Cancer Center Advertising - one center spent over $100M

[SneakyBooger]

From Lancet Oncology: https://www.thelancet.com/journals/lanonc/article/PIIS1470-2045(19)30316-X/fulltext

"The 50th hospital spent $106 300, the average hospital spent $3 064 600, and the top advertising spender—Cancer Treatment Centers of America—spent more than the other 49 hospitals combined, totalling $101 740 900"

"Some hospitals in our sample with excellent outcomes did not have particularly high advertising spending, and the highest-spending set of hospitals—operating as Cancer Treatment Centers of America—had poorer patient outcomes than all other hospitals in our sample."

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Members don't see this ad.

 

[medgator]

Advertising organization files complaint against CTCA

The Truth In Advertising organization, or TINA, has filed a complaint against Cancer Treatment Centers of America.

times-herald.com

Special Report: Behind a cancer-treatment firm's rosy survival claims

When the local doctor who had been treating Vicky Hilborn told her that her rare cancer had spread throughout her body, including her brain, she and her husband refused to accept a death sentence. Within days, Keith Hilborn was on the phone with an "oncology information specialist" at Cancer...

www.reuters.com

 

[scarbrtj]

Gil Lederman (I think it’s Gil; it’s NYU Langone) has an ad in the New Yorker at least once a month for prostate SBRT. Makes it sound wonderful, preferred over surgery. Dishonest? Not really. Something that exposes you to criticism perchance? Yes. Something that brings in a lot of new patients for your center at the expense of other centers? Probably. All of MD Anderson’s ads say with a double entendre they’re "Making Cancer History"... hopeful, and about 0% likely.

 

[medgator]

Gil Lederman (I think it’s Gil; it’s NYU Langone) has an ad in the New Yorker at least once a month for prostate SBRT. Makes it sound wonderful, preferred over surgery. Dishonest? Not really. Something that exposes you to criticism perchance? Yes. Something that brings in a lot of new patients for your center at the expense of other centers? Probably. All of MD Anderson’s ads say with a double entendre they’re "Making Cancer History"... hopeful, and about 0% likely.

Who could forget Gil...

Gil Lederman's Dubious Career - Nymag

When the notorious cancer doctor Gil Lederman cadged an autograph from a dying George Harrison, the world was appalled.But as Lederman scrambles to salvage his reputation, the very nature of his experimental practice has come under attack.

nymag.com

Former Beatle doc, who ran controversial SIUH cancer program, agrees to pay $2.35 million settlement in Medicare fraud case

Dr. Gil Lederman settled a lawsuit initially filed in 2004 by the widow of a former SIUH cancer patient. The government joined the suit in 2008.

www.silive.com

 

[scarbrtj]

Who could forget Gil...

Gil Lederman's Dubious Career - Nymag

When the notorious cancer doctor Gil Lederman cadged an autograph from a dying George Harrison, the world was appalled.But as Lederman scrambles to salvage his reputation, the very nature of his experimental practice has come under attack.

nymag.com

Former Beatle doc, who ran controversial SIUH cancer program, agrees to pay $2.35 million settlement in Medicare fraud case

Dr. Gil Lederman settled a lawsuit initially filed in 2004 by the widow of a former SIUH cancer patient. The government joined the suit in 2008.

www.silive.com

I'll say this about him. He was the first routine SBRT'er in the United States going all the way back to the late 90's. At the time when he was doing SBRT on lung ("stereotactic *body* radiation therapy can't exist," "he's not doing stereotactic" etc) nodules and various mets in the body, people DRAGGED him, called him a huckster, a quack, stupid, etc. And he's still practicing the same way 20 years later while all the rest of rad onc has changed.

From that article, from 2004, which I think would be written completely differently today:
Depending on your point of view, when it comes to new technologies, Lederman is either a forward-thinking early adopter or unacceptably reckless. In 1996, he learned that at Sweden’s Karolinska Institute, where radiosurgery had been invented decades before, two doctors had published preliminary results of a trial in which they used the same treatment on tumors below the neck. It was a controversial procedure because the body could not be stabilized as well as the brain: Organs move around, as much as a centimeter even in a restful state; the brain stays put. But the Swedes had received FDA approval for a device that they claimed stabilized the body enough to make radiosurgery both safe and effective. While many doctors weren’t yet convinced, Lederman, who had been performing brain radiosurgery for years, believed it would work on the body as well. He called Varone from Sweden to tell him about the revolutionary new treatment. Within two months, before there had been any independent scientific studies, Lederman became the first doctor in the United States to offer body radiosurgery.

