Chen Li-Xin, Liu Xiao-Wei, Gan Feng, Tang Qiang, You Ri-An, Zhang Wei-Guang, Fan Wei
State Key Laboratory of Oncology in South China, Guangzhou, Guangdong, 510060, P. R. China.
Ai Zheng. 2006 Nov;25(11):1399-405.
BACKGROUND & OBJECTIVE: Three-dimensional (3D) dose calculation of radionuclide therapy for specified patients is a research interest in nuclear medicine, of which the main methods include S value calculation method, dose point kernel calculation method, and Monte Carlo (MC) simulation method. This study was to compare 3D absorbed dose calculation of 153Sm-EDTMP in treating a specified patient with bone metastasis between MC and S value methods.
A 3D dose calculation program was built based on the MC program EGS4, and the S value of nuclide 153Sm was calculated. For the specified patient with bone metastasis, 153Sm activity in excreted urine was measured at 0, 0.5, 2, 3.5, 5 and 6 h after injection of 153Sm-EDTMP. The accumulative activity is calculated by fitting measurement data. Based on the fusion SPECT/CT images of the patient, 3D absorbed dose is calculated by MC and S value methods.
The iso-dose distribution curves of MC and S value calculation results were similar, and the dose was mainly collected in the bone. According to the 2 methods, the maximum doses were 3.92 Gy and 3.71 Gy with a difference of 5%. On the dose-volume histogram of the calculation volume, D10 (the highest dose of the 10% volume) were 2.14 Gy and 2.00 Gy with a difference of 7%; D20 (the highest dose of the 20% volume) were 0.58 Gy and 0.51 Gy with a difference of 14%. In general, the data of S value calculation were smaller than the data of MC calculation.
MC and S value could be used to calculate the 3D dose of radionuclide therapy based on nuclear medical image. S value is a fast and simple method for the dose evaluation although the error of the calculation is relatively bigger.
特定患者放射性核素治疗的三维（3D）剂量计算是核医学领域的研究热点，主要方法包括S值计算法、剂量点核计算法和蒙特卡罗（MC）模拟法。本研究旨在比较MC法与S值法在计算153Sm-EDTMP治疗特定骨转移患者时的三维吸收剂量。
基于MC程序EGS4构建三维剂量计算程序，并计算核素153Sm的S值。对于特定的骨转移患者，在注射153Sm-EDTMP后0、0.5、2、3.5、5和6小时测量其尿液中153Sm的活度。通过拟合测量数据计算累积活度。基于患者的融合SPECT/CT图像，采用MC法和S值法计算三维吸收剂量。
MC法和S值法计算结果的等剂量分布曲线相似，剂量主要集中在骨骼。两种方法计算得到的最大剂量分别为3.92 Gy和3.71 Gy，相差5%。在计算体积的剂量-体积直方图上，D10（10%体积的最高剂量）分别为2.14 Gy和2.00 Gy，相差7%；D20（20%体积的最高剂量）分别为0.58 Gy和0.51 Gy，相差14%。总体而言，S值法计算的数据小于MC法计算的数据。
MC法和S值法均可用于基于核医学图像的放射性核素治疗三维剂量计算。S值法计算速度快且简单，可用于剂量评估，但其计算误差相对较大。
