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Discuss best practices and workflow advice for Surface Guided Radiation Therapy on all treatment sites.
By marko_laaksomaa Finland flag
Hi all

I have done 100 patient 2D/2D image analysis of residual errors after daily IGRT in the area of c1, c5-7, mandible and base of the skull, which are the typical main bony landmarks of neck cancer radiotherapy for online evaluation with PTV including lymph nodes. SGRT was not used and Orfit 5 point masks were used. Images were taken before treatment. The calculated setup margins before treatment were inside 5 mm in all the investigated areas (m 2.5*Σ + 0.7xσ). Margin in the mandible was 5.0 mm. In the online image match radiation therapists compromised the structures very well and the masks were good enough to reach acceptable margins. Then I did smaller study (patient n=17) to investigate the residual errors of the named structures based on images which were taken after treatment and all the other landmarks were still inside 5 mm margin, but the margin for the mandible was 6 mm in VRT direction.

Is there a theory or way to setup or control the intrafractional movement of the mandible more precise with the AlignRT and to improve these great results? Does anyone have data that they have been able to setup the mandible better with AlignRT than without it? Nodding of the head is not the only movement which leads to this residual error.

Best regards Marko
By marko_laaksomaa Finland flag
Positioning reproducibility with and without rotational corrections for 2 head and neck immobilization systems, Courneyea et al. 2015. Someone could do that kind of study and only change the immobilization comparison to AlignRT open mask vs. closed mask without AlignRT comparison. I am interested in the realized accuracy of the structures on the edges of PTV before and after treatment, not rotations or couch shifts that has been done. Hope that someone does this in the future.
By tom_powis United Arab Emirates flag
Does anyone have any experience of creating a new workflow for head and neck patients using the AlignRT suggested ROIs? In my department we are planning to use these ROIs and I would be interested to hear of other people's experience, things to avoid and best practice. Also how successful did you find the ROIs?
Kind regards,
By marko_laaksomaa Finland flag
Hi Tom
Good question. I think this neck setup with SGRT is in the phase of progression and many hospitals are searching the best way to do it. The goal is to minimize the immobilization to make patient feel more comfortable inside the mask. Mike Tallhamer is having excellent presentation with the heading “Removing the Mask for H&N and Other Advancements in SGRT”. Please, check that video. As well, good new paper “Surface guided motion management in glottic larynx stereotactic body radiation therapy, Zhao et al 2020” handles this topic as well, from larynx RT point of view. Larynx is different target than large neck PTV and I am not handling it in my answer.
We have used AlignRT for neck patients only couple times, so my experience in practice is so far minor. We are planning to test neck setups with AlignRT in the near future anyway, after we have premeditatetly planned the entire workflow in the group.
My thoughts concerning the neck setup right now, at this point of the process, is that I would use 3 point open mask in neck RT with AlignRT, with proper support for chin and head in general ( ... patible/). ROI or monitoring area should not include mask material in any cases. I think it is important that patient bites the teeth naturally at the CT and treatment, to avoid from its part the displacement of the mandible, just like we do with the workflow of closed masks.
To setup the neck patient, I would go to planned couch values, which are typically acquired on the first fraction. Then I would switch AlignRT on, use faceROI (SRS brain ROI) to setup the head with AlignRT, and thereby eliminate the nodding effect of the head. This is supposed to have positive impact on mandible location accuracy in the images. Then I would use postural setup to adjust the shoulders and check the overall view of the patient around the treatment area. Then it is difficult at this point to say would I use both, either or neither cranial chestwallROI or neckROI (neck, clavicles, supsternal notch, laterally to the midcoronal plane). The latest one is suggested in the VisionRT ROI reference guide. At this point, to me it seems difficult idea to do corrections on the neck setup accurately, with the neckROI, even though it is the ROI around the isocenter. We can test this ROI with the colleaques with AlignRT, if you do not get any answers from the users that are following the VisionRT guidelines and use neckROI. In that practise, first we can acquire reference surface of our collaques head and neck, with AlignRT, and after that ask him/her to change the posture (move a little), and then try to re-setup our colleque to original posture with the aid of AlignRT with neckROI. After we are satisfied,the face ROI should be ok as well. Too difficult? May be I choose at this point 1) faceROI and 2) postural setup (shoulders and chest wall), 3) perhaps cranial chest wallROI, skip the neckROI and then go to acquire images.
During the fraction, we should typically monitor the area near isocenter, which in this case means neckROI. Still, only the location of the mandible exceeded the margin of 5 mm in the images taken after treatment in my data of closed 5 point mask patients. With neckROI mandible is not under control. With SGRT and in other hospitals with different workflows, situation can be of course different, if we can for example setup mandible to smaller residual error in the first place. Nevertheless, I would start to use faceROI for intrafractional monitoring with AlignRT and with video feature control the overall view of the patient. It would be great if we could monitor and see simultaneously two ROIs during the treatment with the AlignRT, in this case faceROI and neckROI.
One thing that you could do is to take contact on your local clinical application specialists. They can search some hospitals that are using the AlignRT system in neck treatments. Then you can discuss with the users, if they accept specialists request to discuss with you. Usually they/we do.
I hope I managed to bring something useful to you in my answer, with minimal practical experience concerning neck setup with AlignRT. I also hope that in year 2022 we have own data as an answer.

