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This is the page for Brachial Plexus Contouring session.
You can contour the brachial plexus as follows:
- Identify the C5 vertebrae and the neural foramina of the vertebra
- Window setting - Mediastinum adjusting fat to be black so that the fat space between the muscles become evident.
- Use a 5 mm static brush to contour the brachial plexus:
- Start from the lateral aspect of the spinal canal
- Along the neural foramina
- Laterally upto the fat space that forms the level III
- Along the lateral processes of the vertebrae (thats where the spinal nerves exit)
- Direction antero lateral
- Contour the fat space that is posterolateral to the anterior scalene muscle
- In the lower slices there will be slices where there is no neural foramina .. in them just contour upto the vertebral body
- In the slices where you see the neural foramina extend contour inside. Typically this will be seen every 4 slices in a 2 mm thick slice CT
- After the first rib starts the contour ends medial to the first rib
If you have contoured it all right then there will be four roots coming out alongside the C5, C6, C7 & T1.. see that in the TPS using the topogram view
Practice the contouring below. Please leave your comments below. You can use any name you want including guest.. and no requirements for a password. The contour on the left is "standard" - however if you see a mistake feel free to correct it and tell us why you think its wrong like pranshu did in the comments below. Please remember we are also trainees .. so in case you spot a glaring error correct us
For references and additional comments please see Pranshu's valuable comments below
its great….and the comments are also interesting and informative .
Few small points referred to in the articles above
1] The complete fat space between the anterior and the middle scalene muscles should be contoured. So image 11, 13 would need adjustment accordingly.
2] I think in the slices 18-20 the plexus is lateral and not posterior to the subclavian vessels.
3] For planning of breast fields (especially at field matching between tangents and SCV field) or for pancoast tumors, we may need to extend the contour beyond into axilla for getting complete dosimetry information.
4] Dose constraints
Hi Pranshu, Good points there.
The thing with scribblar is what I am contouring is not necessarily a 5 mm brush.. so when contouring in Eclipse is concerned a 5 mm brush will definitely encompass the fat space.. your contours on the left side (in black) are definitely more correct.
Actually if you read the guidelines given by Wall et al which is essentially quoted in Truong's paper too and I quote here from them
However the contouring atlas given by Wall et al does indeed show the contours as lateral to the vessel .. I think that is essentially an artefact of the way the the planning CT was taken. The anatomy pics thoug make it apparent in axial CT slices it will be posterior as well as lateral to the subclavian artery
I should have been more clear but had to put this in hurry as we had plans for evening.. Anyways this is for head and neck only. For breast and chest I will try to see if I can obtain something with arms above the head which will make a very interesting exercise. Although Wall et al tell us to contour about 1 - 2 slices below clavicular head I usually contour about 1 cm below the PTV specially in cases where PTV can actually go in the supra-calvicular region keeping 1 -2 cm below clavicular head may be inadequate.
About the dose constraint 60Gy Dmax is really conservative in my opinion … the new lung protocol 0839 of RTOG has kept 66 Gy as Dmax. We can have a discussion on this at the forum though
Here is a summary of brachial plexus constraints from some recent North American trials (as you can see everyone is shooting in the dark?):
RTOG 0435 (A randomized, phase III, double-blind, placebo-controlled study to evaluate the efficacy and safety of palifermin for the reduction of oral mucositis in patients with locally advanced head and neck cancer receiving radiation therapy with concurrent chemotherapy (followed by surgery for selected patients))
‘The dose to the brachial plexus must be limited to 60 Gy in patients with level IV node(s).’
RTOG 0522 (A randomized phase III trial of concurrent accelerated radiation and cisplatin versus concurrent accelerated radiation, cisplatin, and cetuximab [followed by surgery for selected patients] for stage III and IV head and neck carcinomas.)
‘The dose to the brachial plexus must be limited to ≤ 60 Gy in patients with level IV node(s).’
RTOG 0615 (A phase II study of concurrent chemoradiotherapy using three-dimensional
conformal radiotherapy (3D-CRT) or intensity-modulated radiation therapy (IMRT) + bevacizumab for locally or regionally advanced nasopharyngeal cancer)
‘The maximum point dose to the brachial plexus should not exceed 66 Gy.’
RTOG 0619 (A randomized phase II trial of chemoradiotherapy versus chemoradiotherapy and vandetanib for high-risk postoperative advanced squamous cell carcinoma of the head and neck)
‘No more than 5% of the volume of the brachial plexus can receive > 60 Gy, and none can receive > 66 Gy.’
NCIC HN.6 (A phase III study of standard fractionation radiotherapy with concurrent high-dose cisplatin versus accelerated fractionation radiotherapy with panitumumab in patients with locally advanced stage III and IV squamous cell carcinoma of the head and neck)
Brachial plexus – maximum point dose – 60Gy (3D-CRT) or 63 Gy (IMRT)
Interesting points there indranil.. the basic issue is do you compromise the target for brachial plexus in head neck? Can be a topic for an interesting discussion
Santam
In a radical setting in HN = I would not compromize dose to the high dose PTV because:
a) underdosing/missing the target is likely to result in a treatment failure that will be difficult to salvage
b) the risk of plexopathy at a reasonable dose above the suggested limit is never absolute, and quite poorly understood (and perhaps never more important than a recurrence)
In an adjuvant setting = I would certainly think about it, because I don't think there is a lot of high quality evidence on optimal adjuvant dosing (i.e. we don't know that giving 56-58 Gy in a small area is definitely worse than giving 60Gy).
This is my personal opinion of course.
1] Int J Radiat Oncol Biol Phys. 2008 Dec 1;72(5):1362-7. Epub 2008 Apr 28.
Development and validation of a standardized method for contouring the brachial plexus: preliminary dosimetric analysis among patients treated with IMRT for head-and-neck cancer.
Hall WH, Guiou M, Lee NY, Dublin A, Narayan S, Vijayakumar S, Purdy JA, Chen AM.
2] Radiographics. 2010 Jul-Aug;30(4):1095-103.
Brachial plexus contouring with CT and MR imaging in radiation therapy planning for head and neck cancer.
Truong MT, Nadgir RN, Hirsch AE, Subramaniam RM, Wang JW, Wu R, Khandekar M, Nawaz AO, Sakai O.
There's another recent reference, which shows contours with arms above the head, specially meant for SBRT lung. Although the above references suffice as well, it must be kept in mind that Hall's guidelines mention only 4 roots of BP instead of the actual 5, therefore should be modified accordingly.
Kong FM, Ritter T, Quint DJ, Senan S, Gaspar LE, Komaki RU, Hurkmans CW, Timmerman R, Bezjak A, Bradley JD, Movsas B, Marsh L, Okunieff P, Choy H, Curran WJ Jr. Consideration of Dose Limits for Organs at Risk of Thoracic Radiotherapy: Atlas for Lung, Proximal Bronchial Tree, Esophagus, Spinal Cord, Ribs, and Brachial Plexus. Int J Radiat Oncol Biol Phys. 2010 Oct 7. [Epub ahead of print]
Shikha
Exactly Sikha. In head and neck with axial scans the 5th root is tough to outline on Ct scans as it curves upwards to join with the 4th root and that is difficult to identify in axial CT especially as we have no references in that area (and here we are contouring the surrogates of the brachial plexus not the plexus it self. Its a limitation Wall et al have highlighted them selves actually.
The brachial plexus contouring session is now available at http://www.isocentre.org/headneck:brachial-plexus-contouring. Leave your comments below
I just tried it. Very good practice! It is not easy though! THANKS A LOT.