Normal tissue tolerance dose for cervical radiotherapy to the NTCP model using a method of least square fit

Abstract

The purpose of this study is to evaluate the impact of Normal Tissue Complication Probability (NTCP) models on radiation treatment plans. We estimated NTCP parameters for the organs at risk (OARs) for cervical cancer radiotherapy. We pooled individual patient data from fifty patients who were treated with External Beam Radiotherapy technique between March 2012 and November 2013 in a part of Northern Nigeria with the exclusion of patients who had other gynaecological malignancies. Three basic methods were followed during the radiotherapy planning of these patients which included the pre-planning stage, planning radiotherapy treatment stage and treatment delivery. Various tests were carried out on these patients which helped to confirm the diagnosis after which they were treated using the linear accelerator, computed tomography simulator and the treatment planning system. We calculated the normal tissue tolerance doses for partial volumes of the organs using the values of the above –said parameters for published data on normal tissue tolerance doses. This article shows a graphical representation of the computed NTCP for left femur, right femur and skin presented and a fairly good correspondence is found between the curves for head of femurs and skin.

Keywords: Normal Tissue Tolerance Dose, Normal Tissue Complication Probability, Method of Least Square Fit, Cervical Radiotherapy