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.
OBJECTIVE
Although Radiation Therapy Oncology Group protocols have proposed a limiting dose to the brachial plexus for patients undergoing intensity-modulated radiotherapy for head-and-neck cancer, essentially no recommendations exist for the delineation of this structure for treatment planning.


METHODS
Using anatomic texts, radiologic data, and magnetic resonance imaging, a standardized method for delineating the brachial plexus on 3-mm axial computed tomography images was devised. A neuroradiologist assisted with identification of the brachial plexus and adjacent structures. This organ at risk was then contoured on 10 consecutive patients undergoing intensity-modulated radiotherapy for head-and-neck cancer. Dose-volume histogram curves were generated by applying the proposed brachial plexus contour to the initial treatment plan.


RESULTS
The total dose to the planning target volume ranged from 60 to 70 Gy (median, 70). The mean brachial plexus volume was 33 +/- 4 cm(3) (range, 25.1-39.4). The mean irradiated volumes of the brachial plexus were 50 Gy (17 +/- 3 cm(3)), 60 Gy (6 +/- 3 cm(3)), 66 Gy (2 +/- 1 cm(3)), 70 Gy (0 +/- 1 cm(3)). The maximal dose to the brachial plexus was 69.9 Gy (range, 62.3-76.9) and was >/=60 Gy, >/=66 Gy, and >/=70 Gy in 100%, 70%, and 30% of patients, respectively.


CONCLUSIONS
This technique provides a precise and accurate method for delineating the brachial plexus organ at risk on treatment planning computed tomography scans. Our dosimetric analysis suggest that for patients undergoing intensity-modulated radiotherapy for head-and-neck cancer, brachial plexus routinely receives doses in excess of historic and Radiation Therapy Oncology Group limits.
Hall
William H
WH
Department of Radiation Oncology, University of California, Davis, Cancer Center, Sacramento, CA, USA.
Guiou
Michael
M
Lee
Nancy Y
NY
Dublin
Arthur
A
Narayan
Samir
S
Vijayakumar
Srinivasan
S
Purdy
James A
JA
Chen
Allen M
AM
D001917:Brachial Plexus / Q000033:anatomy & histology* / Q000473:pathology / Q000528:radiation effects*; D006258:Head and Neck Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D006801:Humans; D008279:Magnetic Resonance Imaging; D009367:Neoplasm Staging; D011879:Radiotherapy Dosage; D015203:Reproducibility of Results