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１９６９年～１９８２年鼻咽癌放疗存活５年以上的１０２６例病人中，有１４１例（１３．７％）引起鼻咽癌放疗后颅神经放射损伤（ＲＩＣＮ）。ＲＩＣＮ侵犯后组颅神经者远多于前组颅神经，且１９６９年～１９７２年放疗者的ＲＩＣＮ发病率６．５％（９／１３８），远低于１９７３年～１９８２年放疗者的１４石％（１３２／８８８），（Ｐ＜０．０１）；提示在１９７３年开始采用的上颈前切野，与耳前野在下颌角处的重叠增高了颈动脉鞘区的剂量，从而导致后组颅神经经过的颈动脉鞘区域的放射性纤维变化和ＲＩＣＮ。等剂量曲线图显示不仅在颈动脉鞘区有过高的总剂量，而且因每次轮流只用一侧耳前野照射中线剂量２００ｃＧｙ，而使当天受照侧的颈动脉鞘区的分割剂量（３１２ｃＧｙ）远高于当天未受照侧（１５４ｃＧｙ）。此外，因射线束的发散效应和上述两相邻野的照射体位不相同，以致在野重叠处挡铅也不能完全消除颈动脉鞘区的高剂量。建议停用上颈前切野以降低ＲＩＣＮ发病率。
Of the 1026 patients who survived more than 5 years after radiotherapy of nasopharyngeal carcinoma from 1969 to 1982, 141 (13.7%) caused cranial nerve radiation injury (RICN) after radiotherapy of nasopharyngeal carcinoma. The incidence of RICN in RICN was significantly higher than that in the former group (6.5% (9/138)) in 1969 ~ 1972, which was much lower than that of radiotherapy in 1973 ~ 1982 % (132/888), (P <0.01). It is suggested that the anterior foreskin incision which was used in 1973 and overlap with the mandibular angle in the mandibular angle increased the dose of the carotid sheath, leading to the posterior group Radiofibrillary changes and RICN in the area of the cranial nerves through which the carotid sheath passes. The isodose curve shows not only an overly high total dose in the carotid sheath region but also a dose (312 cGy) of the carotid sheath region of the irradiated side of the same day because only 200 cGy of midline dose was irradiated with one ear on each side in turn, Much higher than the unlit side of the day (154cGy). In addition, due to the beam divergence effect and the above two adjacent fields of radiation body position is not the same, so overlap in the field of lead blockade can not completely eliminate the carotid sheath high dose. It is recommended to disable the anterior cervical spine to reduce the incidence of RICN.