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  • Articles  (51)
  • Photodynamic therapy  (36)
  • Thermal plasmas  (15)
  • 2010-2014
  • 1990-1994  (27)
  • 1985-1989  (24)
  • 1950-1954
  • Technology  (51)
  • 1
    Electronic Resource
    Electronic Resource
    Fluid boundary layer effects in atmospheric-pressure plasma diamond film deposition (1993)
    Springer
    Plasma chemistry and plasma processing 13 (1993), S. 169-187 
    Details
    ISSN: 1572-8986
    Keywords: Thermal plasmas ; chemical vapor deposition ; diamond film ; impinging jet ; atomic carbon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Diamond films were deposited in an atmospheric-pressure radio frequency plasma reactor. Hydrogen and methane were injected coaxially into the plasma as a high-velocity jet which impinged on the molybdenum substrate. In some cases argon was added to the reactant jet to increase its momentum, thereby reducing the boundary layer thickness. In most cases argon addition substantially, improved diamond growth. A numerical model was developed, which calculated two-dimensional reactor temperature and velocity, distributions, and the chemical kinetics in the boundary layer. The calculations indicate that under the experimental conditions argon addition reduced the thickness of the hydrogen nonequilibrium boundary layer from 3.5 to 1.0 mm. In addition, the calculations suggest that monatomic carbon may be a key diamond growth species under thermal plasma conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01466040
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  • 2
    Electronic Resource
    Electronic Resource
    Spectroscopic study of a magnetically rotating arc between opper electrodes in contaminated argon (1992)
    Springer
    Plasma chemistry and plasma processing 12 (1992), S. 1-16 
    Details
    ISSN: 1572-8986
    Keywords: Thermal plasmas ; electrode erosion ; plasma spectroscopy ; metal vapor plasma ; electrode contamination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract The effects of N2 and CO contaminants in atmospheric-pressure argon on an arc rotating between two concentric copper electrodes has been studied using optical spectroscopy of copper lines. The axial temperature of the magnetically driven arc in Ar + %N2 was determined to be around 10,000 K for arc currents of SO to 200 A. The diffusion process of the copper vapor from the cathode was also studied. A copper density maximum 1 mm from the cathode along the arc column was found in Ar + %N2. Removal of the contaminated cathode surface layers by the arc when contaminant injection in the plasma gas was stopped was found to be a slow process with a time scale depending on the type of the gas contaminant. The presence of gas contaminant in the electrode material controls the cathode erosion mechanism and the overall arc behavior in the transition between a contaminated to a pure argon arc.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01447941
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  • 3
    Electronic Resource
    Electronic Resource
    Computational fluid dynamics modeling of multicomponent thermal plasmas (1992)
    Springer
    Plasma chemistry and plasma processing 12 (1992), S. 299-325 
    Details
    ISSN: 1572-8986
    Keywords: Thermal plasmas ; plasma processing ; rnulticomponent ; chemistry ; diffusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract A comprehensive computational model has been developed Jbr flowing thermal plasmas in the absence of electromagnetic fields, with particular emphasis on plasma jets. The plasma is represented as a rnulticomponent chemicalh, reacting ideal gas with temperature-dependent thermodynamic and transport properties. The plasma flow is governed by the transient compressible Navier-Stokes equations in two or three space dimensions. Turbulence is represented by subgrid-scale and k-ε models. Species diffusion is calculated by an effective binary diffusion approximation, generalized to allow /or ambipolar diffusion of charged species. Ionization, dissociation, recombination, and other chemical reactions are computed by general kinetic and equilibrium chemistry algorithms. Radiation heat loss is currently modeled as a temperature-dependent energy sink. Finite-difference approximations to the governing equations are solved on a rectangular spatial mesh using explicit temporal differencing. Computational inefficiency at low Mach number is avoided br reducing the effective sound speed. The overall computational model is embodied in a new computer code called LAVA. Computational results and comparisons with experimental data are presented Jbr LAVA simulations of a steady-stare axisymmetric argon plasma jet flowing into cold argon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01447028
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  • 4
    Electronic Resource
    Electronic Resource
    Cutaneous phototoxicity in photodynamic therapy: Clinical experience with and without histamine antagonists (1991)
    Springer
    Lasers in medical science 6 (1991), S. 179-182 
    Details
    ISSN: 1435-604X
    Keywords: Photodynamic therapy ; Skin photosensitivity ; Antihistamines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract We have investigated the incidence of cutaneous phototoxicity in 47 patients who received photodynamic therapy between April 1988 and March 1990. Of these, 15 patients received antihistamines as part of a pilot study to evluate their photoprotective role. Patients were followed-up for a minimum of 8 weeks. One out of the fifteen who received antihistamines and 15 out of the 32 patients who did not (p〈0.005), developed cutaneous phototoxicity. On the basis of these results we have initiated a randomized double-blind trial to evaluate the role of antihistamines in haematoporphyrin derivative-induced cutaneous phototoxicity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02032545
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  • 5
    Electronic Resource
    Electronic Resource
    Activity of haematoporphyrin derivative photoproduct in photodynamic therapy in vivo (1991)
    Springer
    Lasers in medical science 6 (1991), S. 425-428 
    Details
    ISSN: 1435-604X
    Keywords: Photodynamic therapy ; Tumour ; Haematopor-phyrin derivative ; Photoproduct ; Laser illumination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Illumination of haematoporphyrin derivative in phosphate-buffered solutions causes the formation of a stable photoproduct with new absorption and fluorescence bands. We report data showing photodynamic activity of the photoproduct. Praestomic tumour OJ-5, carcinosarcoma W-256 (mice) and adenocarcinoma Akatol of colon (rats) have been used. Dynamics of tumour growth, life span of animals and morphological changes of tumour tissues have been the main criteria used to show the photoproduct activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02042465
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  • 6
    Electronic Resource
    Electronic Resource
    Experimental photodynamic therapy with tetrapropyl-porphycene: Ultrastructural studies on the mechanism of tumour photodamage (1991)
    Springer
    Lasers in medical science 6 (1991), S. 437-442 
    Details
    ISSN: 1435-604X
    Keywords: Photodynamic therapy ; Tetrapropylporphycene ; Liposomes, Electron microscopy ; Tumour necrosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Red light irradiation of a transplanted MS-2 fibrosarcoma in mice at 24 h after injection of liposome-zbound tetra-n-propyl-porphycene (TPP, 2mg kg−1 b.w.) caused an efficient tumour necrosis. Electron microscopy analysis of tumour specimens taken at different times after the phototherapeutic treatment showed the development of direct damage of malignant cells between 3 and 6 h; the earliest detectable alterations occurred at the level of mitochondria. The endocellular damage gradually progressed with extensive vacuolization of the cytoplasm and, at later stages, formation of pyknotic nuclei. On the other hand, the vascular system of the tumour appeared to be well preserved up to about 9 h, when several endothelial alterations were detected. The damage of the tumour tissue was essentially complete 24 h after the phototreatment. The pattern of tumour modification is consistent with a preferential transport and tumour release of the liposome-bound TPP by low-density lipoproteins.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02042467
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  • 7
    Electronic Resource
    Electronic Resource
    Heat transfer from a transferred-arc plasma to a cylindrical enclosure (1991)
    Springer
    Plasma chemistry and plasma processing 11 (1991), S. 57-79 
    Details
    ISSN: 1572-8986
    Keywords: Thermal plasmas ; transferred arc ; plasma reactor ; radiated power ; heat transfer to enclosure ; voltage gradient ; electric field
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Hear-transfer rates from an axially enclosed transferred arc to a surrounding water-cooled cylindrical sleeve, 15 cm high, were measured. The arc (argon or nitrogen) was struck between a movable cathode within the sleeve and a bath of molten copper below the sleeve, serving as anode. The distance from the bottom of the sleeve to the surface of the molten copper (L o) was constant. Variables studied were the diameterD of the sleeve (5, 7.5. and 10 cm), the length of the arc within the sleeveL (5, 10, and 15 cm), the currentI (200, 250, and 300 A) and a tangential flow of gas or vortex within the sleeve (0, ?0, and 50 liters/min). The total power transferred to the sleeve,P s was measured caloronetrically and was the sure ofP r the effective power radiated by the arc of lengthL within the sleeve.P a, the power radiated into the sleeve from the arc of length Lo below the sleeve, andP o , the power radiated from the melt surface (a constant of small value), minusP a , the power lost by convection from the sleeve (negligible, except for a strong vortex). BothP r andP o were found to be equal to the product of the Joule heat released within their respective arc lengths, IVgL and IVg0L0 (where Vg and Vg0 are the voltage gradients), and dimenonless efliciency factors, ηr and η0. which are functions ofL/D andL 0 /D, respectively, for each gas, regardless of the geometry of the sleeve, the current, and the strength of the vortex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01447034
