3D-Conformal Radiation Therapy and Intensity-Modulated Radiation Therapy Techniques for Laryngeal Cancer Taking Parotid Glands as Organ at Risk

Background: Three-dimensional conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy (IMRT) techniques are used for the treatment of patients with laryngeal cancer. Objective: This study aimed to investigate the effects of these 2 treatment techniques on the planning target volume (PTV) (laryngeal cancer), dose homogeneity, dose of organs at risk (OARs) (parotid glands), and conformity index. Methods: This study compared 2 treatment techniques and was conducted from October 2018 to April 2019 at the Zhianawa Cancer Center (ZCC), Sulaimaniyah, Iraq. Eight patients with laryngeal cancer were selected for this study. 3D-CRT and IMRT were used to produce the maximum dose of target volume coverage and minimum dose to the parotid glands. Elekta synergy with a photon beam of 6 MV was used for all measurements. Data analysis was performed using the available statistical package of SPSS 25. Results: The comparison of 3D-CRT with IMRT showed that the mean conformity index value for IMRT was more conformal than the 3D-CRT plan (0.956, 0.945, respectively), but the homogeneity index was better with 3D-CRT than with IMRT (0.175, 0.202, respectively). The mean dose for Rt. parotid glands was higher with IMRT than with 3D-CRT (232.71, 23.26, respectively), and in both plans the mean dose was less than 26 Gy (the standard tolerance value). While in the Lt. parotid gland the mean dose was higher with 3D-CRT than with IMRT (26.95, 23.71, respectively), the mean dose with 3D-CRT was greater than 26 Gy. The amount of PTV was significantly greater with the IMRT technique than with 3D-CRT (52.15±1.61, 51.09.4±0.74 Gy, respectively). Conclusion: This study further supports that IMRT has improved the long-term quality of life of patients with laryngeal cancer.