comparison between two-photon treatment planning techniques 3d-conformal radiotherapy and the volumetric modulated arc therapy for head and neck carcinoma

Introduction: achieving precise dose delivery in head and neck cancer is challenging, requiring effective tumor control while minimizing toxicity. this study compares volumetric-modulated arc therapy (vmat) and 3d conformal radiotherapy (3d-crt), focusing on target coverage, organs at risk (oars) sparing and treatment efficiency.material and methods: for 7 randomly selected patients, two plans (3d-crt and vmat) were created using monaco tps. the prescribed doses were 70/63/56gy for five patients and 69.96/59.4/54gy for two, in 35 and 33 fractions. the t-test was used for statistical analysis. vmat plans underwent pretreatment quality control.results: the mean dmean, dmax, and v95% of ptv70gy were 70.86/70.23gy, 78.95/75.28gy, and 95.35% / 96.97% for 3d-crt and vmat. the dmax for the spinal cord, brainstem and chiasma were 49.98/40.76gy, 64.05/50.00gy, and 54.27/47.78gy. the mean dose for the left (l) and right (r) parotids was 66.93/44.18gy and 67.79/44.98gy. the dmax for l/r optic nerves and eyes were 60.17/50.41gy, 59.44/48.49gy, 48.4/39.88, and 44.09/36.93gy. the 0.03cc of the l/r temporal lobes received 73.37/69.59gy 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 were 0.12/0.08 and 0.95/0.97. the treatment time and mus for 3d-crt/vmat were 3.35/6.36 min and 806.86/621.53 mus. vmat gamma index passing rate was 98.6%.  conclusion: the vmat limits irradiation, reduces oars toxicity, assures higher target dose and avoids cold and hot spots. this study shows that vmat provides superior normal tissue protection as compared to 3d-crt.