 

[medgator]

I'll say this about him. He was the first routine SBRT'er in the United States going all the way back to the late 90's. At the time when he was doing SBRT on lung ("stereotactic *body* radiation therapy can't exist," "he's not doing stereotactic" etc) nodules and various mets in the body, people DRAGGED him, called him a huckster, a quack, stupid, etc. And he's still practicing the same way 20 years later while all the rest of rad onc has changed.

From that article, from 2004, which I think would be written completely differently today:
Depending on your point of view, when it comes to new technologies, Lederman is either a forward-thinking early adopter or unacceptably reckless. In 1996, he learned that at Sweden’s Karolinska Institute, where radiosurgery had been invented decades before, two doctors had published preliminary results of a trial in which they used the same treatment on tumors below the neck. It was a controversial procedure because the body could not be stabilized as well as the brain: Organs move around, as much as a centimeter even in a restful state; the brain stays put. But the Swedes had received FDA approval for a device that they claimed stabilized the body enough to make radiosurgery both safe and effective. While many doctors weren’t yet convinced, Lederman, who had been performing brain radiosurgery for years, believed it would work on the body as well. He called Varone from Sweden to tell him about the revolutionary new treatment. Within two months, before there had been any independent scientific studies, Lederman became the first doctor in the United States to offer body radiosurgery.

He also curiously avoids using cone beam CT and actually advertises that fact as a plus, obviously since it wasn't around when he started....

Cancer Treatment Center NY - Radiosurgery New York

Cancer treatment center NY, Radiosurgery New York, cancer center, performing stereotactic radiosurgery, fractionated body radiosurgery and radiation treatments for prostate cancer, acoustic neuromas

rsny.org

"Dr. Lederman has shown generally excellent results and highly accurate and focused stereotactic radiosurgery while AVOIDING the potentially dangerous and unneeded daily CT scans that are performed in other centers. By avoiding the daily CT scans that are commonly performed elsewhere, Dr. Lederman’s technology helps minimize the radiation exposure to healthy tissues that may led to serious side effects in the future."

 

[Pointless]

He also curiously avoids using cone beam CT and actually advertises that fact as a plus, obviously since it wasn't around when he started....

Cancer Treatment Center NY - Radiosurgery New York

Cancer treatment center NY, Radiosurgery New York, cancer center, performing stereotactic radiosurgery, fractionated body radiosurgery and radiation treatments for prostate cancer, acoustic neuromas

rsny.org

"Dr. Lederman has shown generally excellent results and highly accurate and focused stereotactic radiosurgery while AVOIDING the potentially dangerous and unneeded daily CT scans that are performed in other centers. By avoiding the daily CT scans that are commonly performed elsewhere, Dr. Lederman’s technology helps minimize the radiation exposure to healthy tissues that may led to serious side effects in the future."

This is all bad.... so bad.

 

[scarbrtj]

He also curiously avoids using cone beam CT and actually advertises that fact as a plus, obviously since it wasn't around when he started....

He's a CyberKnifer, a stereoscopic kV X-rayer. Of course, the CKers say this is perhaps superior because as opposed to static point-in-time CBCT, the kV X-raying is multi-point-in-time, semi-continuous.

 

[medgator]

He's a CyberKnifer, a stereoscopic kV X-rayer. Of course, the CKers say this is perhaps superior because as opposed to static point-in-time CBCT, the kV X-raying is multi-point-in-time, semi-continuous.

And uses fiducials or tracking instead of actually visualizing the target by the physician....

 

[scarbrtj]

And uses fiducials or tracking instead of actually visualizing the target by the physician....

Devils advocate: The vast majority of patients *who get CBCT* never have their target verified by the physician pre-treatment of course. Automated matching versus human matching is probably more accurate with less random error anyways.

 

[medgator]

Devils advocate: The vast majority of patients *who get CBCT* never have their target verified by the physician pre-treatment of course. Automated matching versus human matching is probably more accurate with less random error anyways.

