The Research On Early Radiation Induced Hepatic Injury In Vivo With High-energy X-ray

This paper mainly concerned about the basic research and technical resolution of electrical impedance tomography (EIT). The main works include following two parts: First, the research on nonirradiation hepatic organize complex impedance spectra; second, the research on irradiation hepatic organize complex impedance spectra.Back ground and objectiveThe complex impedance of bio-tissue varies with the frequency of driven current change. For different tissue, these variations were very different. This characteristic of bio-tissue was called impedance spectra. To measure the impedance spectra of bio-tissue is a fundamental work in EIT. Because bio-tissue impedance spectra showed a close relation with the physiological and pathological states of bio-tissue, the physiological activity and states may be observed by measuring the bio-tissue impedance spectra. The Early Radiation Induced Hepatic Injury in vivo with high-energy X-ray just basic on this theory for research.People do not have a clear idea about whether the irradiation injury (for example oedema) can be showed by the impedance spectra and what the impedance spectra difference between irradiation and nonirradiation livers. There is not paper report about warding the irradiation injury in 12 hours in the world.Subjects and Methods1. To construct an irradiation impedance spectra measurement system, which is based on four-electrode method, can provide driven current from 100Hz to 1MHz;2. To measure the impedance spectra of liver in vivo of the nonirradiation and irradiaton rabbits in 12~24 hours, comparing the difference of the impedance spectroscopy, finding out what time when the change happened;3. From the measured data, computing the characteristic of impedance spectra for liver tissue, analyzing the affect factors of bio-impedance spectra and making pathologic and statistical research.The Main Results and Conclusions:1. Irradiation and nonirradiation rabbits show different impedance spectra characteristic. These difference can be observed by Cole-Cole diagram directly, and can also be represented in impedance spectra characteristics, such as characteristic frequency(fc), low-frequency resistance(R0), high-frequency resistance(R∞);2. The impedance spectra changes remarkably with the variation of driven current frequency: With the increasing of driven frequency, the real part of liver-impedance decreases from low-frequency resistance(R0) to high-frequency resistance(R∞). The change is significant in mid-frequency band (10kHz~100kHz), The imaginary part of bio-impedance first increase from 0 to the maximum, then decreases to 0. It can be neglect in low-frequency band(below a few kilo Hz) and high-frequency band(above a few Mega Hz);3. With the time prolonging, the impedance spectra of irradiation rabbits in vivo produce following changes: low-frequency resistance(R0) increases; imaginary part increases; characteristic frequency(fc) floating to high-frequency band;the real part of tissue in vivo impedance increased significantly, the imaginary part increased in mid-frequency band, the characteristic frequency increase but not significantly.Conclusion and Suggestions:1. The impedance spectra do not have changes when the animal in normal physiological function ;2. The main reason of variation in impedance spectra of tissue in vivo is that, the irradiation injury reduces the extracellular liquid changed.