A Dosimetric Plan Study to Increase the Dose from 63 Gy to 70 Gy in Early-Stage Glottic Larynx Cancer

Abstract

OBJECTIVEThe present study aims to compare the treatment plan parameters of different radiotherapy techniques[3D-Conformal Radiotherapy (3D-CRT), Dynamic – Intensity Modulated Radiotherapy (D-IMRT), IntensityModulated Arc Therapy (IMAT) and Helical Tomotherapy (HT)] in Early-Stage Glottic Larynx(EGL) cancer to increase the treatment dose from 63 Gy to 70 Gy.METHODSThe dose prescription was defined as 2.12 Gy per fraction to a total of 33 fractions. 95% of PlanningTreatment Volume-63 Gy (PTV-63) and Planning Treatment Volume-70 (PTV- 70) treatment volumesreceived the treatment dose of at least 63 and 70 Gy, respectively. The conventional-boost techniquewas used for 3D-CRT and the simultaneous integrated boost technique was used for other techniques.RESULTSThe doses obtained from carotid arteries, thyroid and submandibular glands using IMRT, IMAT, andHT were significantly lower than 3D-CRT. The study results pointed out the possibility of giving a treatmentdose of 70 Gy to the PTV of EGL with all planning techniques, with some advantages and disadvantagesbetween them. All IMRT techniques provided superiority to 3D-CRT on the doses of thecarotid artery, the thyroid gland, the submandibular glands, and the pharyngeal constrictor muscleswith less variation between them.CONCLUSIONThe IMAT and 3D-CRT techniques yielded lower monitor unit values compared to other techniques.Normal tissue radiation exposure was lowest with the 3D-CRT technique. We recommend to increasethe treatment dose from 63 Gy to 70 Gy in the radiotherapy of EGL cancer but to select the techniqueaccording to the patient’s condition.