replace `AsChannelFirstd` with `EnsureChannelFirstd`

[wyli]

Is your feature request related to a problem? Please describe.
EnsureChannelFirstd is mostly more robust than AsChannelFirstd when used with LoadImaged. This is a feature request of replacing the current AsChannelFirstd cases with EnsureChannelFirstd.

[Nic-Ma]

Hi @wyli ,

I think we should also replace all the AddChanneld with EnsureChannelFirstd?
@KumoLiu could you please help update this when you completed all the tutorials?

Thanks in advance.

[wyli]

Yes, ensure channel first is almost always more robust...

[Nic-Ma]

@wyli And should we also update the array level AddChannel and AsChannelFirst?
I think MetaTensor also support EnsureChannelFirst in the array level?

Thanks.

[wyli]

yes, also the LoadImage has this flag, perhaps try the flag in some of the tutorials..