brevity – what if I had designed the trial to show a benefit in reduction of proportion of patients with significant bowel bother (2xMCID on EPIC-26)? If I had, MIRAGE would have been positive since we saw that (50%-->25%). Urinary incontinence (reported by patients) and clinically significant IPSS increase also improved. These are patient-reported.

I will stop there -- best!
 
AUKishan said:
Ah, the good old MIRAGE debate. It's been a while.

Any trial can get criticism. Fair points were brought up in the accompanying editorial.

However, there are some points I do not think are fair/accurate and warrant a response. In advance, I’ll say I cannot respond individually further, but I do want to leave these notes here in response to what I saw recently posted here.

(1) “Margins are not standard” – Not true. PACE-B, NRG GU-005 all used 5 mm margins, allowing down to 3 posteriorly. MIRAGE used 4 mm in one arm and 2 mm in the other. People can cite their own smaller margins all they want, that doesn’t suddenly make the MIRAGE margins nonstandard.

(2) “Margins were different on the arms” – Yes. That was the point of the trial. 2 mm margins would be considered extremely narrow, and we were comfortable with it only using MRI-guidance. The literal objective of the trial: “To determine whether aggressive margin reduction with MRI guidance significantly reduces acute grade 2 or greater genitourinary (GU) toxic effects after prostate SBRT compared with computed tomography (CT) guidance.”

(3) “Toxicity higher than I see” –
(a) For GU: Yes, GU toxicity on the CT-guided arm of MIRAGE was higher than on PACE-B, which I would consider as providing the gold standard data in this setting. This is expected because the PTV dose is 10% higher--if you believe in EQD2, with an EQD2 that’s an 8 Gy dose escalation. Was acute toxicity higher for example with an LDR boost vs 78 Gy? Yes, it was actually 2 fold higher… So seeing higher toxicity with dose-escalation is actually the expectation. In that regard the low toxicity on the MRI arm would be the major result. In any case we did an interim analysis precisely because we expected higher toxicity.

(b) For GI: Simply not true. Acute grade 2 or higher GI toxicity on the PACE-B trial was higher than on MIRAGE CT arm, and much higher than MIRAGE MRI arm, despite the substantially higher PTV dose.

What makes it OK to say GU toxicity is higher (in one arm), but ignore that GI toxicity was lower (in both arms, much lower in one of the arms) and disregard the results? Seems like a double standard…plus we have an explanation for the higher GU toxicity.

(4) “You adapted in one arm” – Nope. Not sure where this even comes from, and the full text is open access.

(5) “Trial was designed to be positive” – Well…it’s a superiority trial, those are typically designed to detect a benefit. Why would anyone run a superiority trial with no hypothesis or precedence to determine superiority? If you are implying that the trial was “rigged” because the margins were different, that is just showcasing that you don’t understand the design/rationale of the trial. Please refer to (1) and (2).

(6) “Endpoint is physician-scored which can be subjective” – Yes, grade 2 GU toxicity is not the best endpoint in the world. For the sake of brevity – what if I had designed the trial to show a benefit in reduction of proportion of patients with significant bowel bother (2xMCID on EPIC-26)? If I had, MIRAGE would have been positive since we saw that (50%-->25%). Urinary incontinence (reported by patients) and clinically significant IPSS increase also improved. These are patient-reported.

I will stop there -- best!
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Thanks for joining and adding to the discourse but i can't let you get away with (6). You can't pick endpoints after the experiment is done.

If you picked GU urgency then p =0.14 with more urgency in MRI arm?

Small studies lead to weird results.


What is the explanation for the difference disappearing at 3 months?

I look forward to longer followup.
 
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Chartreuse Wombat said:
Thanks for joining and adding to the discourse but i can't let you get away with (6). You can't pick endpoints after the experiment is done and what is the explanation for the difference disappearing at 3 months. I look forward to longer followup.
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That endpoint wasn't picked after the trial was done, it was part of the plan to analyze. It was difficult to determine which of the several possible primary endpoints we could pick when designing the trial. I went with GU grade 2 toxicity because we did have data from PACE-B and it was pragmatic for the power calculation. Keep in mind this was a single center trial, and also not the easiest to trial to run -- it required not just treating everyone on the MRI-LINAC which many people did/do, but randomizing them. I didn't think the GI effect would be as large, nor that that there would be that high a rate of clinically relevant bowel toxicity (otherwise, would have picked bowel PRO as the primary endpoint).