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  • 8
    Electronic Resource
    Electronic Resource
    Photodynamic therapy for treatment of cancers in oral and maxillofacial regions: a long-term follow-up study in 72 complete remission cases (1991)
    Springer
    Lasers in medical science 6 (1991), S. 201-204 
    Details
    ISSN: 1435-604X
    Keywords: Photodynamic therapy ; Tumour ; Oral and maxillofacial regions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Seventy-two complete remission cases with tumours of the oral and maxillofacial regions treated by photodynamic therapy, which were followed-up long-term, are presented. The results were satisfactory. All of the 34 cases that have been followed-up for more than 5 years are alive, healthy and free of tumour.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02032549
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  • 9
    Electronic Resource
    Electronic Resource
    Photodynamic therapy in the bladder: Can the light dose be easily quantified? (1991)
    Springer
    Lasers in medical science 6 (1991), S. 147-154 
    Details
    ISSN: 1435-604X
    Keywords: Urology ; Photodynamic therapy ; Dosimetry ; Irradiance ; Space irradiance ; Light energy fluence rate ; Glass bladder model ; Bladder model ; Blood ; Intralipid ; Methylene blue ; Erythrosin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract The shape of the bladder and the optical characteristics of the tissue within the wall can be shown to play an important role in the amount of light actually received at the wall. The use of estimated doses even assuming spherical geometry, cannot therefore be relied upon. This paper describes some experimental work carried out on a glass model that was used to simulate the bladder. A specially constructed dual detector was used which consisted of an isotropic probe and semiconductor detector. This enabled measurements of irradiance and space irradiance (light energy fluence rate) to be made simultaneously. By changing the optical characteristics of the wall a four-fold increase in space irradiance was measured. Contamination of the water contained within the model by blood was also investigated and has shown that with concentrations as low as 0.5% the delivered light dose reaching the wall can be reduced by up to 50% at a wavelength of 510 nm. Some in vivo measurements are also presented together with some comments on the difficulties that have been encountered when transferring measurements from the ‘model’ to the patient.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02032542
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  • 10
    Electronic Resource
    Electronic Resource
    The use of photodynamic therapy (PDT) for the treatment of superficial tumours on the bladder wall (1990)
    Springer
    Lasers in medical science 5 (1990), S. 5-12 
    Details
    ISSN: 1435-604X
    Keywords: Photodynamic therapy ; Superficial bladder tumours ; Dosimetry ; Isotropic light sensors ; Photosensitizers ; Wavelength of irradiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract The use of photodynamic therapy (PDT) for the treatment of superficial tumours on the bladder wall is described. Details are given on the laser, methods of delivering light into the bladder, suitable commercial dosimetry systems and instrumentation suitable for making light measurements on the bladder wall during therapy. New alternative photosensitizers are discussed in some detail. Some early clinical results are presented and the current problems with this type of therapy are highlighted.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02032616
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  • 11
    Electronic Resource
    Electronic Resource
    Fluorescence detection and photodynamic treatment of photosensitized tumours in special consideration of urology (1990)
    Springer
    Lasers in medical science 5 (1990), S. 207-212 
    Details
    ISSN: 1435-604X
    Keywords: Bladder tumour ; Diagnosis ; Fluorescence ; Photodynamic therapy ; Photosensitization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Most methods of modern laser tumour therapy are physically based on the conversion of light to heat. Recently tumours have also been treated using ionizing processes for tissue ablation. Photodynamic laser therapy (PDT), however, involves light-induced non-thermal biochemical processes and the use of a photosensitizer. Several drugs are known to be stored selectively in tumours after systemic application. This transient marking can be used for diagnostic and therapeutic procedures. The marker most commonly used is dihaematoporphyrin ether/ester (DHE) intravenously injected at doses of 0.2–3.0 mg/kg bodyweight for diagnosis and therapy, respectively. The corresponding clearance intervals after injection of DHE range from 3–48 h to 25–75 h. Detection of photosensitized tumours might offer great advantages. The highly sensitive two-wavelength laser excitation method with computerized fluorescence imaging recently has been transferred to the hospital for clinical tests. Photoinduced production of singlet oxygen is claimed to be the initial process which leads to later tumour destruction and therapy. PDT has been applied to 20 patients suffering from superficial tumours (TIS GII–III) recurred after application of other treatments. The results after PDT were evaluated by three-monthly check-ups (endoscopy, cytology, bladder mapping, renal ultrasonography) as well as by computed tomography (CT) examination at 8–13 month intervals. In six patients treated by PDT no tumour recurrence has been found over the whole observation period of up to 5 years. Four patients have remained free of tumour (12 and 14 months) after repeated transurethral resection (TUR) and Nd-YAG laser therapy following PDT. Due to an initial application of insufficient irradiation four patients required a second PDT. In one patient a circumscribed dysplasia appeared at the left ostium 26 months following PDT and was treated successfully by means of thermal Nd-YAG laser irradiation following TUR. In six patients slight mucosal atypia persisted for a period of at least 2.5 years. One cystectomy had to be performed because of bladder shrinkage. The dissected bladder, however, was free of tumour. These preliminary results suggest that PDT is justified in patients who are in a worst-case situation with cystectomy recommended in case of recurrent superficial TIS bladder carcinoma and indicate the future potential of photodynamic therapy of tumours. Homogeneous irradiation of the area to be treated and a reliable light dosimetry are prerequisites for an effective tumour therapy. Standard instruments for a routine application do not exist, but are under development.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02031384
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  • 12
    Electronic Resource
    Electronic Resource
    Chromophores in tissue for laser medicine and laser surgery (1990)
    Springer
    Lasers in medical science 5 (1990), S. 289-292 
    Details
    ISSN: 1435-604X
    Keywords: Cancer ; Laser ; Chromophores ; Photodynamic therapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Chromophores in tissue are of considerable interest for the tissue interactions with lasers in the visible light range. The natural chromophores in man are essentially melanin and red cell haemoglobin. With the development of Photodynamic Therapy (PDT) in the treatment of human cancer, the new technology of exogenous chromophores was developed and continues to expand both in laser medicine and laser surgery. This technology relates specific chromophores to specific wavelengths for the destruction of tumours and has been very effective for PDT in those instances where there is accessibility to the tumour mass by the laser beam. The problems today are concerned with how to mark these malignant foci deep in the tissue, how to detect them, and how to direct selected laser beams to the marked carcinomatous tissue. In laser medicine, the field is expanding especially for tissue and laboratory diagnostics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02032656
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  • 13
    Electronic Resource
    Electronic Resource
    Quantitative and comparative study of haematoporphyrin-derived photosensitizers on a murine tumour model (1990)
    Springer
    Lasers in medical science 5 (1990), S. 309-316 
    Details
    ISSN: 1435-604X
    Keywords: Photodynamic therapy ; PDT ; Fluorescence ; Haematoporphyrin derivative ; HPD ; Diagnosis ; Murine tumour ; Laser ; Pharmacodynamic ; Pharmacokinetic ; Regrowth delay
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Eight commercially available HPD-photosensitizers intended for photodynamic therapy were tested in a murine tumour model with regard to their therapeutic efficacy. The regrowth delay of the fibrosarcoma SSK-2 on the mouse C3H, Neuherberg-line, was determined 3, 24, 48 and 72 h after injection of the drugs (dose: 9 mg kg−1 body weight). The corresponding pharmacodynamics, as measured by regrowth delay, were approximated by an exponential function and the characterizing coefficients derived. These coefficients served to quantify the photodynamic properties of the drugs. The pharmacodynamics of five substances were compared with those obtained fluorometrically. The latter showed shorter decay constants than the therapy-correlated substances which indicates different metabolic behaviour of the therapeutic and diagnostically useful fluorescent components of haematoporphyrin-derived photosensitizers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02032660
