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- af Klinteberg, Claes
(författare)
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On the use of light for the characterization and treatment of malignant tumours
- 1999
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Some aspects on the use of light for tissue characterization and treatment of malignant tumours are discussed within this thesis. The work presented aims at improving optical techniques for tissue characterization, especially to detect malignant and pre-malignant lesions. A knowledge on the interaction between light and tissue is of utmost importance to understand and improve the various techniques. A relatively thorough discussion on the light propagation in scattering media is given. A commonly used mathematical model, the diffusion approximation of the transport equation, is derived. Moreover, knowledge of the optical properties of tissue, i.e., the absorption and scattering coefficients, the scattering anisotropy, and the refractive index, is needed to use the mathematical models. Various techniques for in vivo measurements of the tissue optical properties are presented. Furthermore, some of these techniques have been developed into prototype equipment to be used for breast cancer detection, as an alternative to the ordinary mammography based on ionizing X-rays. A therapeutic modality, photodynamic therapy (PDT), presently being introduced into clinical practice has also been investigated. This technique relies on the selective uptake of a photosensitizing agent, and the subsequent irradiation using light. The light absorbed by the photosensitizer triggers a photochemical reaction, leading to local cell death. In the work presented here, d-aminolevulinic acid (ALA) induced protoporphyrin IX (PpIX) has been used as a photosensitizer. A randomized Phase III clinical trial has been conducted to compare PDT with cryosurgery for the treatment of basal cell carcinomas of the skin. The influence on the treatment of various parameters have been investigated and are discussed. Laser-induced fluorescence studies were performed to detect and demarcate superficial malignant and pre-malignant lesions. Both the tissue autofluorescence and the characteristic emission of fluorescent tumour markers were employed. Fluorescence was also used to monitor the selective buildup and the photodegradation of the photosensitizer in connection to PDT, using a point-monitoring technique. Two fluorescence imaging systems have also been used to outline skin lesions. Laser-Doppler perfusion imaging is a non-contact optical technique used to monitor the superficial blood perfusion, and was here used to evaluate the healing time following cryosurgery and PDT.
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| 2. |
- Andersson-Engels, Stefan, et al.
(författare)
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Preliminary evaluation of two fluorescence imaging methods for the detection and the delineation of basal cell carcinomas of the skin
- 2000
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Ingår i: Lasers in Surgery and Medicine. - 0196-8092. ; 26:1, s. 76-82
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Tidskriftsartikel (refereegranskat)abstract
- Abstract Background and ObjectiveFluorescence techniques can provide powerful noninvasive means for medical diagnosis, based on the detection of either endogenous or exogenous fluorophores. The fluorescence of δ-aminolevulinic acid (ALA)-induced protoporphyrin IX (PpIX) has already shown promise for the diagnosis of tumors. The aim of the study was to investigate the localization of skin tumors after the topical application of ALA, by detecting the PpIX fluorescence either in the spectral or in the time domain.Study Design/Materials and MethodsTwo fluorescence imaging systems were used to identify basal cell carcinomas of the skin in humans, after topical application of 20% ALA ointment. Both systems rely on the comparison between the exogenous and the endogenous fluorescence, performed either in the spectral domain or in the time domain. The first system works by using three images acquired through different spectral filters, whereas the second one measures the spatial map of the average fluorescence lifetime of the sample.ResultsA clear demarcation of skin malignancies was successfully performed in vivo noninvasively with both fluorescence imaging systems.ConclusionThe two complementary approaches considered in the present study show promise for skin tumor detection and delineation based on specific fluorescence features. Lasers Surg. Med. 26:76–82, 2000. © 2000 Wiley-Liss, Inc.
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| 3. |
- Enejder, Annika M K, et al.
