Document Detail


In vivo measurement of parameters of dosimetric importance during interstitial photodynamic therapy of thick skin tumors.
MedLine Citation:
PMID:  16822078     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
A system for interstitial photodynamic therapy is used in the treatment of thick skin tumors. The system allows simultaneous measurements of light fluence rate, sensitizer fluorescence, and tissue oxygen saturation by using the same fibers as for therapeutic light delivery. Results from ten tumor treatments using delta-aminolevulinic acid (ALA)-induced protoporphyrin IX show a significant, treatment-induced increase in tissue absorption at the therapeutic wavelength, and rapid sensitizer photobleaching. The changes in oxy- and deoxyhemoglobin content are monitored by means of near-infrared spectroscopy, revealing a varying tissue oxygenation and significant changes in blood volume during treatment. These changes are consistent with the temporal profiles of the light fluence rate at the therapeutic wavelength actually measured. We therefore propose the observed absorption increase to be due to treatment-induced deoxygenation in combination with changes in blood concentration within the treated volume. A higher rate of initial photobleaching is found to correlate with a less pronounced increase in tissue absorption. Based on the measured signals, we propose how real-time treatment supervision and feedback can be implemented. Simultaneous study of the fluence rate, sensitizer fluorescence, and local tissue oxygen saturation level may contribute to the understanding of the threshold dose for photodynamic therapy.
Authors:
Ann Johansson; Thomas Johansson; Marcelo Soto Thompson; Niels Bendsoe; Katarina Svanberg; Sune Svanberg; Stefan Andersson-Engels
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Publication Detail:
Type:  Clinical Trial; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of biomedical optics     Volume:  11     ISSN:  1083-3668     ISO Abbreviation:  J Biomed Opt     Publication Date:    2006 May-Jun
Date Detail:
Created Date:  2006-07-06     Completed Date:  2006-09-12     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  9605853     Medline TA:  J Biomed Opt     Country:  United States    
Other Details:
Languages:  eng     Pagination:  34029     Citation Subset:  IM    
Affiliation:
Lund Institute of Technology, Department of Physics, Lund, Sweden. Ann.Johansson@fysik.lth.se
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MeSH Terms
Descriptor/Qualifier:
Diagnosis, Computer-Assisted / instrumentation*,  methods
Equipment Design
Equipment Failure Analysis
Female
Fiber Optic Technology / instrumentation*,  methods
Humans
Laser Therapy
Lasers / diagnostic use
Male
Photochemotherapy / instrumentation*,  methods
Radiometry / instrumentation*,  methods
Radiotherapy Dosage
Reproducibility of Results
Sensitivity and Specificity
Skin Neoplasms / diagnosis*,  drug therapy*
Therapy, Computer-Assisted / instrumentation*,  methods
Treatment Outcome

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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