In vivo measurement of parameters of dosimetric importance during interstitial photodynamic therapy of thick skin tumors

Autor: Sune Svanberg, Ann Johansson, Thomas Johansson, Stefan Andersson-Engels, Marcelo Soto Thompson, Niels Bendsoe, Katarina Svanberg
Jazyk: angličtina
Rok vydání: 2006
Předmět:
Male
Bioengineering Equipment
medicine.medical_specialty
spectroscopy
Skin Neoplasms
medicine.medical_treatment
Biomedical Engineering
chemistry.chemical_element
Photodynamic therapy
Blood volume
Absorption (skin)
photobleaching
Oxygen
Sensitivity and Specificity
Biomaterials
chemistry.chemical_compound
delta-aminolevulinic acid
In vivo
medicine
Fiber Optic Technology
Humans
Diagnosis
Computer-Assisted
Radiometry
Protoporphyrin IX
Chemistry
Lasers
Reproducibility of Results
Radiotherapy Dosage
Equipment Design
Photobleaching
Fluorescence
Atomic and Molecular Physics
and Optics
Electronic
Optical and Magnetic Materials
Surgery
Equipment Failure Analysis
Treatment Outcome
Photochemotherapy
photodynamic therapy
Therapy
Computer-Assisted
protoporphyrin IX fluorescence
Biophysics
Female
Laser Therapy
sense organs
absorption
Zdroj: Journal of Biomedical Optics; 11, no 39 (2006)
ISSN: 1083-3668
Popis: 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. (c) 2006 Society of Photo-Optical Instrumentation Engineers.
Databáze: OpenAIRE
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