Radiobiological Optimization in Lung Stereotactic Body Radiation Therapy: Are We Ready to Apply Radiobiological Models?

Abstract

Lung tumors are often associated with a poor prognosis although different schedules and treatment modalities have been extensively tested in the clinical practice. The complexity of this disease and the use of combined therapeutic approaches have been investigated and the use of high dose-rates is emerging as effective strategy. Technological improvements of clinical linear accelerators allow combining high dose-rate and a more conformal dose delivery with accurate imaging modalities pre- and during therapy. This paper aims at reporting the state of the art and future direction in the use of radiobiological models and radiobiological-based optimizations in the clinical practice for the treatment of lung cancer. To address this issue, a search was carried out on PubMed database to identify potential papers reporting tumor control probability and normal tissue complication probability for lung tumors. Full articles were retrieved when the abstract was considered relevant, and only papers published in English language were considered. The bibliographies of retrieved papers were also searched and relevant articles included. At the state of the art, dose–response relationships have been reported in literature for local tumor control and survival in stage III non-small cell lung cancer. Due to the lack of published radiobiological models for SBRT, several authors used dose constraints and models derived for conventional fractionation schemes. Recently, several radiobiological models and parameters for SBRT have been published and could be used in prospective trials although external validations are recommended to improve the robustness of model predictive capability. Moreover, radiobiological-based functions have been used within treatment planning systems for plan optimization but the advantages of using this strategy in the clinical practice are still under discussion. Future research should be directed toward combined regimens, in order to potentially improve both local tumor control and survival. Indeed, accurate knowledge of the relevant parameters describing tumor biology and normal tissue response is mandatory to correctly address this issue. In this context, the role of medical physicists and the AAPM in the development of radiobiological models is crucial for the progress of developing specific tool for radiobiological-based optimization treatment planning.

Mitigation of the Interplay Effects of Combining 4D Robust With Layer Repainting Techniques in Proton-Based SBRT for Patients With Early-Stage Non-small Cell Lung Cancer

“…For lung – ITV, the DVH metrics of the lungs included V 5 , V 20 , and V 30 , which were the percentage volume of lungs receiving 500 cGy [RBE], 2000 cGy [RBE], and 3000 cGy [RBE], respectively. The lung – ITV average dose and EUD ( A = 1.2) ( 17 ) were also calculated for evaluation.…”

Carbon-ion Radiotherapy for Isolated Lymph Node Metastasis After Surgery or Radiotherapy for Lung Cancer

“…Statistical analyses were performed using SPSS software (Version 25.0; SPSS Inc., Chicago, IL, USA). The biologically equivalent doses in 2-Gy fractions (EQD 2 ) were converted based on an alpha/beta ratio of 3.0 Gy (13).…”

Dose–Response of TLD-100 in the Dose Range Useful for Hypofractionated Radiotherapy

“…The irradiation experiments were performed using LiF: Mg, Ti (TLD-100; Harshaw Chemical Company) chips, having sizes of 3.2 Â 3.2 Â 0.89 mm 3 , spatial resolution of 2 mm, density of 2.64 g/cm 3 ("href="http://Thermoscientific.comwebsite"). 16 A total of 100 TLDs from 2 different batches were available (50 TLDs from batch A and 50 from batch B).…”