Evaluation of Abdominal Aortic Bifurcation Level in Pelvic Cancer Patients Undergoing Radiotherapy: A Retrospective CT Based Analysis

Abstract

Indroduction: This retrospective study aims to investigate the implications of the bifurcation of the abdominal aorta on radiation therapy planning for cervical cancer patients, within the broader context of assessing CT scans of various pelvic malignancies. Methods: Patients who undergone radiotherapy for pelvic cancers between 2022 and 2024 were included in this retrospective study. The cohort comprised individuals diagnosed with cervical cancer, rectal cancer, and other pelvic malignancies. All patients undergone adequate immobilization in the supine position and received contrast-enhanced computed tomography (CT) simulation for radiotherapy planning, following a standardized bladder protocol. The level of division of the abdominal aorta into the right and left common iliac arteries, relative to the vertebral level, was determined and studied. Results: In our study of 40 pelvic cancer patients, the division of the abdominal aorta into common iliac arteries primarily occurred above and at the level of the L3-L4 intervertebral space in 52.5% (21/40) of cases, in front of the body of the L4 vertebra in 25% (10/40) of cases, and at the L4-L5 intervertebral space in 22.5% (9/40) of cases. Conclusion: The division of the abdominal aorta typically occurs at a higher level than the L4-L5 intervertebral space level in pelvic cancer patients. Our findings underscore the importance of utilizing CT scan-based planning for radiotherapy to accurately target treatment areas. However, in facilities where CT-based planning is unavailable, it is recommended to shift the upper border of the radiotherapy treatment portal above the L3-L4 intervertebral space for cervical cancers for optimal coverage of the iliac lymph node chain. These recommendations aim to ensure adequate radiation dose delivery while considering anatomical variations in pelvic cancer patients.