Bortfeld T, Boyer A L, Schlegel W, Kahler D L, Waldron T J
Deutsches Krebsforschungszentrum, Forschungsschwerpunkt Radiologie (FS 05), Heidelberg, Germany.
Int J Radiat Oncol Biol Phys. 1994 Nov 15;30(4):899-908. doi: 10.1016/0360-3016(94)90366-2.
We describe the experimental demonstration of the delivery of a three-dimensional conformal radiotherapy dose distribution using in-field modulation of nine fixed-gantry fields.
Two-dimensional in-field modulation profiles, varying from field to field, were realized by quasi-dynamic multileaf collimation using the prototype of a commercially available multileaf collimator installed on a medical linear accelerator. The profiles were calculated to deliver an optimal dose distribution for a patient with a prostate carcinoma. The target volume surface was invaginated and bifurcated. The calculated dose distribution was delivered to a homogeneous polystyrene phantom consisting of 1 cm thick slices that were cut to match the patient's outer contour. Seven therapy verification films were placed between the phantom slices.
Analysis of the films revealed a degree of conformation of the high-dose region to the target shape that would not be possible with unmodulated conformal therapy. However, small observed spatial displacements of the dose distribution confirm the need for very accurate positioning.
It is feasible to deliver clinically relevant, three-dimensional dose distributions that conform to invaginated and bifurcated target volumes using fields modulated by multileaf collimators.
我们描述了利用九个固定机架角度射野的射野内调制来实现三维适形放疗剂量分布的实验演示。
通过使用安装在医用直线加速器上的市售多叶准直器原型进行准动态多叶准直，实现了二维射野内调制轮廓，各射野之间有所不同。计算这些轮廓以给一名前列腺癌患者提供最佳剂量分布。靶区体积表面内陷且有分支。计算得到的剂量分布被传递到一个由1厘米厚切片组成的均匀聚苯乙烯模体，这些切片被切割成与患者外部轮廓匹配。在模体切片之间放置了七张治疗验证胶片。
对胶片的分析显示高剂量区与靶区形状的符合程度，这是未调制适形治疗无法实现的。然而，观察到的剂量分布的小空间位移证实了对非常精确的定位的需求。
使用多叶准直器调制射野来传递符合内陷和分支靶区体积的临床相关三维剂量分布是可行的。
