Brahme A, Roos J E, Lax I
Phys Med Biol. 1982 Oct;27(10):1221-9. doi: 10.1088/0031-9155/27/10/002.
An integral equation relating the lateral absorbed dose profile of a photon beam to the resultant absorbed dose distribution during single-turn rotating-beam therapy has been set up and solved for the case of a cylindrical phantom with the axis of rotation coinciding with the axis of symmetry of the cylinder. In the first approximation the results obtained are also valid when the axis of rotation is somewhat off-centred, even in a phantom that deviates from circular symmetry, provided the rotation is performed in both clockwise and counter clockwise directions. The calculated dose profiles indicate that improved dose uniformity can be achieved using a new type of non-linear wedge-shaped filter, which can easily be designed using the derived general analytic solution to the integral equation.
已经建立了一个积分方程，该方程将光子束的横向吸收剂量分布与单圈旋转束治疗期间的最终吸收剂量分布相关联，并针对旋转轴与圆柱对称轴重合的圆柱形体模情况进行了求解。在一阶近似中，即使在旋转轴稍有偏心的情况下，甚至在偏离圆对称的体模中，只要旋转是在顺时针和逆时针两个方向上进行，所获得的结果仍然有效。计算得到的剂量分布表明，使用一种新型的非线性楔形滤过器可以实现更好的剂量均匀性，该滤过器可以很容易地利用所导出的积分方程的一般解析解来设计。
