Related Experiment Video
Updated: Jan 23, 2026
Single-unit In vivo Recordings from the Optic Chiasm of Rat
Published on: April 2, 2010
Development of a contouring guide for three different types of optic chiasm: A practical approach
Wenhao Chen1, Hui Zhang1, Wenyi Zhang1
1Department of Chemoradiotherapy Oncology, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China.
Introduction:
Sparing of the organs at risk (OARs) 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.
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