Target volume determination with four-dimensional CT in radiotherapy for lung cancer

在基于相位的门控时，剂量测定参数和治疗时间相似，无论门控是在呼气末还是吸气末。在基于幅度的门控时，当门控在吸气末而不是呼气末时，肺剂量的减少更大，但是，治疗时间大大延长。当使用30%的占空比时，肺剂量的显著减少是以适度延长治疗时间为代价的，使用基于相位的门控在呼气末周围。三维肿瘤运动，头尾肿瘤运动，和头尾肿瘤位置是有用的预测肺癌患者的肺门控放射治疗的益处。肿瘤体积不是一个有用的因素。

At phase-based gating, the dosimetric parameters and treatment times are similar, irrespective of whether gating is around end-expiration or end-inspiration. At amplitude-based gating, a greater reduction in the lung dose is obtained when gating is around end-inspiration rather than end-expiration, however, the treatment time is prolonged considerably. When a 30% duty cycle is used, significant reduction in lung dose is achieved at the expense of modest prolongation of treatment time using phase-based gating around end-expiration.Three dimensional tumor motion, craniocaudal tumor motion, and the craniocaudal tumor position are useful for predicting the benefit of respiratory-gated radiotherapy in lung cancer patients. Tumor volume is not a useful factor.