Bootstrap Framework 3.3.6

[david_porter3]

Hi, We are currently using AlignRT (known to some as OSMS) for our breast patients in free-breathing. We still use alignment tattoos for the initial pre-AlignRT patient set-up & then apply couch shifts supplied by planning from the medial reference tattoo, to move to isocentre.  (We use an isocentre at the Sup edge of the breast, not mid-breast as some / most centres do).  We now wish to use AlignRT for DIBH deliveries. We are taking 2 CT scans: 1 free-breathing (FB), & 1 in breath-hold (BH). We are intending to only produce a plan on the BH dataset.   At treatment, the intention is to initially set up the patient in free-breathing using the FB surface (imported as an additional 'Field' under the actual BH plan / 'phase') to move to the isocentre position, & then swap to the BH surface & ask the patient to go into breath-hold.

The medial ref tattoo obviously moves between FB and BH.  What practical workflow do centres follow in order to use the FB skin marks (& surface) for initial positioning but to an isocentre that has been defined for the BH condition, so that you can then move seamlessly into BH & be at the correct iso?  For example, do you:

1) create a 'FB Medial Tattoo' position on the BH scan set (based on raw dicom co-ordinates), & then give the shifts from this?

or 2) register the 2 scan sets (according to their base CT dicom centres) & copy the ('absolute') isocentre position from the BH plan onto the FB scan, and then determine the shifts from the medial ref tattoo on that scan set?

or 3) do something else?

Thanks in advance,

Dave Porter.

[ellen_herron_bsrtt]

Hey David,

We initially used marks to setup to at first and then realized that the FB dicom setup was more accurate than our marks. It is much more precise than what your marks can tell you. So we eliminated the setting up to mark/tattoos and go straight into FB dicom setup then switch to breath hold and the patient usually falls right into the threshold.  We check with films on Verification day then weekly. Daily position is also verified by acquired table position and medial ssd. This makes the process very smooth for therapists and patients.

[david_porter3]

Hi Ellen,

Yes, I anticipated such a response & I can see that this completely avoids the problem (& I personally agree with you!) It's just that our therapists are not quite ready yet to 'cut the cord' of our old technique, so it leaves us trying to satisfy 2 masters!

So do you have no marks at all as an initial guide to get you near enough for Align to give sensible shifts?

Thank you very much for your feedback & I will certainly pass it on - perhaps we can use this new BH technique as the opportunity to go this way.

[david_porter3]

But if not - do you remember how you used to deal with the shifts between FB & BH?

[marko_laaksomaa]

Hi :)

I am working as a radiotherapist at the unit which still uses tattoos for all DIBH patients, from 6 clinacs one of those AlignRT is installed. We initially setup the patient at all the fractions with couch LAT at zero with two tattoos on the sternum to check the straightness and additionally check the indexed numerical value from the fixation device (which has taken at the CT) to meet the middle reference tattoo. At the first fraction we acquire couch values and acquire a gated FB setup surface after succeeded kV/kV imaging and couch shifts, in FB naturally. On the next day we setup the patient based on the tattoos as at the first fraction (straightness+middle point to indexed value) and after that press the automatic couch shift button in manipulator to shift the couch to previously acquired values. Then we do the positional corrections based on FB RTDs and perform the small couch shifts in LNG and LAT.  We keep the couch vertical in the acquired value, but do not allow the vertical to vary more than 3 mm from AlignRT FB surface vertical either. After FB setup with AlignRT we go to BH and usually patient position is inside 1 degree and thereby accepted in BH. Sometimes we have to correct the couch in LNG (or LAT) in BH so that patient falls into BH thresholds in that direction. This may weaker the accuracy between vertebra and sternum in LNG, because either patient targets a breath hold in LNG wrongly (which has been the common case with RPM) or our FB surface/patient vertebra is in wrong coordinates in that direction in comparison to BH surface. This is under investigation:). These small couch shift corrections in LNG has nothing to do with tangential image accuracy, if the RTDs finally goes to zero in BH. In BH we take treatment capture to see the position of the arm is correct. Based on my results here, I do not see any parts where tattoos could remarkably improve the accuracy in DIBH. This can be investigated such that we position the patient ignoring the tattoos for some test patients at some point...

The succeeded FB setup is very important, and obviously happens better with the aid of SGRT than with laser setup. After that very important is also that patient takes similar kind of breath holds. This does not happen in large population easily. It would be interesting to hear more about breath hold guidance workflows, CT workflows and the depth of DIBHs from the units where everything goes just like that in DIBH. Have anyone checked the daily variation (starting points) of the LNG and VRT bars from FB situation to BH, how much they really vary inter-fractionally. I suppose in the succeeded BH they should not vary a lot if FB setup is succeeded?

Regards Marko

[tracey_mosley]

Dave,

We currently use BH but not with Align RT.  At Sim, we mark our fiducial in FB and scan.  When we do the BH scan, we put the patient in BH and move the table back to the fiducial we marked in FB, and scan.  In the treatment room, set the patient up to the FB marks.  Put the patient in BH and move table out/in to get back on the tattoo/mark.  Let the patient breathe and do the shifts. You should now be at the proper shifts for BH.  We only use the BH sim scan for planning as well.

Not sure if this is what you were looking for!



Tracey Mosley

[paul_robertson]

Hi David,

We do the same process as described by Ellen at our AlignRT sites and have found it very smooth. There were concerns from treatment staff at first. We found dry runs and a phased elimination of tattoos very useful. The last to go was the Ant tattoo. We are tattoo-less for breast and chestwall patients now.



Cheers,



Paul