Luminescence lifetime determination for oxygen imaging in human tissue

Abstract

Imaging and monitoring of biochemical parameters in vitro and in vivo have become the goal of many investigations in medical physics. The main imaging technique used is laser-induced luminescence due to its cost effectiveness and diversity of applications [1]. One key parameter in medical investigations, for instance to control photodynamic therapy, is the molecular oxygen concentration. The use of optical methods provides possible means of measuring molecular oxygen. The basis of such a method is the measurement of the luminescence lifetime of a dye which is quenched by molecular oxygen. The molecular oxygen concentration can be monitored two-dimensionally by pixel-wise determination of the luminescence lifetime with a CCD-camera. An oxygen imaging system based on this principle was built and tested with a commercially available oxygen sensitive sol gel-layer. The embedded ruthenium complex is quenched by molecular oxygen and because of the oxygen permeability of the layer; it is suitable for oxygen measurements. The characteristics and dependence on the pH-value and temperature of the luminescence lifetime of the layer were examined in preparation for measurements on tissue to exclude cross-correlation of other quenching processes.

A study of the photodynamic effect on cancerous cells

“…It is therefore concluded from the above discussion that our experimental results are in good agreement with those from previous in vitro and in vivo studies [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36]. In order to prove the experimental results theoretically a model based on singlet oxygen attack of the photosensitizer was used to calculate PDD.…”

Study of the efficacy of 5-ALA mediated photodynamic therapy on human rhabdomyosarcoma cell line (RD)

“…10 that PDT treated RD cells show major cell death, almost 70%, at 80 µg/ml and it becomes 75% up till ALA concentration of 250 µg/ml which has been considered as optimal concentration in current study. Many researchers explored that 5-ALA (PpIX) have good therapeutic results due to high uptake, in vitro as well as in vivo studies [55][56][57][58][59][60][61][62][63][64][65][66][67][68][69][70][71].…”

Indirect imaging of singlet oxygen generation from a single cell

“…Photodynamic therapy (PDT) is a promising therapeutic modality for advanced solid tumors, age-related macular degeneration, localized infection and several benign skin conditions, which utilizes a photoactive drug photosensitizer, light with appropriate wavelength, and tissue oxygen to destroy diseased cells [1][2][3][4][5]. Most current photosensitizers used in PDT are widely believed to elicit their damage primarily through singlet oxygen ( 1 O 2 )-mediated pathways [6][7][8].…”