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  • 14
    Electronic Resource
    Electronic Resource
    Factors controlling the selectivity and efficiency of tumour damage in photodynamic therapy (1990)
    Springer
    Lasers in medical science 5 (1990), S. 115-120 
    Details
    ISSN: 1435-604X
    Keywords: Photodynamic therapy ; Photosensitization ; Pharmacokinetics ; Photofrin II ; Phthalocyanines ; Liposomes ; Lipoproteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract The scope and potential of the photodynamic therapy of tumors can be enhanced through an adequate control of the factors which improve the selectivity of tumour targeting by the systemically injected photosensitizer and increase the efficiency of photosensitized tumour damage. Promising results are obtained by using hydrophobic photosensitizers which can be specifically transported and released to the tumour by serum lipoproteins, especially low-density lipoproteins. The photosensitizer molecule should possess those structural features which induce a high probability of photoactivation by 700–800 nm light, as well as a high yield of long-lived triplet state. The use of liposome-delivered Zn-phthalocyanine as a second generation phototherapeutic agent for tumours is proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02031372
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  • 15
    Electronic Resource
    Electronic Resource
    Light delivery and light dosimetry for photodynamic therapy (1990)
    Springer
    Lasers in medical science 5 (1990), S. 107-113 
    Details
    ISSN: 1435-604X
    Keywords: Photodynamic therapy ; Light delivery ; Light dosimetry ; Tissue optics ; Scattering ; Absorption ; Diffusor ; Dosimetry probe
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Photodynamic therapy (PDT) has attracted attention because it was considered to be a selective form of cancer treatment causing minimal damage to normal tissues. This is not exactly true, because the ratio between the photosensitizer concentrations in tumour and surrounding normal tissues is not always much more than one. Nevertheless, tumour destruction by PDT with relatively little damage to normal tissue is possible in many cases. This requires sophisticated light delivery and/or light dosimetry techniques. In this respect the limited penetration of light into biological tissues can sometimes be useful. In this paper a qualitative and sometimes quantitative discussion is given of the physical phenomena determining the energy fluence in a biological tissue. Most important is light scattering, the contribution of which depends on the geometrical conditions. Finite beam surface irradiation, irradiation of hollow organs (bladder) and interstitial irradiation are discussed separately. The emphasis is on light ‘dose’ and light dose distribution. It is emphasized that PDT dosimetry in general is complicated by photosensitizer distribution (which is usually not known), by photobleaching of the sensitizer, by possible effects of hyperthermia, and by changes in optical properties during and as a result of PDT.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02031371
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  • 16
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    Electronic Resource
    Endoscopic photodynamic therapy in lung cancer (1990)
    Springer
    Lasers in medical science 5 (1990), S. 181-183 
    Details
    ISSN: 1435-604X
    Keywords: Photodynamic therapy ; Haematoporphyrin derivative ; Lung cancer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract The main purpose of cancer therapy is to treat malignant tissue with the least damage to normal surrounding structures. Photodynamic therapy (PDT) seems to be able to fulfil this simple but fundamental premise. The mechanism of action of the photosensitizer—light system can be summarized in two main points. Chiefly, it seems to be a photodynamic process, with energy transfer from the light to the photosensitizer and from it to the oxygen molecules. Oxygen is excited and becomes singlet oxygen, which is extremely reactive and very noxious for tissues in which it develops. Secondly, a thermal mechanism related to light absorption and consequent temperature rise also seems to be involved in malignant necrosis by PDT. Thirteen males were submitted to endoscopic PDT. A total of 15 treatments were given: 2 patients were submitted to 2 sessions of PDT. Forty-eight hours after HPD administration (72 h in a few cases), the lesions were exposed to a 630 nm light from an argon-dye laser system. The total estimated energy dose delivered to the tumour surface was 90–150 J/cm2 in 11 cases. All cases treated responded well and total disappearance was obtained. Median follow-up was 9.5 months (1–20 months) and the estimated energy delivered from 90–600 J/cm2. No major complications were reported.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02031379
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  • 17
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    Photodetection and photodynamic therapy of ‘early’ squamous cell carcinomas of the pharynx, oesophagus and tracheo-bronchial tree (1990)
    Springer
    Lasers in medical science 5 (1990), S. 149-169 
    Details
    ISSN: 1435-604X
    Keywords: Haematoporphyrin derivative ; Photodetection ; Photodynamic therapy ; ‘Early’ squamous cell carcinoma ; Pharynx ; Oesophagus ; Bronchi ; Fluoro-endoscope ; Cationic dyes ; Monoclonal antibodies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract The efficacy of photodynamic therapy (PDT) alone was evaluated on 41 ‘early’ squamous cell carcinomas of the pharynx (10), oesophagus (15) and tracheo-bronchial tree (16). All lesions but two were synchronous second primaries in ENT-patients suffering from a more extensive cancer, governing the overall oncological prognosis. Photofrin I (3 mg/kg) or Photofrin II (2 mg/kg) were injected 72 h prior to the red light irradiation, supplied by an argon pumped dye laser. A diffusing cylinder was used to obtain a homogeneous light distribution at the tumour site (60 J to 150 J/cm2). In the oesophagus and bronchi, the results are good for cancers staged in situ or microinvasive at endoscopy (two recurrencies for 23 lesions treated). For more advanced cancers (submucosal in the oesophagus or invading the bronchial cartilage), the results are less satisfactory (three recurrencies for eight lesions treated). In the pharynx where light dosimetry is more difficult, the rate of recurrencies is higher (3/10 lesions treated). In the bronchi (one case) and oesophagus (one case), the longest disease-free survival is now 5 years. The irradiation of a non-cancerous zone of normal buccal mucosa on 25 patients having received HPD showed necrosis in all cases with light doses as low as 50mW/cm2 for 20 min (60 J cm−2), even with Photofrin II. We encountered six complications (three cicatricial stenosis, two fistulae, one severe sunburn), most of them resulting from the lack of selectivity of HPD. According to these experiments, PDT is efficient at destroying early squamous cell carcinomas in the pharynx, oesophagus and bronchi, but the tumour selectivity of HPD is poor in the digestive tract lined with squamous cell epithelium. The only hope for the future lies in the synthesis of a more selective and more stable photosensitizer. This discussion reviews possible directions of research for the development of new dyes (cationic dyes, dyes attached to monoclonal antibodies, etc), for PDT and hyperthermia, for photodetection of early cancers using a fluoro-endoscope, and finally, for tumour depth profiling in hollow organs using lasers of different wavelengths.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02031377
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  • 18
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    Methods for in vivo haematoporphyrin derivative quantification: a review (1990)
    Springer
    Lasers in medical science 5 (1990), S. 387-394 
    Details
    ISSN: 1435-604X
    Keywords: Haematoporphyrin derivative ; Singlet oxygen ; Photodynamic therapy ; Dosimetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Description / Table of Contents: Résumé La photochimiothérapie est un nouveau traitement des cancers débutants. Alors que des essais cliniques de phase 1–2 sont entrepris, les indications pour ce type de traitement demeurent rares, principalement du fait d'une dosimétrie approximative de la captation de l'hématoporphyrine dérivée par les tissus cancéreux humains. La fluorescence émise par l'HPD peut Être utilisée in-vivo pour un diagnostique ‘topographique’ de la répartition de l'HPD, mais aussi le dosage quantitatif des espèces fluorescentes présentes dans le mélange HPD. Le dosage de l'oxygène singulet, généré lors de la réaction photochimique, est nettement plus difficile à réaliser mais a été proposé pour le dosage in-vivo des formes porphyriniques ‘actives’ présentes dans le milieu. Les applications cliniques de telles mesures représentent une condition essentielle pour le developpement de la photochimiothérapie car à côté des possibilités de diagnotiques offertes par l'analyse de la répartition intratumorale de l'HPD, un dosage précis permettrait d'optimiser le moment du traitement, arbitrairement fixé aujourd'hui à 72 heures.
