Fiducial markers- are they necessary?

I recently underwent 5 sessions of SBRT utilizing MRI guided (not informed) accelerator. My thighs were marked with temporary tattoos so there were no fiducial implants. It actually was a minor factor in my decision for this treatment and treatment center.

In radiation therapy for prostate cancer, custom body molds—also known as immobilization devices—are used to ensure a patient's body is in the exact same position for each treatment. This precision is critical for targeting the radiation beams precisely at the tumor while minimizing exposure to surrounding healthy organs.

The Usually also put tattoos on the body to make sure it’s lined up properly. Did you ask about that when they discussed custom body molds?

I’ve had both IMRT and SBRT radiation. In both cases, they put permanent tattoos on my body. The tattoos are Almost invisible, They are dots you would be hard pressed to find.

My tattoos were not permanent and there was no custom body molds used. Can I assume it’s because of the utilization of MRI guided Technology?

I was never given a choice. I have fiducials, tattoos, and a custom body mold. Guess they just wanted to be sure they hit the right thing. Here's a quick article describing fiducial marker use.
https://www.cancercenter.com/treatment-options/radiation-therapy/fiducial-markers

I had LDR brachytherapy. When I asked the implanting oncologist about fiducials he said “you’ve already got 63 of ‘em. Once I got home I still got tattooed and had forms for my legs.

Also had fiducials, tattoos, and body form. You can’t be too careful.

@jeffmarc so do you think the use of the gold markers that are inverted into the body is an old process?

I know that for some types of radiation treatments they use the gold markers. It could be that the cancer they are seeing is better located by gold markers than regular tattoos. Ask your doctors why they are using gold markers instead of tattoos. I know that they use them for both SBRT and IMRT radiation, But when I had that kind of radiation, they just used tattoos.

It’s possible they get a better target for the radiation using the gold markers since they are placed quite close to the spots to be radiated.

I had gold fiducial beads permanently implanted in my perineal area along with the SpaceOAR protective gel.

They did not permanently tattoo me but they did apply clear stickers with "X"s on both outer thighs and mid waist to align the IMRT machines for my 5 weeks of external beam treatments. I easily removed the stickers after the treatment ended and saved one to remind me always of the process

I had my SBRT this past April. Two weeks before the start of my radiation, the care team implanted gold seeds (fiducial markers). The cancer center has an MRI-Guided Linac, but I wasn't treated with it. I asked why, and I was told because I had fiducial markers; those who couldn't have the markets are treated with the MRI-Guided machine. I had MRI-Guided radio planning, but treatment wasn't guided. I was told a mini-CT was done before each treatment -- comparing the CT with the planning images to make any necessary adjustment before radiating. I was assured the non-MRI guided Linacs were all very good (they have so many of them at the cancer center). I have had no post-graduation issues more than six months now.