Investigation of dose optimization in early stage glottic laryngeal radiotherapy

In this study, it was aimed to statistically investigate the treatment plans retrospectively obtained by 3-Dimensional Conformal-RT (3B-CRT), Intensity Modulated-RT(IMRT), Intensity Modulated Arc-RT(IMAT) and Tomo-Helical-IMRT(TH-IMRT) techniques of 15 patients who had radiotherapy, in terms of target volume doses, risky organ doses and MU. The computerized tomography images of the patients were obtained from the Institute of İ.Ü Basic Oncology.2.12 Gy per fraction in total 33 fractions treatment dose is prescribed. It was aimed that 95% of PTV-63 and PTV-70 treatment volumes received the treatment dose of at least 63 and 70 Gy respectively. No lymph nodes were irradiated. Conventional-boost technique is used for 3D-CRT and simultaneous-integrated-boost (SIB) technique is used for IMRT, IMAT and TH-IMRT. The ICRU 83 reporting guidelines were followed for the evaluation of treatment volumes. Statistically significant better conformity and homogeneity index values were obtained byIMRT, IMAT and TH-IMRT compared to 3D-CRT (p<0,05).No significant difference was found betweenIMRT, IMAT and TH-IMRT (p>0,05).The average spinal cord maximum dose values obtained by 3D-CRT and receiving 5 Gy volumes were found to be lower than the IMRT, IMAT and TH-IMRT(p<0,05). When dose-volume values of the carotid arteries, thyroid and submandibular glands were examined, significantly lower values were obtained byIMRT, IMAT and TH-IMRT than 3D-CRT (p<0,05).Optimal MU values were obtained byIMAT. In EGL radiotherapy, there are cases in which 4 different techniques give superiority to each other. IMRT, IMAT, TH-YART are more appropriate than 3D-CRT for target volume and critical organ dose values outside the spinal cord.