The explanation for the resolving toxicity is that it is acute toxicity, which we (a) see and treat and (b) of course goes away. I know and agree that late toxicity is the real endpoint we want to improve, but again pragmatically that trial would have been very difficult to run. We do know that acute toxicity is (a) related to dose to OARs and (b) associated with late toxicity (oral at ASTRO from PACE-B group, published: The Association between Acute and Late Genitourinary and Gastrointestinal Toxicities: An Analysis of the PACE B Study - PubMed). I do not think it is wrong to reasonably infer that reducing dose delivery to OARs will lead to less late toxicity down the line.
 
AUKishan said:
That endpoint wasn't picked after the trial was done, it was part of the plan to analyze. It was difficult to determine which of the several possible primary endpoints we could pick when designing the trial. I went with GU grade 2 toxicity because we did have data from PACE-B and it was pragmatic for the power calculation. Keep in mind this was a single center trial, and also not the easiest to trial to run -- it required not just treating everyone on the MRI-LINAC which many people did/do, but randomizing them. I didn't think the GI effect would be as large, nor that that there would be that high a rate of clinically relevant bowel toxicity (otherwise, would have picked bowel PRO as the primary endpoint).

The explanation for the resolving toxicity is that it is acute toxicity, which we (a) see and treat and (b) of course goes away. I know and agree that late toxicity is the real endpoint we want to improve, but again pragmatically that trial would have been very difficult to run. We do know that acute toxicity is (a) related to dose to OARs and (b) associated with late toxicity (oral at ASTRO from PACE-B group, published: The Association between Acute and Late Genitourinary and Gastrointestinal Toxicities: An Analysis of the PACE B Study - PubMed). I do not think it is wrong to reasonably infer that reducing dose delivery to OARs will lead to less late toxicity down the line.
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Last sentence is proton speak DVH idolatry. NTCP curves have threshold.
 
AUKishan said:
Ah, the good old MIRAGE debate. It's been a while.

Any trial can get criticism. Fair points were brought up in the accompanying editorial.

However, there are some points I do not think are fair/accurate and warrant a response. In advance, I’ll say I cannot respond individually further, but I do want to leave these notes here in response to what I saw recently posted here.

(1) “Margins are not standard” – Not true. PACE-B, NRG GU-005 all used 5 mm margins, allowing down to 3 posteriorly. MIRAGE used 4 mm in one arm and 2 mm in the other. People can cite their own smaller margins all they want, that doesn’t suddenly make the MIRAGE margins nonstandard.

(2) “Margins were different on the arms” – Yes. That was the point of the trial. 2 mm margins would be considered extremely narrow, and we were comfortable with it only using MRI-guidance. The literal objective of the trial: “To determine whether aggressive margin reduction with MRI guidance significantly reduces acute grade 2 or greater genitourinary (GU) toxic effects after prostate SBRT compared with computed tomography (CT) guidance.”

(3) “Toxicity higher than I see” –
(a) For GU: Yes, GU toxicity on the CT-guided arm of MIRAGE was higher than on PACE-B, which I would consider as providing the gold standard data in this setting. This is expected because the PTV dose is 10% higher--if you believe in EQD2, with an EQD2 that’s an 8 Gy dose escalation. Was acute toxicity higher for example with an LDR boost vs 78 Gy? Yes, it was actually 2 fold higher… So seeing higher toxicity with dose-escalation is actually the expectation. In that regard the low toxicity on the MRI arm would be the major result. In any case we did an interim analysis precisely because we expected higher toxicity.

(b) For GI: Simply not true. Acute grade 2 or higher GI toxicity on the PACE-B trial was higher than on MIRAGE CT arm, and much higher than MIRAGE MRI arm, despite the substantially higher PTV dose.

What makes it OK to say GU toxicity is higher (in one arm), but ignore that GI toxicity was lower (in both arms, much lower in one of the arms) and disregard the results? Seems like a double standard…plus we have an explanation for the higher GU toxicity.

(4) “You adapted in one arm” – Nope. Not sure where this even comes from, and the full text is open access.

(5) “Trial was designed to be positive” – Well…it’s a superiority trial, those are typically designed to detect a benefit. Why would anyone run a superiority trial with no hypothesis or precedence to determine superiority? If you are implying that the trial was “rigged” because the margins were different, that is just showcasing that you don’t understand the design/rationale of the trial. Please refer to (1) and (2).