Really? I personally review all cbct prior to tx delivery, esp in stereo cases, which is what Gils claim to fame is

 

[scarbrtj]

Really? I personally review all cbct prior to tx delivery, esp in stereo cases, which is what Gils claim to fame is

I think it's fine to stand at the machine all day for all the CBCTs prior to every fraction, although it's not a billing requirement or standard of care; I don't think it improves patient care. I'm sure Gil checks imaging prior to all SBRTs though. There is no evidence that CBCT use improves SBRT outcomes; specifically, no evidence that CyberKnife SBRT outcomes are inferior.

 

[medgator]

I think it's fine to stand at the machine all day for all the CBCTs prior to every fraction, although it's not a billing requirement or standard of care; I don't think it improves patient care. I'm sure Gil checks imaging prior to all SBRTs though. There is no evidence that CBCT use improves SBRT outcomes; specifically, no evidence that CyberKnife SBRT outcomes are inferior.

Fair point, but there is no real data supporting the assertion on gils website either regarding the dangers of the dose from a cbct in what is (mostly) an elderly population that is being treated with SBRT.

Plus Gil has gotten in trouble for saying/advertising things before.

"Legally", rad oncs in hospitals can probably use NPs to cover. Realistically, I've never seen that happen

 

[scarbrtj]

Plus Gil has gotten in trouble for saying/advertising things before.

One of the things clinically/scientifically I remember him getting in the most trouble for: he could cure some people with mets.
If Gil says it in 2000, he's a quack. (And I thought he was a quack.) If Sam Hellman says it in 2013, a new era has dawned.

 

[medgator]

One of the things clinically/scientifically I remember him getting in the most trouble for: he could cure some people with mets.
If Gil says it in 2000, he's a quack. (And I thought he was a quack.) If Sam Hellman says it in 2013, a new era has dawned.

Touting high cure rates of the primary in metastasized cancers is still quackery in 2019...

Gil Lederman's Dubious Career - Nymag

When the notorious cancer doctor Gil Lederman cadged an autograph from a dying George Harrison, the world was appalled.But as Lederman scrambles to salvage his reputation, the very nature of his experimental practice has come under attack.

nymag.com

The details Lederman omitted are significant. Take the claim of 94 percent successful control of primary pancreatic cancer. The statistic comes from an abstract that Lederman published in 2000 about 45 patients he treated for the disease. Curiously, only 17 were evaluated for the study; it was 94 percent of that much smaller group whose cancers were controlled. What happened to the other 28 patients? “Not every patient would agree to send films,” Lederman explains. And when patients die? “If they die, then they don’t send in films,” he says, though he claims that it isn’t only the patients with good results who follow up.

“This is retrospective review,” says Robert Timmerman, a professor of radiation oncology at the University of Texas–Southwestern Medical School who is currently conducting a study of stereotactic radiation therapy for lung and liver cancer. “Retrospective data analysis results in claims of control and survival that have shown to be very different from reality. It’s just so flawed that it’s almost not worth doing.” And what does “control” of pancreatic cancer mean, anyway? “Local control is one thing,” says Albert Koong, a Stanford radiation oncologist who recently published the results of his study on treating pancreatic cancer with stereotactic radiosurgery. “But if you have patients who’ve had the disease spread outside the primary tumor, what’s the point? It’s like slamming the barn door shut after the horse has run out. You can control the tumor locally, but that’s not what’s going to kill you. What’s going to kill you is the metastases, and that’s clearly the role of chemotherapy.”

 

[xrthopeful]

I think it's fine to stand at the machine all day for all the CBCTs prior to every fraction, although it's not a billing requirement or standard of care; I don't think it improves patient care. I'm sure Gil checks imaging prior to all SBRTs though. There is no evidence that CBCT use improves SBRT outcomes; specifically, no evidence that CyberKnife SBRT outcomes are inferior.

You don’t think that going to the machine to look at a cone beam prior to every fraction of SBRT is the standard of care? I would bet that more than 90 percent of rad oncs who do SBRT use on board imaging and review for each fraction. I don’t think this is controversial. Am I wrong?

 

[scarbrtj]

You don’t think that going to the machine to look at a cone beam prior to every fraction of SBRT is the standard of care? I would bet that more than 90 percent of rad oncs who do SBRT use on board imaging and review for each fraction. I don’t think this is controversial. Am I wrong?

Well as phrased no, looking at a cone beam prior to every SBRT is not the standard of care

 

[Neuronix]

You don’t think that going to the machine to look at a cone beam prior to every fraction of SBRT is the standard of care? I would bet that more than 90 percent of rad oncs who do SBRT use on board imaging and review for each fraction. I don’t think this is controversial. Am I wrong?

