Bootstrap Framework 3.3.6

[erin_sculley]

Due to field size limitations, we are unable to treat our breast and node cases monoisocentrically, and we therefore have to make a shift in between our sclav and tangent fields. When not treating with DIBH, our therapists are accustomed to tattooing the match line on the patient's film day and holding that for all treatments. We are looking for the best way to ensure that our match line is reproducible when treating these cases with DIBH. We can follow the same process of tattooing the match line, but we are concerned that we might introduce a systematic error if the patient holds their breath differently between the two fields, for example. Any advice? Is anyone doing this treatment without a monoisocentric setup?

[marko_laaksomaa]

Hi Erin

I suppose you have AlignRT in use. In the multi-iso DIBHs we imaged and treated the first isocenter normally. When it was time to treat the second isocenter, inside treatment room we asked patient to inhale inside first isocenter thresholds, manually did planned LNG couch shifts, stopped monitoring, switched to the second isocenter BH, took the reference capture and allowed patient to breath again. If you are uncertain that what did you or the patient did during described procedure between the isocenters, check from the second isocenter BH DICOM that the small displacements in the RTDs are pretty much similar with your online matched small isocenter corrections done at the first isocenter. If the first isocenter went to DICOM, we only performed planned couch shifts between the isocenters and treated the second isocenter to BH DICOM.  I think AlignRT is more accurate than the tattoos also in this case, needs to be studied to say for sure. Thus, you can always acquire AP+LAT images also after treatment for example at the first three fractions to see the position of the arm, th1-2 and the isocenter to verify the realized accuracy and succesful of the workflow for the lymph node area and the breast/chest wall.

Best regards Marko

[jacqui_dorney]

Hi Erin,

We do exactly the same as Marko with the addition of a quick port film  in BH at the 2nd iso position.  So to detail the process

1st Iso Position: set up to FB surface, switch over to BH surface, pt takes a breath in, with the pt in BH small late and long shifts are corrected.  Pt breaths out.  Rads exit the room and coach pt back into BH for CBCT.  Pt breaths out while CBCT is analysed.  Back into BH for imaging shifts.  Treat fields in BH for first iso.

2nd Iso Position:  With the BH dicom data for the 1st iso still loaded in AlignRT coach the pt back into BH and manually shift the bed to the second iso position, switch over (quickly) to the 2nd iso dicom BH data and capture a new ref image.  Pt breaths away.  Flick to BH dicom data of  2nd iso and check delta values are within 2mm.  Shift back to ref capture for imaging.  Coach pt back into BH, take a quick port to check positioning.  Trt if all looks good

Hope that helps!

Jacqui