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[目的]探讨鼻咽癌放疗全疗程使用同一面罩固定的可靠性及引起偏移的因素。[方法]对42例使用热塑面罩固定,CT-SIM定位的鼻咽癌放疗患者分别在治疗前,治疗第2周及第5周时在同一治疗参数的条件下拍摄X线射野定位片,通过将后2次的射野定位片中的骨性标志:下颌骨、蝶窦、蝶鞍等与第一次拍摄的射野定位片进行重叠来比较中心点的位移,并计算出中心点的偏差值。[结果]第2周中心点的位移为0～3.5mm,平均位移为1.3mm,根据标准分组,其中位移<3mm的患者有37例,占88%;3mm<位移<5mm的患者有5例,占12%;无位移>5mm的患者;第5周中心点的位移范围为0～8.5mm,平均位移为2.3mm,根据标准进行分组,其中位移<3mm的患者有28例,占67%;3mm<位移<5mm的患者有9例,占21%;位移>5mm的患者有5例,占12%。[结论]全疗程使用同一热塑面罩固定在治疗的后期面罩会出现一定的松动,应在治疗后期检查面罩固定的情况,对于中心点偏移较大的患者及时采取补救措施,以确保理想化的放疗计划得到精确的实施。
[Objective] To investigate the reliability and cause of offset of nasopharyngeal carcinoma radiotherapy using the same mask. [Methods] Twenty-four patients with nasopharyngeal carcinoma treated by thermoplastic mask fixation and CT-SIM radiography were treated with X-ray radiographs under the same treatment parameters before treatment, the second week and the fifth week respectively , The displacement of the center point was compared by overlapping the bony loci in the radiographs of the second radiographs: the mandible, the sphenoid sinus, the sella, and the like with the first radiographing sheet and the center point was calculated The deviation value. [Results] The displacement of central point in the second week was 0 ~ 3.5mm and the average displacement was 1.3mm. According to the standard group, there were 37 cases (88%) with displacement <3mm and 5 cases , Accounting for 12%; patients with no displacement> 5mm; the displacement range of central point in the fifth week was 0 ~ 8.5mm, the average displacement was 2.3mm, grouped according to the standard, of which 28 cases were displaced by 3mm, accounting for 67% ; 9 cases (21%) of patients with 3mm 5mm. [Conclusion] The whole course of the mask covered by the same thermoplastic mask will be loosened in the latter part of the treatment. The masks should be fixed in the later stage of treatment, and remedial measures should be taken promptly in patients with large center deviation to ensure idealization The radiotherapy plan has been accurately implemented.