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[kira_oliver]

Hi all,

We are currently implementing our AlignRT systems on our Varian Edge linacs, and there is some discussion amongst the RT group regarding the use of either the delta couch shift from the patient Eclipse plan, OR AlignRT to set up.

I was wondering if anyone had this combo and had a preference of set up variation?

Thanks in advance

[marko_laaksomaa]

Hi Kira

We have four treatment machines without SGRT. Thereby all the patients have tattoo marks. With the machine where AlignRT is installed we use tattoo marks only to check the initial straightness of the patient with the "AlignRT patients". After that we shift the couch automatically to planned values (acquired on the first treatment fraction). Then we setup rotation, pitch and roll correction based on AlignRT and finally with the AlignRT move couch function move the patient to correct isocenter. With the indexed fixation (which is a demand to use this workflow) we have not seen any advantage to use delta couch shift function, which is in use with the machines without SGRT. With the DIBH treatments we do not use move couch function, since we want to use both planned couch vertical value (daily the same value) and AlignRT FB zero vertical (error in the FB setup surface is zero as it would be with move couch function). If move couch is used in the DIBH in the daily setup, we think that there seems to be the risk that we shift the vertebra out of its planned location in vertical and the breath hold level in the images may be wrong.

Best regards Marko