At every place I have ever trained, worked, and moonlit a physician was required to verify the imaging pre-treatment for SBRT cases and to document that fact.

And uses fiducials or tracking instead of actually visualizing the target by the physician....

This is reasonable depending on disease site in my opinion. You can't always see the target on CBCT either given low contrast, CBCT artifacts, and questionable breathholding.

He's a CyberKnifer, a stereoscopic kV X-rayer. Of course, the CKers say this is perhaps superior because as opposed to static point-in-time CBCT, the kV X-raying is multi-point-in-time, semi-continuous.

Here I am with MRI-guidance, best of all worlds. Best visualization for setup, real-time image guidance, no added radiation.

 

[medgator]

This is reasonable depending on disease site in my opinion. You can't always see the target on CBCT either given low contrast, CBCT artifacts, and questionable breathholding.

I don't disagree, just pointing out the argument made by anti CK folks.

Here I am with MRI-guidance, best of all worlds. Best visualization for setup, real-time image guidance, no added radiation.

Ain't cheap . I think there will be a role for MRI linacs when the price becomes reasonable...

 

[seper]

I remember reading that very vivdly (was a resident in NYC, but still taken aback).

“I got the impression that if a stray dog had insurance, Lederman would treat it.”.

 

[xrthopeful]

At every place I have ever trained, worked, and moonlit a physician was required to verify the imaging pre-treatment for SBRT cases

Yep that’s what I thought

 

[evilbooyaa]

Devils advocate: The vast majority of patients *who get CBCT* never have their target verified by the physician pre-treatment of course. Automated matching versus human matching is probably more accurate with less random error anyways.

Not at all true for SBRT cases. I was under the impression this was a mandated requirement to bill something as SBRT for pre-treatment physician review. Maybe it's state by state.

EDIT: Nvm, didn't realize multiple people had jumped on that point already.

More On-topic: CTCA is welcome to blow their money on stupid crap as much as they wish, IMO.

The best don't need to advertise directly to patients - it's the pretenders or those that are doing experimental things that do need to advertise directly to patients.

 

[Neuronix]

The best don't need to advertise directly to patients - it's the pretenders or those that are doing experimental things that do need to advertise directly to patients.

I drive by ads for MD Anderson, MSKCC, and a few local cancer centers just on my drive in to work every day!

 

[xrthopeful]

MDACC especially is notorious for their advertisements. I've seen then in airports.

 

[medgator]

I drive by ads for MD Anderson, MSKCC, and a few local cancer centers just on my drive in to work every day!

Evil should have included local affiliates paying for the big name in that group

 

[evilbooyaa]

I drive by ads for MD Anderson, MSKCC, and a few local cancer centers just on my drive in to work every day!

Like MDACC mothership? Or the local place that has already paid to put the MDACC or MSKCC name. If the latter, then yeah, I'm not surprised. Had to buy a name to make them seem more legit anyways.

 

[RadOncDoc21]

Like MDACC mothership? Or the local place that has already paid to put the MDACC or MSKCC name. If the latter, then yeah, I'm not surprised. Had to buy a name to make them seem more legit anyways.

I would also have to add the former as to allow their “brand” to be marketed at a price. They can talk about quality and such but we all know the real deal!

 

[scarbrtj]

Not at all true for SBRT cases. I was under the impression this was a mandated requirement to bill something as SBRT for pre-treatment physician review. Maybe it's state by state.

EDIT: Nvm, didn't realize multiple people had jumped on that point already.

More On-topic: CTCA is welcome to blow their money on stupid crap as much as they wish, IMO.

The best don't need to advertise directly to patients - it's the pretenders or those that are doing experimental things that do need to advertise directly to patients.

don’t have to check a ****CBCT**** before SBRT, do have to get an image, do have to check there’s an image. blah blah blah

What defines "the best"? According to Steve Jobs "People don't know what they want until you show it to them." So that's what healthcare advertisers in general are doing: showing people what they don't know about. "And this thing you didn't know about: you NEED this." E.g., the Mayo Clinic is bombarding the airwaves that essentially they have the answers when other healthcare providers don't. All advertising is fundamentally dishonest (to a certain extent). Kraft Macaroni & Cheese says: "You know you love it." Mayo Clinic: you know where to go. You know. Actually I like to throw people for a loop this way when I feel they might try to disagree with me; I start my sentence with "As you know..."