    Notes: Abstract Photodynamic therapy is a new treatment for early carcinomas. Although undergoing phase 1/2 clinical assays, clinical indications for this therapy remain rare mainly because of the approximate dosimetry of HPD uptake by tumour tissues in human beings. In this review we present the potential interest and limits of both direct fluorescence detection or dosimetry of HPD and in vivo measurements of singlet oxygen, produced during photodynamic therapy. Clinical applications of such measurements should represent one of the main conditions for the future development of photodynamic therapy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02032596
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  • 19
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    Hydrodynamics and heat transfer in a plasma spouted bed reactor (1990)
    Springer
    Plasma chemistry and plasma processing 10 (1990), S. 71-85 
    Details
    ISSN: 1572-8986
    Keywords: Thermal plasmas ; spouted bed ; hydrodynamics ; heat transfer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract The literature reveals very little intformation about plasma spouted bed hydrodynamics. Spouting of corindon particles with diameters ranging from 0.4 to 3.36 mm with argon plasma was conducted in a 90-mm-diameter column in the temperature range 300–1300°C. It was found that the maximum spoutable height (Hm) decreases with increasing particle diameter and decreasing mean bed temperature. A relation between the inlet plasma velocity and Hm is proposed. Concerning heat transport phenomena in the annulus, measurements and calculations indicate a large axial diffusivity but a poor radial mixing. Typical values of Dz and Dr are proposed on the basis of an identification procedure.
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    One-dimensional analysis of the wall region for a multiple-temperature argon plasma (1990)
    Springer
    Plasma chemistry and plasma processing 10 (1990), S. 189-206 
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    ISSN: 1572-8986
    Keywords: Thermal plasmas ; modeling ; heat and mass transfer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract The present analysis is restricted to the wall region for a confined gas plasma and applied specifically to an argon plasma. The wall may be either positive or negative in potential with respect to the plasma, and the electric current may flow either parallel or normal to the wall. Estimates of the Debye shielding distance and the mean free path of various components are made to obtain the range of validity of the analysis, in addition to the situation where the wall acts like a cathode, an anode, or an electrical insulation. Analysis is for a one-dimensional case with an outer boundary, where the plasma temperature is specified. The computational domain is split into a continuum region, where both equilibrium compositions for a two-temperature plasma and a chemically reacting plasma are studied, and a free-fall region. The results allow a quantitative assessment of temperature nonequilibrium and electrical potential distribution in the free-fall region.
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    URL: http://dx.doi.org/10.1007/BF01460455
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    Photodynamic therapy in the treatment of diseases of the skin (1990)
    Springer
    Lasers in medical science 5 (1990), S. 199-201 
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    ISSN: 1435-604X
    Keywords: Photodynamic therapy ; Basal cell carcinoma ; Squamous cell carcinoma ; Carcinoma in situ lesions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02031382
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    Photodynamic therapy of malignant brain tumours (1990)
    Springer
    Lasers in medical science 5 (1990), S. 245-252 
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    ISSN: 1435-604X
    Keywords: Photodynamic therapy ; Supratentorial tumours ; Cerebral gliomas ; Cerebral metastasis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Experience with intraoperative PDT in 50 patients with malignant supratentorial tumours is reported; in 33 cases the tumour was recurrent. In 45 patients the tumour was a cerebral glioma and in five cases a solitary cerebral metastasis. There were 29 males and 17 females with an age range of 17–73 (mean 48) years. All patients received either haematoporphyrin derivative (HPD) or dihaematoporphyrin ether (DHE) 18–24 h preoperatively. A photoilluminating device, of the authors' design, was coupled to an argon dye pump laser in order to deliver light at 630 nm to a tumour cavity created by radical tumour resection and/or tumour cyst drainage. The total light energy delivered ranged from 440 to 3888 J and the light energy density ranged from 8 to 175 J/cm2. In eight patients a line fibre(s) was used to administer interstitial light as a supplement to the cavitary photoillumination. The additional light dose ranged from 60 to 945 J/cm. There were two postoperative deaths as the consequence of haematoma accumulation in the tumour resection cavity. In three patients neurological function was worse postoperatively and did not recover. Postoperative cerebral oedema was pronounced in some cases and required second craniotomy in two patients (the histology from both showed haemorrhagic necrosis of residual tumour). Four patients developed wound infections; two of these required surgical treatment. Four patients, two of whom were hemiparetic, developed deep vein thrombosis and required anticoagulant therapy. There were no adverse systemic reactions to the administration of either photosensitizer and only three skin photosensitivity reactions. Follow up ranged from 1 to 30 months. In the group of 45 patients with gliomas the death rate per observation year was 0.92 for the interval between PDT and death. For the interval between first diagnosis and death the rate was 0.41 deaths per observation year. The median survival was 8.6 months with a 1 and 2 year actuarial survival rate of 32% and 18%, repectively. In 12 patients a complete or near complete CT scan response was identified post PDT. These patients tended to have a tumour geometry (e.g. cystic) that allowed complete or near complete light distribution to the tumour. The median survival for this group was 17.1 months with a 1 and 2 year actuarial survival of 62% and 38%, respectively. In the 33 cases without a complete response the median survival was 6.5 months with a 1 and 2 year actuarial survival of 22% and 11%, respectively. Photodynamic therapy of malignant brain tumours can be carried out with acceptable risk. Good responses appear to be related to adequate light delivery to the tumour.
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    URL: http://dx.doi.org/10.1007/BF02031391
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    Liposome- or LDL-administered Zn(II)-phthalocyanine as a photodynamic agent for tumours III. Effect of cholesterol on pharmacokinetic and phototherapeutic properties (1990)
    Springer
    Lasers in medical science 5 (1990), S. 339-343 
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    ISSN: 1435-604X
    Keywords: Phthalocyanines ; Photodynamic therapy ; Pharmacokinetics ; MS-2 fibrosarcoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract The pharmacokinetic behaviour of Zn-phthalocyanine (Zn-Pc) has been studied in mice bearing a transplanted MS-2 fibrosarcoma using liposomes of dipalmitoyl-phosphatidylcholine containing 15% moles of cholesterol as drug delivery systems. The presence of cholesterol optimizes the Zn-Pc localization in the tumour inducing a significantly larger uptake as well as a better selectivity. Experimental photodynamic therapy of the MS-2 fibrosarcoma has been performed using two different protocols. The data obtained show that an efficient tumour necrosis can be photosensitized by very low Zn-Pc doses (0.035–0.3 mg kg−1) at both short and long time intervals after injection of the dye.
