Evaluation of the Usefulness of Intensity Modulated Radiation Therapy Using Jaw-Tracking Method

Abstract

This study aimed to compare the changes in the radiation dose to the normal tissue and tumor in prostate cancer patients between the jaw tracking and fixed-jaw method through radiation treatment planning. To compare the volume dose in the IMRT (Intensity Modulated Radiation Therapy) plan according to the use of Jaw Tracking (JT), the HI (homogeneity index) and the CI (conformity index) for prostate cancer were compared based on the respective DVH (Dose Volume Histogram), and the volume doses of the bladder and rectum, as the normal organs in the vicinity of the prostate, were analyzed. The Delivery Time (DT) and Monitor Unit (MU) values were analyzed to compare the radiotherapy efficiency of the IMRT plan. The mean HI and CI with Fixed Jaw (FJ) were 0.9849 and 1.0863, respectively, while those with Jaw tracking (JT) were 0.9847 and 1.0802, respectively. The mean difference between the FJ and JT methods was 0.0002(CI) and 0.0061(HI). The dose evaluation result for the normal organs showed that the Dmean was 301.8 cGy in the rectum for JT, while the mean V20 and V30 were lower, at 2.8% and 1.1%, respectively. Also the dose evaluation result for the normal organs showed that the Dmean was 46.9 cGy in the bladder for JT, while the mean V20 and V30 were lower, at 2.6% and 0.9%, respectively. The MU and delivery time were also shown to be lower, at 0.1 MU and 0.1 min, respectively, upon the use of the JT. Based on our findings, the use of JT could reduce the mean dose and volume dose in normal organs, as well as the MU and delivery time, thereby improving the treatment efficiency.