Radiobiological Studies of Microvascular Damage through In Vitro Models: A Methodological Perspective

Ionizing radiation (IR) is used in radiotherapy as a treatment to destroy cancer. Such treatment also affects other tissues, resulting in the so-called normal tissue complications. Endothelial cells (ECs) composing the microvasculature have essential roles in the microenvironment’s homeostasis (ME). Thus, detrimental effects induced by irradiation on ECs can influence both the tumor and healthy tissue. In-vitro models can be advantageous to study these phenomena. In this systematic review, we analyzed in-vitro models of ECs subjected to IR. We highlighted the critical issues involved in the production, irradiation, and analysis of such radiobiological in-vitro models to study microvascular endothelial cells damage. For each step, we analyzed common methodologies and critical points required to obtain a reliable model. We identified the generation of a 3D environment for model production and the inclusion of heterogeneous cell populations for a reliable ME recapitulation. Additionally, we highlighted how essential information on the irradiation scheme, crucial to correlate better observed in vitro effects to the clinical scenario, are often neglected in the analyzed studies, limiting the translation of achieved results.

The Influence of Lobe-based Radiotherapy Plan Optimization Method on Different Lymph Node Irradiation Schemes for Operable LA-NSCLC Patients

Purpose Various target volume delineation schemes differ greatly for stage IIIa NSCLC radiotherapy. Although tightened target volume may give patients the opportunity to receive radiotherapy, it is not absolutely safe to narrow the irradiation area. For IIIa NSCLC patients who will undergo lobectomy, a new neoadjuvant radiotherapy based on sparing preserved lung lobes may improve the dose distribution of the preserved lobe, and provide freedom for physicians in optimizing treatment strategies. Materials and methods Computed tomography imaging data of 20 IIIA- p N2 NSCLC patients were used to produce conventional IMRT(IMRT) and Preserved Lobe based IMRT(P-IMRT) plan respectively according to two different target volume delineation schemes(OPT1 and OPT2). Dose results of target coverage, Total lung, Ipsilateral lung, Preserved Total Lung, Preserved Ipsilateral Lung, Contralateral Lung, Resected Lobe and other OARs in the four groups were analyzed. Results All plans met dose limits. Lobe-based IMRT significantly reduce the irradiated dose of Lung lobes, especially Preserved Total Lung and Preserved Ipsilateral Lung, for both delineation schemes. Mean Dose of Preserved Total Lung decreased from 819.93 cGy to 690.98 cGy (OPT1) and 542.47 cGy to 469.62 cGy (OPT2), Mean Dose of Preserved Ipsilateral Lung decreased from 1282.95 cGy to 1068.55 cGy (OPT1) and 955.83 cGy to 795.97 cGy (OPT2), respectively. While the dose indices of Resected Lobe increased slightly for only about 1%. Comparing the four groups of plans, it’s more effective in optimizing the dose of lung lobes by this method for the delineation scheme with a large target volume. The lung dose metrics in P-IMRTOPT1 can be reduced to a value very close to that in IMRTOPT2, and some values are even lower than that in IMRTOPT2. Conclusion For IIIA-N2 NSCLC patients who will undergo lobectomy, no matter which target delineation scheme is chosen, preoperative neoadjuvant radiotherapy using a lobe -based planning can significantly reduce the radiation dose that preserves the lobes. Especially for the large-scale lymph node irradiation scheme, this method can also reduce the dose of preserved lung lobe to a level that is comparable to or lower than that of the conventional IMRT small-area lymph node irradiation scheme, and reduce the obstacles for clinicians in selecting the optimal individualized scheme.

Comparison between illumination model and hydrodynamic simulation for a direct drive laser irradiated target

A spherical target irradiated by laser beams located at 49o and 131° with respect to the polar axis has been considered. The illumination model has been used to evaluate the irradiation non-uniformity assuming circular and elliptical super-Gaussian laser intensity profiles and the irradiation scheme has been optimized by means of the polar direct drive technique. A parametric study has been performed providing the irradiation non-uniformity as a function of the polar direct drive displacement and of the laser intensity profile parameters. Moreover, two-dimensional axis-symmetric hydrodynamic simulations have been performed for a plastic sphere irradiated by laser beams characterized by a constant flat temporal power pulse. In these simulations, the front of the inward shock wave has been tracked providing the time-evolution of any non-uniformity. The results provided by the two methods — illumination model and hydrodynamic data — have been compared and it is found that the illumination model reproduces the main behavior exhibited by the hydrodynamic data. The two models provide compatible values for the optimum polar direct drive parameter and similar optimal super-Gaussian profiles.

Fast ignition driven by quasi-monoenergetic ions: Optimal ion type and reduction of ignition energies with an ion beam array

Fast ignition of inertial fusion targets driven by quasi-monoenergetic ion beams is investigated by means of numerical simulations. Light and intermediate ions such as lithium, carbon, aluminum and vanadium have been considered. Simulations show that the minimum ignition energies of an ideal configuration of compressed Deuterium-Tritium are almost independent on the ion atomic number. However, they are obtained for increasing ion energies, which scale, approximately, as Z2, where Z is the ion atomic number. Assuming that the ion beam can be focused into 10 µm spots, a new irradiation scheme is proposed to reduce the ignition energies. The combination of intermediate Z ions, such as 5.5 GeV vanadium, and the new irradiation scheme allows a reduction of the number of ions required for ignition by, roughly, three orders of magnitude when compared with the standard proton fast ignition scheme.