Pelvic cancer is a severe disease which can be treated with Image guided radiotherapy (IGRT). IGRT is widely used for treatment of cancerous tumors. The goal of the IGRT process is to improve the accuracy of the radiation field, and to reduce the exposure of healthy tissue during radiation treatments. This is obtained by acquiring 3D medical images of the patient and from the images delineate the tumor clinical target volume (CTV). An accurate delineation of the CTV allows an increased dose of radiation to the target, while reducing the exposure to the surrounding healthy tissue. Delineation of pelvic lymph nodes is important for treatment of several types of cancer in the pelvic region including cervical, prostate, colon, and rectal cancer. The pelvic lymph nodes are located adjacent to the arteries and their branches and are not visible in standard CT orMRI. However the iliac arteries are visible and can be used as a target for the lymph nodes by
adding a margin to the vessels.
AIM and SOLUTION: Based on CT images a segmentation of iliac arteries and there branches must be performed in order to define a target for the lymph nodes.
This is done by using region growing with 26 neighbours based on intensity and edge detection as the primary segmentation method as well as a removal of bone based on simple morphology. This segmentation method was constructed from knowledge of five datasets from patients with cancer in the pelvic region. The method was afterwards tested on nine datasets in order to demonstrate the delineation of CTV.