SBRT dilemma (MRI Linac vs regular CT+fiducials)

[witantric]

I have honed in on getting SBRT. However, I am mulling between two options: MRI Linac vs CT+fiducials. The complication is for MRI Linac I will have to travel and SBRT with CT is local.

I have heard that MRI-Linac SBRT has better side effects profile. But the question is: is it worth the travel?

[cesanon]

My personal philosophy is with prostate cancer it's always worth it to travel for better.

Can you explain the differences and pro/cons between: MRI Linac

CT+fiducials

SBRT with CT

[witantric in reply to cesanon]

If you look at the Mirage trial, MRI Linac had lower toxicity than CT+fiducials. Essentially MRI Linac takes real time images as the radiotherapy is done and so can adjust real time.

[janebob99]

How far do you have to travel? Do you have the time and money to travel?

I did SBRT with CT and fiducial tattoo marks about 5 months ago. It was a local machine. I would have had to travel to UCLA from New Mexico five times to get MRI-guided, which I didn't want to do (travel). The results from either type of RT really depend on the skill and experience of the person who is programming the machine to contour the irradiation profiles, rather than if it's MRI-guided or CT-guided.

It's also important to do a good prep so that you don't have gas bubbles in your colon and that your bladder is not large. Plus, I got a SpaceOAR rectal spacer, which reduces the X-ray dose to the rectum by a significant amount. I wanted to get Barrigel, but the RO wasn't set up to do that.

The side effects from traditional SBRT are already quite low to start with (but, greater than MRI-guided). The only side effect I had was some blood smears on the toilet paper a couple of times. Other than that, there were no noticible side effects.

My PSA is now 0.03 (but, I also am doing a 6 month course of Orgovyx...).

[witantric in reply to janebob99]

Money is not an issue. I just have to spend time away from my home.

[janebob99 in reply to witantric]

Then, that's a tough decision...

If you can make the time, then do SBRT at UCLA with Amar Kishan. They will have the best machine and operators. Spend a week and 1/2 there. Take your wife or partner with you and go see some museums.

The level of side effects is reduced 50% with the MRI-guided Linac, according to Dr. Kishan.

Bob

[Justfor_]

MRI guided any time for me.

[witantric]

Not positive. You mean the brand of the machine?

[Derf4223]

I think the point of MRI-guidance is to dynamically detect and adjust beam direction for prostate movement during the session. OTOH CT RT provides a snapshot of gold fiducial locations (ie the prostate) immediately before the 2-3 minutes of RT per session, where the beam position is adjusted accordingly once. The bigger issue is that prostate RT is often done for metastatic PCA, in which case the beam will on purpose overshoot the area a bit, providing margins ie areas just beyond the tumor, so as to be sure to cook tumor extensions too small to image. You probably don't get gold fiducial rods with MRI.

MRI is a very raucous unpleasant noise generator. Not everyone wants that for 20 to 30 consecutive weekdays.

A Linac is the generator of the high energy x-ray beam that is used whether CT or MRI provides guidance.

Some people worry about the incidental x-ray dose of a CT scan, but the Linac beam hits your prostate with about 1000 times more.