Constructing a Catheter Balloon

[MarkWrobelUCL]

Hi,

I have been working on a simulation of right heart catheterisation (similar to the CTR example but with a single instrument). I would like to integrate a balloon to the tip of the catheter (as is common for these kind of procedures). My idea is to create a new sphere object and attach it to the tip of the catheter via 'AttachConstraint'. The issue is that the catheter model does not appear until you move it forwards and so at the start of the simulation there is nothing to attach the balloon to. I would appreciate and help or ideas as this approach does not seem viable. (I am using SOFAPython)

Thanks

[epernod]

Hi,

as you are using SOFAPython, a quick workaround would be to check the position of your tip while simulating. And as soon as the tip curved abscissa reach a given threshold, you add your Sphere + AttachConstraint to the given dof.

Then a better and more realistic approach would be to create a second tool with bigger radius (and sphere collision ) and deploy the second tool after the first one has been deployed. You can check the scene 3Instruments to see how to define several tools on the same catheter simulation.

Best regards

[MarkWrobelUCL]

Hi,

thanks for your reply. I am trying with the more realistic approach now and I have been looking at 3Instruments.scn. I may be slightly confused but in this example it seems to me that the instrument is made up of 3 components; the guide, coils and catheter. Even though they all have a visual component defined, the only model that can be seen is the one that was defined first i.e. the catheter. Is this because the other components are within the instrument so SOFA only visualizes the outer most component? If this is the case, is that not different to what I am looking to do since I essentially want two components end to end rather than inside the same instrument?

[epernod]

No normally each tool has its own visual modelling: https://github.com/sofa-framework/BeamAdapter/blob/master/doc/screenshots/WireSections.png

the only thing they share is the trajectory as the 2nd tool will follow the path of the 1st one and go out at the tip of the 1st tool. And 3rd one will do the same respect to the 2nd one.
You need to switch tool during the simulation to deploy more than the 1st tool.

[MarkWrobelUCL]

Thank you. Switching the tool is indeed what I was missing. In terms of adapting it to my needs, how do i go about fixing the second tool to be at the end of the first one? As you mentioned, the second tool (which has a bigger radius) follows the path of the first tool but they do not move together (like a sphere attached to the end of a wire).

[MarkWrobelUCL]

@epernod Thanks for the help thus far. Unfortunately I've struggled to make progress with the second method since I cannot understand how I would make one of the tools fixed with respect to the other one. Therefore, I am trying to persevere with the first method using the AttachConstraint. I have two issues currently. The first is that the way I know to continually check the position of my catheter is via a class as so:


which I then use in my createScene function. The issue that I am having is that my add_sphere function (line 85) does not work when called within this class (crashes SOFA, no errror) but works if I call it in my createScene function (which confuses me since I believe the root argument that I am passing to it should be the same either way).

The second issue is arises when testing the AttachConstraint when manually adding the sphere in the createScene function.

object1 definitely has a Rigid3d template so I am unsure what is causing this. I have also tried putting the attachConstraint inside a class and only call it once the catheter has moved forwards enough to make sure that it has actually been created however, this causes the same error.

Any help would be greatly appreciated. Thanks.

[epernod]

Hi,
at this stage it seems to be more a question/problem related to SofaPython3 then BeamAdapter. I'm not able to help regarding this bug, @hugtalbot maybe you can redirect to the good person.

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@MarkWrobelUCL
Feedback has been given to you by the project reviewers, however we have not received a response from you. Without further news in the coming weeks, this discussion will be automatically closed in order to keep this forum clean and fresh 🌱 Thank you for your understanding

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@MarkWrobelUCL
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