Comparative analysis of simultaneous integrated boost intensity-modulated radiotherapy treatment plans in the cervical and upper thoracic esophageal carcinoma

TAN Cheng; YANG Yanguang; HANG Daming; NI Feng; CAI Jing

Abstract：Objective To compare the dosimetric parameters of 4 simultaneous integrated boost intensity-modulated radiother-apy (SIB-IMRT) treatment plans with different beams. Methods Four SIB-IMRT treatment plans with different beams of 3, 5, 7 and 9 were designed for twenty-four eligible patients with cervical and upper thoracic esophageal carcinoma. PTV-G and PTV-C were de-fined as the GTV and CTV plus 10 mm in all directions, which were delivered simultaneously to 60. 2 Gy and 56 Gy in 28 fractions, re-spectively. Compared and evulated the dosimetric parameters of planning target volums and organs at risk(OARs) through the DVH di-agram. Results The values of conformity index (CI) and heterogeneity index (HI) of four SIB-IMRT treatment plans with different beams of 3, 5, 7 and 9 were 0. 33,0. 55,0. 77,0. 80 and 1. 09,1. 07,1. 07,1. 05 in PTV-G,with significant difference(P<0. 05). The values of CI and HI of SIB-IMRT treatment plans with four different beams were 0. 69, 0. 71,0. 72,0. 79and 1. 22,1. 13,1. 075,1. 073 in PTV-C,with significant difference (P<0. 05). The values of maximal dose of spinal cord were 4511. 27,4288. 31, 4224. 60 and 4201. 43 cGy in 3,5,7,9-beams SIB-IMRT plans (P<0. 05). With increased beam numbers, the V5 increased and the V20 decreased. The 9-beams plan had significantly increased V5 and nonsignificantly decreased V20 compared to the 7-beams plan. The V5 and V20 were 44. 56% and 19. 28% in 9-beams plan and 32. 36% and 19. 65% in 7-beams plan. Conclusion 7-beams SIB-IMRT plan was the pre-ferred technique in cervical and upper thoracic esophageal carcinoma with uniform target dose and high degree conformity, which could provide the best protection to the lung and other vital organs.