Comparison of Dosimetric Parameters between Three-dimensional Conformal and Intensity modulated Radiotherapy for Cervicothoracic Spine Metastases / 中国医学物理学杂志

ABSTRACT

Objective:To compare the dosimetric parameters between three-dimensional conformal and intensity-modulated radiotherapy for cervicothoracic spine metastases.Methods:Totally 10 cases of patients with cervicothoracic spine metastases were devided into 2 groups3 patients with vertebral metastases;the other 7 patients with vertebral+annex metastases.The prescription dose for gross target was 60 Gy,D_(max) of spinal cord≤50 Gy,D_1≤45 Gy.Each patient was designed.One set of 3DCRT plan and three sets of IMRT plan were designed for each patient.We used 6 beams for 3DCRT plan,including 2 beams for the upper neck.3 sets of Step and shoot IMRT plans were consisted of 5-fields,7-fields and 9-fields,respectively,with equal angle and coplanar.DVH.CI and HI dose distributions of PTV and OARs were compared between 3DCRT and different set of IMRT plans.Results:(1)When the gross target included only vertebral,the CI of 3DCRT plan was lower than that of IMRT plan,but the HI of3DCRT plan was higher than that of IMRT plan.Moreover,5-fields IMRT plan was better than other plans.(2)When the gross target included vertebral and annex,the D_(80)、D_(mean) of IMRT PTV were higher than that of 3DCRT.As for spinal cord,5-fields D_(max)＜50Gy,7-fields D_(max)=49 Gy-51 Gy,9-fields D_(max)＞50 Cry.The CI of 3 sets of IMRT plans were 0.69,0.66,0.69,respectively.The CI of 3DCRT PTV was 0.53,worse than that of IMRT(P＜0.05).The average segments of 3 sets of IMRT plans were 83,104,160,and the average Mu of IMRT plans were 727,755,953,respectively.Conclusion:Compared with 3DCRT plan,the dose distribution,OAR and CI Of MRT plans were better.5-fields IMRT plan is recommended strongly.