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Development of a contouring guide for three different types of optic chiasm: A practical approach
Author(s) -
Chen Wenhao,
Zhang Hui,
Zhang Wenyi,
Su Meng,
Xie Raoying,
Li Kejie,
Xia Xiaofang,
Zou Changlin
Publication year - 2019
Publication title -
journal of medical imaging and radiation oncology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.31
H-Index - 43
eISSN - 1754-9485
pISSN - 1754-9477
DOI - 10.1111/1754-9485.12903
Subject(s) - medicine , contouring , optic chiasm , magnetic resonance imaging , supine position , nuclear medicine , atlas (anatomy) , radiation therapy , optic nerve , radiology , head and neck , computed tomography , anatomy , surgery , engineering drawing , engineering
Sparing of the organs at risk ( OAR s) is a crucial task in daily radiotherapy practice. Irradiation of the optic chiasm ( OC ) results in radiation‐induced optic neuropathy ( RION ). The structure of the OC is complex, and OC morphology can vary in axial images. Therefore, a standard atlas can result in inaccurate descriptions of OC morphology in different patients. The aim of our study was to provide a guide based on computed tomography ( CT ) for the delineation of different types of OC . Methods Thirty‐six patients were selected to participate in our study. These patients underwent CT analysis of the brain, head and neck regions in a supine position. Axial images 3 mm in thickness were obtained at 3‐mm intervals. A magnetic resonance imaging ( MRI ) study was also performed using the same set‐up. The OC was then delineated. The contours were revised by three neuroradiologists and nine radiation oncologists with > 5 years of expertise. Results Three types of OC were distinguished by magnetic resonance ( MR ). The location and boundaries of normal, prefixed and postfixed chiasms were developed with a CT ‐based atlas. Discrepancies were observed in the delineation of the prefixed and postfixed OC . Conclusions Our guide allows improved definitions of the anatomical boundaries for different types of OC . Our experience could provide useful information for radiation oncologists in daily practice.