Cheung J Y, Yu K N, Yu C P, Ho R T
Department of Physics and Materials Science, City University of Hong Kong, Kowloon Tong, Hong Kong.
Med Phys. 1998 Sep;25(9):1673-5. doi: 10.1118/1.598347.
The accuracy of single-beam dose profiles used in the algorithm of the Gamma Knife treatment planning system (Leksell GammaPlan) is verified. EGS4 Monte Carlo calculation was employed to calculate the dose distributions of single-beams in a spherical water phantom with diameter 160 mm. The beams were directed to the center of the phantom. Collimators of 4, 8, 14, and 18 mm sizes were studied. The single-beam dose profiles provided by Elekta (Manufacturer of Leksell Gamma Knife) were excellently consistent with the results of Monte Carlo for the 4, 14, and 18 mm collimators. The maximum discrepancy was less than 3% at all radial distances. For the 8 mm collimator, the maximum discrepancy was 8% in the relative dose in the radial distance range from 4.3 mm to 5.2 mm. Excellent agreement in dose profiles along x, y, and z axes for all collimator helmets by summing over all 201 sources was observed between the cases using the default single-beam dose profiles and the calculated Monte Carlo results, except for the 8 mm collimator helmet along z axis. Such difference may however be too small to give a clinical significance.
验证了伽玛刀治疗计划系统（Leksell GammaPlan）算法中使用的单束剂量分布的准确性。采用EGS4蒙特卡罗计算方法，计算直径为160 mm的球形水模体中各单束的剂量分布。射线束指向模体中心。研究了尺寸为4、8、14和18 mm的准直器。Elekta（Leksell伽玛刀制造商）提供的单束剂量分布与4、14和18 mm准直器的蒙特卡罗结果高度一致。在所有径向距离处，最大差异小于3%。对于8 mm准直器，在径向距离范围为4.3 mm至5.2 mm时，相对剂量的最大差异为8%。在使用默认单束剂量分布的情况与计算得到的蒙特卡罗结果之间，观察到对于所有准直器头盔，通过对所有201个源求和，沿x、y和z轴的剂量分布具有良好的一致性，但8 mm准直器头盔沿z轴的情况除外。然而，这种差异可能太小，不具有临床意义。