(6) “Endpoint is physician-scored which can be subjective” – Yes, grade 2 GU toxicity is not the best endpoint in the world. For the sake of brevity – what if I had designed the trial to show a benefit in reduction of proportion of patients with significant bowel bother (2xMCID on EPIC-26)? If I had, MIRAGE would have been positive since we saw that (50%-->25%). Urinary incontinence (reported by patients) and clinically significant IPSS increase also improved. These are patient-reported.

I will stop there -- best!
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I just want to write welcome and thanks for coming and discussing 👍

PS: Viewray is dead 🙁
 
AUKishan said:
“Margins were different on the arms” – Yes. That was the point of the trial. 2 mm margins would be considered extremely narrow, and we were comfortable with it only using MRI-guidance.
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This of course is the "rub" as they say. It is essentially 100% likely (I can say this, thanks to your trial) that if a trial of 2mm vs 4mm PTV margins using daily CBCT were run, the 2mm group would have less toxicity.

Thus, MRgRT has *zero* to do with reducing toxicity for prostate cancer. All that you have shown is that the "comfort" (w/ 2mm margins) of which you speak is just not there, mentally, in the mind of the trialists who would use non-MRgRT technique. (And you have proven a minus-2mm, vs 4mm, unidimensional PTV margin decrease lowers toxicity.) No one has EVER proved that 2mm PTV margins cannot be used to cure prostate cancer with non-MRgRT technique. The focus on 2mm PTV margins for MRgRT is an affectation (and so is the focus on that 2mm margins would somehow lead to PSA-infaust outcomes with non-MRgRT technique), no matter how well-meaning, and not an evidence-based belief.

Come back to me after a 2mm PTV margin trial is run on MRgRT vs daily CBCT, and the daily CBCT patients have worse bDFS (or worse toxicity!). Then you might even win a Nobel Prize, who knows.
 
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TheWallnerus said:
No one has EVER proved that 2mm PTV margins cannot be used to cure prostate cancer with non-MRgRT technique.
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no one has ever proved that you can't use 0 mm margins either, for anything. kind of a silly comment.

bottom line, in my opinion:

1) the trial design was reasonable, given what standard margins are on national trials for prostate sbrt. It was an IIT. the comparison to the proton CSI trial is a good one. using novel technology to compare to what is standardly done. that's kind of the point.
2) one can certainly question the clinical importance of the endpoint
3) people should highly consider using smaller margins with CT based prostate RT (among other things IMO)
 
drowsy12 said:
no one has ever proved that you can't use 0 mm margins either, for anything. kind of a silly comment.
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The designers of MIRAGE bake in, as if it's proved, that you cannot use 2mm margins for CBCT. (And they would sure say the same thing for 0mm).

So from that standpoint, asking "Are 2mm margins proven not to work for CBCT?" is a moot point/silly comment re: MIRAGE, because functionally and for all intents and purposes the "trial-conducting" difference between proven vs unproven 2mm margins, vis-a-vis MIRAGE, is:

time house GIF


"People should highly consider using smaller margins with CT based prostate RT"

So, during my consideration phase, how small a margin should I be considering?
 
Whatever margin you feel comfortable with? I don’t get the question. You’re the one raising the point. What do you use for standard prostate RT?
 
AUKishan said:
(1) “Margins are not standard” – Not true. PACE-B, NRG GU-005 all used 5 mm margins, allowing down to 3 posteriorly. MIRAGE used 4 mm in one arm and 2 mm in the other. People can cite their own smaller margins all they want, that doesn’t suddenly make the MIRAGE margins nonstandard.

(2) “Margins were different on the arms” – Yes. That was the point of the trial. 2 mm margins would be considered extremely narrow, and we were comfortable with it only using MRI-guidance. The literal objective of the trial: “To determine whether aggressive margin reduction with MRI guidance significantly reduces acute grade 2 or greater genitourinary (GU) toxic effects after prostate SBRT compared with computed tomography (CT) guidance.”
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how do you square the statement that you can’t use 2mm margins with the paper you just published in PRO: https://www.practicalradonc.org/article/S1879-8500(23)00237-0/fulltext

Table 2 lists a number of conventional linac technologies where you can use 2 mm margins. I would say a truebeam doing frequent intra-fraction triggered kV imaging with fiducials is analogous to EM beacons or cyberknife tracking.
 
