[问答题,简答题] 试述高剂量率后装治疗的优点。

腰椎牵引时产生摩擦力的重量约为人体体重的() ["A．40%","B．50%","C．60%","D．70%","E．80%"] 试述放射线作用机制。 锁骨上皮肤皱褶的宽度一般为() ["A．2～3cm","B．3～5mm","C．2～3mm","D．5～6mm","E．3～5cm"] 气管隆突是指气管() ["A．分叉部","B．分叉部偏左侧","C．分叉部上壁","D．分叉部右壁","E．分叉部下壁"] 高剂量率、中剂量率和低剂量率有何不同? 试述高剂量率后装治疗的优点。