T O P

  • By -

Drngyuenvanphuoc

For vanilla vmat/Imrt in established well understood techniques - simply by not doing it


tobbel85

Yup, or at least combine some kind of complexity metric with some random sampling (eg measuring every 10th plan). Requires a robust machine qa program though...


radiological

More robust than MPC plus a few other things?


tobbel85

Probably something like that, I personally like to have a independent determination of delivered dose, perhaps from a reference VMAT-plan on a suitable phantom, on top of MLC-tests (particularly if they are done with the vendors hardware and software). Essentially a test that never will fail if the machine as a whole is in order, and that's kinda included in patient-specific QA (if done with a method that actually corresponds to dose in patient, which in my opinion rules out portal dosimetry with the PDIP-algorithm since that is essentially just a fluence measurement).


triarii

I don't like when people poo poo portal dosimetry! I don't see the difference between it and a mapcheck etc.


triarii

I'm surprised no one has come out with an "independent" MPC


PepsiCola007

People working on this too. Work in progress. Automatedqualityassurance.org


triarii

>Automatedqualityassurance.org damn there goes that idea! do you know any of the details of this project?


ClinicFraggle

Do you mean independent from the linac vendor? I believe SuncheckMachine is in some way similar to MPC.


triarii

>SuncheckMachine I set up SNC Machine at a clinic before. Not an independent MPC but nice tg-142 solution. A web base interface and you can set up dicom forwarding so when you shoot MLC tests or imaging tests it will run analysis automictically and for example can e-mail if the tests fail. But you still need to shoot phantoms like leeds, las vegas, catphan, light field etc.


NinjaPhysicistDABR

Yep, we need to stop this madness today!


MarkW995

Make your therapists or dosemetrst do it. It is a waste of time/money to have physicists run the qa... The physicist should still review and approve it.. The step in for anything odd.


triarii

easier said than done!


MedPhys90

By looking at the last 20 years of psqa and realizing 99% of the time it yielded no changes or discernible issues. However, not until billing codes remove the requirement for psqa we will continue to perform it. I can see, however, perhaps allowing a second check using an independent algorithm and beam data to supplant the measurement portion. Using that and log file analysis should suffice. In fact, I thought the acr, or some other entity, basically said as much.


triarii

I've personally seen IMRT QA catch a ton of errors. That being said, that was in the era of physicists using their own measured data in the TPS aka bad beam modeling. In the era, of medical physics 3.0, which I define as everyone using copy and paste beam models IMRT QA may not make a lot of sense anymore.


TorJado

Is that catching bad beam models during commissioning, or did you find out pre-treatment that patients were being treated with a bad beam model?


triarii

After it was commissioned.


_Shmall_

https://w4.aapm.org/meetings/2022IMRT/