threshold value of a dose
L.V. Zhorina, L.I. Zalevskaya, O.I. Zalevskaya, G.N. Zmievskoy
Heightened interest to photosensitizers (PS) a phytogenesis, concerning to tetra-pirrol derivatives of chlorophyll series is observed in photodynamic therapy now. In Russia the unique technology of biologically active components complex, containing in quality of the basic component Chlorine е6, extraction from vegetative raw materials is developed. For preparation of various medicinal forms chlorines in the form of 7 %-s' water solutions representing a substance "Radachlorin" are used.
In proposed work dose characteristics «Radachlorin» (optical density of pattern depend on irradiation dose) at supervision of photodynamic effect (PDE) on an erythrocytes suspension are defined and their comparison with dose characteristics twice sulfanated aluminum phtalocyanine AlPCS2 (analogue of a domestic PS "Photosense") is spent.
Measurements have shown that the dose corresponding to the beginning of photo destructive reaction (a threshold dose) for Radachlorin is much less than for AlPCS2, and it takes place both for the PS incubated samples and for not incubated ones. Thus has been expected revealed that the more time of samples incubation with PS in a blood solution, the less threshold dose to PDE beginning (the more PS uptake within the cell, the more destroying agents at inactivation is formed at the same irradiation doses).
For definition of PDE threshold dose and threshold light source power level the irradiation of unlatented samples of blood with Radachlorin by continuous laser radiation with different power levels was used. In all cases the PDE was observed, so on power level the threshold even at obviously small intensities was absent. The constancy of a threshold dose remained.
The received results allow considering the sensibilised preparations optical density as correlated response parameter of the organism upon photo-influence in the PDE presence. This fact can be used for definition of a necessary dose of an irradiation not from empirical reasons as it usually becomes in practice, but by preliminary laboratory researches. Corresponding calculation of a dose can be done depending on character of pathology and its arrangement in an organism a priori, instead of а posteriori when efficiency on degree of tumor regress is estimated after the spent course of treatment. The main advantage of an offered technique is that the influence biodosimetric control has the expressed individual character and it is focused on the concrete patient.