Effects of horizontal beam on IMRT plan for lung cancer / 中华放射医学与防护杂志

ABSTRACT

Objective To explore the effect of horizontal beam on IMRT plan for lung cancer.Methods Totally 18 patients were enrolled,including 10 cases of left lung cancer and 8 cases of right lung cancer.Two intensity modulated radiation therapy (IMRT) plans were generatedone was the normal IMRT plan and another was the IMRT plan including a horizontal beam (H-IMRT).MUs,sub-field and the dose distribution of target and organs at risk (OARs) were compared.Results There were no statistically significant differences between two plans in D Dminand D of PTV,the V30 and D of the ipsilateral lung,V20 and V30 of the contralateral lung,and V30 of the total lung.When the horizontal beam was added,the PTV heterogeneity index (HI) and conformity index (CI) were significantly increased (t=-9.33,10.88,P＜0.05),the other dose index in lung was inferior (t =-1.55--7.58,P＜ 0.05),whleheart sparing were clearly better (t =1.84-3.99,P＜0.05),the number of MUs and segments were less(t =12.57,3.19,P ＜ 0.05).Conclusions IMRT in the treatment of lung cancer can further improve the PTV coverage when the horizontal beam is added.However,the increasing lung volume of low dose irradiation is not conducive to lung protection.