软组织中β点源和球源剂量分布估算

Calculation of dose for β point and sphere sources in soft tissue\

目的 比较文中所给出的３ 个具有代表性的β核素源的吸收剂量估算方法对核素源在软组织中的剂量率分布计算结果。方法 分别用３ 种方法计算３２Ｐ点源和球源在软组织中的剂量分布，并对其结果进行比较。结果 ３ 个公式计算结果之差：在ｒ＝ ０－０８ ～０－２（ｇ／ｃｍ２） 范围内，在５％ 以内；ｒ＝ ０－０１ ～０－３５（ｇ／ｃｍ２）之间，在１０ ％ 以内；ｒ＞０－３５ （ｇ／ｃｍ２），基本大于１０％ 。对５０ μｌ 的球源，在距球表面ｚ≤０－１５ ｇ／ｃｍ２ 范围内３ 个公式计算结果相差在１０ ％ 以内。结论 由３ 个点核函数及其由它们推导出来的球源剂量率的计算结果，在距离点源或球源表面较近时，一致性较好；距离较远时，一致性变差。

Objective\ To compare the results of the distribution of dose rate calculated by three typical methods for point source and sphere source of β nuclide. Methods Calculating and comparing the distributions of dose rate from 32 P β point and sphere sources in soft tissue calculated by the three methods published in references,[1],[2] and [3],respectively. Results For the point source of 3.7×10 7 Bq(1mCi),the variations of the calculation results of the three formulas are within 10% if r<=0.35 g/cm 2 ,r being the distance from source,and larger than 10% if r>0.35 g/cm 2 .For the sphere source whose volume is 50 μl and activity is 3.7×10 7 Bq(1 mCi),the variations are wthin 10% if z<=0.15 g/cm 2 ,z being the distance from the surface of the sphere source to a point outside the sphere. Conclusion The agreement of the distributions of the dose rate calculated by the three methods mentioned above for point and sphere β source are good if the distances from point source or the surface of sphere source to the points observed are small,and poor if they are large.\;