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    URL: http://dx.doi.org/10.1007/BF02032589
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    In vivo to post-mortem change in tissue penetration of red light (1990)
    Springer
    Lasers in medical science 5 (1990), S. 395-398 
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    ISSN: 1435-604X
    Keywords: Photodynamic therapy ; Lasers ; Light dosimetry ; Skeletal muscle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract For precise light dosimetry in photodynamic therapy (PDT), the light penetration characteristics of the tissue concerned need to be assessed. Several attenuation coefficients have so far been measured using 633 nm wavelength red light and human tissue obtained from autopsy or surgery. However, the validity of such ex vivo derived values remains uncertain, and hence is evaluated further in this study. Using a rat thigh muscle model, the tissue transmittance of 633 nm red light was compared between in vivo and ex vivo. Transmittance (in vivo) following preliminary injection of 40 mg kg−1 haematoporphyrin derivative (HPD) was also measured in muscle and liver. The effective attenuation coefficient (⌆eff) ex vivo in muscle was 0.98±0.06 mm−1 and in vivo 0.97 ± 0.05 mm−1. Values agreed within experimental error indicating that in this tissue, changes from in vivo to post-mortem produced no alteration in optical penetration at 633 nm. Preliminary injection of HPD did not influence the penetration depth in muscle although significant changes were observed in an organ of high porphyrin avidity, the liver (0.68±0.08 mm vs 0.40±0.08 mm with HPD). Until techniques for in vivo measurements of light attenuation coefficient become available, the use of ex vivo derived values with 633 nm wavelength light would seem appropriate.
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    URL: http://dx.doi.org/10.1007/BF02032597
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    Biodistribution of55Fe (II) phthalocyanine tetrasulphonate (55Fe (II)-TsPc) (1990)
    Springer
    Lasers in medical science 5 (1990), S. 21-24 
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    ISSN: 1435-604X
    Keywords: Phthalocyanines ; Photodynamic therapy ; Biodistribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Phthalocyanines may be an alternative group of macrocycles applicable for use in photodynamic therapy (PDT) of cancer. Although as a class, phthalocyanines localize in tumours, efficacy of cytotoxicity appears to depend to some degree on the specific compound. Biodistribution patterns of the phthalocyanines are similar to those for dihaematoporphyrin ether (DHE); the major sites of deposition being liver, kidney and spleen while the remaining organs show varying degrees of accumulation. The optimal time for PDT when using phthalocyanine appears to be between 24 and 48 h.
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    Photodynamic therapy of tumours in gastroenterology—a review (1990)
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    Lasers in medical science 5 (1990), S. 233-239 
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    ISSN: 1435-604X
    Keywords: Photodynamic therapy ; Tumours ; Gastroenterology ; Laser ; Endoscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Photodynamic therapy (PDT) is the local destruction of tissue by the interaction of light with a previously administered photosensitizer producing a photochemical effect. This technique has been demonstrated to permit the eradication of small tumours in experimental and clinical practice, with clear biological advantages. This paper reviews PDT experience in gastroenterology, together with concepts currently under experimental investigation.
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    Light delivery to tumour tissue through implanted optical fibres during photodynamic therapy (1990)
    Springer
    Lasers in medical science 5 (1990), S. 345-350 
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    ISSN: 1435-604X
    Keywords: Photodynamic therapy ; Light transmission in tissue
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract The maximum rate at which the light dose may be delivered during interstitial photodynamic therapy (PDT) has been measured for several types of delivery fibre. Measurements of light irradiance at the skin surface overlying subcutaneous experimental tumours were made during interstitial irradiation by 200Μm core diameter fibres whose output ends were either plane-cut or 5 mm long cylindrical diffusers. For plane-cut fibres, a rapid fall in light transmission, due to blood coagulation at the fibre tip, was observed at output powers greater than 229 mW and 104 mW in tumours with and without photosensitizer, respectively. Such a rapid fall was not observed with cylindrical diffusing fibres at output powers up to 1 W. In the clinical use of PDT the fibre output power is held constant at a level below which thermal effects may occur. In a second study, therefore, the irradiance at the skin surface was monitored for this treatment regime. A decrease in light transmission during treatment was observed. Plane-cut fibres showed a greater decrease than cylindrical diffusing fibres and for a given fibre type, non-photosensitized tumours showed a greater decrease than photosensitized tumours. For cylindrical diffusing fibres at output powers of 150 mW or less there was a 9% decrease in irradiance measured at the skin surface during the first 1000 s of treatment. The decrease was larger (30–40%) for fibre output powers in the range 200–300 mW.
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    Photodynamic therapy for the treatment of advanced gastrointestinal tumours (1989)
    Springer
    Lasers in medical science 4 (1989), S. 183-186 
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    ISSN: 1435-604X
    Keywords: Photodynamic therapy ; Gastrointestinal tumour ; Advanced lesions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract In the study, 120 patients with advanced gastrointestinal tumours were treated by PDT; 5 mg/kg of HpD was intravenously given 48–72 h prior to PDT. The light source was an argon dye laser with an output beam of 630 nm. The irradiation time varied from 15–25 min with a power of 100–350 mW cm−2. The entire tumour was irradiated with a light dose of 100–250 J cm−2. Of the 120 patients, 20 had cancer of esophagus, 72 had cancer of the gastric cardia, 18 had cancer of the stomach and 10 had cancer of the rectum. Eighty-eight patients (73.3%) had a response to PDT. Twelve patients with CR were followed up for one to five years, two patients died during the two years after PDT.
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    URL: http://dx.doi.org/10.1007/BF02032433
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    Photodynamic therapy in the treatment of malignant tumours of the upper aerodigestive tract (1989)
    Springer
    Lasers in medical science 4 (1989), S. 279-284 
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    ISSN: 1435-604X
    Keywords: Photodynamic therapy ; Haematoporphyrin ; Argon dye laser ; Early stage esophageal cancer ; Head and neck cancer ; Squamous cell carcinoma ; Adenocarcinoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract This is the report of a pilot study in which the technique of photodynamic therapy (PDT)—in which malignant tissues are destroyed by light after being previously photosensitized by haematoporphyrin or its derivative—was performed using a high power argon-dye laser system which operated at 630±5 nm and optical fibres with either a microlens or a diffusing tip. A total of thirty-seven patients were utilized for this study, including twenty-five patients affected by esophageal carcinoma, five by recurrences of head and neck cancer, four by gastric cancer and three by lung cancer. Among the sixteen cases with superficial or localized cancer of the esophagus, complete and partial responses were observed in seven and six patients, respectively. In advanced and recurring cancers less satisfactory results were obtained. Thus, PDT seems to be useful in cases of small superficial cancers, either primary or recurrent after previous treatments.
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    Thermal plasma composition in the presence of easily and noneasily ionized components (1989)
    Springer
    Plasma chemistry and plasma processing 9 (1989), S. 445-463 
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    ISSN: 1572-8986
    Keywords: Thermal plasmas ; equilibrium composition ; metal halide discharge ; easily and noneasily ionized components
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract The influence of easily and noneasily ionized components on equilibrium particle density ratios in thermal plasmas has been investigated. Particular emphasis is given to the modeling of metal halide discharges with iodine as a halide. The calculations were done for “standard” air with lithium or iodine, “standard” argon with aluminum, and with a mixture of aluminum and iodine. The system setup is in agreement with spectroscopic results for an open-chamber gas-stabilized d.c. arc, with a pressure of 1×105 Pa and temperatures corresponding to the radial distribution of temperature for this type of discharge. It is shown that the behavior of the plasma core is dominated by the easily ionized component (Li or Al) while the periphery is characterized by the noneasily ionized component (iodine).
