Schoeppel S L, Fraass B A, Hopkins M P, La Vigne M L, Lichter A S, McShan D L, Noffsinger S, Perez-Tamayo C, Roberts J A
Department of Radiation Oncology, University of Michigan Medical Center, Ann Arbor 48109-0010.
Int J Radiat Oncol Biol Phys. 1989 Nov;17(5):1103-9. doi: 10.1016/0360-3016(89)90164-8.
A new acrylic version of the familiar Fletcher intracavitary applicator, the Ann Arbor (AA) applicator, has been developed. This new device eliminates the problem of "streak" artifacts on CT images, but unlike other plastic applicators the ability to shield portions of the bladder and rectum is retained through the use of tungsten alloy shields which are afterloaded with the radioactive sources. To minimize changes in placement geometry and to take advantage of the wide clinical experience with the Fletcher system, the new applicator nearly duplicates the physical dimensions of the Fletcher applicator. With the Ann Arbor applicator in place, dummy sources are easier to locate on standard radiographic simulations. CT scans are free of artifact and provide clear, detailed visualizations of cross-sectional anatomy. The new applicator thus allows CT images to be used to their potential in evaluating crucial anatomic relationships and in performing 3-D dosimetry with dose volume analysis. Using a treatment planning system with 3-D capabilities, solid surface graphic display of applicator, cervix, rectum, bladder, and treatment isodose volume has been performed. In addition, dose volume histograms can be generated to obtain precise measurements of the volume of cervix, rectum, or bladder receiving specified doses.
一种新型的熟悉的弗莱彻腔内施源器的丙烯酸版本——安阿伯（AA）施源器已经研发出来。这种新装置消除了CT图像上的“条纹”伪影，但与其他塑料施源器不同的是，它通过使用与放射源后装的钨合金屏蔽来保留屏蔽膀胱和直肠部分的能力。为了尽量减少放置几何形状的变化，并利用弗莱彻系统广泛的临床经验，新施源器几乎复制了弗莱彻施源器的物理尺寸。使用安阿伯施源器时，在标准放射模拟中更容易定位虚拟源。CT扫描没有伪影，能清晰、详细地显示横断面解剖结构。因此，新施源器使CT图像能够充分发挥其潜力，用于评估关键的解剖关系以及进行三维剂量测定和剂量体积分析。使用具有三维功能的治疗计划系统，已经对施源器、子宫颈、直肠、膀胱和治疗等剂量体积进行了实体表面图形显示。此外，可以生成剂量体积直方图，以精确测量接受特定剂量的子宫颈、直肠或膀胱的体积。