Chartreuse Wombat said:
Last sentence is proton speak DVH idolatry. NTCP curves have threshold.
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Disagree in part - proton DVH idolatry is invalid because what the computer screen shows is NOT what the patient is getting. With photons we can have similar confidence across the arms regardless of whether the IGRT is CT based or MR based.

However, whether any differences in OARs are sufficient to make changes in toxicity are an open question. They show that with the new tech and decreased margins, there is a benefit in terms of acute GU toxicity. We all accept higher acute rates of toxicity (although primarily GI) by doing mod hypo vs conventional, so I don't foresee MRI-linac becoming THE SOC for prostate SBRT simply because patients require less Flomax.

Long-term results on potential benefits to LATE toxicity will be of significant value.

All those talking about OTHER ways to do 2mm margins... are you treating with 2mm margins routinely? I can comfortably say that I'm not. Because if a patient developed a local recurrence with a 2mm margin I would be devastated. Some consider a 3mm margin posteriorly to be infaust as well. So, for people who say 2mm on CBCT is just as good, then go ahead and run the trial of CBCT based RT with 2 vs 4 or whatever margins and publish. It's very easy to criticize research and say it's useless and then not do any of your own.

Still a higher evidence basis for MR-Linac for prostate SBRT than for protons for prostate. Let that sink in.

Rad Oncs - continuing to be their own worst enemies.
 
evilbooyaa said:
Disagree in part - proton DVH idolatry is invalid because what the computer screen shows is NOT what the patient is getting. With photons we can have similar confidence across the arms regardless of whether the IGRT is CT based or MR based.

However, whether any differences in OARs are sufficient to make changes in toxicity are an open question. They show that with the new tech and decreased margins, there is a benefit in terms of acute GU toxicity. We all accept higher acute rates of toxicity (although primarily GI) by doing mod hypo vs conventional, so I don't foresee MRI-linac becoming THE SOC for prostate SBRT simply because patients require less Flomax.

Long-term results on potential benefits to LATE toxicity will be of significant value.

All those talking about OTHER ways to do 2mm margins... are you treating with 2mm margins routinely? I can comfortably say that I'm not. Because if a patient developed a local recurrence with a 2mm margin I would be devastated. Some consider a 3mm margin posteriorly to be infaust as well. So, for people who say 2mm on CBCT is just as good, then go ahead and run the trial of CBCT based RT with 2 vs 4 or whatever margins and publish. It's very easy to criticize research and say it's useless and then not do any of your own.

Still a higher evidence basis for MR-Linac for prostate SBRT than for protons for prostate. Let that sink in.

Rad Oncs - continuing to be their own worst enemies.
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At 3mm margins posteriorly the rate of GI SEs is low enough that going to 2mm might just be gilding the lily.
 
NotMattSpraker said:
Fascinating convo there on the X.

I think a lot of people are not fully understanding the wombat excerpt.
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I am not on X but it wouldn't be the first time I have been misinterpreted. I think the statement that the margins in clinical revenue have fallen over thirty years is inarguable.
 
Chartreuse Wombat said:
I am not on X but it wouldn't be the first time I have been misinterpreted. I think the statement that the margins in clinical revenue have fallen over thirty years is inarguable.
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You were quite clear, and I agree with what you said.

Some people just don't thoroughly understand what you mean when you say "it depends on the chair" and I thought it came through in that convo on X.

A lot of academic cancer centers remain very well funded despite hypofractionation. They would remain so under ROCR or whatever proposal gets pooped out our "policy efforts" these days.

Rad Onc isnt an independent entity inside that center. The rules that govern cancer centers aren't natural laws... whether someone can "afford" a fairly paid physician scientist, how much time they are in clinic, etc... those things are decided, often by chairs. So on and so forth.
 
evilbooyaa said:
Having evaluated adaptive RT on Ethos on prostate - the juice is not worth the squeeze (IMO) in vast majority of patients. There is a tiny dosimetric benefit that is unlikely to ever pan out into an actual clinical toxicity benefit.
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The idea of adapting for 15 - 20 minutes because a patient has a huge deuce in his rectum; rather than just having him go take a dump...

Or maybe adapting due to a gas bubble and as soon as you get done and ready to treat... you hear the patient rip a huge fart.

Bladder not full? We should be ready in 15 minutes or so.......... New CBCT; Damn! Looks like it filled up; I guess we adapt again?

Somewhat facetious.... somewhat not. Maybe once its nearly instant; but I'm having trouble buying in now.