(författare)
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Blood perfusion studies on basal cell carcinomas in conjunction with photodynamic- and cryo therapy employing laser-Doppler imaging
- 2000
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Ingår i: Acta Dermato-Venereologica. - : Medical Journals Sweden AB. - 1651-2057 .- 0001-5555. ; 80:1, s. 19-23
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Tidskriftsartikel (refereegranskat)abstract
- Superficial blood perfusion mas monitored using laser-Doppler perfusion imaging in connection with a phase LII clinical trial comparing photodynamic therapy, utilizing topically applied aminoleuvlinic acid, with cryotherapy of basal cell, carcinomas. A total of 526 images mere recorded before and immediately after the treatment and during the follow-up period. Before treatment, the lesions exhibited a blood perfusion 3+/-2 times that in normal tissue. Both treatment modalities induced an increased blood perfusion inside the lesions, which slowly approached normal values in conjunction with successful treatments. The blood perfusion in successfully treated lesions approached normal values 2 months after photodynamic therapy, and about 1 year after cryotherapy, The tissue perfusion in recurrent lesions did not decrease to normal values after the treatment, suggesting that the laser-Doppler perfusion imaging technique can be used to follow the healing process and discover possible persistent tumour growth.
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| 4. |
- Johansson, Thomas, et al.
(författare)
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Feasibility study of a system for combined light dosimetry and interstitial photodynamic treatment of massive tumors
- 2002
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Ingår i: Applied Optics. - 2155-3165. ; 41:7, s. 1462-1468
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Tidskriftsartikel (refereegranskat)abstract
- A system for the photodynamic laser treatment of massive tumors that employs multiple optical fibers to be inserted into the tumor mass is described. The light flux through the tumor can be assessed by use of the individual fibers both as transmitters and as receivers. With a computer model that describes the diffusive light propagation, optical dosimetry is under development, The system has been tested in an experimental animal tumor model in preparation for clinical work. Currently, delta-aminolevulinic acid is used as a sensitizer, activated by 635-nm radiation from a 2.0-W compact diode laser system. With the availability of future, highly selective drugs absorbing approximately 750 nm, larger tumor volumes should be treatable, and surrounding, sensitive normal tissue should be spared.
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| 5. |
- Soto Thompson, Marcelo, et al.
(författare)
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Photodynamic therapy and diagnostic measurements of basal cell carcinomas using esterified and non-esterified delta-aminolevulinic acid
- 2001
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Ingår i: Journal of Porphyrins and Phthalocyanines. - 1099-1409. ; 5:2, s. 147-147
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Tidskriftsartikel (refereegranskat)abstract
- Various optical techniques were used to investigate relevant parameters involved in photodynamic therapy (PDT) of human basal cell carcinomas (BCCs). The aim of the study was to compare the diagnostic and therapeutic outcome when using topically applied methyl-esterified delta -aminolevulinic acid (ALA-ME) and delta -aminolevulinic acid (ALA). A total of 35 pathologically verified BCCs in 14 patients were investigated. A diode laser. emitting continuous light at 633 nm, was used to induce PDT. The diagnostic measurements were performed before, during, and after PDT. Laser-induced fluorescence (LIF) was used to monitor the build-up of the ALA/ALA-ME-induced protoporphyrin IX (PpIX), The superficial tissue perfusion was measured with laser-Doppler perfusion imaging (LDPI) and the temperature of the lesion and the surrounding tissue was imaged with an IR-camera. A clear demarcation between the lesion and the normal skin was detected with LIF before the treatment for both PpIX precursors. The fluorescence measurements suggest that PpIX builds up to a higher degree and more selectively in the tumour following ALA-ME as compared to ALA. The LDPI measurements indicate a local transient restriction in blood perfusion immediately post-PDT. The measurement with the IR-camera revealed a temperature rise of about 1-2 degreesC during the treatment.
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| 6. |
- Svanberg, Sune, et al.
(författare)
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Generation, characterization, and medical utilization of laser-produced emission continua
- 2000
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Ingår i: Laser and Particle Beams. - 0263-0346. ; 18:3, s. 563-570
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Tidskriftsartikel (refereegranskat)abstract
- Intense continua of electromagnetic radiation of very brief duration are formed in the interaction of focused ultra-short terawatt laser pulses with matter. Two different kinds of experiments, which have been performed utilizing the Lund 10 Hz titanium-doped sapphire terawatt laser system are being described, where visible radiation and X-rays, respectively, have been generated. Focusing into water leads to the generation of a light continuum through self-phase modulation. The propagation of the light through tissue was studied addressing questions related to optical mammography and specific chromophore absorption. When terawatt laser pulses are focused onto a solid target with high nuclear charge Z, intense X-ray radiation of few ps duration and with energies exceeding hundreds of keV is emitted. Biomedical applications of this radiation are described, including differential absorption and gated-viewing imaging.
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