Evaluation of adequacy of conventional radiotherapy fields based on bony landmarks in cervical cancer patients using contrast enhanced CT

Abstract

Introduction: Cervical cancer is the second leading cause of cancer death in Indian women. Although, it is known that in Western women the conventional pelvic fields based on bony landmarks provided inadequate coverage for pelvic lymph nodes in cervical cancer; it remains unclear in Indian patients because of the pelvic anatomic discrepancies. In the present study, we have tried to evaluate the adequacy of conventional pelvic fields based on bony landmarks by using CECT using pelvic vessels as surrogate of lymph nodes. Aims and Objectives: To evaluate the lymph node location in CECT pelvis using vessels as surrogate markers.(a) To compare the data, so obtained, with the usual radiotherapy field; where bony landmarks are used to define the field.(b) To evaluate the adequacy of radiation portal defined on bony landm-arks in covering pelvic lymph nodes. Materials and Methods: This study was conducted in the Department of Radiotherapy and Oncology, Regional Cancer Centre, IGMC, Shimla in patients suffering from carcinoma of cervix. Two dimensional radiation portals were designed on conventional simulator “Acuity.” CECT pelvis was done in the same position along with same immobilization accessories used during conventional simulation. 2 mm thick slices were taken from L1 to mid femur. Using vessels as surrogates for lymph nodes and applying Taylors guidelines, adequacy of conventional GOG field was judged. Results: Most of the parameters failed in this study, signifying inadequacy of GOG defined field in Indian population, detailed results will be discussed at the time of presentation.