Background: Lung cancer is a common disease for patients over the age of 50 years, especially males due to smoking habits. This study aimed to compare the modulation complexity score (MCS) for the advanced treatment planning techniques which the intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT). Materials and Methods: Thirty patients who had non-small lung cancerous tumors on their left side participated in this study. The range ages were 68 to 98 years, the heights were between 151 and 182cm and they having weights from 46 to 79 kg. For Each patient will create two plans dial using two different techniques, which will be Intensity Modulated Radiation Therapy (IMRT) and Volumetric Modulated Arc Therapy (VMAT) in the Monaco 5.1 version, and then those plans will be forwarded to the Infinity Linear Accelerator (LINAC). For the purposes of evaluation, the dose volume histogram is utilized to perform the calculation necessary to determine the dose for tumors and Organs at Risk (OAR). After that, the modulation complexity score, also known as the MCS, was determined using the multiyear collimators of the plans. Results: Showed that the mean age of males was (82.6 ± 4.93) years, while the mean age of females was (72.12 ± 3.13) years. The proportion of males was significantly higher than that of females. The female patient had a higher body mass index than the male patient. The mean height of men in this study was (172.85 ± 2.02) cm, while the mean height of women was (156.32± 1.21) cm. The coverage planning target volume (PTV) for the left lung tumor shows that the VMAT was significantly higher than the IMRT at 95%, 98%, 5%, and 2%. When comparing IMRT and VMAT for the PTV 105%, there was no discernible difference between the two. According to the statistics, the conformity and homogeneity of the dose delivered by the VMAT was noticeably higher than those delivered by the IMRT. According to the findings of the study, the MCS score for the VMAT is noticeably higher than that of the IMRT. In the case of the IMRT technique, the relationship between the MCS and the total number of monitor units was found to be positive and direct, whereas in the case of the VMAT technique, the relationship was found to be negative and inverse. Conclusions: The volumetric modulated arc therapy (VMAT) shows a better coverage and less complexity technique and could protect the heart, spinal cord, and right lung than the IMRT.