Best regards Marko
By marko_laaksomaa Finland flag
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
By marko_laaksomaa Finland flag
So, I matched offline some claviculas in the setup images in Group L (laser) with 5- point closed mask and in Group A (AlignRT) with 3 point open mask, one clavicula at the time. Workflow is outlined earlier in the text. Offline matching was performed to the claviculas point, which located 9 cm laterally from the bony vertebral midline in AP- kV- image. In total, 232 clavicula-match was performed in A and 528 matches in L. The combined (left + right clavicula) results demonstrate the residual errors of the clavicula after daily IGRT. If the re-setup was performed in either group due to displacement of the claviculas, the images before re-setup were included in the study. Thus, the results better demonstrate the real reproducibility of the setup itself. In the named point, residual error of the clavicula exceeded 6 mm in the setup images in the LNG in 23% (L) and 35% (A) of the fractions. The random error was smaller in group L than in Group A (3.8 mm vs. 5.7 mm p= 0.01). Margin needed in that point of clavicula, with daily IGRT, calculated with VanHerk formula was 1.1 cm in both groups.
I think that in the cases where raw systematic displacement of the clavicula exists, with SGRT it is easier to reduce this error with new reference surfaces. If systematic clavicular displacement error exists in Group L, it is in theory more difficult to approximate the new correct location of the shoulders inside the 5-point mask and reproduce this at the setup daily. The number of patients is still too small, but the beginning demonstrates that with postural setup, we need more practice to setup shoulders accurately. Otherwise AlignRT with neck patients seems promising. Lastly, on the first phase of the study patients had ring on their hands to hold. In these results given above, most of the patients had this ring. We considered not to use that ring now, instead arms now lay relaxed on the side. It seems to be easier to setup such arms/shoulders with postural setup. I know, that we will get this shoulder reproducibility with AlignRT to acceptable level soon, but this text could be a word of caution, change to SGRT in neck will not necessarily happen completely without challenges.
The ones that are using postural setup to setup shoulders in neck RT, please could you give some tips here or with e- mail Thank you.
By marko_laaksomaa Finland flag
Hi all
…With current workflow, where patients arms now are set relaxed on the sides, clavicular displacement errors after daily IGRT (online match typically performed based on c3) in LNG direction are smaller in comparison to previous data with AlignRT. As well we begin to learn how to use postural setup etc. 6 mm or larger clavicular displacement exists now in 21% of the offline matched cases (offline matched claviculas n=180 in new data). The random error is 4.3 mm and no difference between 5 point open mask and AlignRT open mask group exist anymore (p=0.41). All the patients still have outliers concerning shoulder reproducibility and still even 2 cm clavicular displacements were noticed in latest data too. This is typical with 5- point masks as well and shifts can occur equally both early and late in treatment. (Neubauer et al. Assessment of shoulder position variation and its impact on IMRT and VMAT doses for head and neck cancer). Weight loss and thereby changed body contour for example is well controlled with new reference surfaces with AlignRT in comparison to 5- point masks without SGRT, in the cases when treatment is allowed to continue without re- planning. I have never offline matched claviculas before this study and it was a surprise how much claviculas can have displacement inside 5 point masks. At the same time with clavicular matches (reported here), I have done comparison of residual errors to c1, c5/7, mandible and base of the skull between the Groups (AlignRT+ 3 point open mask+ daily IGRT) and (laser setup+ 5-point mask+ daily IGRT). No difference in the residual errors or errors between the structures exist between the groups so far. Calculated residual margins in the named locations are 5 mm or below with daily IGRT. Methods to offline evaluate the images are taken from paper published over 10 years ago, but which is still relevant to demonstrate the complexity to treat accurately the large neck PTV (van Kranen et al. Setup Uncertainties of Anatomical Sub-Regions in Head-and-Neck Cancer Patients After Offline CBCT Guidance). It has also been reported that when we reduce the mask material (from 5- point mask to 3 point mask for example), patient is feeling less anxiety (Sharp et al. Randomized trial on two types of thermoplastic masks for patient immobilization during radiation therapy for head-and-neck cancer). This is our goal as well with SGRT and with open masks. With AlignRT faceROI in SRS treatments good setup results for the skull are found in comparison to CBCT 6D data, which was considered as a reference (Lee et al. Accuracy of surface-guided patient setup for conventional radiotherapy of brain and nasopharnx cancer). If in addition to this patient keeps the mouth closed similarly at the CT and at the linac, faceROI should be a good starting point to reach good accuracy in the mandible and in the base of the skull, which are important landmarks in the neck RT. Now it seems that this AlignRT head and neck setup workflow which was presented in the SGRT community first by M. Tallhamer, seems to work well with small additional adjustments. Lastly, it seems that taking the new SGRT surface for the setup is often necessary (after perfect images) if we want to see and setup the straightness of the patient with postural setup, since DICOM typically ends too cranially. Lets hope that we can keep the same good course as we have at the moment with AlignRT neck RT and slightly improve the shoulder reproducibility. I will let you know again at some point. All the best!

