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背景与目的:中耳咽鼓管损害高峰发生在放疗后半年,并且在很多病例可持续终身,至今为止临床上尚无有效的治疗方法,寻求放射治疗中中耳鼓室及咽鼓管更好的保护仍是放射治疗医师面临的责任,在精确放疗技术应用逐渐普遍的今天,肿瘤周围正常组织和器官的保护受到越来越多的重视,但到目前为止,有关中耳放射损伤的研究报道极少。我们采用回顾性分析的方法,通过比较鼓室腔及骨性段咽鼓管剂量分布与放疗后分泌性中耳炎的发生率,评价在鼻咽癌3-D计划放射治疗中中耳功能保护的可能性,同时了解放疗后时间、化疗、T分期等因素对结果的影响。方法:40例80耳有完整听力学检查材料的鼻咽癌3-D计划放射治疗的患者进入此项研究。所有病例放疗前后均经耳部检查,电测听及声阻抗测听,放疗后随访时间为6~24个月。电测听以500,1 000,2 000,4 000 Hz听阈平均值计算气骨导差,声阻抗根据鼓室图分为A、B、C 3型,A型为正常鼓室图,B型为中耳鼓室积液,C型为咽鼓管功能不良。结果:79耳符合声阻抗分析条件。放疗后62%耳与放疗前保持不变,13%耳得到改善,25%耳恶化。鼓室腔及骨性段咽鼓管剂量分布在恶化耳与其他各组耳之间比较差异有显著性。80耳电测听分析结果,放疗后无变化耳58%,改善耳12%,恶化耳30%。分析剂量因素对声阻抗结果的影响,恶化组的鼓室腔及骨性段咽鼓管平均受照剂量为(5379.81±706.01)cGy,不变组的平均受照剂量为(4735.72±812.30)cGy,改善组的平均剂量为(4652.86±809.78)cGy;分析剂量因素对电测听结果的影响,恶化组的中耳及骨性咽鼓管平均受量为(5229.38±778.11)cGy,不变组的平均受量为(4719.64±744.82)cGy,改善组的平均剂量为(4702.38±922.21)cGy。统计分析发现3组的剂量差异有显著性。T分期变化及1年内或1年后时间分组对听力测试结果的影响差异有显著性,而化疗对听力测试结果的影响不明显。结论:在鼻咽癌3-D放射治疗中,如将鼓室腔及骨性段咽鼓管剂量控制在4700 cGy以下,则可明显减少延迟性放射性中耳炎的发生率。对中耳鼓室腔及骨性段的保护随着肿瘤体积的增大可能性减少。放射性中耳功能损伤发病高峰在1年内,在放疗前具有正常听觉功能者,放疗1年后有更多的机会从放射损伤中恢复。
BACKGROUND & OBJECTIVE: The ear damage of middle ear eustachian tube occurs half a year after radiotherapy, and in many cases it can last for a long time. To date, no effective treatment has been clinically available to seek better middle ear tympanic and eustachian tubes in radiotherapy Protection is still the responsibility of radiation therapists. With the application of accurate radiotherapy technology becoming more and more commonplace, the protection of normal tissues and organs around the tumor is receiving more and more attention. However, up to now, the research on middle ear radiation damage has been reported less. We retrospectively analyzed the likelihood of middle ear function protection in 3-D scheduled radiotherapy for nasopharyngeal carcinoma by comparing the dose distribution of the tympanic cavity and the bony Eustachian tube to the incidence of post-radiotherapy otitis media with effusion , At the same time understand the time after radiotherapy, chemotherapy, T staging and other factors on the results. METHODS: Forty patients (80 ears) with nasopharyngeal carcinoma undergoing 3-D planned radiotherapy with intact audiology materials were enrolled in this study. All cases before and after radiotherapy were ear examination, audiometry and acoustic impedance audiometry, radiotherapy follow-up time was 6 to 24 months. Electrical audiometry 500,1 000,2 000,4 000 Hz average hearing threshold calculation of air conduction, acoustic impedance according to the tympanogram is divided into A, B, C 3 type, type A for the normal tympanogram, type B for the Eardrum effusion, C-type Eustachian tube dysfunction. Results: 79 ears comply with the acoustic impedance analysis conditions. After radiotherapy 62% of the ears remained unchanged with radiotherapy, 13% of the ears improved, 25% of the ear deterioration. The distribution of tympanic cavity and bony Eustachian tube was significantly different between the deteriorated ear and other groups of ears. 80 audiometry analysis results, no change in the ears after radiotherapy 58%, 12% improvement in ear, ear deterioration 30%. The average dose of tympanic cavity and eustachian tube in the malignant group was (5379.81 ± 706.01) cGy, and the average dose of invigorating group was (4735.72 ± 812.30) cGy, (4652.86 ± 809.78) cGy. The effect of dose on the results of electrical audiometry was evaluated. The mean amount of middle ear and bony eustachian tube in the deteriorating group was 5229.38 ± 778.11 cGy, The average dose was (4719.64 ± 744.82) cGy, and the average dose in the improved group was (4702.38 ± 922.21) cGy. Statistical analysis found that the three groups of dose differences were significant. T staging changes and 1 year or 1 year after the sub-group on the hearing test results were significantly different, and the impact of chemotherapy on the hearing test results is not obvious. CONCLUSIONS: In the 3-D radiotherapy of nasopharyngeal carcinoma, if the tympanic cavity and the pharyngeal eustachian tube dosage is controlled below 4700 cGy, can significantly reduce the incidence of delayed otitis media. The protection of the middle ear tympanic cavity and bony segments decreases with the increase of tumor volume. The peak incidence of radiation-induced middle ear injury within 1 year, before radiotherapy with normal hearing function, radiotherapy after 1 year have more opportunities to recover from radiation injury.