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    Nonequilibrium effects in thermal plasma chemistry (1989)
    Springer
    Plasma chemistry and plasma processing 9 (1989), S. 435-443 
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    ISSN: 1572-8986
    Keywords: Thermal plasmas ; nonequilibrium ; finite rates ; dissociation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Numerical calculations have been performed to assess the potential significance of nonequilibrium effects on chemical reactivity in thermal plasmas The calculations consider situations in which the electron temperature and/or the electron density are elevated above their equilibrium values corresponding to the local gas temperature. Such nonequilibrium may occur in the plasma torch itself or could be purposefully imposed by a controlled hybrid discharge in a downstream reactor region so as to augment reactivity over a longer residence time. The calculations account for finite ionization/recombination rates of atomic and molecular species, electron-impact dissociation, dissociative recombination, dissociative attachment, and predissociation effects, as well as thermal reactions between neutral chemical species. As an example of the possible nonequilibrium enhancement of molecular decomposition, initial consideration has focused on the dissociation rates of diatomic species where heavy particle reaction rates and cross sections can be reasonably estimated. The results show that for O2 or H2 in argon at moderate temperatures, electron-temperature elevation can give rise to a notable enhancement of the dissociation rate, in comparison with the equilibrium case. Depending on the situation, it is found that either relatively energetic electron-impact dissociation or dissociative attachment (for O2) can dominate the enhanced dissociation rate—which can be more than a factor of 2 greater than in the absence of a discharge. Similar effects would be expected for the decomposition of more complicated molecules.
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    Some characteristics of transferred-Arc plasmas (1989)
    Springer
    Plasma chemistry and plasma processing 9 (1989), S. 65S 
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    ISSN: 1572-8986
    Keywords: Thermal plasmas ; transferred arcs ; plasma radiation ; plasma heat transfer ; plasma columns ; plasma stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Although the theoretical foundations of the characteristics of transferred arcs were established more than three decades ago, the design of reator systems based on this method of plasma are generation is still in an early stage of development. Although deceptively simple in concept, attempts to use transferred arcs im practical applications at scales of arc length and power somewhat larger than those previously studied in the laboratory soon revealed that considerably more information was required on the arc's unique properties before a sound reactor design could be carried out. This was principally due to the much higher temperature levels (up to 20,000 K) with consequent much higher radiative power achieved in this type of arc, as well as the fluid mechanical effects of the high-velocity plasma gas flowing in the latter. These, in turn, had profound effects on the various modes of heat transfer occurring in the system, on the stability of the arc, on the injection of the material to be treated, and on the overall efficiency of energy utilization in the whole system. The objective of this paper is to summarize the experimental evidence concerning transforred arc characteristics which have been obtained by the author and his colleageus during recent years.
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    Particle behavior in thermal plasmas (1989)
    Springer
    Plasma chemistry and plasma processing 9 (1989), S. 167S 
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    ISSN: 1572-8986
    Keywords: Thermal plasmas ; heat, mass, and momentum transfer ; material processing ; overview
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract In this overview, effects exerted on the motion and on heat and mass transfer of particulates injected into a thermal plasma are discussed, including an assessment of their relative importance in the context of thermal plasma processing of materials. Results of computer experiments are shown for particle sizes ranging from 5–50 μm, and for alumina and tungsten as sample materials. The results indicate that (i) the correction terms required for the viscous drag and the convective heat transfer due to strongly varying properties are the most important factors; (ii) noncontinuum effects are important for particle sizes 〈10 μm at atmospheric pressure, and these effects will be enhanced for smaller particles and/or reduced pressures; (iii) the Basset history term is negligible, unless relatively large and light particles are considered over long processing distances; (iv) thermophoresis is not crucial for the injection of particles into thermal plasmas; (v) turbulent dispersion becomes important for particle 〈10 μm in diameter; and (vi) vaporization describes a different particle heating history than that of the evaporation process which, however, is not a critical control mechanism for interphase mass transfer of particles injected into thermal plasmas.
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    Silicon nitride synthesis in an atmospheric pressure convection—Stabilized arc (1989)
    Springer
    Plasma chemistry and plasma processing 9 (1989), S. 277-289 
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    ISSN: 1572-8986
    Keywords: Thermal plasmas ; synthesis of Si3N4 ; experiments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Submicron α-, β-, and amorphous-phase silicon nitride particles have been synthesized in an experimental plasma reactor, using metallic silicon and ammonia as reactants. Injection of ammonia at different locations of the reactor results in different yields. A maximum yield of 85 wt% has been achieved by injecting NH3 at both downstream and upstream locations of the reactor. The powders synthesized in this way contained approximately 60 wt% silicon nitride in crystal form with equal amounts of α and β phases. The remainder consisted of the amorphous phase. The average size of the particles ranged from 50 to 90 nm, with a standard deviation of 1.47–1.87 depending on the location of ammonia injection. Seeding with 1 and 10 wt% of preexisting silicon nitride particles for fostering heterogeneous nucleation did not improve the yield, but it changed the particle size distribution.
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    Coagulation of blood at the tip of optical fibres used for light delivery in photodynamic therapy (1989)
    Springer
    Lasers in medical science 4 (1989), S. 125-129 
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    ISSN: 1435-604X
    Keywords: Photodynamic therapy ; Diffusing fibre tips ; Interstitial light delivery ; Light dosimetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Optimal delivery of light to the tumour is of considerable importance in photodynamic therapy. The most effective way of delivering laser light to the tumour tissue is through an implanted optical fibre. In order to investigate the possible effects taking place at the tips of fibres implanted in tissue, fibres were used to deliver light to human blood and the transmission of light by the blood was measured at different power levels. The maximum power level which could be delivered without charring or coagulation at the fibre tip was measured for five different fibres. Three plane cut fibres and two with 1.5 cm long diffusing tips were studied. Charring and coagulation, which resulted in practically no light being delivered more than 0.5 mm from the fibre tip, were observed at relatively low-output powers (70-130 mW) for all the plane-cut fibres. This is less than the level required to deliver a clinically useful dose in a reasonable time. In contrast, neither charring nor coagulation was observed at the diffusing tips for output powers up to 1.1 W and consequently these should be the fibres of choice for interstitial photodynamic therapy. Observed changes in light transmission through the blood with increasing output power indicate that, for accurate light dosimetry, a means of monitoring delivered light in vivo during photodynamic therapy is essential.
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    In vivo nuclear imaging studies of uptake and retention of Tc-99m-labelled HpD in a murine tumour (1989)
    Springer
    Lasers in medical science 4 (1989), S. 205-210 
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    ISSN: 1435-604X
    Keywords: Tumour imaging ; Tc-99m-HpD ; Kinetics ; Photodynamic therapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract The in vivo uptake of Tc-99m-labelled HpD in a murine tumour has been investigated using nuclear imaging techniques. Eighty-four per cent of the palpable tumours were visualized with good contrast resolution. The peak tumour-to-surrounding-normal-tissue ratio of 5:1 was at 4 h post-injection indicating the optimum time of imaging. The high level of HpD in the blood-pool component of the tumour could indicate that photodynamic therapy administered within 2 h after intravenous injection (‘early PDT’) could lead to damage of tumour vasculature and tumour necrosis. The therapeutic response achieved by this early method needs to be investigated.
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    A method for the construction of disposable cylindrical diffusing fibre optic tips for use in photodynamic therapy (1989)
    Springer
    Lasers in medical science 4 (1989), S. 229-235 
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    ISSN: 1435-604X
    Keywords: Photodynamic therapy ; Cylindrical diffuser ; Interstitial treatment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract A simple method for the manufacture of disposable, cylindrical, diffusing fibre tips is described. The method is suitable for plastic clad silica fibres with core diameters in the range 200–600μm. Light diffusing tips up to 40 mm in length have been constructed. The method is highly reproducible, construction is typically less than five minutes and the financial cost is negligible. The diffusers are highly efficient, delivering an amount of light at least equal to that transmitted by a plane cut fibre of the same core diameter. The uniformity of light emission along the diffuser can be modified to meet the requirements of any given treatment. The diffusers have been successfully used in interstitial photodynamic therapy.