Best regards Marko
By marko_laaksomaa Finland flag
…to be continued. Head and neck groups evaluated further, 3- point open masks with AlignRT (A), 5 point closed masks with laser setup (L) with daily IGRT. Residual errors are evaluated after online match couch corrections, online matched location was near vertebrae c2-c3. I have offline matched both claviculas (only LNG direction, AP image), one at the time, at the location of 9 cm from mid-vertebrae laterally. Earlier reported results with 5- point mask: 528 claviculas (264 right, 264 left) matched (LNG), 23 % exceeded 6 mm, systematic error 3.4 mm, random error 3.8 mm, margin 1.1 cm. Now with 3 point masks, with the aid of postural video, with AlignRT: 440 claviculas (220x2) offline matched (LNG), 18 % exceeds 6 mm, systematic error 2.1 mm (p=0.06), random error 4.3 mm (p=0.13), margin 8.3 mm. With SGRT, systematic error is improved (as expected and which is a good thing), but there is still too much daily variation. On the other hand, neither errors are statistically different between the groups. Latest we have noticed that “surface deformation” workspace is a good and quick aid, in the cases when the shoulder positioning is challenging with video view only. I am waiting for the CBCT- studies, which compares the residual errors of the bony sub- regions around and inside PTV (posture/deformations) with SGRT setup and with laser setup. We have promising results with AlignRT.

By helga_gripsgard Iceland flag
Hi, and thanks for a usefull discussion!
We are considering the value of using align in h&n patients, hoping to be able to improve reproducibility of mandible- and shoulder position. We use daily cbct for image guidace in h&n, sometimes combined with kV imaging to adjust the mandible. Patients are immobilized with three-point or five-point mask. In your experience, what is the potential value in reducing the need of replanning and what kind of mask is required to get the best out of using align for h&n?
By marko_laaksomaa Finland flag
Hello Helga
Thank you very much of your feedback. Neck is a complex treatment site for radiation therapy in several ways. It is a site, which demands high accuracy to protect the organs at risk, such as parotid and submandible glands and medulla. As well, shrinking of the body outline due to weight loss and tumor shrinking may cause underdosage of the target. Volume changes and/or displacement of the named structures typically leads to re- planning to optimize local control, overall survival and quality of life.
In addition to changes in internal soft tissue anatomy, head and neck patients have daily variation in bony structures. Bony regions best demonstrate whether the posture of the patient is good or not. This is something that we can affect with fixation, positioning and with good workflows in making the masks. In the literature, this relationship between the bony sub-regions around and inside large neck PTV is firstly and best demonstrated in the study of van Kranen et al. For C1, C7/TH1, mandible and occiput bone we have 5 mm action level after daily image guidance in our unit. The reason that we do not accept larger than 5 mm residual errors in bony structures is from this part to save the organs at risk and to ensure correct hitting to the target.
If I consider the posture things between AlignRT and 3 point open masks and 5 point closed masks with laser setup then. Inside 5 point closed mask systematic shoulder position errors seems to be more difficult to evaluate and daily correct than with 3 point open masks with AlignRT and postural video. FaceROI and positioning the pitch delta to zero error with AlignRT, seems to lead to excellent mandible accuracy, if patient bites the teeth similarly at the CT and at the linac and if the systematic errors in the DICOM are corrected with taking the new reference surface for the setup, when needed. Good headrest is important in all the cases and using time to find a good headrest at the CT seems mandatory, since I do not for example know, is it possible with SGRT to detect small spine pitch errors at the positioning. Small spine pitch is typical, but not the main problem with these neck patients with 5 point closed masks. May be deformation workspace could be useful to detect these errors with colors. We have not had such large systematic spine pitch errors yet, so difficult to say. With AlignRT, we have used Orfit 3 point open face hybrid masks, which are rather robust. The good thing is that typically head is in good posture in the first place with those masks (rotation deltas below 1°) after automatic send to couch with Truebeam, but if it is not, the head posture seems difficult to correct inside the mask from rotations and rolls part. To remove the mask and position the head without mask may improve the positioning, but may as well force the head to the same incorrect rotations after installing the mask back onto patients face. AlignRT 6D correction is not the solution in neck cases, since faceROI is NOT demontrating the whole area of the large neck PTV. Possibly, for this head positioning problem and to make patient feeling more comfortable, to use even more minimal mask material only to support the chin (which is done in USA for examle), seems justifiable. One thing to mention is that 3 point open mask positioning is slightly more time consuming, since with 5 point closed masks with laser setup, we only need to check the straightness of the patient with lasers, check that the head/mandible and shoulders are in their correct location inside the mask, then use Truebeam automatic function to go to planned couch values. This is the moment where the laser setup with 5 point masks ends, but as well the moment where positioning with faceROI and with postural video with AlignRT and 3 point open masks only begins. However, I think that everything is worth it with AlignRT, due to found excellent accuracy on the mandible with faceROI, small systematic errors of the shoulders, improved patient comfort (publication) and possibility for intrafractional control. Evaluation is in progress, but this is how it seems now.

Best regards Marko