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  • 1
    Electronic Resource
    Electronic Resource
    Torsional band assignment and intramolecular twist potential of 9,9'-bianthryl and its 10-cyano derivative in a free jet (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 4543-4555 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Using a pulsed supersonic beam and laser-induced fluorescence spectroscopy the torsional structure of the S0 and S1 states of 9,9'-bianthryl (BA) and its derivative 10-(cyano)-9,9'-bianthryl (CBA) was investigated. Taking into account the very different equilibrium positions of the S0 and S1 potentials which result in a nonobservable 0–0 transition within the jet spectra, a new and straightforward procedure of torsional band assignment is carried out. This is based on a characteristic pattern of Franck–Condon factors within the dispersed fluorescence spectra. The torsional potentials were determined by a fit procedure of a one-dimensional model to the experimental data. The results show that the S1 double minimum potential for BA is shallower than for CBA indicating a stronger interaction between the molecular halfs of the latter compound. The observed rotational contours of torsional bands recorded for CBA reflect the change from a symmetric top molecule (for states above the S1 torsional barrier) to an asymmetric top (for states below the barrier) and manifest the tunneling splitting of the level just below the barrier. The dispersed fluorescence spectra of CBA are discussed in terms of intramolecular vibrational redistribution (IVR) processes. The measured fluorescence decay rates as a function of excess vibrational energy of CBA reflect a saturation behavior already within the origin region in contrast to BA (saturation near 380 cm−1). This is tentatively ascribed to a low lying dark background state possibly of charge transfer character.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.458695
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  • 2
    Electronic Resource
    Electronic Resource
    Resonance effects of diabatic surface crossing within the torsional spectrum of 9-(N-carbazolyl) anthracene observed by supersonic jet fluorescence spectroscopy (1993)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 98 (1993), S. 2580-2592 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Using the supersonic jet technique and laser-induced fluorescence spectroscopy, the ground and excited state surface of isolated 9-(N-carbazolyl) anthracene (C9A) is investigated. Ground and excited state torsional potentials of high accuracy are deduced from excitation and fluorescence spectra, considering characteristic patterns of Franck–Condon factors within the dispersed fluorescence. S0 exhibits a very flat double minimum potential (equilibrium twist angle 77.5°, barrier 17 cm−1); the barrier for perpendicularity in S1 is approximately 1050 cm−1 and the equilibrium angle is shifted towards coplanarity (64°). An unusual intensity profile of the long progression found in the fluorescence excitation spectrum is ascribed to a resonant nonradiative decay channel within the excited state surface. State selective fluorescence decay rates vs excess vibrational energy confirm this resonant relaxation process. This uncommon observation leads to a model of diabatic surface crossing along the torsional coordinate where the crossing "dark'' state is discussed as a predicted charge transfer state or a higher lying triplet state, mediating further electronic relaxation. Although extended intermolecular vibrational redistribution (IVR) is present in the fluorescence spectra from high vibrational levels, this process is of secondary importance for the resonant nonradiative relaxation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.464140
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  • 3
    Electronic Resource
    Electronic Resource
    Interventional laser-induced thermotherapy of hepatic metastases from breast cancer. Method and clinical outcome (1999)
    Springer
    Der Gynäkologe 32 (1999), S. 666-674 
    Details
    ISSN: 1433-0393
    Keywords: Key words Livermetastases • Breast carcinoma • ; Laser induced thermotherapy • Minimally invasive therapy ; Schlüsselwörter Lebermetastasen • Mammakarzinom • Laserinduzierte Thermotherapie • Minimal-invasive Therapien
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Im Rahmen der hämatogenen Metastasierung des Mammakarzinoms stellt die Leber ein häufig betroffenes Organ dar. Im Falle eines isolierten Befalls der Leber werden bei fehlendem Ansprechen auf Chemo- und Hormontherapie im Einzelfall lokal sanierende Maßnahmen wie die chirurgische Resektion oder auch minimal-invasive Verfahren wie Tumorablationen diskutiert. Im Rahmen eines klinischen Programms wurden daher prospektiv 51 Patienten mit sekundär metastatischem Befall der Leber bei Mammakarzinom mittels MR-gesteuerter laserinduzierter Thermotherapie in Lokalanästhesie therapiert. Die mittels MR-gesteuerter LITT erzielte lokale Tumorkontrolle in der Leber lag in der 3-Monats-Kontrolle bei 98,2 %, in der 6-Monats-Kontrolle bei 97,1 %. Die mittlere Überlebensrate, berechnet ab Diagnosestellung der gelaserten Metastase betrug 50,29 (95-%-Konfidenzintervall (KI) 41,99–58,59) Monate. Berechnet ab dem Tag der Laserbehandlung betrug die mittlere Überlebensrate 36,31 (95-%-KI 30,40 – 42,22) Monate. Die LITT erlaubt heute eine hohe lokale Tumorkontrollrate; mögliche Indikationen liegen bei Patienten mit primär hepatischer Metastasierung, bei denen trotz Chemo- und Hormontherapie residuelle Lebermetastasen nachgewiesen werden oder diese progredient sind.
