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SBRT Cyberknife exploratory visit today
Today I explored cyberknife sbrt for unfavorable intermediate . The RO explained that the cyberknife provides real time imaging using xrays(about two a minute). The margins would be 0-3mm posterior and 5mm lateral and anterior. Four fiducials would be installed no spaceoar needed. 40 gray to the prostate and 36 gray to the margins. ROI could get 42 gray. 5 fractions. Urethral sparing technique can and that the updated models are more appropriate for other cancers.
be used in my case.
This RO has been administering cyberknife for 20 years. The facility has the G4 model. Since the G4 release there are the G5 M6 S7 models. The RO indicated that the G4 is appropriate for prostate cancer We talked a bit about mri linac and the RO commented that the mri linac is not constantly tracking motion and an image is only obtained prior to the fraction.
Doing a little research revealed that the S7 model is more efficient than previous models.
I understand that mri-linac uses 2mm margins. Does the RO have the ability to use larger margins if desired with mri linac?
Appreciate any comments re margins, real time imaging,etc.
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HugInterested in more discussions like this? Go to the Prostate Cancer Support Group.
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@erbill
I did not have cyberknife sbrt.
I had 30 rounds of proton radiation. I had 4 gold markers used to set up my treatment each time. And yes a couple of times adjustments had to be made on my simulation bed to re-align me. I had gas one time in rectum that was moving prostate around. I did have the Space Oar to move rectum away from prostate and drank water prior to treatments to move bladder away from prostate.
Regarding margins. Your R/O decides where your margins are. My R/O at UFHTPI has a physics department that assists with treatments set up and specific programming. My R/O stated he treats the entire prostate and margins. He explained that prostate cancer can be in areas at cellular level and those wanted to make sure he treats all prostate and margins.
The margins are set up by your R/O based on his or her findings, biopsies, MRIs, CTs, and as a safeguard.
How hard would it be for you to go to a facility that has the S7 model? If I had an option, I would go to a facility with the most upgraded and new type of radiation treatment possible if you are going to just consider cyberknife only.
Have you considered getting a second opinion on your diagnosis and treatment options? I chose UFHPTI as they had proton radiation and had the latest upgrades and newest proton equipment and gantries. I declined going to Mayo Jacksonville as only had photon (building new cancer center with proton and will open in 2026).
@erbill, our expert member is @bens1 so hopefully he will weigh in on the discussion. If not you can probably private message him directly.
I can tell you that all MRI linacs are not created equal and the best use real time constant MRI targeting to avoid peripheral tissue toxicity.
Phil
I had the mridian machine with 3 mm margins. The built-in MRI is the reason that the margins were able to be so small as everything is done in real time.
I have read that the Proton Therapy S7 machines use smaller margins than the older Proton Therapy machines but no Proton Therapy machine has real time built-in MRI at least not yet.
My side effects were minimal.
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1 ReactionI went to this RO based on experience level(20yrs cyberknife). The RO now only works part time with cyberknife in partnership with 5 other RO. This RO has other interest in derm
and palliative care i subsequently found out. This RO was a pioneer with cyberknife and does the dosimetery. physicist on board. I was disappointed to find out the physical machineG4 has not been updated but the RO said the software has been updated to S7 software. so who knows. I get it- go to center of excellence and very experienced. I got 2nd opinion at JH Dr Arvin George and validated get rap or rad. either one. I have heard only positiveness from proton rad patients.
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1 Reactionthanks bens1 .I did get your advice previously regarding mri linac in Florida. Thought I would listen to cyberknife and you can read more in response to jc76. The cyberknife imaging result looks similiar to mri. I just learned that the RO picks the margins with mri linac specifically. I thought it was always 2mm with mri linac. This cyberknife RO gave me two hours of time and answered all my questions.
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1 ReactionI think the institution has more sway with the RO’s that worked at the Orlando Cancer center, where I was treated, as I remember my RO saying that “they” just approved the 3 mm margins as I was about to be treated in 2023. I believe institutional “biases” do impact the information we receive including centers of excellence not just with margins but many decisions and recommendations.
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1 ReactionI mistyped. I meant 2 mm
i'm hearing that re mri linac devices. Today 'm going to a facility where the RO nurse has revealed that they have viewray mri linac but it is not used for prostate "adaptive" radiology.
I am going to explore HDR there as well as talk about the adapative mri linac radiology.
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1 Reaction@erbill
One reason I chose not to be treated at Moffitt was the particular RO had an attitude and said if I wanted to use the adaptive capability of the MRIdian, that I should go someplace else, so I did.
When I spoke to another RO at Weill Cornell, who also used the MRIdian, and told him the story, he said that RO’s should be able to use all the capabilities of the MRIdian even if the prostate does not move as much as other organs.
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2 Reactionsthe RO at moffit told me that their view Ray mri linac will be permanently taken out of service next week because they can no longer get it serviced.