放射治疗中剂量梯度概念及其在临床中的应用

射线剂量场的剂量梯度可用哈密顿算子求出，剂量梯度可矢量运算方法求和，文中给出射线束的射束轴上各点剂量梯度的计算公式：当各射线束束轴相交于一点时，可由矢量和求出该点的合成剂量梯度。由此可估算出靶区剂量不均匀情况。文中提出中心零梯度假设：如果靶区中心剂量梯度为零，则靶区剂量分布均匀。文中学例证实了这一点。

THE CONCEPTION OF THE DOSE GRADIENT AND ITS APPLICATION TO RADIOTHERAPY

The dose gradient could be derived from radiation dose distribution function using Hamilton operator,The total gradient at any point is got according to the vector sum. The equations to calculating the gradI-ent on the centre axis of field are:If all the central axes of the fields intersected at one point ,The sum of the gradient at this point could be calculated and the heterogeneity of dose distribution in the terget could be estimated.The hypotheses proposed inthe paper is:if the gradient sum at the target centre is zero,the dose in the taget is homogeneous in this case.It isverified in the example.