 

[MegaVoltagePhoton]

“Can you BE any more pedantic?” - Chandler Bing’s take if scar could cameo on “Friends”

 

[thecarbonionangle]

Im curious about CTCA, what are they about? what is it like working for them?

 

[medgator]

Im curious about CTCA, what are they about? what is it like working for them?

Don't know anyone who's worked for them, but as this thread states, they advertise heavily and are for profit, founded by a former investment banker with a libertarian bent and a love of alternative therapies in addition to allopathic treatment

Making a Profit from Offering Ineffective Therapies to Cancer Patients

A chain of for-profit cancer hospitals profit from offering unscientific treatments alongside conventional therapy. The hospitals were founded by secretive businessman Richard Stephenson, a major supporter of right wing and Tea Party political candidates.

www.forbes.com

 

[seper]

I've never worked for them, but I am in an area where one of their centers is located. Some of my patients have gone there for a second opinion, some stayed and gotten treated, some returned to me. I've read their consult notes and treatment records. CTCA is geared towards the maximal utilization of chemotherapy and radiotherapy. For example, a stage IV endometrial Ca patient was offered (in writing) immediate start of triple-agent chemo followed by SBRT to the uterus on day#5 the cycle.

Im curious about CTCA, what are they about? what is it like working for them?

 

[scarbrtj]

“Can you BE any more pedantic?” - Chandler Bing’s take if scar could cameo on “Friends”

Heh. Let me see how to reply to that. As when Cardinal Wolsey told Thomas More “you were a fool for opposing me on the council today” and More retorted “Thank God I am the only fool on the council”... Thank God I am the only pedant in radiation oncology.

 

[thecarbonionangle]

I've never worked for them, but I am in an area where one of their centers is located. Some of my patients have gone there for a second opinion, some stayed and gotten treated, some returned to me. I've read their consult notes and treatment records. CTCA is geared towards the maximal utilization of chemotherapy and radiotherapy. For example, a stage IV endometrial Ca patient was offered (in writing) immediate start of triple-agent chemo followed by SBRT to the uterus on day#5 the cycle.

When would you treat the primary in a metastatic endometrial pt?

 

[medgator]

When would you treat the primary in a metastatic endometrial pt?

If Symptomatic. And probably not with SBRT.....

 

[OTN]

If Symptomatic. And probably not with SBRT.....

Medgator: If symptomatic, and probably not with SBRT
CTCA: If the payer will cover it or if the patient can self-pay

 

[evilbooyaa]

I've never worked for them, but I am in an area where one of their centers is located. Some of my patients have gone there for a second opinion, some stayed and gotten treated, some returned to me. I've read their consult notes and treatment records. CTCA is geared towards the maximal utilization of chemotherapy and radiotherapy. For example, a stage IV endometrial Ca patient was offered (in writing) immediate start of triple-agent chemo followed by SBRT to the uterus on day#5 the cycle.

Lmao. We do some off the wall stuff but wowza.

Triple agent chemotherapy? Carbo/Taxol and a sprinkle of what exactly

 

[Mandelin Rain]

Lmao. We do some off the wall stuff but wowza.

Triple agent chemotherapy? Carbo/Taxol and a sprinkle of what exactly

Chaga

 

[medgator]

Exposure to direct-to-consumer advertising is associated with overestimation of benefits regarding ultrahypofractionated radiation therapy for prostate cancer

I guess all those CK and proton ads worked over the years...

 

[KHE88]

When would you treat the primary in a metastatic endometrial pt?

I mean, if your goal is to eliminate the primary, it sucks we are stuck with frying everything nearby to get an ablative dose of radiation in and turn the uterus into a big ball of scars.
If only there were an easy way to, like, make it so the uterus was not there anymore. SBRT it is... Prob best to stage it and treat the uterus in thirds sequentially. 5 fx at a time, naturally.

 

[beamseyeview]

Exposure to direct-to-consumer advertising is associated with overestimation of benefits regarding ultrahypofractionated radiation therapy for prostate cancer

I guess all those CK and proton ads worked over the years...

Meh. I'm not sure what this study really adds

If you look at the images that they used for the different groups, it's pretty obvious that anyone in group 2 would be more hesitant to get Cyberknife than groups 3 and 4

 

[IonsAreOurFuture]

At every place I have ever trained, worked, and moonlit a physician was required to verify the imaging pre-treatment for SBRT cases and to document that fact.



