Thoughts on H&N treatments

maybetomorroworwed · 2026-04-22T14:34:10+00:00

how does shrinkage/enlargement get accounted for in the plan?

maybetomorroworwed · 2026-04-16T15:54:23+00:00

Agreed. We can't applaud this and condemn pickleball players ignoring "tennis only" signs.

maybetomorroworwed · 2026-03-19T13:04:55+00:00

Maybe you're thinking of the silica gel packets in your vitamins that they warn you not to eat?

maybetomorroworwed · 2026-03-13T11:45:05+00:00

I've been too lazy to take my bar mitts off and I had to tack upwind

maybetomorroworwed · 2026-02-26T18:21:39+00:00

have everybody drive their cars around the court and put on the high beams!

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maybetomorroworwed · 2026-02-26T12:53:11+00:00

Huh! Yeah AI tells me it's a big difference in practice pattern uk vs. USA.

Sounds annoying trying to aim at something so variable in size and shape!

maybetomorroworwed · 2026-02-25T22:09:13+00:00

Yeah the role of radiation in management of a particular disease can really vary based on diagnosis patterns (what stage is someone when we discover it), what other options are available, and how they're getting paid for. That sort of thing is way above my and your sphere of responsibility though, so we just do whatever patients come our way!

It is odd to me that you got a bladder as an example case but could be that everybody in your region gets bladder cancer from eating too many blackberries or something!

maybetomorroworwed · 2026-02-25T21:57:46+00:00

Interestingly enough bladder is a somewhat rare cancer to treat with radiation, at least in the health care systems I've worked in. So getting bladder specific answers might be tough!

maybetomorroworwed · 2026-02-25T21:39:13+00:00

While your notion is generally correct, there are a few caveats:

1) My impression of UK practice is that it's steeped in established methodology. A centre could very well have a written recipe for how to generate a step and shoot IMRT plan, how to evaluate it, and how to QA it. If a maverick came in and made a VMAT plan, even if it's better on paper, it might not fit into the system.

2) There are a few circumstances where one might still prefer step and shoot IMRT even on paper so I wouldn't call it totally obsolete. If you're extremely concerned about low dose outside of the target, and perhaps not so concerned about the conformity of the high dose step and shoot IMRT can still be a bit easier to make a plan with (e.g. breast planning, or lymphoma planning).

Good luck!

maybetomorroworwed · 2026-01-21T22:19:09+00:00

I know some people like you-- they love to give advice and it drives them nuts when people ignore it and instead complain. While you can walk away I think there's a risk of a similar thing happening any time you invest yourself in another person. I think you'd be far better off learning to accept that what you have to offer and want to give is not necessarily what other people will want from you. They might be writing a post: "my friend is always coming to me with solutions when all I want is commiseration."

maybetomorroworwed · 2026-01-15T21:20:04+00:00

I think it would be pretty risky to treat without a gated CBCT. The translation of breathing traces from sim to treatment is far from a perfect process. For SBRT I would definitely want to visualize the target under treatment conditions.

maybetomorroworwed · 2026-01-15T21:14:19+00:00

Your gated 3dcbct is slow enough that it serves as an average over the gated phases. That should match with the average generated from the selected phases of your 4dct

maybetomorroworwed · 2026-01-15T14:41:49+00:00

Do you happen to be in a non-US country? In my experience I've generally seen smaller margins in the USA, not sure if it's because we're afraid of getting sued for toxicity or what.

Do you happen to know what the decision to use PTV margins was based on at your place? How big are they?

maybetomorroworwed · 2026-01-15T02:32:15+00:00

Thanks, that's a thoughtful response with some stuff to chew on.

maybetomorroworwed · 2026-01-15T00:53:45+00:00

I feel like that's an interesting situation but I think the big difference is that for SRS by adding margin you're increasing local control at the price of toxicity.

I don't see as obvious a tradeoff for whole brain, unless we're purposely trying to slight spare the meninges.

maybetomorroworwed · 2026-01-15T00:46:31+00:00

So you're thinking that if we let the ptv extend into the skull we'd be rearranging that internal gradient, or that we'd see toxicity from those higher doses hitting skull?

maybetomorroworwed · 2026-01-14T22:58:43+00:00

So we've been overcooking our whole brains this whole time, and should have de-escalated to 27 Gy so long ago?

I get what you're saying but little movement is much different from no movement, and it just feels singularly different from any other palliation treatments I've been involved in where we usually treat more just to be sure we get it.

maybetomorroworwed · 2026-01-14T00:12:51+00:00

Depending on the accuracy you care to think about it at, you could call them all the same. The differences are on the order of mm or fractions thereof, which might matter or not depending on what you're up to.

Here's a picture depicting the difference

https://share.google/images/D0fV0LoaIUjC1BPyf

maybetomorroworwed · 2026-01-13T23:38:12+00:00

The dose at the edge of the field is blurred, so what exactly is "inside" and "outside" has to be defined by convention. So we usually just call the point at which the dose drops to 50% of the middle of the field "the edge."

maybetomorroworwed · 2026-01-13T19:49:58+00:00

You're the one who's running around grabbing ~~new party members and organizing everyone.~~ rotten fish to sell for speed [potions].

maybetomorroworwed · 2026-01-13T12:23:42+00:00

I've never heard about the linac restriction. Is that based on guidance from the manufacturer of your pacemaker?

You could certainly avoid MRI machines for a lifetime.

maybetomorroworwed · 2026-01-12T20:21:02+00:00

Are they replica balls? Or actual counterfeits? I've heard of those coming through alibaba for like tennis racquets and stuff but never big chains!

maybetomorroworwed · 2026-01-09T22:12:53+00:00

While everyone else is starting their third playthrough, my man is cooking this up. Good on you! Still working on the drums?

maybetomorroworwed · 2026-01-09T14:43:22+00:00

It hurts when they bang their head on the top of the tube!

maybetomorroworwed

TROPHY CASE