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MRIdian Viewray Experience
Making a decision related to which radiation machine one uses seems to be something that does not get a lot of discussion by urologists and radiation oncologists in terms of the differences, other than their success with the machine they use. I chose the MRIdian Viewray. There are multiple choices with different capability and toxicity risks.
I had my first treatment, out of 5, on January 31. I had spaceoar gel inserted. The machine is both a radiation and MRI built into one unit. They can see healthy tissue and the cancer in real time and adjust accordingly using the machines dynamic mapping capability, if necessary. They used 2 mm margins based on a recent randomized trial called Mirage. The machine turns off automatically if your internals move and the radiation goes outside the mapped out area. No pain or real side effects after the first treatment. Second treatment is on Friday. My prostate cancer is contained within the prostate and I am almost 70 with Gleason 3+4 on one core and 3+3 on another. Psa was 10.2.
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Is it always 5 treatments or is that based on individual?
Correction: According to the SpaceOar website, it appears that it is injected through the perineum and guided via ultrasound to between the prostate and the rectal wall.
Rockin2047: you are totally right. I meant to say that I had it between the prostate and rectal wall.
merwether: I have not heard of more than 5 treatments for prostate cancer on the mridian.
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1 ReactionYou're welcome
And thank you.
Photon radiation will hit the targeted area in the prostate but will have an entry and exit, thus passing through healthy tissue. Proton radiation (as I was told at Mayo) releases the radiation when it hits the target therfore the radiation does not have an entry or exit. Theoretically proton should have less side affects, but no random clinical trials have been conducted at this time to prove this. Brachytherapy (HDR & LDR/seeds) places the radiation inside the gland and therefore has no entry or exit point. The mapping process and technolgy does help reduce radiation to healthy tissue compared to radiation treatment several years ago when it was more of a shot gun approach.
I can tell you that the margins used by proton or photon machines vary but the larger the margin number the greater the amount of healthy tissue is affected which impacts side effects. The MRIdian uses 2 mm margins while other photon and proton machines use 4-6 mm margins.
Ok, this is getting clearer to me. So when the MRIdian system delivers the photon beams to the tumor they are then stopped upon reaching the 2mm margin? Also, is this 2mm margin established at any given point around the entire tumor via the mapping process? Then there's the subject of fiducial markers. I've read that sometimes they are used and sometimes not. One article even mentioned the use of permanent ink markers (a black Hilighter pen??) On the mskcc.org website it describes the entire nasty procedure. Sounds like a probe with a needle is inserted into the rectum and then the needle passes through the rectal wall to access the prostate to place the markers. Is this your understanding? Seems like it would make more sense to make the trip up through the perineum to avoid the chances of infection in the rectum. Then don't forget the SpaceOar hydrogel which may be given using a needle which is inserted up through the perineum. After all of this rooting around prep work will there be anything left of my prostate? Just give me a silver bullet to bite down on!!
Thanks for the feedback. Please read my reply to @bens1 . The forum will not allow one to place the same reply to 2 different participants.