Treatment Planning Comparison of Intensity Modulated Arc Therapy and CyberKnife Techniques in Early Stage Glottic Larynx Radiotherapy

Abstract

We aimed to compare two radiotherapy techniques (the robotic-based linear accelerator Stereotactic Body Radiotherapy (SBRT) and linear accelerator-based Intensity Modulated Arc Therapy (IMAT)) dosimetrically on Early Glottic Larynx Cancerx (EGL) treatment plans in the terms of target volume and critical organ doses. The computerized tomography (CT) images of 15 patients treated with EGL diagnosis were used retrospectively. The Planning Target Volumes (PTV) was generated with a margin of 0.5 cm from the laryngeal volume. The PTV dose was defined as 45 Gy delivered in 10 fractions within each of treatment plans. At least 95% of PTV treatment volumes (D95%) were to receive the treatment dose. The average PTV volume was 95.56 cm3 (range: 68.8 cm3 - 142.6 cm3). The average D98%, D2% and Dmean values of PTV were lower in IMAT plan than in CK plan. In CK plans, the mean of the spinal cord maximum dose (Dmax) for all patients was statistically significantly lower than in IMAT plans. Dmax and Dmean values for the right and left carotid arteries was significantly lower in IMAT plans. Also, the Dmean value of thyroid gland was significantly lower in IMAT plans. Our dosimetric comparison study made using images of 15 EGL cancer patients shows that the desired critria for the critical organ doses can not reached with CK plans, especially when the treatment volume is large.