This is reasonable depending on disease site in my opinion. You can't always see the target on CBCT either given low contrast, CBCT artifacts, and questionable breathholding.



Here I am with MRI-guidance, best of all worlds. Best visualization for setup, real-time image guidance, no added radiation.

MRI sounds very interesting. How long does acquiring the MRI for IGRT take? Is it real-time feedback, or some latency built in? Do you see any changes in an SBRT tumor during the course of therapy (edema etc)? Thanks.

 

[OTN]

Currently $8M for an MRI-based linac, so unless the prices comes down it will only be feasible for those with access to hospital-based or NCI-exempt billing.

 

[medgator]

Currently $8M for an MRI-based linac, so unless the prices comes down it will only be feasible for those with access to hospital-based or NCI-exempt billing.

Still more accessible than protons. Slightly more useful hopefully

 

[Neuronix]

MRI sounds very interesting. How long does acquiring the MRI for IGRT take? Is it real-time feedback, or some latency built in? Do you see any changes in an SBRT tumor during the course of therapy (edema etc)? Thanks.

The way the Viewray system is currently configured for patient setup before beam-on, scans can be obtained ranging from ~20 seconds to several minutes. For breath hold it's usually ~25 seconds. For non-moving targets I typically use 2-3 minute setup scans. These appear on the screen immediately after acquisition.

During treatment it typically obtains a single slice 4 times per second in the sup-inf direction to catch respiratory motion. There are some other parameters you can play with, but this is the best quality imaging I've found during treatment on that device. Each image goes through deformable co-registration with the last image to track the target in near real-time in relationship to a pre-defined gating boundary window. My understanding is that the delay from acquisition to gate on or gate off is ~250 msec.

Yes I do see changes during a course of RT. We have a few papers published on this topic and some more in review. The changes you see are disease site specific, obviously. Abdominal structures have a lot of anatomy changes. Post-op cavities can have fluid changes. Tumors can shrink or grow. Since you asked specifically about edema, you can see brain edema on the device for example.

Still more accessible than protons. Slightly more useful hopefully

Protons are so incredibly expensive that I don't know how anyone can make a cost-effectiveness argument for protons vs. MRI-linac. If you're comparing a $3 million Truebeam to a $8 million MRI-linac, the benefits required on the MRI-linac to justify the added cost are much smaller than the benefits required to justify a $3 million Truebeam compared to a $30 million single gantry proton unit.

 

[scarbrtj]

During treatment it typically obtains a single slice 4 times per second in the sup-inf direction to catch respiratory motion.

Seems like you might be the guy who would know the answer to this question. It's not that easy to describe, but let me try...
Imagine you have a video camera with an HDMI out. Now imagine you have small LCD monitor to watch the HDMI feed from this camera. Often times, when I am working with external monitors, there will be a 1-2s lag from "real life" to what I see in the monitor. You can only know this, of course, because your eyeballs can see real life and the monitor at the same time to know there's video lag. Of course, your eyeballs can't see a lung tumor or liver tumor in real life. I am sure there's a lag in "MRI video" too.

I have seen no one talk about the lag time between real life and what folks see on the "real time" MRI monitor. (I don't even know how this could be measured except with some indepth phantom studies; have they been done?) The thing is, real life will always be ahead of the monitor (monitors don't show the present or future, only the past). This would be like if I had a video scope on a rifle and trying to hit a moving target; with even a 100ms lag, depending on target speed, the targeting can be off. Now what I have seen is the MRI targeters trying to aim for "moments of stillness." Me, I would build in one second of stillness pause to beam-on and only allow maybe one second of beam-on after that well before I "see" the target move again. I wouldn't wait up until the very instant that target migrated out of the targeting zone; again, because of "video lag" it could have left well before it "appeared" to leave. You also mention a 4-frames-per-second video rate for the MRI. In other words, the best spatial resolution it could ever have is 250ms.

So the question is this: are we... the med physicsts and rad onc targeters... cognizant of the "video lag" in these devices and aware of the limitations a 250ms max temporal resolution can provide?

 

[Neuronix]

So the question is this: are we... the med physicsts and rad onc targeters... cognizant of the "video lag" in these devices and aware of the limitations a 250ms max temporal resolution can provide?

For a breath hold case, gate on delay is essentially negligible. If you're under a second late to a 20 second breath hold with beam on, who cares? it just makes the treatment a little longer.

