| 1. |
- Eker, C, et al.
(författare)
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Clinical spectral characterisation of colonic mucosal lesions using autofluorescence and delta aminolevulinic acid sensitisation
- 1999
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Ingår i: Gut. - : BMJ. - 1468-3288 .- 0017-5749. ; 44:4, s. 511-518
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Tidskriftsartikel (refereegranskat)abstract
- Background and aims-Laser induced fluorescence (LIF) from colonic mucosa was measured in vivo with and without delta aminolevulinic acid (ALA) in an attempt to differentiate between neoplasia and non-neoplasia in real time during colonoscopy. Methods-Spectra from 32 adenomas, 68 normal sites, and 14 hyperplastic polyps in 41 patients were obtained with a point monitoring system. Twenty one of the patients had been given a low dose of ALA as a photosensitiser before the examination. Light of 337, 405, or 436 nm wavelength was used as excitation. Stepwise multivariate Linear regression analysis was performed. Results-With 337 nm excitation, 100% sensitivity and 96% specificity was obtained between normal mucosa and adenomas. Seventy seven per cent of the hyperplastic polyps were classified as non-neoplastic. When exciting with 405 and 436 nm, the possibility of distinguishing different types of tissue was considerably better in the ALA patients than in the non-ALA patients. Conclusions-The in vivo point measurements imply that a good discrimination between normal tissue and adenomatous polyps can be obtained using the LIF technique. Excitation at 337 nm and at 405 nm or 436 nm using ALA gives good results. LIF also shows potential for distinguishing adenomatous from hyperplastic polyps. The number of detection wavelengths could be reduced if chosen properly.
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| 2. |
- Wang, I, et al.
(författare)
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Photodynamic therapy utilising topical delta-aminolevulinic acid in non-melanoma skin malignancies of the eyelid and the periocular skin
- 1999
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Ingår i: Acta Ophthalmologica Scandinavica. - : Wiley. - 1395-3907. ; 77:2, s. 182-188
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Photodynamic therapy utilising delta-aminoleuvlinic acid-induced protoporphyrin IX photosensitisation, was evaluated as a treatment modality for nonmelanoma skin malignancies of the eyelids and the periocular skin, Methods: Photodynamic therapy with laser light at 635 nm was performed in 13 patients with 19 basal cell carcinomas and one patient with 3 cutaneous T-cell lymphoma lesions. A topical application regimen was used and in median 3 treatment sessions were given to each lesion. Results: A visually judged complete response was achieved in 42 % (8/19) of the basal cell carcinomas and in 100% of the T-cell lymphoma lesions (3/3), Partial tumour response was seen in 42% (8/19) and no response in 16% (3/19) of the basal cell carcinomas. The median follow-up time was 12 months. No, or very little scarring and loss of cilia were induced by the treatment. Conclusion: Photodynamic therapy with delta-aminolevulinic acid can eradicate eye-close non-melanoma skin malignancies without compromising the function of the eyelids. Further development of the method is needed to reach the same cure rates as those of the conventional treatment modalities.
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| 3. |
- Tillman, Carl, et al.
(författare)
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Survival of mammalian cells exposed to ultrahigh dose rates from a laser-produced plasma x-ray source
- 1999
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Ingår i: Radiology. - 1527-1315. ; 213:3, s. 860-865
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To determine whether intense laser-produced x rays have an increased radiation hazard. MATERIALS AND METHODS: Mammalian cells were exposed to x rays from a laser-produced plasma that produced ultrahigh peak absorbed dose rates, up to a factor of 10(10) higher than those produced by conventional x rays used in imaging. The cell survival was studied as a function of the absorbed dose. The survival of mammalian cells exposed to high peak absorbed dose rates with laser-produced x rays was compared with the survival of cells exposed to standard absorbed dose rates with conventional x-ray sources. Comparative survival studies were performed by using a conventional x-ray tube and a cobalt 60 source. The absorbed doses in the irradiation field were measured with thermoluminescent dosimeters. RESULTS: Cell survival following irradiation by filtered, laser-produced x rays with a high dose rate was not markedly different from the survival following irradiation by conventional sources. There was, however, a notable difference between the survival after exposure to filtered, laser-produced x rays and the survival after exposure to unfiltered laser-produced x rays. CONCLUSION: Exposure to filtered, laser-produced x rays with a high dose rate does not lead to increased harm to mammalian cells exposed in vitro compared with the harm from exposure to x rays from conventional sources, which indicates that the use of high-power laser facilities for medical imaging is justified
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| 4. |
- Wang, I, et al.
(författare)
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Fluorescence diagnostics and kinetic studies in the head and neck region utilizing low-dose delta-aminolevulinic acid sensitization
- 1999
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Ingår i: Cancer Letters. - 1872-7980. ; 135:1, s. 11-19
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Tidskriftsartikel (refereegranskat)abstract
- Diagnostic measurements and pharmacokinetic studies were performed in 17 patients with various kinds of malignant, premalignant and benign lesions in the head and neck region by means of point monitoring laser-induced fluorescence. For marking different types of tissue, delta-aminolevulinic acid (ALA)-induced protoporphyrin IX (PpIX) was used. The ALA-induced PpIX synthesis was monitored at different time intervals after oral administration of ALA in low doses, 5 and 15 mg/kg b.w. Besides the porphyrin-related signal the tissue endogenous fluorescence was also recorded. The fluorescence spectra were evaluated at two different wavelengths corresponding to the specific drug-related fluorescence peak and the endogenous tissue fluorescence emission at 635 and 490 nm, respectively. The evaluated fluorescence data were correlated to the histopathological tissue investigation. A fall-off in the overall fluorescence intensity at 490 nm was obtained for an the malignant and premalignant areas, as well as an increased red fluorescence. A ratio between the red and the blue/green fluorescence intensity was formed for each time interval after the ALA administration. The lower drug dose seems to be sufficient to obtain a useful demarcation ratio between normal and diseased tissue with a very low PpIX fluorescence intensity in the normal tissue. A PpIX fluorescence maximum seems to occur between 3 and 4 h in normal tissues, whereas malignant tumour tissue shows a higher level for a longer period of time. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.
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