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Wow - so definitely this is a treatment that requires training and specialized equipment - not something that can simply be adapted to a linac.
www.ncbi.nlm.nih.gov
If it makes dollars, it'll make sense. (In America)There was quite a hype when Intrepid came out.
Some real world data however later on were less favorable and raised concerns on safety, for example:
Microvascular abnormalities and long-term efficacy after stereotactic radiotherapy under continued intravitreal anti-VEGF treatment for neovascular AMD - PMC
For treatment of neovascular age-related macular degeneration (nAMD), multiple intravitreal injections of drugs targeting vascular endothelial growth factors (VEGF) result in a high burden for patients and healthcare systems. Low-energy stereotactic ...
I have briefly worked with the device.
It‘s very elegant, but I personally do not think the treatment is going to establish itself.
Oh we totally get those referrals once in a while. We treat a few per year
There was quite a hype when Intrepid came out.
Some real world data however later on were less favorable and raised concerns on safety, for example:
Microvascular abnormalities and long-term efficacy after stereotactic radiotherapy under continued intravitreal anti-VEGF treatment for neovascular AMD - PMC
For treatment of neovascular age-related macular degeneration (nAMD), multiple intravitreal injections of drugs targeting vascular endothelial growth factors (VEGF) result in a high burden for patients and healthcare systems. Low-energy stereotactic ...
I have briefly worked with the device.
It‘s very elegant, but I personally do not think the treatment is going to establish itself.
I recall that the IRay system has a very sharp penumbra, it would be interesting to compare this to protons. The next issue is likely the Bragg Peak, the "target" in the eye is likely very flat.
actually as far as I understand, the study was done solely by opththamologists... after speaking with a fellow opththamologist (outside of the US) the burden is quite real... Pharma actually tries to develop drugs which can be administerd less frequently (e.g. bianually than monthly)...
This is not something to perform with a LINAC.
www.ncbi.nlm.nih.gov
Do you know how much this machine costs?This is not something to perform with a LINAC.
You are applying single-shot 16 Gy to a very delicate area.
Have a look at this article to understand more about the technique.
Assessment of targeting accuracy of a low-energy stereotactic radiosurgery treatment for age-related macular degeneration - PMC
Age-related macular degeneration (AMD), a leading cause of blindness in the United States, is a neovascular disease that may be controlled with radiation therapy. Early patient outcomes of external beam radiotherapy, however, have been mixed. ...
The radiosurgery system has a custom two-camera video imaging and tracking system that continuously monitors the positions of the fixture fiducials. For the initial alignment, the two fiducials on the stabilizer bar are used to bring the x-ray source into treatment position; the system has a mechanical targeting precision of approximately 200 μm. During treatment, the relative positions of all three fiducials are monitored in real time to calculate the gaze angle of the eye, the position of the eye relative to the starting position and the effective position of the treatment beam on the retina.
...
A prescribed absorbed dose of 16 Gy is delivered to a 4 mm diameter disc, which is the CTV, centered on the fovea.
...
The beams are 4 mm in diameter (90% isodose) at the location of the fovea. Each beam enters the globe through three distinct positions on the pars plana, at azimuthal angles of 150°, 180° and 210°, and converges on the CTV. These field orientations were selected so that the beams would avoid the lens, cornea and optic nerve
The penumbra is very steep, because the x-ray source is really very close to the eye.
"John! John! Come here quick! No, I don't care what you're doing, get into my office NOW! You're not gonna believe this!"This is not something to perform with a LINAC.
You are applying single-shot 16 Gy to a very delicate area.
Have a look at this article to understand more about the technique.
Assessment of targeting accuracy of a low-energy stereotactic radiosurgery treatment for age-related macular degeneration - PMC
Age-related macular degeneration (AMD), a leading cause of blindness in the United States, is a neovascular disease that may be controlled with radiation therapy. Early patient outcomes of external beam radiotherapy, however, have been mixed. ...
The radiosurgery system has a custom two-camera video imaging and tracking system that continuously monitors the positions of the fixture fiducials. For the initial alignment, the two fiducials on the stabilizer bar are used to bring the x-ray source into treatment position; the system has a mechanical targeting precision of approximately 200 μm. During treatment, the relative positions of all three fiducials are monitored in real time to calculate the gaze angle of the eye, the position of the eye relative to the starting position and the effective position of the treatment beam on the retina.
...
A prescribed absorbed dose of 16 Gy is delivered to a 4 mm diameter disc, which is the CTV, centered on the fovea.
...
The beams are 4 mm in diameter (90% isodose) at the location of the fovea. Each beam enters the globe through three distinct positions on the pars plana, at azimuthal angles of 150°, 180° and 210°, and converges on the CTV. These field orientations were selected so that the beams would avoid the lens, cornea and optic nerve
The penumbra is very steep, because the x-ray source is really very close to the eye.
This machine uses 100 kv X-rays. Is that below the threshold for rad onc involvement?
A SUSPICIOUS QUESTION BASED ON YOUR CHOSEN SCREENAME...
I have no idea.
It’s not like we treat the trigeminal nerve root with 60 Gy single fraction prescribed to 60% of maximum dose with < 5 mm distance to brainstem . . . oh wait
Somebody actually did try this already with other machines (thou not linac)
pubmed.ncbi.nlm.nih.gov
pubmed.ncbi.nlm.nih.gov
