Estimation of Dose Received by Sensitive Organs in External Radiation Therapy of Cervical Carcinoma

Abstract

The main objective of this study was to estimate dose received by sensitive organs in cervical carcinoma irradiation, out of 200 patients referred to Radiation and Isotopes Center of Khartoum (RICK). After successful investigations, the patients were decided to receive a radical radiotherapy course for stage I and II without hematologic spread. The collected variables were the organs position and depth, patient’s separations, equivalent field size, percentage depth dose DD% and back scatter factor. The graphs and correlation were carried out using EXCELL software and the analysis of results showed that: the bladder, cervix and rectum were situated parallel to each other from anterior to posterior respectively and they have linear correlation in depth wise with patient separation based in equation: y = 0.38x + 5.56, y = 0.39x + 1.82, y = 0.4x – 1.74 respectively, where y refers to organ depth and x refers to patient separation in cm with a significant correlation at R2

= 0.8. The DD% for the tumor (cervix), Bladder, head of femur and the rectum were 89.6%, 61.2, 50.2% and 38.1% respectively. The back scattered radiation increases as the tissue volume increases leading to increment of DD% and the back scatter factor increases exponentially with field size increment based on the following equation: y = 0.022lnx + 0.98, which is so significant at R2

= 0.7, where y refers to BSF and x refers to equivalent field size in cm.