Document Type : Original Paper
Authors
1
Higher Institute of Nursing Professions and Health Techniques, Ministry of Health and Social Protection, Rabat-Morocco
2
Radiotherapy Department, National Institute of Oncology, University Mohamed V, Rabat - Morocco
10.22038/ijmp.2024.78807.2394
Abstract
PURPOSE:To investigate the performance of Volumetric-Modulated Arc Therapy VMAT with the traditional 3D Conformational Radiotherapy 3D-CRT on head and neck carcinoma. The techniques were compared in terms of the planning target volume dose distributions, Organs At Risk dose volume histograms and treatment delivery parameters.
METHODS AND MATERIALS: For 7 randomly selected patients, Two plans were generated in Monaco Treatment Planning System: one with 3D-CRT and the other with VMAT. The prescribed dose was on Three levels of planning target volumes with 70/63/56Gy for five patients and with 69.96/59.4/54Gy for Two, in 35 and 33 fractions, respectively. The results were statistically analysis with the t-test. The pretreatment quality control for VMAT plans was done.
Results:The mean of the Dmean, Dmax, V95% of PTV70Gy were 70.86/70.23Gy, 78.95/75.28Gy, 95.35% / 96.97%, respectively for the 3D-CRT and VMAT. The spinal cord, brainstem and chiasma Dmax were 49.98/40.76Gy, 64.05/50.00Gy and 54.27/47.78Gy, respectively. For the Left and Right parotids the average of the mean dose was 66.93/44.18Gy and 67.79/44.98Gy. The Dmax in L and R optic nerves and eyes were 60.17/50.41Gy, 59.44/48.49Gy, 48.4/39.88, 44.09/36.93Gy. The 0.03cc of the L and R temporal lobes received 73.37/68.33Gy and 73.17/68.33Gy. The mean dose in 2cc of the mandible was 72.88/66.99Gy. The mean volume of the larynx with 66Gy was 23.72% / 0.76%. The Homogeneity and Conformity Index (HI and CI) had as average 1.32/1.07 and 0.95/0.97, respectively .The mean of the treatment time and the MUs for 3D-CRT/VMAT were 3.35/6.36 min and 1478.86/621.53 MUs.For the VMAT plans, the mean passing pixel percentage for the gamma index was 98.6%.
CONCLUSION:The VMAT limits the irradiation, minimizes the toxicity of OARs and allows a higher dose to the target volume and avoiding the cold and the hot spots. This study demonstrates that VMAT achieves superior normal tissue protection as compared to 3D-CRT.
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