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    Misonidazole combined with photodynamic therapy of rat 9L gliosarcoma tumours (1989)
    Springer
    Lasers in medical science 4 (1989), S. 79-84 
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    ISSN: 1435-604X
    Keywords: Photodynamic therapy ; Haematoporphyrin derivative ; Misonidazole ; Radiosensitizers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Fifty-six Fischer 344 rats bearing subcutaneous 9L-gliosarcoma tumours were studied to determine if Misonidazole (MISO), combined with photodynamic therapy (PDT), would be more effective than PDT alone. PDT, like conventional radiation, is potentiated by oxygen, and if there are areas of hypoxic cells within the tumour it is possible that the addition of the radiosensitizing drug should make the treatment more effective. Thirty-nine rats were divided into eight groups as controls. Seventeen rats were divided into three groups and received MISO combined with PDT, five rats were exposed to a laser dose of (nm = 630) 300 J at 300 mW, seven rats to a laser dose of 600 J at 600 mW and five rats to a laser dose of 2160 J at 600 mW. The tumours were approximately 1 cm3 when treated. Animals treated with either PDT at 300 J or 600 J failed to show any effect on growth of the tumour. At 2160 J a definite delay in growth was observed but addition of MISO did not potentiate this effect. The results indicate this combined therapy did not slow the growth rate of the tumours in this model. The implication of these results are discussed.
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    Photodynamic therapy in gynaecological cancer (1989)
    Springer
    Lasers in medical science 4 (1989), S. 155-158 
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    ISSN: 1435-604X
    Keywords: Photodynamic therapy ; Gynaecological oncology ; Lasertherapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Tumour recurrences in the gynaecological field after conventional therapy are a big problem because there is little choice for other therapies without inflicting further damage. Photodynamic therapy (PDT) is indicated because it is selective and without side-effects in flat or small recurrences. We treated 15 patients with vaginal and vault recurrences of cervix carcinoma, adenocarcinoma in the corpus uteri and rectum. The PDT was performed after 24–48 h with Hp, 5 mg/kg body weight, injection, and an argon-dye laser for 13 cases, tungsten and xenon lamps in 2 cases. All patients were previously treated with conventional therapy (i.e. surgery, radiotherapy, chemotherapy). Doses ranged from 60 to 500 J cm−2. The results were: 8 complete local responses, 6 partial responses, 1 no change. Four patients died because of distant metastases or progression. One partial response was treated with brachytherapy and is now disease free. All the other patients are still living. In all cases we have seen no side-effects from PDT. The patients were sheltered from the sunlight for 20–30 days after therapy.
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    URL: http://dx.doi.org/10.1007/BF02032429
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    The spectral dependence of the optical properties of human brain (1989)
    Springer
    Lasers in medical science 4 (1989), S. 221-227 
    Details
    ISSN: 1435-604X
    Keywords: Optical properties ; Photodynamic therapy ; Glioma ; Brain tumour
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract The in vitro optical properties of slices of human brain tissue were measured. The experiments were performed with an integrating sphere and covered the wavelength range from 400 to 1100 nm. Both normal brain tissue (white and grey matter) and tumour tissue (a malignant glioma and a melanotic melanoma) were investigated. From the experimental data the Kubelka-Munk absorption and scattering coefficients were determined. From these data we calculated the transport absorption and scattering coefficients by using the diffusion approximation. Blood and water appeared to be the dominant chromophores. In the wavelength range mentioned, the absorption coefficients varied over more than two orders of magnitude. The scattering coefficients increased slowly towards the shorter wavelengths.
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    URL: http://dx.doi.org/10.1007/BF02032451
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  • 41
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    Modelling particle formation and growth in a plasma synthesis reactor (1988)
    Springer
    Plasma chemistry and plasma processing 8 (1988), S. 145-157 
    Details
    ISSN: 1572-8986
    Keywords: Thermal plasmas ; particle nucleation and growth ; modelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract A model for particle nucleation and growth in a thermal plasma reactor is discussed. A nondimensional form of the aerosol general dynamic equation is derived under a set of simplifying assumptions which are appropriate to plasma powder synthesis, and the resulting set of equations is solved numerically. The results are converted to dimensional form for the case of iron powder, for which experimental data are available, and for silicon carbide. Calculated particle sizes increase significantly with increasing reactant concentrations and with decreasing cooling rate, although the influence of cooling rate is mainly a residence time effect.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01016154
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    Evaluation of photodynamic therapy in gastric cancer (1986)
    Springer
    Lasers in medical science 1 (1986), S. 67-74 
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    ISSN: 1435-604X
    Keywords: Argon dye laser ; Photodynamic therapy ; Gastric cancer ; Adenocarcinomas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Twenty-eight patients with gastric cancer were treated by photodynamic therapy. Haematoporphyrin derivative was used as a photosensitizer and an argon dye laser as a light source. Histologically, all tumours were adenocarcinomas. On the basis of endoscopy, 17 cases were categorized as early-stage cancer and were classified as type IIc (10 lesions), Ha (three lesions), combined type IIc and type III (three lesions) and type I (two lesions). In 11 patients with advanced-stage cancer, endoscopy showed one case of Borrmann I, three of Borrmann II, six of Borrmann III and a single case of Borrmann IV. In the 17 patients with early-stage cancers (18 lesions), complete remission was obtained in 10 patients (11 lesions). Of 13 resected cancers complete remission was confirmed in six lesions on the basis of detailed histological examination of resected specimens. In the advanced stage tumours all 11 patients showed incomplete remissions. It is considered that an incomplete response in the early-stage cancers is due to insufficient light dosage because of the wide area of tumour, because the site of the lesion is anatomically difficult to photoradiate and because the invasion extends to the muscular layer and serosa.
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    URL: http://dx.doi.org/10.1007/BF02030738
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    A comparison of gold-vapour and dye lasers for photodynamic therapy (1986)
    Springer
    Lasers in medical science 1 (1986), S. 117-120 
    Details
    ISSN: 1435-604X
    Keywords: Gold-vapour laser ; Argon-pumped dye laser ; Photodynamic therapy ; Cancer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract This paper compares the relative merits of the continuous wave argon-pumped dye laser and the pulsed gold-vapour laser as used clinically for photodynamic therapy. At comparable power and energy outputs, the biological effect of the two appears to be the same. However, for 1 W output (a suitable level for clinical use), the gold laser is simpler and easier to install and run, although it requires a larger diameter fibre for light delivery (0.6 mm v. 0.2 mm). The wavelength of the dye laser is tunable, whereas that of the gold is not, although the gold laser can be easily converted to a copper-vapour laser which can pump a tunable dye laser.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02038960
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    Photodynamic therapy in the management of malignant gliomas: a review (1986)
    Springer
    Lasers in medical science 1 (1986), S. 163-174 
    Details
    ISSN: 1435-604X
    Keywords: Photodynamic therapy ; Malignant glioma ; Laser ; Haematoporphyrin derivative ; Photosensitizer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Interest in photodynamic therapy in the treatment of malignant gliomas began in the 1950s. Following the publication of papers showing that haematoporphyrin was excluded from the intact blood-brain barrier and that glioma cells grown in culture and subcutaneously could be killed by a combination of light and haematoporphyrin, a number of clinical trials was started, none of which has shown any measurable improvement in patient survival. The reason for this may relate to a lack of understanding of the mechanisms of photodynamic therapy and a lack of the scientific data needed to optimize photodynamic selectivity. This review discusses the potential role of photodynamic therapy in glioma treatment, and reviews the current clinical and experimental work in the field.