    Notes: Summary The liver is one of the most involved organs in the case of hematogenous metastases of breast carcinoma. In strictly intrahepatic involvement of breast cancer local ablative methods like surgical resection and minimal-invasive treatment modalities are discussed when systemic chemo- or hormone therapies are ineffective. In the clinical programme 51 patients with secondary metastastic involvement of the liver due to breast carcinoma were prospectively treated via MR-guided laser-induced thermotherapy in an outpatient setting. Patients were included with a maximum of five lesions up to a maximum diameter of 5 cm. Patients with additional extrahepatic involvement are excluded. MR-guided LITT allowed local tumor control in the liver at three months of 89.2 % and at six months of 79.1 %. The cumulative median survival rate was 50,29 months (confidence interval 95 %, 41.99–42.22 months). MR-guided LITT allows high local tumor control. Possible indications for the treatment with LITT are patients with strictly intrahepatic metastases who are not demonstrating a complete response after chemo- or hormone therapy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00003280
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  • 4
    Electronic Resource
    Electronic Resource
    Laserinduzierte Thermotherapie Technische Voraussetzungen zur Behandlung maligner Lebertumoren (1998)
    Springer
    Der Chirurg 69 (1998), S. 930-937 
    Details
    ISSN: 1433-0385
    Keywords: Key words: Laser-induced thermotherapy ; Liver metastases ; Diffusing tip ; Lesion volume ; Multiple-fiber application. ; Schlüsselwörter: Laserinduzierte Thermotherapie ; Lebermetastasen ; Diffuser-Tip-Applikator ; Läsionsgröße ; Multifaserapplikation.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung. Die laserinduzierte Thermotherapie (LITT) ist eine Form der In-situ-Ablationsmethode zur lokalen Behandlung von Lebertumoren. Eine Grundvoraussetzung zur Induktion ausreichend großer Behandlungsvolumina für den klinischen Einsatz war die Entwicklung thermostabiler Applikationssysteme. In einer Ex-vivo-Versuchsreihe zeigte ein eigens entwickeltes Applikationssystem (Diffuser-Tip) mit 5760 J im Vergleich zu dem Ringmode®-Applikator mit 4200 J eine höhere thermische Belastbarkeit, so daß signifikant größere Läsionen mit einem Volumen von 7,6 cm3 induziert werden konnten. Die Ergebnisse einer weiterführenden In-vivo-Versuchsreihe demonstrierten, daß die Läsionen in einem Zeitraum von 6 Monaten, einer in 4 Phasen verlaufenden bindegewebigen Organisation unterlagen. Darüber hinaus resultierten in der In-vivo-Versuchsreihe bei gleicher Laserenergie (4200 J) mit 2,5 cm3 signifikant geringere Läsionsvolumina als in der Ex-vivo-Studie. In einer weiteren tierexperimentellen Studie wurde der Einfluß der Leberperfusion auf das induzierbare Läsionsvolumen untersucht. Durch die temporäre Unterbrechung der hepatischen Blutperfusion (Pringle-Manöver) während der Laserapplikation war bei Verwendung eines optischen Strahlteilers eine Vergrößerung des Wirkvolumens auf 50,3 cm3 (p 〈 0,01) erzielbar. Diese Daten zeigen, daß die technischen Voraussetzungen zur Induktion ausreichend großer Läsionsvolumina für die Behandlung humaner Lebermetastasen mit der LITT geschaffen wurden.
