Yoshida Ken, Yamazaki Hideya, Kotsuma Tadayuki, Akiyama Hironori, Takenaka Tadashi, Masui Koji, Yoshioka Yasuo, Uesugi Yasuo, Shimbo Taiju, Yoshikawa Nobuhiko, Yoshioka Hiroto, Arika Takumi, Tanaka Eiichi, Narumi Yoshifumi
Department of Radiology, Osaka Medical College, Osaka.
Department of Radiology, Kyoto Prefectural University of Medicine, Kyoto.
J Contemp Brachytherapy. 2017 Feb;9(1):66-70. doi: 10.5114/jcb.2017.65163. Epub 2017 Jan 16.
We report our study on two patients to highlight the risk of underdosage of the clinical target volume (CTV) due to edema during high-dose-rate interstitial brachytherapy (HDR-ISBT) of mobile tongue cancer.
To treat the lateral side of the CTV, flexible applicator tubes were implanted on the mouth floor. Two-dimensional planning was performed using X-ray images for Case 1, and three-dimensional (3D) planning was performed using computed tomography (CT) for Case 2. Prescribed doses for both cases were 54 Gy in nine fractions.
Case 1 was treated for cancer of the right lateral border of the tongue in 2005. Tongue edema occurred after implantation, and part of the lateral border of the tongue protruded between the applicator tubes. Acute mucosal reaction abated in the protruded area earlier than in the other parts of the CTV. In this case, the tumor recurred in this area 5 months after the treatment. Case 2 was treated for cancer of the left lateral border of the tongue. Because tongue edema occurred in this case also, plastic splints were inserted between the applicator tubes to push the edematous region into the irradiated area. The mucosal surface of the CTV was covered by the 70% isodose, and 100% isodose line for before and after splint insertion. Local control of the tumor was achieved 4 years after treatment.
To ensure sufficient target coverage, 3D image-based planning using CT should be performed, followed by re-planning using repeated CT as needed. Also, the development of devices to prevent protrusion of the edematous tissue outside the target area will help to ensure the full dosing of CTV.
我们报告对两名患者的研究，以突出在活动期舌癌的高剂量率组织间近距离放疗（HDR-ISBT）期间，水肿导致临床靶区（CTV）剂量不足的风险。
为治疗CTV的外侧，在口底植入了可弯曲的施源器管。病例1使用X射线图像进行二维计划，病例2使用计算机断层扫描（CT）进行三维（3D）计划。两个病例的处方剂量均为54 Gy，分9次给予。
病例1于2005年接受右侧舌缘癌治疗。植入后出现舌水肿，舌外侧缘的一部分在施源器管之间突出。突出区域的急性黏膜反应比CTV的其他部位更早消退。在这种情况下，治疗后5个月该区域肿瘤复发。病例2接受左侧舌缘癌治疗。因为该病例也出现了舌水肿，所以在施源器管之间插入了塑料夹板，将水肿区域推至照射区域。夹板插入前后，CTV的黏膜表面均被70%等剂量线覆盖，100%等剂量线包绕。治疗后4年实现了肿瘤的局部控制。
为确保足够的靶区覆盖，应使用CT进行基于3D图像的计划，然后根据需要使用重复CT进行重新计划。此外，开发防止水肿组织突出到靶区外的装置将有助于确保CTV的充分剂量。
