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Is all SRT the same?

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Posted 7/11/2017 5:02 AM (GMT 0)
Hi folks

This is probably a really silly question (par for the course I hear you all say!), but is all SRT the same? - not taking into account the skill of the operator of course.

In terms of targeting different areas, I seem to recall reading something about some tx just being directed toward the pelvic bed, but others including regional lymph nodes etc - is that a thing or have I just imagined that?

Appreciate any/all advice.
Thanks a million.
Jaybee
Posted 7/11/2017 5:10 AM (GMT 0)
I don't know the answer, but I'm very curious because I'l be starting SRT myself pretty soon. I went to see two RCs, one very conveniently in my hometown and the other an hour away in a major cancer center. They recommended the same treatment. I asked the people at the major center if there was any reason I shouldn't do it close to home. They saw no reason not to do it close to my home.
Posted 7/11/2017 12:45 PM (GMT 0)
I'm right there with you, fiddlecanoe (hey, that rhymes!) ... Diagnosed last July, surgery the last day of August, had SVI, and now must choose between a local Uro-RO ten minutes away or drive less than an hour to a major cancer center (Moffitt). I'm going with the local guy, hoping to start next month. I see him next week for our third meeting, hopefully to set up my SRT schedule.

Good luck with yours, I hope all goes well for both of us!
Posted 7/11/2017 1:09 PM (GMT 0)
The SRT will be based on what your doctor assessment shows. In some it is basically the prostate bed. If higher risk indicates it could also include the pelvic lymph nodes. The actual radiation dose may vary somewhat but should in a small range that has been proven high enough to be effective but not overly toxic. In all events it will be personalized to each man due to anatomical differences. So while the intent and process will be fairly uniform the actual delivery will vary from one person to another.
Posted 7/11/2017 1:14 PM (GMT 0)
An RO customizes the treatment program for each person depending on their diagnosis. Each body and case has differences that the RO accounts for when programming the machines. Including areas covered, radiation amounts to each area, etc.

It's one of the reasons you have to wait awhile before you cat start treatment - takes a little planning before your treatment program is ready.

Andrew
Posted 7/11/2017 1:21 PM (GMT 0)
The old standard was using a technique called IMRT. They would administer a dose of around 70 Gy broken up into 40 fractions..A newer technique using newer equipment is called SBRT and while the dose is similar the number of fractions is usually 20 or so..

I would ask the make and model of the LINAC to be used. I would insist it be a Varian Rapid-Arc or newer...The newer equipment can deliver the beam with great accuracy and less damage to healthy tissue...
Posted 7/11/2017 2:29 PM (GMT 0)
Fairwind, you are very wise in such matters, so I must ask... in regard to my post above about choosing between convenience or a highly accredited cancer center, my RO has specifically stated that my treatment will be 38 fractions of IMRT. Should I seek alternative treatment that may be more modern and less risky? Thank you for your advice.
Posted 7/11/2017 3:56 PM (GMT 0)
Jaybee-

In my case SRT targeted both the prostate bed and lymph nodes - I had the 68 Ga PSMA scan which identified uptake in bothe the bed and nodes.

35 fractions - 70gy to the bed and 52gy to the nodes with 62gy to the nodes identified by the scan.

Bobby Mac
Posted 7/11/2017 4:55 PM (GMT 0)
SBRT is no more modern or less risky than IMRT. It just delivers more radiation per dose, so that fewer doses are needed. SBRT is a form of IMRT. I would much rather have IMRT from a great center than SBRT from a so-so center and vice versa.

Basically any machine that delivers IMRT/IGRT SBRT are going to be equally safe. The Varian class machines use a method where they continuousy deliver the radiation while the gantry is moving around the body. Other machines do a start and stop method. The Varian is not safer, per se, it is just faster. I was treated by an Elekta IMRT machine and it would take about 10 minutes per treatment because the radiation was delivered from 9 different positions of the gantry. The radiation was delivered only when the gantry was in a fixed position. A friend had IMRT from a Varian machine and his routine was about six minutes. We both received the same amount of radiation and experienced very similar side effects. His only advantage was time. The advantage to the radiation center was they could treat more people in the same amount of time and thus make more money. Technology development isn't just oriented for client effectiveness, but also provider income.

As to choosing the center, they will all have to follow the same accepted protocols for safety. Make sure your local center is well regarded and does a lot of PCa work. If so, then the convenience will be valuable. If they have only done a handful of SRT procedures this year, I would go where they are delivering radiation to treat PCa every day. With IMRT/IGRT/SBRT it is the people, not the brand of the machine that is the most important factor.
Posted 7/11/2017 5:06 PM (GMT 0)
SBRT is also known as Cyberknife..It was developed to deliver a pinpoint beam to a small area..It used a special-built LINAC made just for that purpose..Today, the newer full-size LINACS used to deliver IMRT can be set up to deliver SBRT also if your R.O. feels that would be more effective...When performing SRT to prostate patients, the IMRT format is likely to be used as it is better suited to treating a larger area, sometimes called "full pelvic". Near the end of the treatment, they sometimes narrow the beam and zero in on likely troublesome areas. In my case they referred to this as "boost"..

See if you can picture this...The older LINACS, the x-ray machines that deliver the radiation, usually moved into position and stopped, became stationary, while the dose was administered. It would then move on to a new position and fire again..Typically, it would repeat this 7 times during a treatment session. This reduced the exposure to healthy tissue to one seventh of what the target received..With the newer LINACS, the gantry is in motion (Rapid-Arc) when the beam is activated so healthy tissue receives much less exposure..The RO writes a treatment plan so these moving arcs seldom if ever overlap as the gantry can accommodate a wide range of motion, but the target, the focal point, receives the full intended dose..Also, the new machines have a built-in CAT scanner that checks organ position just before the beam is activated...If anything has moved out of position for any reason the beam is aborted until the situation is corrected...

The company that developed this new technology is Varian and the first generation of these LINACS were called Rapid-Arcs. They were introduced 7 to 9 years ago..I would insist on being treated with one. Today, the newest models are even more advanced....Most of the up to date treatment centers use this new equipment..Equally important is the skill of the R.O.'s that operate it....
Posted 7/11/2017 5:08 PM (GMT 0)

JNF said...
As to choosing the center, they will all have to follow the same accepted protocols for safety. Make sure your local center is well regarded and does a lot of PCa work. If so, then the convenience will be valuable. If they have only done a handful of SRT procedures this year, I would go where they are delivering radiation to treat PCa every day. With IMRT/IGRT/SBRT it is the people, not the brand of the machine that is the most important factor.

Thank you so much for your reply. I understand that the method of SRT is less significant than its accuracy. Fortunately, the local center does exclusively urologic radiotherapy and I have heard only good things about the RO and his practice. I am considering Moffitt only because they are a larger center and presumably would have more extensive resources. Given that my SRT has already been delayed by several months I may be forced to get the ball rolling if I encounter further complications by having focused on convenience rather than proven expertise.
Posted 7/11/2017 5:58 PM (GMT 0)

Fairwind said...
SBRT is also known as Cyberknife..It was developed to deliver a pinpoint beam to a small area..It used a special-built LINAC made just for that purpose..Today, the newer full-size LINACS used to deliver IMRT can be set up to deliver SBRT also if your R.O. feels that would be more effective....Most of the up to date treatment centers use this new equipment..Equally important is the skill of the R.O.'s that operate it....

Thanks Fairwind. You posted your reply while I was typing my response to JNF. I now have some more questions for my RO and any prospective RO I may consider. Much depends on how my appts go next week with my RO and Uro. I need to get this SRT underway without further delays.
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