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目的：颈部分割野是鼻咽癌放疗设计常用的照射野。目前常规的剂量计算方法计算结果误差很大，特别是大野照射时，误差可达１０％以上，本文是为了寻求一种能减少误差的计算方法。方法：通过实验导出一种处方剂量计算的近似方法。结果：经实验推导出的公式为：Ｄｆ＝Ｄｏａ·ｆＤａ·（ｆｏ／（ｆｏ＋ｄ））２·Ｓｃ·ＴＡＲｆ。其中，Ｄｆ为颈模参考点的剂量，ＤＯａ为空气中１０ｃｍ×１０ｃｍ野的输出剂量，（ｆｏ／（ｆｏ＋ｄ））２为距离平方反比因子，ｆＤａ为分割野的空气中输出剂量修正因子，Ｓｃ为空野的准直器散射校正因子，ＴＡＲｆ为分割野的组织空气比。结论：采用此公式，可减少颈部分割野的剂量计算误差，除ｆＤａ外，不用再额外测量其它数据。
Objective: The neck is the common field of radiotherapy for nasopharyngeal carcinoma radiotherapy. At present, the calculation error of the conventional dose calculation method is very large, especially when there is an error of more than 10% in the field irradiation. This article is to find a calculation method that can reduce the error. Methods: An approximate method of prescription dose calculation was derived experimentally. Results: The experimentally derived formula is: Df = Doa · fDa · (fo / (fo + d)) 2 · Sc · TARf. Where Df is the dose of the reference point of the neck mold, DOa is the output dose of 10cm × 10cm field in the air, (fo / (fo + d)) 2 is inverse square distance factor, fDa is the output dose correction factor of air in the split field, Sc For the wild collimator scatter correction factor, TARf is the fractional field tissue air ratio. CONCLUSIONS: This formula reduces the dose calculation error for neck-split fields, eliminating the need for additional measurement of data other than fDa.