Evaluation of a new bi-valve vaginal speculum applicator design for gynecologic interstitial brachytherapy
Evaluation of a new bi-valve vaginal speculum applicator design for gynecologic interstitial brachytherapy
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DOI：
10.5114/jcb.2020.92406
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发表时间：
2020-01-01
影响因子：
1.4
通讯作者：
Sasai, Keisuke
中科院分区：
文献类型：
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作者：
Kunogi, Hiroaki;Yamaguchi, Nanae;Sasai, Keisuke
目的：设计一种双阀阴道镜高剂量率(HDR)组织间近距离照射治疗器。这样既可以直接看到宫颈，也可以在图像引导下放置近距离放射治疗敷贴器。材料和方法：涂抹器设计为25 mm弧形，可横向扩展到35 mm宽，有10个插孔；使用生物兼容的牙科SG树脂使用立体平版印刷机生产。对于树脂，使用计算机断层扫描(CT)测量Hounsfield单位(HU)的放射密度。将新的敷贴器与传统的腔内敷贴器进行比较，我们评估了治疗体积(包括中心轴100%等剂量体积的尺寸)、假想宫颈的V-100/D-90/D-98(2厘米长和4厘米直径的圆柱体)以及危险器官的剂量点(距离串联25 mm和30 mm)。基于颈部剂量-体积直方图(DVH)分析，确定处方剂量百分比剂量差的容差范围为5%。结果：制备的牙科SG树脂的平均放射密度为118HU，符合磁共振成像要求。在中轴线上测量的100%等剂量体积的尺寸：新敷贴器为4.4x6.6x7.4 cm，腔内敷贴器为4.3x6.0x7.7 cm。新型敷贴器和传统敷贴器100%处方剂量体积分别为110cc和113cc。新的腔内敷贴器和腔内敷贴器在假设的宫颈V-100、D-90和D-98上的百分比差异在5%以内。新涂布器在25 mm和30 mm的剂量点与传统涂布器之间的百分比差异在5%以内。结论：我们研制的镜式涂布器可以再现传统的梨形剂量分布。我们目前的临床实践将使用这种敷贴器，它可以提高患者的治疗效果。
Purpose: We designed a bi-valve vaginal speculum high-dose-rate (HDR) interstitial gynecologic brachytherapy applicator. This allows for both a direct view of the cervix and image-guided brachytherapy applicator placement. The purpose of this study was to assess the validity of the new applicator.Material and methods: The applicator was designed to have a 25-mm arc, which can be spread transversely to 35-mm wide, with 10 insertion holes; it was produced using a stereolithographic printer with biocompatible Dental SG resin. For resin radiodensity was measured in Hounsfield units (HU) using computed tomography (CT). Comparing the new applicator with a conventional intracavitary applicator, we evaluated the treated volume (including dimensions of 100% isodose volume at the central axis), V-100/D-90/D-98 for a hypothetical cervix (a 2-cm-long and 4-cm-diameter cylinder), and dose points of organs at risk (OARs) (at 25 and 30 mm from the tandem). Based on dose-volume histogram (DVH) analysis of the cervix and dose points of OARs, the range of tolerance for the percent dose difference in the prescription dose was set at 5%.Results: The mean radiodensity of the Dental SG resin, which was magnetic resonance imaging compatible, was 118 HU. Dimensions of the 100% isodose volume measured at the central axis were 4.4 x 6.6 x 7.4 cm for the new applicator and 4.3 x 6.0 x 7.7 cm for the intracavitary applicator. The 100% prescription dose volumes were 110 cc and 113 cc for the new and conventional applicator, respectively. The percent difference in the hypothetical cervix V-100, D-90, and D-98 between the new and intracavitary applicator were within 5%. The percent differences in dose points of OARs at 25 and 30 mm between the new and conventional applicators were within 5%.Conclusions: Our speculum applicator can reproduce a conventional pear-shaped dose distribution. Our current clinical practice will use this applicator, which can improve the patient's treatment results.