EJNMMI Physics (Jul 2022)
Towards personalised dosimetry in patients with liver malignancy treated with 90Y-SIRT using in vivo-driven radiobiological parameters
Abstract
Abstract 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 ( $$T_{{\text{p}}}$$ T p , $$T_{{\text{k}}}$$ T k , $$\alpha$$ α , $$\alpha {/}\beta$$ α / β ) for twenty-five patients were derived using the generalised linear–quadratic model, the diagnostic ([18F] FDG PET/CT) and therapeutic ([90Y]-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 $$\alpha$$ α and $$\alpha {/}\beta$$ α / β parameters range in ≈ 0.001–1 Gy−1 and ≈ 1–49 Gy, respectively. We have demonstrated that the time factors, $$T_{{\text{p}}}$$ T p , $$T_{{\text{k}}}$$ T k and $$T_{{{\text{critic}}}}$$ T critic are the key parameters when evaluating liver malignancy lesional response to [90Y]SIR-Spheres treatment. Patients with cholangiocarcinoma have been shown to have the longest average $$T_{{\text{p}}}$$ T p (≈ 236 ± 67 d), highest TCP (≈ 53 ± 17%) and total liver lesion glycolysis response ( $$\Delta {\text{TLG}}_{{{\text{liver}}}}$$ Δ TLG liver ≈ 64%), while patients with metastatic colorectal cancer tumours have the shortest average $$T_{{\text{p}}}$$ T p (≈ 129 ± 19 d), lowest TCP (≈ 28 ± 13%) and $$\Delta {\text{TLG}}_{{{\text{liver}}}}$$ Δ TLG liver ≈ 8%, respectively. Conclusions Tumours with shorter $$T_{{\text{k}}}$$ T k have shown a shorter $$T_{{{\text{critic}}}}$$ T critic and thus poorer TCP and $$\Delta {\text{TLG}}_{{{\text{liver}}}}$$ Δ TLG liver . Therefore, these results suggest for such tumours the [90Y]SIR-Spheres will be only effective at higher initial dose rate (e.g. > 50 Gy/day).
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