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  • 1
    ISSN: 0942-0940
    Keywords: Keywords: Brain metastasis; stereotactic radiosurgery; surgery.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary  Stereotactic radiosurgery (RS) and surgery have proved to be effective treatment modalities for brain metastasis. We followed 133 patients whose treatment for intracranial disease was either RS or a single surgical resection at the University of Vienna from August 1992 through October 1996. All patients who received additional Whole Brain Radiotherapy were included. This was a retrospective, case-control study comparing these treatment modalities.  Sixty-seven patients were treated by RS and 66 patients were treated by microsurgery. The median size of the treated lesions for RS patients was 7800 mm3, and 12500 mm3 for microsurgery patients, respectively. The median dose delivered to the tumour margin for RS patients was 17 gray.  The median survival for patients after RS was 12 months, and 9 months for patients after microsurgery. This difference was not statistically significant (p=0.19). Comparison of local tumour control, defined as absence of regrowth of a treated lesion, showed that tumours following RS had a preferred local control rate (p〈0.05). Univariate and multivariate analysis showed that this fact was due to a greater response rate of “radioresistant” metastasis to RS (p〈0.005). Postradiosurgical complications included the onset of peritumoural oedema (n=5) and radiation necrosis (n=1). Two patients after microsurgery experienced local wound infection. One postoperative death occurred due to pulmonary embolism in this group.  On the basis of our data we conclude that RS and microsurgery combined with Whole Brain Radiotherapy are comparable modalities in treating single brain metastasis. Concerning morbidity and local tumour control, in particular in cases of “radioresistant” primary tumours, RS is superior. Therefore we advocate RS except for cases of large tumours (〉3 cm in maximum diameter) and for those with mass effect.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-8752
    Keywords: Radiochromic film ; densitometer ; dosimetry ; GafChromic film ; γ-knife
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract GafChromic MD-55 films were irradiated by the Vienna γ-knife unit with a 14 and 8 mm collimator helmet (spherical field of close to 11 mm diameter) at the same isocenter to compare the dose cross-profiles along the x and z directions with different scanning systems. Dose-response curves for GafChromic MD-55 film (Nuclear Associates Model No. 37-041) were measured using two different densitometer systems: a commercial He-Ne laser densitometer (PTW FIPS Plus, Freiburg, Germany) and a newly developed analog diode laser densitometer. For this purpose, we chose the diode laser as the light source, emitting at 675.2 nm with a single-mode surface, measured with a Lock-In Amplifier by a solar cell. The highest uniformity was seen in the change of absorption ranging from 4% to 6%, depending on the polarizing direction of the light with the new scanning system. The reproducibility of the reading method increases from 0.14% in the region of 2 Gy to 0.18% near 16 Gy. Measurements of the dose cross-profiles of the 11 mm collimator with the 675.2 nm laser scanner generally show good agreement with the values of the dose planning program. Reference studies with the He-Ne laser reveal a general tendency between 1.5 and 2.2 mm in diameter as compared to computer-simulated dose profiles and the 675.2 nm laser densitometer values.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-7373
    Keywords: stereotactic radiosurgery ; brain neoplasm ; brain metastases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Stereotactic radiosurgery (SR) is being used with increasing frequency in the treatment of brain metastases. This study provides data from a clinical experience with radiosurgery in the treatment of cases with multiple metastases and identifies parameters that may be useful in the proper selection and therapy of these patients. From January 1993 to April 1997, 97 patients (43 women and 54 men; median age 58 years) suffering from multiple brain metastases (median 3; range 2–4) in MRI scans, received SR with the Gamma Knife. The median dose at the tumor margin was 20 Gy (range 17–30 Gy). Median tumor volume was 3900 cmm (range 100–10 000). Different forms of hemiparesis, focal and generalized seizures, cognitive deficit, headache, dizziness and ataxia had been the predominant neurological symptoms. Major histologies included lung carcinoma (44%), breast cancer (21%), renal cell carcinoma (10%), colorectal cancer (8%), and melanoma (7%). The median survival time was 6 months after SR. The actual one-year survival rate was 26%. In univariate and multivariate analysis, a higher Karnofsky performance rating and absence of extracranial metastases had a significantly positive effect on survival. Local tumor control was achieved in 94% of the patients. Complications included the onset of peritumoral edema (n=5) and necrosis (n=1). SR induces a significant tumor remission accompanied by neurological improvement and, therefore, provides the opportunity for prolonged high quality survival. We conclude that radiosurgical treatment of multiple brain metastases leads to an equivalent rate of survival when compared to the historic experience of patients treated with whole brain radiotherapy. Patients presenting initially with a higher Karnofsky performance rating and without extracranial metastases had a median survival time of nine months. Each such case should therefore be evaluated based on these factors to determine an optimal treatment regimen.
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  • 4
    ISSN: 0942-0940
    Keywords: Keywords: Renal cell carcinoma; stereotactic radiosurgery; metastasis; Gamma Knife
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary  From Jan. 1993 to Sept. 1995 23 patients suffering from brain metastases from renal cell carcinoma were treated with the Leksell Gamma Knife at the University of Vienna. At the time of diagnosis 13 patients had single and 10 patients presented with multiple metastatic lesions with a total of 44 metastases in MRI scans. Median tumour volume was 5500 cmm (range 100–24000 cmm). Predominant neurological symptoms and signs were different forms of hemiparesis, focal and generalized seizures, cognitive deficit, headache, dizziness, ataxia and CN XII paresis.  Fourteen patients received Gamma Knife Radiosurgery (GKRS) with a median dose of 22 Gy (range 8–30 Gy) at the tumour margin. Nine patients underwent a combined treatment of a radiosurgical boost with a median dose of 18 Gy (range 10–22 Gy) at the tumour margin followed by Whole Brain Radiotherapy (total dose 30 Gy/2 weeks).  In 20 patients tumour volume reduction up to 30% of the primary tumour volume was found after 4 weeks, evaluated on CT or MRI. A total remission was seen in 4 cases 3 months after GKRS. We achieved a local tumour control of 96%. Rapid neurological improvement after GKRS was seen in 17 patients. The median survival time was 11 months; the one-year actual survival in this unselected group was 48%. Five long term survivors were still alive, 18 patients had subsequently died, 15 of them of general tumour progression.  GKRS induces a significant tumour remission accompanied by rapid neurological improvement and therefore provides the opportunity for extended high quality survival. Neither local tumour control was improved nor CNS relapse free survival was prolonged significantly by additional WBRT.
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  • 5
    ISSN: 1934-2659
    Source: Berkeley Electronic Press Academic Journals
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new simulation method for investigating mixed aqueous electrolyte systems at thermodynamic equilibrium is presented. Based on the commercial simulation package IPSEpro, a graphical procedure for assembling equilibrium systems followed by simultaneous solution of the underlying equation system was developed. At graphical setup, species and reactions objects are connected by the information of activity and stoichiometry in a network-like manner. Consequently, the resulting equations of mass action, the electro-neutrality and balance conditions are solved incorporating the Pitzer activity coefficient model and equilibrium constants from thermodynamic standard data. The method developed allows fast and flexible application of the complex thermodynamic principles to engineering tasks. The modeling approach and all basic models for graphical input and simultaneous solution of coupled equilibrium conditions are explained. For demonstration of the simulation method, example simulations for the systems of H2SO4-H2O, CaSO4-H2SO4-H2O and NaCl-CaSO4-CO2-H2O are described and evaluated successfully.
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