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    URL: http://dx.doi.org/10.1007/BF02040233
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  • 45
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    Photodynamic therapy and γ-irradiation of tumours: Effect of tumour-cell reoxygenation (1986)
    Springer
    Lasers in medical science 1 (1986), S. 193-195 
    Details
    ISSN: 1435-604X
    Keywords: Photodynamic therapy ; γ-Irradiation ; Hypoxia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract The presence of adequate oxygen appears to be essential for photodynamic therapy (PDT) of tumours (1, 2). We used the mouse sarcoma 180 tumour model to investigate how the reoxygenation of the tumour cell population after a single exposure to γ-irradiation influenced the effect of photodynamic therapy. The combination of γ-irradiation with PDT leads to a significant enhancement of the therapeutic effect. The best effect is observed when the γ-irradiation precedes the PDT by 24 h, at which time reoxygenation of the tumour is greatest. Also, there is some enhancement of the effect when PDT is given before γ-irradiation, although the mechanism of this is not yet clear.
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    URL: http://dx.doi.org/10.1007/BF02040237
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    Role of photodynamic therapy in the management of early cancers of the upper aerodigestive tract (1986)
    Springer
    Lasers in medical science 1 (1986), S. 217-220 
    Details
    ISSN: 1435-604X
    Keywords: Upper respiratory tract cancer ; Oronasopharyngeal cancer ; Photodynamic therapy ; Argon pumped dye laser ; Gold-vapour laser
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Photodynamic therapy has been effective in the management of cancers arising in multiple sites, particularly skin, bronchi and bladder. In head and neck cancer, however, its use has been confined to the palliation of advanced lesions that have proved refractory to conventional therapy. While this use is unquestionably valid, the true therapeutic value of photodynamic therapy appears to be in managing early mucosal cancers of the upper aerodigestive tract. These include early superficial cancers and ‘condemned mucosa’. At the University of Cincinnati, photodynamic therapy has been used on a variety of such early cancers where, for a variety of reasons, conventional therapy was not possible, and with most encouraging results. The first 20 cases are reported here, to highlight the technical aspects encountered in management, together with the pitfalls and problems. This experience has led to the development of a multi-institutional study to compare the safety and efficacy of photodynamic therapy with those of carbon dioxide laser excision of superficial carcinoma of the oral cavity and oropharynx.
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    URL: http://dx.doi.org/10.1007/BF02040242
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  • 47
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    Effect of photosensitizer concentration in tissue on the penetration depth of photoactivating light (1986)
    Springer
    Lasers in medical science 1 (1986), S. 235-244 
    Details
    ISSN: 1435-604X
    Keywords: Dihaematoporphyrin ether ; Aluminium chlorosulphonated phthalocyanine ; Penetration depth ; Diffusion theory ; Photodynamic therapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract The additional optical absorption in tissue resulting from the uptake of exogenous photosensitizers increases the effective attenuation of photoactivating light. This may be significant for the irradiation of solid tumours in photodynamic therapy, since it reduces the depth or volume of tissue treated. The effect has been studied in vitro by using dihaematoporphyrin ether (DHE) and 630 nm light in tissues representing a wide range of absorption and scattering conditions. While the attenuation may be markedly changed by small concentrations of DHE in pure scattering media, tissues with significant inherent light absorption are little affected by the additional absorption of DHE at concentrations relevant to clinical photodynamic therapy. However, it is shown that for other potential photosensitizers such as the phthalocyanines, which have substantially greater absorption at the treatment wavelength than DHE, the penetration of light in tissues may be significantly reduced.
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    URL: http://dx.doi.org/10.1007/BF02032418
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    Hypoxia, misonidazole and hyperthermia in photodynamic therapy of tumours (1986)
    Springer
    Lasers in medical science 1 (1986), S. 181-186 
    Details
    ISSN: 1435-604X
    Keywords: Photodynamic therapy ; Hypoxia ; Misonidazole ; Hyperthermia ; Tumour models ; Xenon lamp ; Argon-dye laser system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Three animal tumour models, colon carcinomaK 173 in rats, sarcoma 180 in mice and pigmented melanoma IC-Sofia in hamsters, were subjected to photodynamic therapy (PDT) in combination with the administration of misonidazole or with hyperthermia (43°C±0.1°C). The results showed that combined application of PDT with these modalities increases the therapeutic effect, which depends particularly on the sequence of their application. Misonidazole reduced the inhibition of PDT caused by acute hypoxia.
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    URL: http://dx.doi.org/10.1007/BF02040235
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    Particle dynamics and particle heat and mass transfer in thermal plasmas. Part I. The motion of a single particle without thermal effects (1985)
    Springer
    Plasma chemistry and plasma processing 5 (1985), S. 211-237 
    Details
    ISSN: 1572-8986
    Keywords: Thermal plasmas ; particle motion ; computer experiments ; review
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract A particle injected into a thermal plasma will experience a number of effects which are not present in an ordinary gas. In this paper effects exerted on the motion of a particle will be reviewed and analyzed in the context of thermal plasma processing of materials. The primary purpose of this paper is an assessment of the relative importance of various effects on particle motion. Computer experiments are described, simulating motion of a spherical particle in a laminar, confined plasma jet or in a turbulent, free plasma jet. Particle sizes range from 5 to 50 µm, and as sample materials alumina and tungsten are considered. The results indicate that (i) the correction term required for the viscous drag coefficient due to strongly varying properties is the most important factor; (ii) non-continuum effects are important for particle sizes 〈10 µm at atmospheric pressure and these effects will be enhanced for smaller particles and/or reduced pressures; (iii) the Basset history term is negligible, unless relatively large and light particles are considered over long processing distances; (iv) thermophoresis is not crucial for the injection of particles into thermal plasmas; (v) turbulent dispersion becomes important for particle 〈10 µm in diameter.
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    URL: http://dx.doi.org/10.1007/BF00615122
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    Particle dynamics and particle heat and mass transfer in thermal plasmas. Part II. Particle heat and mass transfer in thermal plasmas (1985)
    Springer
    Plasma chemistry and plasma processing 5 (1985), S. 391-414 
    Details
    ISSN: 1572-8986
    Keywords: Thermal plasmas ; heat and mass transfer ; review
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract This paper is concerned with a review of heat and mass transfer between thermal plasmas and particulate matter. In this situation various effects which are not present in ordinary heat and mass transfer have to be considered, including unsteady conditions, modified convective heat transfer due to strongly varying plasma properties, radiation, internal conduction, particle shape, vaporization and evaporation, noncontinuum conditions, and particle charging. The results indicate that (i) convective heat transfer coefficients have to be modified due to strongly varying plasma properties; (ii) vaporization, defined as a mass transfer process corresponding to particle surface temperatures below the boiling point, describes a different particle heating history than that of the evaporation process which, however, is not a critical control mechanism for interphase mass transfer of particles injected into thermal plasmas; (iii) particle heat transfer under noncontinuum conditions is governed by individual contributions from the species in the plasma (electrons, ions, neutral species) and by particle charging effects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566011
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    Generation and behavior of fine particles in thermal plasmas—A review (1985)
    Springer
    Plasma chemistry and plasma processing 5 (1985), S. 1-37 
    Details
    ISSN: 1572-8986
    Keywords: Thermal plasmas ; fine particles ; review
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract The generation and processing of fine powders in thermal plasmas has attracted increasing interest over the past years, precipitated by a growing awareness that conservation of materials is no longer an option but rather a necessity. Plasmaspheroidization, densification, fuming, metallurgical reduction, and the production of refractory oxides, carbides, nitrides, and borides in thermal plasmas are fast developing technologies which, in some cases, have already reached industrial production scale. In this survey, pertinent literature (198 references) will be reviewed with emphasis on basic studies in this field, reported over the past 20 years. The first part of this review covers powder handling, quenching characteristics, nucleation and growth, and modeling of plasma-particle interactions. The second part is concerned with plasma furnaces for the production of fine particles, including RF induction plasmas, DC anode furnaces, DC plasma jets, DC transferred arcs, cathode pump fed arcs, hybrid induction-DC plasmas, and three-phase AC furnaces.
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    URL: http://dx.doi.org/10.1007/BF00567907
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