Although the idea of quickly contouring; planning and delivering fractions all in one sitting (and not needing much dosimetry support) is where I see the Ethos making the biggest actual impact; which would be more logistical rather than clinical.
 
Maybe the next phase we need is for an AI generated plan or machine that can adapt to changes instantly without the need for recontouring or reimaging.

The workflow (and price) of an MRI linac was never going to make it into to 95% of rad onc departments and similar to protons was a way for places to claim they have the most modern and the best technology.

Although I believe better imaging and more time spent on each patient could (possibly) lead to better outcomes, it just wasn’t practical. As stated above, we already have a lot of tools and techniques we use daily that can help provide similar outcomes without all of the disruption.

It’s time to move on to something that not only helps patients but providers.
 
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RadOncDoc21 said:
Maybe the next phase we need is for an AI generated plan or machine that can adapt to changes instantly without the need for recontouring or reimaging.

The workflow (and price) of an MRI linac was never going to make it into to 95% of rad onc departments and similar to protons was a way for places to claim they have the most modern and the best technology.

Although I believe better imaging and more time spent on each patient could (possibly) lead to better outcomes, it just wasn’t practical. As stated above, we already have a lot of tools and techniques we use daily that can help provide similar outcomes without all of the disruption.

It’s time to move on to something that not only helps patients but providers.
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I can’t speak to a ViewRay but the Unity for prostate specifically is much faster than people think. The 2 min T2 scan is more than sufficient. When I adapt, get the first scan, autocontour most of the structures, then the adapted plan takes about 5 min to optimize. Acquire next scan while plan is running. Patient time in room with full adaptation is about 25 min.

The other meet little trick is each patient is their own structure library. If fx 3 looks more like 2 than 1, can start with fx 2 as the baseline plan. Can keep from needing to actually adapt if you have a plan that is close enough. As folks have said, perfection and adaptation are mutually exclusive. Spend forever getting it just right and take a guess what the verification image will show you.

Again, that’s prostate. My panc plans where I have to do more manual contouring and the optimizer has many more structures to balance…very different beast.

Work flow is a problem, but for pelvic sites, it’s actually a lot better than people think. Wouldn’t buy one of these for pelvic diseases, but if your department has one, it’s really not a hassle to use for this indication.
 
ramsesthenice said:
I can’t speak to a ViewRay but the Unity for prostate specifically is much faster than people think. The 2 min T2 scan is more than sufficient. When I adapt, get the first scan, autocontour most of the structures, then the adapted plan takes about 5 min to optimize. Acquire next scan while plan is running. Patient time in room with full adaptation is about 25 min.

The other meet little trick is each patient is their own structure library. If fx 3 looks more like 2 than 1, can start with fx 2 as the baseline plan. Can keep from needing to actually adapt if you have a plan that is close enough. As folks have said, perfection and adaptation are mutually exclusive. Spend forever getting it just right and take a guess what the verification image will show you.

Again, that’s prostate. My panc plans where I have to do more manual contouring and the optimizer has many more structures to balance…very different beast.

Work flow is a problem, but for pelvic sites, it’s actually a lot better than people think. Wouldn’t buy one of these for pelvic diseases, but if your department has one, it’s really not a hassle to use for this indication.
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I think this is the first time I have ever quoted one of my own posts 🙂

But I did want to follow up. We have had an MR in our department for MR simulations for many years and had 4 MR certified RTTs before we even got an MR linac. And 3 physicists with MR-specific backgrounds. That makes for a very different learning curve than say a private practice with no/limited in house MR experience looking to get a competitive advantage on the regional proton center. If I regularly had to do more than confirm contours and approve a final plan for prostate treatments, I would despise that machine. Who you have running the machine matters a lot.
 
ramsesthenice said:
I think this is the first time I have ever quoted one of my own posts 🙂

But I did want to follow up. We have had an MR in our department for MR simulations for many years and had 4 MR certified RTTs before we even got an MR linac. And 3 physicists with MR-specific backgrounds. That makes for a very different learning curve than say a private practice with no/limited in house MR experience looking to get a competitive advantage on the regional proton center. If I regularly had to do more than confirm contours and approve a final plan for prostate treatments, I would despise that machine. Who you have running the machine matters a lot.
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And thus the “radiographer (aka therapist) run MRgRT programs” in the U.K. that were touted over last few years. Very hands off for the docs, like they weren’t even there.
 
