I'm looking at 20 IMRT treatments from one of the above delivery mechanisms. Based on my limited understanding, MRIdian will track the position of the prostate in real time and stop the radiation if any movement of the prostate occurs. The Ethos benefit appears to be the ability of doctors to create a new treatment plan every day based on your anatomy that day.
A recent paper by Dr Kishan at UCLA documents the benefits in reduced side effects with MRIdian and is my preferred treatment option.
However, due to unsuccessful efforts (so far) to find affordable housing in LA for 5 weeks, I am looking at treatment options in the Boston area (have a place to stay). Dana Farber does have a MRIdian but do not utilize it for 20 treatment plans (I'm not eligible for 5 treatment SBRT on ViewRay due to toxicity to higher doses of radiation). Instead, Dana Farber would treat me on an Ethos machine by Varian.
To my layman mind, the MRIdian seems superior but am looking for any thoughts from those who are more familiar with both machines.
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Have you checked with MD Anderson. I had 28 sessions of IMRT four years ago, overseen by Dr Tang and it seems to have gone flawlessly. The tech team doing the procedure is probably as important as the equipment.
I've seen that some programs apply one of two different adaptive planning methods daily. UCLA & Cornell do not routinely apply adaptive planning. The A3i MRIdian significantly reduce the time it takes for online adaptive planning. UCLA upgrade will occur in early August. Automatic gating due to 2D displacement occurs in roughly 20% . Adaptive planning is required with 3D displacement which was seen in 6% of treatment sessions.
Thank you for the suggestion. Just called to check their rates and though it looks great, it is beyond what I can spend. I have spoken to a social worker at UCLA and have a couple of potential options that may work once I finalize treatment dates. In the meantime I'll keep looking.
I got my answers and, for me, MRIdian is the best option. The primary difference is that MRIdian allows the doctor to use smaller margins during treatment. And even though Ethos sets a new plan each day, there is still the risks of the prostate having slight movements during treatment, therefore the need for larger margins with Ethos.
My goal from the beginning is to give myself the best chance to minimize or even eliminate long term side effects. I'm going to be here for another 30 years (if not, it won't be because of PC) and will enjoy it both mentally and physically. I love dockam's QoL posts and I'm there in spirit with him. Particularly loved the Mary Poppins crosswalk musical. Hilarious!
Personally speaking, getting the fastest treatment is the highest priority. From initial PSA-too-high (at 25 ng/mL) circa Nov 2021, I was biopsied, scanned 4 different ways, by which time (5 months later) my PSA rose 20%, before getting Firmagon for 2 months and finally Lupron and abi and IMRT. While we play doctor-on-TV, get multiple opinions, etc, our PCa exponentially worsens 24x7. In the end the treatment "plan" we get is limited to what is SoC and insured. The initial round of treatment aims to slow PCa progression a lot.
Additionally, get a DEXA scan of bone density for yourself and if applicable, your significant other.
For getting extensive field IMRT / VMAT treatments such as -to entire prostate, prostate bed and +/- pelvic LN fields in 28-30 fractions, then you might favor Ethos or other Cone CT (daily) guided systems. Slight day to day variations and organ movements can help limit accumulated toxicity to nearby organs at risk. Spreading the distribution between sessions.
With 5 treatment SBRT it becomes much more critical to have precise delivery with minimal margins. So that is where MRIdian VMAT is most advantageous, when safe targeting of a metastasis is problematic. Though not always needed. That is my understanding.
Movement during a single session is a real thing either with IMRT or SBRT. Prescribed dosage may may not be achieved, and could be delivered to OAR instead increasing the risk of side effects.
MRIdian machines with A3i upgrade also offer adaptive radiation therapy. The Prostox cheek swab test data to date did not look specifically at MRIdian. The smaller margins and gating might in fact reduce toxicity that some might see with SBRT. As MRIdian and SpaceOAR or Barrigel both reduce the the dose to OAR when compared to other IMRT, it's not clear that Prostox testing positive individuals should best avoid MRIdian SBRT. The Garuda trial is ongoing and further results should be seen by next summer.
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risk of Sbrt Mridian with inguinal hernia?
Have to make a decision next week 
initial treatment Locally advanced combo therapy results compared
Time to PSA Nadir ... following Radiation and Androgen Deprivation Therapy.
