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Discuss cardiac sparing for left breast patients with SGRT.
By Steven de Boer United States flag
Following the guidelines for ROI drawing for lung cases we have excluded regions below the rib cage (where the Varian marker block is located). We are finding that many patients will have a strong 2.5 cm Varian marker block different between free breathe and breath hold, but we have only 3 mm signal for alignRT. When we extend the ROI to include more inferior regions we do see the surface changes but the area of the rib cage ROI out weighs the lower area and the deltas do not track the breathing. On these patients, if we only draw the ROI in the abdomen region then we can get a decent breathing signal but then we are limited in the accuracy of the overall setup. Do people have significantly differ ROIS for breath hold and non breath hold patients (lung or breast)?
By marko_laaksomaa Finland flag

This is a topic which comes into sights in the discussions year after year here. In C- Rads Catalyst there is a secondary tracking point, which measures the breathing signal in AP- direction simultaneously with surface guidance. This is useful when controlling the breathing motion of diaphragm for example.

Now, with VisionRT, there is, which is designed for gating. I hope its development will proceed to cover BH- treatments as well in the future, since the need for that kind of option, to simultaneously track secondary area in BH, seems obvious.

By marko_laaksomaa Finland flag
In a dream world of my SGRT we are when needed tracking two ROIs simultaneously. Think how great it would be to monitor face ROI and chest ROI simultaneously at the head and neck setup for example, instead of jumping between the ROIs or creating some confusing combinations under ”one” ROI. In BH to monitor only diaphragm in 6D with SGRT may be too complicated. For that purpose secondary point could be more practical.

To give my answer to your question; so far, if the patient is totally a belly breather in breast DIBH or the target locates near diaphragm, I think we should include ALSO at least part of the diaphragm to ROI. In other cases, most commonly in other words, our ROI includes bony chest in the middle (sternum and enough informative topography of both breast) and a belt at the sides at caudal part of ROI on a rigid surface.
By Steven de Boer United States flag
Thanks Marko, I was just telling our trainer that we need two ROIs. I think the phase based gating product they are developing has that so maybe it would be feasible to add that to the breath hold work flow. I think we are adapting (as you suggested) different ROIs for free breathing and breath hold patients. For breath hold, the ROI will be more inferior where there is better breathing signal. For the setup ROI we can include the large area to ensure proper patient positioning.
By marko_laaksomaa Finland flag
You are welcome Steven. So, our ROI in breast FB and DIBH (in FB setup as well) is in 95% of the cases upside- down T- ROI ... 0062/63790. We verify our BHL with measuring distance between spine and sternum in LAT image. With belly breathers (DIBH breast) and if the target in lung for example locates near diaphragm, we include also diaphragm to ROI. This may better verify the lung filling and correct target location in those rare cases. If you feel that it is necessary and you want to test this larger ROI to your all DIBH patients, it is up to you. We have not considered it necessary. On the other hand, we do not have CBCT data of diaphragm level and thereby knowledge of real lung filling in DIBH. Distance between spine and the sternum is only an approximate evaluation of realized BHL. It is great if this respitarory module could be used in DIBH for this purpose as a help. With two simultaneous ROIs I ment that I hope that some day we have two ROIs at the same time on the monitor and thereby we could simultaneously check at the setup how our positioning affects on two different regions deltas in the surfaces, without jumping between ROIs. I do not know wheter this is technically even possible.

Shortly concerning the ROIs in breast (FB+DIBH). I think that with our T- ROI we can setup the patient accurately as a goal to reach good patient position and posture (rotations) in the bony structures at the chest. With video we check and position the arm. in this way arm positioning is having only minor effect on T-ROI deltas, which is a good thing. With deformation tool, with video or with ROI2 we can additionally check the breast tissue at the setup. I would share the setup to such components instead of using large confusing ROI. This is because VisionRT is offering such great features for the setup.