Kneschaurek P, Wehrmann R, Hugo C, Stepan R, Lukas P, Molls M
Klinik und Poliklinik für Strahlentherapie und radiologische, Technische Universität München.
Strahlenther Onkol. 1995 Feb;171(2):61-9.
Improvement of the relapse rate by locally increasing the tumor dose.
To increase the dose in the tumor bed a method for intraoperative radiation therapy has been developed. The radiation is applied using a high-dose-rate afterloading system. Flexible plastic flabs are used as applicators. Each flab contains tubes for the alterloading source. The size of the applicator is chosen to correspond to the size of the target volume. In the dosage system we use the dwell times at all source positions are equal. The dwell time has been precalculated to give the reference dose at the reference position which is located at the surface of the flab in the center of the target volume.
The dose distributions around the flab have been calculated as a function of the thickness of the flab. If the source is not placed on a regular grid within the applicator due to a non ideal positioning of the tubes within the applicator, the dose distribution is not altered too much, if the positioning error is not larger than +/- 2 mm. The influence of a curvature of the flab has been evaluated and methods to decrease the dose at critical organs are discussed.
The flab methods for IORT is safe and easy and has been demonstrated for more than 150 cases. This method allows the increase in tumor dose even in regions which are not easily treated by electron IORT due to the rigid electron applicators. Because of the rapid dose fall off, the flab method can only be used for flat target volumes like the tumor bed.
通过局部增加肿瘤剂量来提高复发率。
为了增加肿瘤床的剂量，已开发出一种术中放射治疗方法。使用高剂量率后装系统进行放射。柔性塑料板用作施源器。每个塑料板都包含用于后装源的管道。施源器的尺寸根据靶区体积大小选择。在剂量系统中，我们使用的所有源位置的驻留时间相等。驻留时间已预先计算，以便在位于靶区体积中心的塑料板表面的参考位置给出参考剂量。
已根据塑料板厚度计算出塑料板周围的剂量分布。如果由于施源器内管道定位不理想导致源未放置在施源器内的规则网格上，若定位误差不大于±2毫米，则剂量分布不会有太大变化。已评估了塑料板弯曲的影响，并讨论了降低关键器官剂量的方法。
用于术中放射治疗的塑料板方法安全简便，已在150多例病例中得到验证。即使在因电子术中放射治疗施源器刚性而难以治疗的区域，这种方法也能增加肿瘤剂量。由于剂量迅速下降，塑料板方法仅适用于像肿瘤床这样的扁平靶区体积。
