Approximated Poncelet configurations

In this short note we present the approximate construction of closed Poncelet configurations using the simulation of a mathematical pendulum. Although the idea goes back to the work of Jacobi, only the use of modern computer technologies assures the success of the construction. We present also some remarks on using such problems in project based university courses and we present a Matlab program able to produce animated Poncelet configurations with given period. In the same spirit we construct Steiner configurations and we give a few teaching oriented remarks on the Poncelet grid theorem. (DIPF/authors

Efficiency analysis of double perturbed pairwise comparison matrices

Efficiency is a core concept of multi-objective optimization problems and multi-attribute decision making. In the case of pairwise comparison matrices a weight vector is called efficient if the approximations of the elements of the pairwise comparison matrix made by the ratios of the weights cannot be improved in any position without making it worse in some other position. A pairwise comparison matrix is called double perturbed if it can be made consistent by altering two elements and their reciprocals. The most frequently used weighting method, the eigenvector method is analyzed in the paper, and it is shown that it produces an efficient weight vector for double perturbed pairwise comparison matrices

A van Neck–Odelberg-betegség bemutatása két eset kapcsán

Absztrakt Az osteochondritis ischiopubica (van Neck–Odelberg-betegség) esetében a ramus ossis ischii és a ramus inferior ossis pubis nem megszokott elcsontosodásáról van szó. Klinikai tünetei általában a fájdalom, sántító járás és a csípőízületi mozgáskorlátozottság. A radiológiai kép összetéveszthető egy esetleges töréssel, tumorral vagy gyulladással. Bizonyos esetekben nehézséget okozhat a pontos diagnózis megállapítása és mint elkülönítő kórisme mindenképpen gondolni kell e kórképre. A szerzők két eset ismertetése kapcsán kívánják felhívni a figyelmet e ritka, gyermekkorban jelentkező csontosodási zavar differenciáldiagnosztikai nehézségeire. Orv. Hetil., 2016, 157(21), 836–839

Image guided high-dose-rate brachytherapy versus volumetric modulated arc therapy for head and neck cancer

Background The aim of the study was to present dosimetric comparison of image guided high-dose-rate brachytherapy (IGBT) with volumetric modulated arc therapy (VMAT) for head and neck cancer regarding conformity of dose distribution to planning target volume (PTV) and doses to organs at risk (OARs). Patients and methods Thirty-eight consecutive patients with T1-4 mobile tongue, floor of mouth and base of tongue cancer treated with IGBT were selected. For these patients additional VMAT treatment plans were also prepared using identical computed tomography data. OARs and PTV related parameters (e.g. V98, D0.1cm3, Dmean, etc.) were compared. Results Mean V98 of the PTV was 90.2% vs. 90.4% (p > 0.05) for IGBT and VMAT, respectively. Mean D0.1cm3 to the mandible was 77.0% vs. 85.4% (p 0.05). Dmean to ipsilateral and contralateral submandibular glands was 16.4% vs. 21.9% (p > 0.05) and 8.2% vs. 16.9% (p < 0.05), respectively. Conclusions Both techniques showed excellent target coverage. With IGBT dose to normal tissues was lower than with VMAT. The results prove the superiority of IGBT in the protection of OARs and the important role of this invasive method in the era of new external beam techniques

A CyberKnife sztereotaxiás sugárterápia alkalmazásának lehetősége fej-nyaki daganatok kezelésében

The treatment of squamous cell carcinoma of the head and neck is multimodal, including surgery, chemotherapy, and radiotherapy, or the combination of those. Though aggressive treatment results in complete tumor remission in many patients even in locally advanced stages, unfortunately local relapse is not uncommon. For patients not candidate for salvage surgery, chemotherapy and conventional fractionated external beam irradiation can be applied. However, for patients previously treated with full-dose radiotherapy, the deliverable reirradiation dose is limited, considering the elevated risk of toxicity caused by cumulative doses. CyberKnife is a highly conformal radiosurgical technology which can successfully treat this subset of patients. In addition, it can be applied for hardly resectable rare tumors of the skull base and the head and neck region like chordoma, chondrosarcoma and paragangliomas. The CyberKnife stereotacic radiosurgery technology is now available in Hungary, in the National Institute of Oncology

The characteristics of head and neck squamous cell cancer in young adults: A retrospective single-center study

We aimed to characterize clinical and prognostical factors of primary head and neck squamous cell carcinoma (HNSCC) in 85 young patients (≤39 years, median age: 37 years; between 2000–2018) in comparison with 140 institutional general HNSCC patients (median age: 61.5 years). The patient’s medical records were collected from the institutional database. The prevalence of smoking and alcohol consumption (65.8% and 48.1%) in the young group exceeded the regional population average but was below the institutional (86.4% and 55%) general HNSCC patient population. Primary tumor sites in the group of young patients were as follows: oral cavity (56.4%), oropharynx (17.6%), hypopharynx (11.7%), and larynx (14.1%). Cumulative five-year overall survival was 44.2% in the young group, but significantly better with early T (T1-2 vs. T3-4: 52.6% vs. 26.7%; p = 0.0058) and N0 status (N0 vs. N+: 65.2% vs. 32.3%; p = 0.0013). Young age, abstinence, earlier stage and laryngeal tumor site might predict a better prognosis. The age distribution and the high prevalence of traditional risk factors among the young patients as well as the predominance of oral cavity tumor localization suggest that the early onset of tumor development could be originated from the premature failure of the intrinsic protective mechanisms