Time between simulation and starting radiation treatment for prostate?

Not sure what you mean by simulation. I’ve never heard of somebody having a simulated radiation treatment before the real thing. In my case, my doctor wanted an MRI after the PSMA pet scan showed where the metastasis was. The MRI allowed them to more closely, identify where the SBRT radiation treatment should be targeted. When I had salvage radiation 12 years ago, they definitely was no simulation, they just needed to mark me with a couple of Tattoo dots so they could radiate the proper areas.

So what do you mean by simulation?

If you’re going to wait that long to have treatment, you should probably be on ADT To stop the cancer from growing and reducing in. Has that been discussed with your Radiation oncologist?

Yes, it is called a "simulation" (at least here in Ontario), and it involves lying on the actual table to take readings and apply small tattooed dots for alignment. For the radiation to my spinal lesion, they also made what I called a "Hannibal Lecter mask" ( face cage) custom molded to hold my head back in an awkward position and my upper and middle spine still — be grateful you don't have to deal with that for radiation to the prostate (!!!)

After the simulation, the cancer centre's physicist designs your treatment plan and programmes it into the computer. It took about a week for me between each of my similations and the start of actual radiation therapy (SBRT), but I don't know what the maximum allowed time would be.

Best of luck!

I had a simulation prior to proton therapy. They used a CT to develop an imobilization cradle to keep you comfortably in the same position for each treatment, map fudicial markers, verify positioning of prostate to everything around it when the bladder is full, aid in planning beam angles to effectiely reach every part of the prostate, tatoo reference points on the abdomen to help with positioning of the gantry and provide the physicists a 3d scan to review the angles and amount of radiation that will hit each portion of the prostate and tissue in close proximity.

I'm not sure, but waiting doesn't seem like it would impact very much, unless there was significant weight gain/loss which might change the position of body relative to the precalculated angles. That's a great question for your RO team. Wishing you all the best on your treatment and outcome!
Bill

@jeffmarc, as others have mentioned, a radiation simulation appointment is the appointment to set up the radiation treatment. During simulation, your radiation therapy team will help you find a comfortable position. You must lie still during treatment, so being comfortable is important.

You'll lie down on the same type of table that will be used during your treatment. Cushions and props will help hold you in the right placement. Next, the radiation therapy team marks the place on the body that will get the radiation. This might be done with a marker or with small permanent tattoos.

@johnw22, sometimes the time between simulation and actual treatment begin will be short (a few days) or longer, as in your situation, (a few weeks). This is likely due to scheduling of the equipment and number of patients. The simulation will not have to be repeated. What type of radiation will you have?

IMRT to prostate and para-aortic node. Scheduling issues at facility and my personal schedule cause of delay.

@northoftheborder Like you, I'm also in Ontario. My gold seeds/fiducial markers will be put in place on March 26. On the 2t7h or the 28th, will be my simulation (planning). Yes, I will be on the same treatment table that I will be on, for the 5-dose (Mon-Wed-Fri-Mon-Wednesday) actual treatment. The dates have not been set as of the past week, but I was told that usually they're after two weeks from the time the gold seeds are put in place. As @colleenyoung mentioned, actual treatment can be a few weeks from simulation date.

@johnw22
Your post about a simulation being done and what it is called is correct. That is what Mayo Jacksonville and UFHPTI use to describe what is done to prepare your treatment bed and you for your actually radiation treatments.

At UFHPTI an actually bed is made that you will lie in that will eventually hardened. This bed is specific to your body and will be used each time you received treatments. UFHPTI uses a low dose xray to find your markers and then align your markers and you before you receive radiation beams. At UFHPTI even though you are in your simulatrion bed prior to your radiation treatments they did a low dose xray before each treatment to make fine adjustments to the proton beam using the inplanted marker. For me when gantry moved from one side to the other a low dose xray done again. Only once when I had gas did they have to move things around, and another time when they found me not seated in my bed properly. They can see this on the low dose xrays and where I should be alignig up for treatments.

At UFHPTI it takes time for physics department to set up your precise treatment plan and let your new simulation bed hardened and be ready for you before each treatment. So yes it is called a simulation bed and does not involve getting radiation treatment for your prostated but setting up your bed to ensure you are in the same position (as much as possible) when you come for treatments.

The simulation techs will be looking at the markers, your Space/Oar (if you had that), water you drank to move your bladder away to fine tune your bed and the procedure is called simulation. They can adjust how much water to drink next time if needed, and again keep moving the bed and you to ensure your body and the main objective the prostate will be in the same position each time.

A delay is common after the bed is done. This allows bed to hardened and physics or R/O settting up the parameters for your upcoming treatments. All again what I am told at UFHPTI both before, during, and after simulations are done. I think my treatments began 2 weeks out from whent I had simulation done.

There seems to be a lot of variation from one treatment center to another as to the protocol for radiation therapy - both in terms of what happens prior to the start of treatments and what happens the day of each treatment.

In my case, I had fiducial markers and a SpaceOAR gel pack put in and they wanted me to wait at least a week before doing my simulation. On the day of the simulation, they asked me to prepare myself as I would before each actual treatment - empty my bowels and then drink 20 ounces of water a half-hour prior to my appointment.

During the simulation, they got me positioned comfortably on the table with a support (not customized) under my knees and ankles, with an elastic band around my feet to keep them together. Hands across my chest with fingers interlocked - lie still. Then they did CAT scan images of my pelvic region. Right after that, I was sent for an MRI to pinpoint the location of my lesions relative to the fiducial markers.

My understanding is that someone very smart used the images from that day to develop the computer program that would guide the TrueBeam machine so as to zap the cancer cells effectively with as little "collateral damage" to healthy tissue as possible. It took about three weeks to develop the treatment program and get me into the schedule.

I had a second "set-up" appointment the day before the start of actual treatments. On that day, they positioned me on the table, did a CAT scan, repositioned me slightly, ran another CAT scan, then came back and put the tattoos on my hips and belly (my "tattoos" were done with a Sharpie marker and then covered with a clear plastic sticker that stayed on for the duration of my treatments).

On the day of each treatment, the techs would position me on the table, aligning my tattoos with laser beams projected from the ceiling of the treatment room. Then they would retreat to the control room and do a CAT scan. My understanding is that they would overlay that day's CT image with the one from my simulation and then the computer would align me more precisely by making "micro-adjustments" to the position of the table.

It usually took a minute or two for the initial positioning on the table. Then a minute or two for the CAT scan and micro-adjustments. Then maybe three minutes for the actual radiation treatments. Pretty quick process.

My simulation and beginning of SBRT were about a week.

I got those little alignment dots twice — once for the radiation to the spinal metastasis (5 sessions) and once for the radiation to the prostate (20 sessions) — and I joked with my family that I was "inked" now.

I forgot to ask if they could do a skull or anchor instead of just the dots. 🙂