Mathematical Formulation of DMH-Based Inverse Optimization

Purpose: To introduce the concept of dose-mass based inverse optimization for radiotherapy applications.Materials and Methods: Mathematical derivation of the dose-mass based formalism is presented. This mathematical representation is compared to the most commonly used dose-volume based formulation used in inverse optimization. A simple example on digitally created phantom is presented. The phantom consists of three regions: a target surrounded by high and low density regions. The target is irradiated with two beams through those regions and inverse optimization with dose-volume and dose-mass based objective functions is performed. The basic properties of the two optimization types are demonstrated on the phantom.Results: It is demonstrated that dose-volume optimization is a special case of dose-mass optimization. In a homogenous media dose-mass optimization turns into dose-volume optimization. The dose calculations performed on the digital phantom show that in this very simple case dose-mass optimization tends to penalize more the dose delivery through the high density region and therefore it results in delivering more dose through the low density region.Conclusions: It was demonstrated that dose-mass based optimization is mathematically more general than dose-volume based optimization. In the case of constant density media dose-mass optimization transforms into dose-volume optimization

Abscopal effect observed in visceral and osseous metastases after liver SBRT in combination with nivolumab and relatlimab for sinonasal mucosal melanoma—a case report

BackgroundPrimary sinonasal mucosal melanoma (SNMM) is a rare, aggressive histology usually diagnosed at advanced stages and associated with poor prognosis. Evidence regarding etiology, diagnosis, and treatment mainly derives from case reports, retrospective series, and national databases. In the treatment of metastatic melanoma, anti-CTLA-4 and anti-PD-1 checkpoint blockade increased 5-year overall survival from ~10% (prior to 2011) to ~50% (between 2011 and 2016). In March of 2022, the FDA approved the use of relatlimab, a novel anti-LAG3 immune checkpoint inhibitor, for the treatment of melanoma.Case presentationA 67-year-old woman with locally advanced SNMM underwent debulking surgery, adjuvant RT, and first-line immunotherapy (ImT) with nivolumab but developed local progression. The patient started a second course of ImT with nivolumab and ipilimumab, but this was discontinued after two cycles due to an immune-related adverse event (irAE, hepatitis with elevated liver enzymes). Interval imaging identified visceral and osseous metastases including multiple lesions in the liver and in the lumbar spine. She went on to receive a third course of ImT with nivolumab and the novel agent relatlimab with concurrent stereotactic body radiation therapy (SBRT) to the largest liver tumor only, delivered in five 10-Gy fractions using MRI guidance. A PET/CT performed 3 months after SBRT demonstrated complete metabolic response (CMR) of all disease sites including non-irradiated liver lesions and spinal metastatic sites. After two cycles of the third course of ImT, the patient developed severe immune-related keratoconjunctivitis and ImT was discontinued.ConclusionThis case report describes the first complete abscopal response (AR) in an SNMM histology and the first report of AR following liver SBRT with the use of relatlimab/nivolumab combination ImT for metastatic melanoma in the setting of both visceral and osseous lesions. This report suggests that the combination of SBRT with ImT potentiates the adaptive immune response and is a viable path for immune-mediated tumor rejection. The mechanisms behind this response are hypothesis-generating and remain an area of active research with exceedingly promising potential

Mathematical Formulation of Energy Minimization – Based Inverse Optimization

Purpose: To introduce the concept of energy minimization-based inverse optimization for external beam radiotherapy. Materials and Methods: Mathematical formulation of energy minimization-based inverse optimization is presented. This mathematical representation is compared to the most commonly used dose–volume based formulation used in inverse optimization. A simple example on digitally created phantom is demonstrated. The phantom consists of three sections: a target surrounded by high and low density regions. The target is irradiated with two beams passing through those regions. Inverse optimization with dose–volume and energy minimization-based objective functions is performed. The dosimetric properties of the two optimization results are evaluated. Results: Dose–volume histograms for all the volumes of interest used for dose optimization are compared. Energy-based optimization results in higher maximum dose to the volumes that are used as dose-limiting structures. However, the average and the integral doses delivered for the volumes outside of the target are larger with dose–volume optimization. Conclusion: Mathematical formulation of energy minimization-based inverse optimization is derived. The optimization applied on the digital phantom shows that energy minimization-based approach tends to deliver somewhat higher maximum doses compared to standard of care, realized with dose–volume based optimization. At the same time, however, the energy minimization-based optimization reduces much more significantly the average and the integral doses

Integral Dose-Based Inverse Optimization May Reduce Side Effects in Radiotherapy of Prostate Carcinoma

