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[jose_carlos_pichardo]

Is there anyone out there using AlignRT with MONACO TPS (Elekta)? I have five years experience with AlignRT and Eclipse, and the surfaces and ROIs have always been very smooth. We just started using AlignRT with an Elekta linac and MONACO and I was shocked by how terrible the ROIs look. They are completely jagged and the RTDs are much more unstable that what I am used to seeing. Is there something we can do about this?

[luc_sirois]

It is a known issue as far as I know. We reached out to support regarding this exact issue many years ago and actually asked about it again just yesterday. I'd love to know if there is a solution.

[sandt]

Hello
I use AlignRT with Monaco since 2019 and yes, we have exactelly the same bad look on patient surface, with big holes that are affecting ROIs...
Hopefully we also use another software for contouring (ArtPlan). External contour on this other software is heavier in ko but very good looking on AlignRT ! And the use of these new external surfaces doesn't affect fps. So now we use ArtPlan for all external contouring.
Another thing to try on monaco : the way you generate external contour : clic outside of the surface versus inside the patient may change the way the structure is generated.
I hope it will help !

[strue]

Hi all,
we also have the same issue. We have the following workflow to minimize the holes: We use the automatic contouring tool ABAS (Elekta), there the outer contour is smooth. Or another way to smooth the external contour in MONACO is to set a margin to 0 mm.

[jose_carlos_pichardo]

I am in the process of discussing this issue with Elekta, because I am wondering if MONACO re-voxelizes the CT for Monte Carlo purposes, so voxels may be of different sizes. There has to be a way to export the original CT, I hope.

[hayley_petrarca]

Hi all! I am a Clinapp for Vision RT in the Southeast. I wanted to give provide you with what Vision RT expects given this known situation with the surface not looking optimal with the use of the Monaco TPS. I also wanted to provide some tips that may help you feel better about daily workflows.

With our previous version (Dollis Hill or v5) and now with AlignRT Advance (v6), we are seeing this same DICOM surface/CT sim surface situation with Monaco. We continue to investigate how/why this may be happening, however we are confident in the setups and tracking we get with using these surfaces.

A few tips:
I find drawing an ROI that gives some forgiveness in how you need to cover the patient (to avoid the jagged edges of the ROI) can be helpful.
On the first day, if you get a great setup and have an SGRT surface (reference capture) taken, I recommend fine tuning the ROI to your liking on that surface, and use this surface to setup daily. Like always, it's important to keep an eye on the ROI daily to ensure what you are setting up with and tracking is stable and only on patient surface.
Once you have an SGRT surface that you feel is reliable for daily setup, you can go into the preparation screen and deselect the CT Sim surface (unapproving it essentially), and it will not be available to use in the treatment screen. This can streamline the workflow/clean things up.

All this being said, the CT Sim surface that comes from Monaco is reliable enough to use daily for setup. But I wanted to give another perspective/option for a workflow to go by if any feel less confident in the surface they are getting from the Monaco TPS.

We do recognize this situation and we do look out for reasons as to why this is occurring.
Any more feedback is always appreciated and will be taken back to the team for review!

[anandakrishnan_k]

Monaco TPS is an Voxel based planning system. So the created countours won't be smooth enough. Im Using Monaco and AlignRT for the last 1.5 years. I use to smooth the body surface manually with the help of paintbrush tool especially for the SRS and SBRT patients.

[jose_carlos_pichardo]

I was able to get in touch with an Elekta physicist who confirmed my suspicions. The issue with MONACO and the poor quality surface and ROIs has to do with the fact that MONACO alters the CT upon import. The CT is revoxelized to allow for faster calculations, so voxels are not equal in size. Since contours in MONACO are generated from the revoxelized CT, all contours match the CT voxel architecture. When the patient surface is exported to AlignRT, the software created triangles to generate the surface, and the triangles are not all the same size. Consequently, the ROIs look jagged and non-continuous.

Unfortunately the only workaround at the present time is to generate the patient contour in a third-party software e.g., Eclipse, and then export the structure into the MONACO plan structure set. When the plan is exported to AlignRT, you can then choose the smooth patient surface, rather than the MONACO one. This results in a very smooth surface and ROIs.

All of that being said, I tested monitoring our pelvis patients with the smooth and non-smooth surfaces, and I did not notice any difference in the accuracy of ROIs or AlignRT's ability to monitor the patient.