Anyone use HyperArc?

[radiadouken]

I know what Varian claims, but curious what the “real world” experience is with this workflow, and any limitations you have encountered if you use it. Obviously single iso / multiple mets in 15 min is pretty appealing. What does your physicist think about uncertainty? What PTV margins do you use?

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[Neuronix]

You're welcome to PM me. I use and have studied this quite a bit.

 

[HardenedBeam]

I really like hyperarc. Aside from treating 15 brain mets with multiple non-coplanar arcs in 5 minutes, you can also treat (and re-treat) fractionated cases with multiple non-coplanar arcs in 5 minutes. Makes beautiful brain x-ray plans and the treatments are super fast. Enjoy it!

 

[madchemist89]

With hyperarc, what intrafractional imaging are you doing? We have identify. Our physics staff are concerned that intrafractional motion is an issue without continuous kv imaging. I just wanted to get others thoughts on this. They will currently only let me treat single site single isocenter with current setup.

 

[Palex80]

With hyperarc, what intrafractional imaging are you doing? We have identify. Our physics staff are concerned that intrafractional motion is an issue without continuous kv imaging. I just wanted to get others thoughts on this. They will currently only let me treat single site single isocenter with current setup.

When we started radiosurgery treatments with a thermoplastic mask on a non-FFF Linac, our physicists also had this concern. So we ran a CBCT halfway through the 20' treatment to see if the patients moved. We were not able to detect movement on that half-way-CBCT taking place under the mask during treatment.
Immobilization aids probably also play an additional role.

 

[BobbyHeenan]

With hyperarc, what intrafractional imaging are you doing? We have identify. Our physics staff are concerned that intrafractional motion is an issue without continuous kv imaging. I just wanted to get others thoughts on this. They will currently only let me treat single site single isocenter with current setup.

I don't have hyperarc, but any VMAT based radiosurgery with flattening filter free mode is incredibly quick. I've done single iso, multi arc VMAT cases on a Truebeam for a long time now. I don't think it's worth reimaging for a beam on time of < 3 minutes.

 

[Neuronix]

OSMS (should be similar to identify I'd imagine), 1 mm PTV, max iso to target distance 6 cm (we have a paper on this in revision). If necessary we split into two isocenters.

What motion is physics worried about? You can do the math and find that for short iso to target distances you need a lot of rotation for geometric miss. That much rotation should be picked up by surface monitoring. When that happens we assess why the patient is moving and repeat come beam, adjust 6D couch, and then resume treatment.

We picked 6 cm isocenter distance because once you get that far out you can get small rotational errors that are hard to detect that can move the mets more than 1 mm. You can do CBCT after or during treatment to confirm surface monitoring is reasonably accurate and math it out if you want to confirm met position vs. rotational changes as measured by CBCT.

 

[medgator]

OSMS (should be similar to identify I'd imagine),

Identify is the newer version of it but also with some other QA upgrades, supposedly has a better way of "identifying" the patient before treatment

 

[madchemist89]

OSMS (should be similar to identify I'd imagine), 1 mm PTV, max iso to target distance 6 cm (we have a paper on this in revision). If necessary we split into two isocenters.

What motion is physics worried about? You can do the math and find that for short iso to target distances you need a lot of rotation for geometric miss. That much rotation should be picked up by surface monitoring. When that happens we assess why the patient is moving and repeat come beam, adjust 6D couch, and then resume treatment.

We picked 6 cm isocenter distance because once you get that far out you can get small rotational errors that are hard to detect that can move the mets more than 1 mm. You can do CBCT after or during treatment to confirm surface monitoring is reasonably accurate and math it out if you want to confirm met position vs. rotational changes as measured by CBCT.

I don't know what they are worried about. I think they are just resistant to change.

 

[RickyScott]

I don't know what they are worried about. I think they are just resistant to change.

I have had this battle for years.

 

[Palex80]

I don't know what they are worried about. I think they are just resistant to change.

If they can't change, it's time to think of changing them.

 

[madchemist89]

Thats not going to happen. They'll change me first.