258 research outputs found

    Investigation of vibro-acoustic properties of modern lathe collet chuck

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    Manufacturing industry has been attempting to attain the required cutting performance in order to achieve high precision, fast productivity and lower maintenance costs. Vibrations generated during machining can be a serious problem degrading component quality, precision, tool service life, lathe performance and cutting rates. This paper is concerned with analysis of cutting process by using modal testing. Static and dynamic deformations of lathe collet chuck have a significant impact on cutting process stability, which affects workpiece quality and production output. Modal analysis was applied to develop a mathematical model of chucks dynamics, which consist of a number of mode shapes each with natural frequency and modal damping. Modal analysis and experimental measurements were performed on a collet chuck of CNC lathe installed in metal working company UAB “Stevila”

    148. Changes in lateral dimensions of irradiated volume and their impact on the accuracy of dose delivery during radiotherapy for head and neck cancer

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    AimTo assess changes in lateral dimensions of irradiated volume during head and neck cancer radiotherapy and their impact on dose delivery accuracy.Material and methodsLateral dimensions of irradiated volumes were measured in 5 predefined points using computed tomography, simulator and manually with calipers, prior to treatment and then bi-weekly. For each measurement reference point dose was calculated and verified using in vivo dosimetry. Early radiation reactions, patient's weight changes and the need to modify radiotherapy accessories were also assessed. All these parameters were analyzed in relation to tumor site and stage, treatment field size, radiation dose and the degree of radiation reactions.ResultsThe study included 33 head and neck cancer patients (24 men and 9 women) aged 24–77 (median 56). All patients were irradiated using the parallel opposed megavoltage fields ranging from 49 to 180 cm2 (median 121 cm2) to the dose of 44 to 80 Gy (median 66 Gy). Radiation reactions included mucositis (grade 3 – 1 patient, grade 2 – 17 patients, grade 1 – 13 patients) and dysphagia (grade 2 – 12 patients, grade 1 – 16 patients). The body mass changes during radiotherapy ranged from −18 to +4 kg (median −5 kg). In 1 patient radiotherapy accessories had to be modified three times during the treatment, in 6 – twice and in 10 – once. Lateral dimensions changes >5 mm occurred in all but one patient (range −37 to +16 mm). Theoretical doses calculated for changed dimensions varied from prescribed by −2.5% to +6% (median +2%). Differences larger than 5% were present in 4.8% of calculations. In vivo dose measurements (after introduction of necessary corrections) demonstrated difference from prescribed dose larger than 5% in 7.6% of measurements.ConclusionChanges in the lateral dimensions of irradiated volume during head and neck cancer radiotherapy may lead to some inaccuracies in delivered doses. Such situations may necessitate adequate corrections of dose calculations and modification of radiotherapy accessories during the course of treatment

    Clinical use of biomarkers in breast cancer: Updated guidelines from the European Group on Tumor Markers (EGTM)

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    Abstract Biomarkers play an essential role in the management of patients with invasive breast cancer. For selecting patients likely to respond to endocrine therapy, both oestrogen receptors (ERs) and progesterone receptors (PRs) should be measured on all newly diagnosed invasive breast cancers. On the other hand, for selecting likely response to all forms of anti-HER2 therapy (trastuzumab, pertuzumab, lapatinib or ado-trastuzumab emtansine), determination of HER2 expression or gene copy number is mandatory. Where feasible, measurement of ER, PR and HER2 should be performed on recurrent lesions and the primary invasive tumour. Although methodological problems exist in the determination of Ki67, because of its clearly established clinical value, wide availability and low costs relative to the available multianalyte signatures, Ki67 may be used for determining prognosis, especially if values are low or high. In oestrogen receptor (ER)-positive, HER2-negative, lymph node–negative patients, multianalyte tests such as urokinase plasminogen activator (uPA)-PAI-1, Oncotype DX, MammaPrint, EndoPredict, Breast Cancer Index (BCI) and Prosigna (PAM50) may be used to predict outcome and aid adjunct therapy decision-making. Oncotype DX, MammaPrint, EndoPredict and Prosigna may be similarly used in patients with 1–3 metastatic lymph nodes. All laboratories measuring biomarkers for patient management should use analytically and clinically validated assays, participate in external quality assurance programs, have established assay acceptance and rejection criteria, perform regular audits and be accredited by an appropriate organisation

    A Technology of Wastewater Sludge Treatment

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    At many communities, industrial and agricultural enterprises, treatment and recycling of wastewater sludge is an urgent task as the sludge is poured and stored in sludge banks for many years and thus worsens the ecology and living conditions of the region. The article suggests a new technology of wastewater sludge treatment using water-soluble binder and heat treatment in microwave ovens

    37. Multicenter, randomized study assessing the impact of amifostine on normal tissue radiation tolerance during head and neck cancer radiotherapy

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    A prospective, randomized multicenter study was conducted to assess the value of amifostine (Ethyol®) as a radioprotectant in head and neck cancer radiotherapy. The aim of the study was to evaluate the impact of the addition of daily amifostine (150 mg/m2) on the degree of early (mucositis, dysphagia, xerostomia) and late (mucosal, cutaneous, salivary gland, mandible and spinal cord) radiation reactions. Assessed were also patients’ quality of life, local control and overall survival. Sixty two patients from five Polish institutions were randomly assigned to radiotherapy alone (Arm A – 28 patients) or radiotherapy + amifostine (Arm B – 34 patients). There were 43 men and 19 women. Primary tumor was located in the oral cavity (27 patients), oropharynx (25 patients), nasopharynx (2 patients) and larynx/hypopharynx (8 patients). In 43 patients radiotherapy was used as the sole modality of treatment and 19 patients were irradiated postoperatively. The side effects of amifostine were manageable. In 6 patients amifostine infusion had to be temporarily stopped due to hypotension and in 5 patients its administration was permanently terminated due to hypotension, nausea and vomiting, septicemia or fever and visual disturbances. The early results of the study, focusing on early radiation reactions, will be presented at the conference

    34. A multicenter randomized study of two regimens in paliative radiotherapy of bone metastases

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    In this study we compared two methods of radiotherapy in patients with painful bone metastases: 20 Gy in five fraction in five consecutive days vs 8 Gy in one fraction. A total of 115 patients (34 males, 81 females), median age 56 years (23–80), were randomly allocated to one of the treatment arms. In 56 pts. Primary tumor was located in the breast, in 14 pts in the lung, in ten pts in the kidney, in seven pts in the prostate, and in 28 pts in other sites. A total of 146 metastatic bone lesions were irradiated, seventy five (51%) were treated with 20 Gy and seventy one (49%) – with 8 Gy. The most frequent location of metastatic lesions was spine (36%), followed by pelvis (25%), long bones (18%), ribs (12%) and other sites (12%). Treatment techniques included single field (73%) or two parallel opposed fields (27%). Complete pain relief was achieved in 36% of the lesions irradiated with 20 Gy and in 41% of those irradiated with 8 Gy. Partial improvement was observed in 46% and 43% of lesions, respectively. The median time to reappearance of pain in both groups was 5.4 a 4.8 months and 5.0 a 5.4 months respectively. We conclude that a single exposure to 8 Gy is of the same efficacy as 20 Gy in five fractions in pain control of bone metastases and should be recommended as routine management
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