You may not be aware that for radiotherapy, the beam is shot from many different directions, at the prostate. The reason for this is to reduce damage to surrounding tissue.
The following is a very simplified explanation of a radiotherapy plan:
To delivery a full dose of RT to the prostate. 25% is fired from above, 25% from below, 25% from the left and 25% from the right.
This means that any part of the body only gets a quarter dose, except the prostate which gets hit by all four doses.
The plan gets more complicated, because the radiotherapist wants to avoid hitting the rectum and some other organs, so the beam from below won't be fired directly from below it will be fired from slightly one side. Also no two paths should be exactly opposite each other, but I won't explain why. In reality they will use more than four paths, probably up to ten if they can.
As the hip prosthesis are probably made of metal they will block or scatter x-rays so the radiotherapy plan becomes much more difficult to design, as they have to avoid any x-rays hitting the hips.
Also the metal will make any scans of the prostate very blurred, so it will be harder to know where the target actually is.
I would not have thought this would make radiotherapy impossible, just more difficult, but I'm not a radiotherapists so how would I know.
I googled hip prosthesis radiotherapy, and this article came up.
https://humanhealth.iaea.org/HHW/MedicalPhysics/Radiotherapy/Topicsofspecialinterest/ManHipProsRT/index.html
I guess the fact I have a degree in physics might be the reason I found this easy to read and understand.
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Originally Posted by: Online Community MemberYou may not be aware that for radiotherapy, the beam is shot from many different directions, at the prostate. The reason for this is to reduce damage to surrounding tissue. The following is a very simplified explanation of a radiotherapy plan: To delivery a full dose of RT to the prostate. 25% is fired from above, 25% from below, 25% from the left and 25% from the right. This means that any part of the body only gets a quarter dose, except the prostate which gets hit by all four doses.
This is a description of original IMRT (and it's not even correct for that which used 5 aiming points so the exit beams didn't lay directly on entry beams from another angle).
All external beam treatment today (in the UK at least, and probably for 5+ years) is IG-VMAT, which treats continuously while doing a 360 degree arc (excluding some SABR treatments). It's not possible to treat through a metallic hip because that reflects the X-rays to other places and some intended dose is lost from the prostate, but this is allowed for in the planning, by disabling the beam for the short time it would have hit the metal, and compensating throughout the rest of the treatment arc.
Proton beam treatment isn't possible with metallic hips, as proton beam only treats from two positions, and that's through each hip.
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You may not be aware that for radiotherapy, the beam is shot from many different directions, at the prostate. The reason for this is to reduce damage to surrounding tissue.
The following is a very simplified explanation of a radiotherapy plan:
To delivery a full dose of RT to the prostate. 25% is fired from above, 25% from below, 25% from the left and 25% from the right.
This means that any part of the body only gets a quarter dose, except the prostate which gets hit by all four doses.
The plan gets more complicated, because the radiotherapist wants to avoid hitting the rectum and some other organs, so the beam from below won't be fired directly from below it will be fired from slightly one side. Also no two paths should be exactly opposite each other, but I won't explain why. In reality they will use more than four paths, probably up to ten if they can.
As the hip prosthesis are probably made of metal they will block or scatter x-rays so the radiotherapy plan becomes much more difficult to design, as they have to avoid any x-rays hitting the hips.
Also the metal will make any scans of the prostate very blurred, so it will be harder to know where the target actually is.
I would not have thought this would make radiotherapy impossible, just more difficult, but I'm not a radiotherapists so how would I know.
I googled hip prosthesis radiotherapy, and this article came up.
https://humanhealth.iaea.org/HHW/MedicalPhysics/Radiotherapy/Topicsofspecialinterest/ManHipProsRT/index.html
I guess the fact I have a degree in physics might be the reason I found this easy to read and understand.
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I have had a PSMA PET and a hip replacement, I was also told to have my hip replaced BEFORE any salvage therapy as the radiation can impede the hip healing.
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Originally Posted by: Online Community MemberYou may not be aware that for radiotherapy, the beam is shot from many different directions, at the prostate. The reason for this is to reduce damage to surrounding tissue. The following is a very simplified explanation of a radiotherapy plan: To delivery a full dose of RT to the prostate. 25% is fired from above, 25% from below, 25% from the left and 25% from the right. This means that any part of the body only gets a quarter dose, except the prostate which gets hit by all four doses.
This is a description of original IMRT (and it's not even correct for that which used 5 aiming points so the exit beams didn't lay directly on entry beams from another angle).
All external beam treatment today (in the UK at least, and probably for 5+ years) is IG-VMAT, which treats continuously while doing a 360 degree arc (excluding some SABR treatments). It's not possible to treat through a metallic hip because that reflects the X-rays to other places and some intended dose is lost from the prostate, but this is allowed for in the planning, by disabling the beam for the short time it would have hit the metal, and compensating throughout the rest of the treatment arc.
Proton beam treatment isn't possible with metallic hips, as proton beam only treats from two positions, and that's through each hip.
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I find the first post (AskingForFIL) somewhat confusing and totally at odds with my own experience.
I shall not go too deeply (nor name names) into my "saga" as I am considering making a formal complaint against an NHS hospital to which I was referred to by my District Hospital (no radiation facilities)
I am 77 with prostate cancer and I have 2 replacement hips.
Earlier this year I underwent the full panoply of Prostate investigations by my District Hospital ending with a cancer diagnosis and a way ahead of hormone/radiation therapy for, hopefully, "curative" treatment. My District Hospital was magnificent: I had CT, MRI and Nuclear bone scans - at NO time were my two replacement hips mentioned let alone being flagged as a potential problem. I was then referred to another hospital for the radiation therapy - I was "denied" (my Oncologist's word) treatment because of my two hips and referred back to my District Hospital. Both my Oncology and Urology consultants were "taken aback" ( I am being very polite here) by this. I was then referred to another treatment centre where I had a Planning Appointment followed by radio therapy, which I am now three quarters of the way through. On my very first treatment session I asked the senior radiologist what effects/problems/difficulties my two replacement hips had posed.........his exact words were........"none whatsoever".
All the way through this my replacement hips have attracted about as much attention as the colour of my socks !! Except by the hospital which turned me away.
WHY ?? Is there a huge difference in the technology/capability of the equipment for radiotherapy in different hospitals ? My District Hospital must surely know what local radio therapy hospitals are capable of doing.
My own feeling is that I have wandered, unknowingly, into some kind of "turf war" when I was referred to the first hospital. I really felt that had I been referred there to have my toenails cut some excuse would have been found to refuse me for even that.
I would be really interested any any comments/experiences that readers may offer................
PS: I am REALLY glad that I ended up at the second hospital for the radio therapy..................SO good !!
Edited by member 14 Nov 2024 at 21:31
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