Research on calculation modes of tumor control probability following internal radionuclide therapy

Objective: To construct a calculation model of tumor control probability (TCP) with consideration of the effect of dose and biological factors. It is expected that the result calculated by the model following internal radionuclide therapy would be appropriate to the actual value. Methods: Referring to the TCP models of radiotherapy and the models of cell survival rate reported by other authors, a TCP model (model 3) following internal radionuclide therapy, which considered the effect factors of dose, repair of DNA single-strand damage, radiosensitivity has been set up. Then using nuclide 32P as an example, model 3 will be compared with the other two models (model 1 and 2) by calculation the TCP value under the same treatment conditions. Results: Compared with model 1 and 2, the result calculated by model 3 shows that: 1. With a certain treatment activity (3.7 x 107 Bq), the radius of tumor which can be cured is closer to the experiment result. 2. If the given activity is infinitely great, the largest tumor radius which can be cured is smaller and coincide with the largest range of nuclide 32P. So the result calculated by model 3 is fitter with the actual value than that calculated by the other two models. Conclusion: The model 3 has considered more factors than others, so if the biological parameters are known, it could be used to calculate the TCP value under a certain kind of treatment condition to predict the internal radionuclide therapy result and estimate whether the treatment plan is reasonable