TheWallnerus said:
And thus the “radiographer (aka therapist) run MRgRT programs” in the U.K. that were touted over last few years. Very hands off for the docs, like they weren’t even there.
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100%. Nothing specific to MRgRT here. Can't be 2 places at once. Im going to take a wild guess that I am not the only one who is already a bit overloaded with clinical work.
 
TheWallnerus said:
And thus the “radiographer (aka therapist) run MRgRT programs” in the U.K. that were touted over last few years. Very hands off for the docs, like they weren’t even there.
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Not just like... the docs weren't even there. They had more important things to do, such as writing the next trial to reduce fractions or eliminate RT altogether.
 
TheWallnerus said:
4mm margins & recurrence, you all good 🙂

Wonder how Amar feels when he sees a recurrence w/ 2mm margins


Man that's my word
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5mm in non-posterior dimensions, 3mm posteriorly

Haven't personally had a prostate SBRT patient fail yet, but I know it's a matter of time.

And have pride that I probably know 'infaust' because of you

dieABRdie said:
The idea of adapting for 15 - 20 minutes because a patient has a huge deuce in his rectum; rather than just having him go take a dump...

Or maybe adapting due to a gas bubble and as soon as you get done and ready to treat... you hear the patient rip a huge fart.

Bladder not full? We should be ready in 15 minutes or so.......... New CBCT; Damn! Looks like it filled up; I guess we adapt again?

Somewhat facetious.... somewhat not. Maybe once its nearly instant; but I'm having trouble buying in now.

Although the idea of quickly contouring; planning and delivering fractions all in one sitting (and not needing much dosimetry support) is where I see the Ethos making the biggest actual impact; which would be more logistical rather than clinical.
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Have you done an adaptive case on Ethos?

Some scenarios are easy to fix. What if the patient with big deuce can't empty? What if patient can't fill his bladder similarly at end of RT because of acute urinary frequency/urgency from RT?

Again, I agree that prostate is not where the real clinical benefit will be. But, those are the ongoing trials funded by Varian that are going to be the easiest to accrue.
 
If every MRIdian site would pay MRIdian an FTE radonc stipend (stipend, fee, subscription, whatever) per year, they could have kept the company afloat. If I’m ViewRay, I would have pitched this to each site. If you want this tech, and you think it’s so great, you need to really put money where mouth is sometimes.
 
TheWallnerus said:
If every MRIdian site would pay MRIdian an FTE radonc stipend (stipend, fee, subscription, whatever) per year, they could have kept the company afloat. If I’m ViewRay, I would have pitched this to each site. If you want this tech, and you think it’s so great, you need to really put money where mouth is sometimes.
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So because viewray couldn't get a CPT code it's the customers fault?

Honestly, both are at fault here and hopefully both sides take something away from this saga for the next time.... No one will trust new tech again the same way unless Medicare recognizes its value.

Prob better that way anyways... Don't need any more data-free proton boondoggles happening
 
TheWallnerus said:
If every MRIdian site would pay MRIdian an FTE radonc stipend (stipend, fee, subscription, whatever) per year, they could have kept the company afloat. If I’m ViewRay, I would have pitched this to each site. If you want this tech, and you think it’s so great, you need to really put money where mouth is sometimes.
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medgator said:
So because viewray couldn't get a CPT code it's the customers fault?

Honestly, both are at fault here and hopefully both sides take something away from this saga for the next time.... No one will trust new tech again the same way unless Medicare recognizes its value.

Prob better that way anyways... Don't need any more data-free proton boondoggles happening
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I don't think that's what he was saying -

Now, @TheWallnerus can correct me if I'm wrong, but I believe that if you took every department that had a Viewray machine, which was what, 50-55?

So you have those 50-55 sites each just pay the equivalent of a 1.0 FTE RadOnc physician salary/compensation package, that would have been enough money to get them out of bankruptcy.

With these high CapEx ventures, which basically every company selling a radiation machine is, you are banking on the service contract as your LTV because you only sell a machine to a department once every 10-15 years if you're lucky.

I don't know what the service contract with Viewray was (and obviously it was not enough), but rather than hoping angels would swoop in during Chapter 11 and save the company, an alternative strategy would have been to have each existing site pay the equivalent of a 1.0 RadOnc package.

Then, the company wouldn't have died, and really, on an institutional level, that would have been a drop in the bucket investment for each site that was able to pay for a machine and keep it going.

Basically - these letters and social media posts are nice, but words ain't cash.
 
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