[Three-dimensional dose calculation of 153Sm-EDTMP in treating bone metastasis--comparison of Monte Carlo and S value calculation methods].
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.


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.


RESULTS
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.


CONCLUSIONS
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.
Chen
Li-Xin
LX
State Key Laboratory of Oncology in South China, Guangzhou, Guangdong, 510060, P. R. China.
Liu
Xiao-Wei
XW
Gan
Feng
F
Tang
Qiang
Q
You
Ri-An
RA
Zhang
Wei-Guang
WG
Fan
Wei
W
D001859:Bone Neoplasms / Q000532:radiotherapy* / Q000556:secondary; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D009010:Monte Carlo Method; D009942:Organometallic Compounds / Q000627:therapeutic use*; D009943:Organophosphorus Compounds / Q000627:therapeutic use*; D011868:Radioisotopes / Q000627:therapeutic use; D011879:Radiotherapy Dosage; D012493:Samarium / Q000627:therapeutic use; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods; D014057:Tomography, X-Ray Computed / Q000379:methods
D009942:Organometallic Compounds; D009943:Organophosphorus Compounds; D011868:Radioisotopes; D012493:Samarium; C061972:samarium Sm-153 lexidronam