Determination of Radiotherapy Target Volume in Treatment of Chest Organs Using Image Processing Programs

Abstract

Motion during radiation treatment is consider as one of major challenges directly affect the treatment process and outcome. The general aim of this study was to measure the organ displacement caused by respiration specially in AP direction during radiotherapy of chest organ in order to predict the maximum and minimum margin of displacement caused by such problem in order to determine the radiotherapy target volume using Auto contouring process in GE-CT machines. Analytical case control study containing more than 150 patients with known case of ca. lung or ca. esophagus and normal cases underwent CT scan using GE 16-slice machine for purpose of diagnosis and preplanning of conventional radiotherapy treatment at diagnostic centers and RICK in period from 2017-2019. Single slice (using SMART-PREP) are taken at the center of the mass at constant time interval usually 2 second, then using auto-countering process the maximum diameter and volume of the organs were taken in both respiration and expiration process also the tumor displacement measured also the organs displacement considered because we need to study the effect of organ general motion in treatment process. Right, left lungs and esophagus volumes and diameters were major study variables. The result showed there were significant difference for diameters and volumes measurement between both respiratory cycle when paired sample t-test was conducted at (p<0.05, CL=95%), and the mean value of difference (displacement) in diameter was 2.6, 3.2 and 3.9mm for right, left lung and esophagus respectively where the mean volume equal 129.6, 99.9, 2.8cm3 for inspiration and 127.2, 94.1, 2.9cm3 for expiration respectively. This study was concluding that conventional radiotherapy treatment planning need precise determination of treatment filed in order to exclude as much as possible the normal tissue from the treatment field.