    Notes: Summary. Laser-induced thermotherapy is an in situ ablation method for the local treatment of liver tumors. The basic prerequisite for induction of adequate treatment volumes for clinical use was the development of a thermostable application system. In an ex vivo test series, the specially developed application system (diffuser tip) with 5760 J had a higher thermic loading capacity than the Ringmode applicator with 4200 J, thus enabling the induction of significantly larger lesions with a volume of 7.6 cm3. The results of a further in vivo test series demonstrated that the lesions were subject to a four-phase connective-tissue organization within a 6-month period. Furthermore, the same laser energy (4200 J) was associated with a significantly lower lesion volume of 2.5 cm3 in the in vivo than in the ex vivo test series. The influence of liver perfusion on the inducible lesion volume was examined in a further animal experimental study. By temporarily interrupting hepatic blood perfusion (Pringle's maneuver) during laser application, the effective volume could be increased to 50.3 cm3 (P 〈 0.01) using an optical beam splitter. These results show that the technical prerequisites for reliable clinical application of laser-induced thermotherapy have been fulfilled.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001040050517
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  • 5
    Electronic Resource
    Electronic Resource
    Laser-induced thermotherapy for the treatment of liver metastasis (1998)
    Springer
    Surgical endoscopy and other interventional techniques 12 (1998), S. 1317-1325 
    Details
    ISSN: 1432-2218
    Keywords: Key words: Laser-induced thermotherapy — Liver metastasis — Rabbit — Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Purpose: To evaluate gadolinium (Gd)-diethylenetriamine-pentaacetic-acid (DTPA)-enhanced magnetic resonance imaging (MRI) for follow-up monitoring of laser-induced thermotherapy (LITT) and to determine a useful examination schedule. Methods: LITT of the liver was performed in 55 rabbits using a neodymium: yttrium-aluminum-garnet (Nd:YAG) laser (4-W power output, 840-s exposure time). Gd-DTPA MRI and histologic examinations were performed at different times (0–168 days). Results: Laser-induced lesions underwent regeneration and volume size reduction (69% after 168 days). The correlation coefficient (MR vs. macroscopic analysis) for the mean lesion diameter was r= 0.96. Histology of lesions comprised the four zones that correlated best with MRI findings. Coagulation necroses immediately after LITT was seen as an area of no enhancement on Gd-DTPA MRI. Circular enhancement was first seen 72–96 h after LITT, which was due to early mesenchymal proliferation. Conclusions: Gd-DTPA MRI is a good monitoring procedure for LITT. MRI should be performed 24 and 96 h after LITT.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004649900849
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  • 6
    Electronic Resource
    Electronic Resource
    Diffusing Fibre Tip for the Minimally Invasive Treatment of Liver Tumours by Interstitial Laser Coagulation (ILC): An Experimental Ex Vivo Study (1999)
    Springer
    Lasers in medical science 14 (1999), S. 32-39 
    Details
    ISSN: 1435-604X
    Keywords: Keywords: Interstitial laser coagulation; Laser applicator; Laser induced thermotherapy; Liver tumours; Nd-YAG laser
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract. A newly developed diffusing laser applicator was examined for interstitial laser coagulation (ILC) of liver tumours. The applicator consisted of a matted quartz core and a quartz glass dome, also matted on its inner surface and sealed to the fibre. The applicator provided a homogeneous light intensity distribution over an active length of about 20 mm. Lesions were created in an ex-vivo porcine liver model using a Nd-YAG laser comparing the new diffusing tip with a Ringmode®-ITT applicator in order to find optimal laser parameters and damage thresholds. The lesions were investigated using macroscopic size measurement, volume calculation and histological examination (H&E, NADPH-dehydrogenase). The damage threshold of the diffusing tip was 6 W at 14 min exposure time whereas the Ringmode®-ITT applicator had its limit at 5 W and 12 min exposure. Comparing various exposure times showed that treatment over a time of more than 840 s did not significantly increase the lesion volume. At 5 W and 720 s the mean lesion volume was 6.9±1.1 cm3 with the diffusing tip and 6.3±0.6 cm3 with the Ringmode®-ITT applicator, both having a slight ellipsoidal shape. Hence, the created lesions were not significantly different for both applicators when the same laser parameters were applied. On the other hand, the new diffusing tip had a higher damage threshold and was therefore capable of producing maximal coagulation volumes of up to 7.9±0.5 cm3 at 5 W and 20 min. The experiments showed that lesions with a dimension of 31×22 mm can be achieved with the diffusing applicator which seem suitably sized for treating small human liver metastases in a single laser session.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s101030050018
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  • 7
    Electronic Resource
    Electronic Resource
    The effect of preparation technique on the optical parameters of biological tissue (1999)
    Springer
    Applied physics 69 (1999), S. 445-453 
    Details
    ISSN: 1432-0649
    Keywords: PACS: 42.10; 42.20; 78; 87
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. The absorption coefficient μa, the scattering coefficient μs, and the scattering anisotropy factor g of porcine liver were studied in vitro using the integrating sphere technique and inverse Monte Carlo simulation in the wavelength range 450 to 700 nm. A reference preparation technique was developed using a dermatome providing specimens of 200 to 800 μm thickness without pre-freezing the tissue. The optical parameters as measured applying the reference preparation were compared to those measured after cryo-homogenisation. We found significant deviations of the scattering coefficient and the anisotropy factor which were compensated when the reduced scattering coefficient μs ′ was calculated. We also compared the effects of freezing reference specimens at -20 °C and at 77 K without homogenisation. For both freezing protocols noticeable deviations were found in all three optical parameters as well as in μs ′. The impact of tissue storage at 4 °C was measured in the range 4 to 48 h post mortem and showed a clear reduction of μa and a significant increase of μs even after 24 h of storage. Short-time storage of the specimens in saline solution reduced all three optical parameters significantly. In conclusion, the tissue preparation must be controlled in order to provide in vitro optical parameters that sufficiently mimic the in vivo situation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003400050833
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