For gate off, there might be some loss of your dose as the target moves out of the gating window (i.e. for a maximum inhalation case, as they exhale). This should be a very small amount of the dose in theory. I typically prescribe to PTV=GTV + 3 mm and then track the GTV and gate +/-3 mm (boundary = PTV) (different centers do this differently).

So in theory the tumor could move out of the high dose area before the machine beams off. But this would be a very small amount of time relative to overall treatment time. For example, if treatment is given in 20 second breath holds and there's a 250 ms delay in beam off, that's 1.25% of the overall treatment time or ~1.25% of the dose potentially missed by the tip of the GTV. Of course the dose does not go full dose to zero dose in no space as well, so that's likely an overestimate of the error. It's just not something that I consider a major concern in a breath hold case. Thus, I suspect that the error in dose delivery from the delay is very low, but I don't have anything to back that up. I'm sure that someone has published more specific answers and models to answer your question.

The delay would be more of a problem for a patient using gating with a large respiratory excursion in a patient who won't hold their breath and with a small gating window. We try not to do that in part for the reason we're discussing, and also these treatments would become very long because of duty cycle (fraction of time beam is on over total time on table).

I don't have a ready reference looking at this issue of dose smearing due to processing delay, but I bet someone has looked at it. This is not entirely a new discussion, Cyberknife also tracked respiratory motion with Calypso. People are working on MRI-linacs tracking the target with the MLCs instead of gating.

 

[scarbrtj]

For a breath hold case, gate on delay is essentially negligible. If you're under a second late to a 20 second breath hold with beam on, who cares? it just makes the treatment a little longer.

For gate off, there might be some loss of your dose as the target moves out of the gating window (i.e. for a maximum inhalation case, as they exhale). This should be a very small amount of the dose in theory. I typically prescribe to PTV=GTV + 3 mm and then track the GTV and gate +/-3 mm (boundary = PTV) (different centers do this differently).

So in theory the tumor could move out of the high dose area before the machine beams off. But this would be a very small amount of time relative to overall treatment time. For example, if treatment is given in 20 second breath holds and there's a 250 ms delay in beam off, that's 1.25% of the overall treatment time or ~1.25% of the dose potentially missed by the tip of the GTV. Of course the dose does not go full dose to zero dose in no space as well, so that's likely an overestimate of the error. It's just not something that I consider a major concern in a breath hold case. Thus, I suspect that the error in dose delivery from the delay is very low, but I don't have anything to back that up. I'm sure that someone has published more specific answers and models to answer your question.

The delay would be more of a problem for a patient using gating with a large respiratory excursion in a patient who won't hold their breath and with a small gating window. We try not to do that in part for the reason we're discussing, and also these treatments would become very long because of duty cycle (fraction of time beam is on over total time on table).

I don't have a ready reference looking at this issue of dose smearing due to processing delay, but I bet someone has looked at it. This is not entirely a new discussion, Cyberknife also tracked respiratory motion with Calypso. People are working on MRI-linacs tracking the target with the MLCs instead of gating.

Thanks neuronix. The beam on/off lag and "dose smearing" from frame rates etc... these are whole other bailiwicks. Maybe important but not what niggles me. Just talking the imaging or "WYSIWIG" lag, if you will. I have seen some of these videos where the target pops in the circle for two seconds, then out, and there was beam on during that time. I mean I'm pretty sure there's not a 1s or more delay between "real life" and what we see on screen; but in an instance like this a ~1s lag would be infaust. When I Google "real time MRI lag" best as I can tell the best-achievable lag is in the 0.2-0.3s neighborhood. Not a "killer" but not ideal either IMHO. Complex electronics are finicky and I bet that value migrates around a bit. I am anal retentive enough I would try to make some MRI-able "test" before I used MRI linacs, or make the physicist do this as routine QA. For example, you could video this guy inside the MRI and determine the lag between the video (which should have <10ms "WYSIWIG lag" if you get the right setup) and the real-time MRI you're viewing on the viewscreen. (This would be a good resident project/ASTRO poster.) Beyond this, proof always in the clinical pudding. If there's some hint of decreased LC with MRI linacs, could be lag. If no hint, I'm an alarmist/it's a problem already handled.

 

[Neuronix]

Well at least today I learned the word infaust.

I'm pretty sure that this delay has been tested both by the manufacturer and by physics QA procedures in academics and published. I'm having a busy week and can't find links to prove it right now.