Towards personalised dosimetry in patients with liver malignancy treated with 90Y-SIRT using in vivo-driven radiobiological parameters

Background: The prediction of response is one of the major challenges in radiation-based therapies. Although the selection of accurate linear-quadratic model parameters is essential for the estimation of radiation response and treatment outcome, there is a limited knowledge about these radiobiological parameters for liver tumours using radionuclide treatments. Methods: The clinical radiobiological parameters (T-p, T-k, alpha, alpha/beta) for twenty-five patients were derived using the generalised linear-quadratic model, the diagnostic -([F-18] FDG PET/CT) and therapeutic -([Y-90]-SIR-Spheres PET/CT) images to compute the biological effective dose and tumour control probability (TCP) for each patient. Results: It was estimated that the values for a and alpha/beta parameters range in approximate to 0.001-1-Gy(-1) and approximate to 1-49 Gy, respectively. We have demonstrated that the time factors, T-p, T-k and T-critic are the key parameters when evaluating liver malignancy lesional response to -[Y-90]SIR-Spheres treatment. Patients with cholangiocarcinoma have been shown to have the longest average T-p (approximate to 236 +/- 67 d), highest TCP (approximate to 53 +/- 17%) and total liver lesion glycolysis response (Delta TLG(liver) approximate to 64%), while patients with metastatic colorectal cancer tumours have the shortest average T-p (approximate to 129 +/- 19 d), lowest TCP (approximate to 28 +/- 13%) and Delta TLG(liver) approximate to 8%, respectively. Conclusions: Tumours with shorter Tk have shown a shorter T-critic and thus poorer TCP and Delta TLG(liver). Therefore, these results suggest for such tumours the -[Y-90]SIR-Spheres will be only effective at higher initial dose rate (e.g. > 50 Gy/day).

Automated summary

The study investigates the radiobiological parameters for liver tumours in radiation-based therapies. It highlights the importance of time factors in evaluating the response to [Y-90]SIR-Spheres treatment for liver malignancy. Different types of tumours show different responses to this treatment.