Forums SGRT – Best Practice Head and neck setup Reply To: Head and neck setup

Marko Laaksomaa

Now I have something to tell about head and neck setups. I do not have any data yet due to small amount of patients treated with AlignRT and 3 point open masks. I can give you our first experiences of workflow. We have used open 3-point masks and AlignRT with some patients in our preliminary study. The thing that we consider important at the CT is that the shoulders of the patient are relaxed and kept caudally, and patient bites teeth normally. The ROI we use for setup and monitoring is the faceROI. At the setup process we first use lasers to check tattoo on the patient sternum and markings on the mask to see the initial straightness of the entire patient. Then with the AlignRT faceROI we setup the head. We can use AlignRTs send to couch feature at the time pitch, roll and rot are below 1 degree, after we have done possible setup corrections on patients head with faceROI in other words. This means that with faceROI we do not correct the entire patient rotation. Then we check with postural setup the shoulders. If there is need to setup the shoulders or chest wall posture based on 3 cameras with postural setup, we do that. If this video based shoulder setup affected on faceROI deltas, we will correct those before IGRT, with the head setup when rotations are concerned and with send to couch feature if isocenter needs corrections. This practice seems promising. We tested to use two ROI at the same reference surface in our own testings: faceROI and neck/cranial chest wallROI, but with that combination nodding movement of the head for example was underestimated in the deltas. The other and possibly more accurate possibility is to separate those named ROIs in the setup process, but it takes more time than current faceROI+postural, and this is why we try this less time-consuming combination in the first place. Then we do not need to jump between ROIs at the setup. To achieve good SGRT surfaces seems important to achieve good accuracy in the images, so when the images looks good without displacement of the structures, we acquire SGRT surface and try to use that as accurately as possible on the next days setup. It is interesting to see the first results.
Outside the results, I can say that sometimes we have had difficulties to setup the shoulders accurately. Even with using the SGRT surfaces acquired after perfect images, on the next day images clavicula/s are not at their correct location and re-setup is needed. So, mostly it seems like we have to concentrate on to improve somehow the shoulder reproducibility in our workflow described earlier in the text, right now. Please, share your experiences.
Best regards Marko