Study of new methods of increasing effectiveness of radiotherapy by physical means and related application of luminescence
The aim of the first part of this thesis (Chapter 1, 2 and 3) is based on the chemiluminescence probing (CLP) applications as a technique to study the redox metabolic activity of Ehrlich Ascites tumour cells (EAT). Lucigenin was introduced as a non-isotope substrate label. Lucigenin CL result from reductive oxygenation, involves two electrons reduction reactions. Lucigenin can serve as substrate in an oxygen-redox reaction, yielding electronically excited N-methyl acridone as a product. Chapter 4 deals with the effect of nitroimidazole agents on the CL of EAT cells plus lucigenin and on their redox activity. The ability of the nitroimidazole compounds to accept electrons makes these drugs mimic oxygen, and have possible involvement of free radical intermediate in the electron transfer processes of EAT cells. The electron affinity have provided the basis for the nitroimidazole in chemotherapy, i.e. potential for radiotherapy. Chapter 5 deals with the combination action of hyperthermia (HT) and pharmacological treatment of EAT cells, investigated by means of CL. This chapter is devoted to study the thermal tolerance and redox activity of EAT cells in the presence and absence of 5-nitroimidazole using CLP techniques. A biochemical agent, lucigenin, is used as the probe label. The aims of Chapters 4 and 5 are to - 1. evaluate the effect of HT alone on EAT cells in vitro, 2. investigate the cytotoxic effect of nitroimidazole particularly 5-nitroimidazole together with HT, 3. study the influence of thermal tolerance on cell killing by 5-nitroimidazole. 4. study the effect of timing and order of administration of HT and 5-nitroimidazole in vitro. HT can increase the therapeutic effectiveness of the hypoxic drug sensitizer as a selective agent inteferring with cellular respiration and formation of metabolites which accumulate in cells. HT is likely to effect cellular electron transfer within cells and may accelerate the processes. Sensitizer will undoubtedly serve as a marker for cancer hypotic cells in studies of tumour and tumour cell kinetics and might have a role in cancer diagnosis and therapy. The second part of the thesis (Chapter 6) covers the lyoluminescence (LL) techniques (i.e. emission of light on dissolution of irradiated solids) in the study of the dosimetric problem of internally incorporated β-emitter in tissue equivalent saccharides and amino acids. The third part of the thesis (Chapter 7) covers the possible dosimetric application of piezoluminescence (i.e. emission of light from crystals subjected to pressure of irradiated solid crystal) in alkali halides irradiated with γ-rays and the possible mechanism of piezoluminescence (PL). In this investigation, crystals of NaCl, KBr and KCl were used. In addition, standard LiF chips (TLD-100), CaF2-(Dy) (TLD-200) and CaF2 with different impurities of an alkaline earth halide were used. The lower limit of doses (0.25 Gy) was limited by the amount of produced light. It is conceivable that with specially prepared crystals, containing controlled impurities and optimized for a PL readout, the range of doses could be extended down.