PURPOSE: The purpose of this work is to apply a novel inverse optimization approach, based on utilization of quantitative imaging information in the optimization function, to prostate carcinoma. MATERIALS AND METHODS: This new inverse optimization algorithm relies upon quantitative information derived from computed tomography (CT) imaging studies. The Hounsfield numbers of the CT voxels are converted to physical density, which in turn is used to calculate voxel mass and the corresponding integral dose, by summation over the product of dose and mass in each dose voxel. This integral dose is used for plan optimization through its global minimization. The optimization results are compared to the optimization results derived from most commonly used dose–volume-based inverse optimization, where objective functions are formed as summation over all dose voxels of the squared differences between voxel doses and user specified doses. The data from 25 prostate plans were optimized with dose–volume histogram (DVH) and integral dose (energy) minimization objective functions. The results obtained with the energy- and DVH-based optimization schemes were studied through commonly used dosimetric indices (DIs). Statistical equivalence tests were further performed to establish population-based significance results. RESULTS: Both DVH- and energy-based plans for each case were normalized so that 95% of the planning target volume receives the prescription dose. The average differences for the rectum and bladder DIs ranged from 1.6 to 25%, where the energy-based quantities were lower. For both femoral heads, the energy-based optimization-derived doses were lower on average by 32%. The statistical tests demonstrated that the significant differences in the tallied dose indices range from 2.7% to more than 50% for rectum, bladder, and femoral heads. CONCLUSION: For majority of the clinically relevant dosimetric quantities, energy-based inverse optimization performs better than the standard of care DVH-based optimization in prostate carcinoma. The population averaged statistically significant differences range from ~3 to ~50%. Therefore, this newly proposed optimization approach, incorporating explicitly quantitative imaging information in the inverse optimization function, holds potential for further reduction of complication rates in prostate cancer

Integral dose based inverse optimization objective function promises lower toxicity in head-and-neck

The voxels in a CT data sets contain density information. Besides its use in dose calculation density has no other application in modern radiotherapy treatment planning. This work introduces the use of density information by integral dose minimization in radiotherapy treatment planning for head-and-neck squamous cell carcinoma (HNSCC). Eighteen HNSCC cases were studied. For each case two intensity modulated radiotherapy (IMRT) plans were created: one based on dose-volume (DV) optimization, and one based on integral dose minimization (Energy hereafter) inverse optimization. The target objective functions in both optimization schemes were specified in terms of minimum, maximum, and uniform doses, while the organs at risk (OAR) objectives were specified in terms of DV- and Energy-objectives respectively. Commonly used dosimetric measures were applied to assess the performance of Energy-based optimization. In addition, generalized equivalent uniform doses (gEUDs) were evaluated. Statistical analyses were performed to estimate the performance of this novel inverse optimization paradigm. Energy-based inverse optimization resulted in lower OAR doses for equivalent target doses and isodose coverage. The statistical tests showed dose reduction to the OARs with Energy-based optimization ranging from ∼2% to ∼15%. Integral dose minimization based inverse optimization for HNSCC promises lower doses to nearby OARs. For comparable therapeutic effect the incorporation of density information into the optimization cost function allows reduction in the normal tissue doses and possibly in the risk and the severity of treatment related toxicities

Simulation Investigation of the Wind Load of Photovoltaic Panels

In this article, a simulation and evaluation of the mechanical stress exerted by the wind on photovoltaic panels is performed. The stresses of the solar cells in a PV module are calculated using the finite element method, taking into account the wind pressure and the allowable mechanical stresses, according to the regulatory requirements. Seven different operating positions of the photovoltaic panel during its rotation from 0° to 90° are considered. In each of these positions, a distributed load for computer simulations is 1 kN/m2. It is clear from them that for all operating positions of the panel, the maximum stresses are obtained in its frame. These stresses in different cases vary around the value of 50 MPa and are not dangerous for the structure

The Use of Information Technology in Financial Management

The article explores the concept of information technology and clarifies the essence of information technology in finance. The types of information technology in finance have been studied and their classification according to business entities has been carried out. A brief description of the main software products, the purpose of which is to ensure the implementation of the process of automation of financial research is given. The main tools for managing household (or person) finance using modern information technology are presented. The implementation of e-government in Ukraine is analyzed. The evaluation of the effectiveness of e-government implementation with the help of E-Government Development Index in Eastern European countries and in Ukraine is performed. A detailed analysis of the E-Government Development Index in Ukraine using a system of indicators has been studied. Digital technologies in the economy in general and in finance in particular have been studied separately. The indicators of world indexes digital economy development for Ukraine and for Eastern European countries are analyzed. The advantages and problems of the modern cryptocurrency market are clarified. The main directions of using artificial intelligence in finance are determine

Reduction of the Battery Capacity of Hybrid Electric Vehicle with the Help of Electrically Assisted Turbocharger

In this manuscript, the reduction of the battery capacity of a hybrid electric vehicle with the help of electrically assisted turbochargers was analyzed. Using the battery for vehicle propulsion and the options for its recharging, it could be concluded, that the most efficient way would be to use the battery energy for boosting mainly through eTurboTM and recharge the battery mainly with the traction motor in regenerative braking. Based on both steady-state and transient analysis it is clear, that for having the same dynamic HEV performance, the boosting with propulsion through ICE requires significantly less energy from the battery compared to the boosting through the traction motor. Therefore using the eTurboTM as boosting device can lead to reduce the battery capacity and reduce fuel consumption and emission of the vehicle