Abstract：Objective This paper was intended to quantify the anatomic changes in NPC (Nasopharyngeal Carcinoma) patients during their IMRT (Intensity Modulation Radiated Therapy) through analysis of CT images acquired by the CT-on-rail system, including shrinkage of the primary tumor, lymphatic nodal masses as well as changes in the edema area and weight, so as to provide the basis for re-design of clinical treatment plans. Methods Sixteen pathologically-confirmed NPC patients whose primary lesions or lymphatic nodes were ≥4 cm in maximal diameter were enrolled in this pilot study. All the eligible patients were treated with IMRT and the CT-on-rail system thrice a week during the entire course of IMRT, which allowed for verification of CT images in patients with the same position in each radiotherapy session. Both gross tumor volumes (GTV) and normal tissues were manually contoured on every axial slice. Results Shrinkage of GTV occurred at the mean speed of 0.22 cm3/d throughout the course of IMRT, which meant 2.06% shrinkage per day in comparison with the original volumes. On the last day of treatment, the GTV averagely shrunk 68.12% of the original one; while, the volume of parotid glands also degraded at the mean speed of 0.10 cm3/d. Conclusion Patients with NPC may experience anatomic changes throughout the course of IMRT. Changes in GTV as well as the volume and position of the affected organ became even more obvious especially in 3 to 4 weeks post-treatment and could result in large deviation between the actual radiation dose used in adaptive radiotherapy for each organ and that in the initial treatment plan. The regularity of anatomic changes during IMRT should be taken into account, which was convenient to deploy the adaptive radiotherapy and maximize the therapeutic ratio.
夏邦传，徐子海，廖福锡，周燕华，朱超华. 基于CT共轨系统的鼻咽癌调强放疗中解剖结构变化的研究[J]. 中国医疗设备, 2015, 30(3): 17-20.
XIA Bang-chuan, XU Zi-hai, LIAO Fu-xi, ZHOU Yan-hua, ZHU Chao-hua. Study on Anatomic Changes During IMRT for NPC Based on the CT-on-Rail System. China Medical Devices, 2015, 30(3): 17-20.
Kam MK,Teo PM,Chau RM,et al.Treatment of nasopharyngeal carcinoma with intensity-modulated radiotherapy: the Hong Kong experience[J].Int J Radiat Oncol Biol Phys,2004,60:1440-1450.
