Bando Ryota, Ikushima Hitoshi, Kawanaka Takashi, Kudo Takaharu, Sasaki Motoharu, Tominaga Masahide, Kishi Taro, Furutani Shunsuke, Kubo Akiko, Tamura Koichi
Department of Clinical Support, the Tokushima University Hospital, Tokushima, Japan.
J Med Invest. 2013;60(1-2):46-51. doi: 10.2152/jmi.60.46.
The treatment period over which radiation therapy is administered extends over several weeks. Since tumor shrinkage in response to radiation therapy and weight loss due to radiation-induced mucositis may impact on the dose distribution in both target and organ at risk in patients with head and neck cancer, the anatomical changes of tumor and neck volumes during this period should be taken into consideration. We investigated the anatomical changes that occurred in the target and normal structure of the neck during radiation therapy for pharyngeal cancer, and evaluated the necessity of an adaptive strategy. Ten patients with pharyngeal cancer who underwent radical chemoradiation therapy using 3-dimensional conformal radiation therapy RT (66-70 Gy in 33-35 fractions) between April 2009 and September 2010 were enrolled in the study. Patients underwent CT scans every week during their course of treatment. We analyzed the CT data in the radiation treatment planning system and measured changes of tumor, organ at risk, and neck volume. Gross tumor volume (GTV) was rapidly reduced by 28% of the original volume on average in the first 3 weeks. The right and left submandibular glands volume decreased to 70% and 63% of their initial volumes on average, respectively. The volume of the neck in the radiation fields decreased to 89% of its initial volume on average by the sixth week mainly caused by body weight loss due to acute radiation morbidity. Considerable anatomical change in the radiation filed that will affect dose distribution of the target and organ at risk was observed during radiation therapy for head and neck cancer.
放射治疗的疗程持续数周。由于头颈部癌患者对放射治疗的肿瘤缩小反应以及放射诱导的粘膜炎导致的体重减轻可能会影响靶区和危及器官的剂量分布，因此在此期间应考虑肿瘤和颈部体积的解剖学变化。我们研究了鼻咽癌放射治疗期间颈部靶区和正常结构发生的解剖学变化，并评估了适应性策略的必要性。本研究纳入了2009年4月至2010年9月期间接受三维适形放射治疗（33 - 35次分割，66 - 70 Gy）的10例鼻咽癌患者进行根治性放化疗。患者在治疗过程中每周进行CT扫描。我们在放射治疗计划系统中分析CT数据，并测量肿瘤、危及器官和颈部体积的变化。在前3周内，大体肿瘤体积（GTV）平均迅速减少至原始体积的28%。右侧和左侧下颌下腺体积分别平均减少至初始体积的70%和63%。到第6周时，放射野内颈部体积平均减少至初始体积的89%，主要是由于急性放射反应导致体重减轻。在头颈部癌放射治疗期间，观察到放射野内有相当大的解剖学变化，这将影响靶区和危及器官的剂量分布。
