Particles Of Ionizing Radiation Energy Deposited In Human Tissue Microdosimetry Study

The world wide research on biological effects had been spread in many countries since L.E.Lea recognized the importance of the micro-distribution of radiation energy deposition in biological material in 1946. The researches about these kinds of energy deposition events including photon, neutron, proton and electron on the scale of micron were begun in the 60's of the last century in some foreign countries such as U.S.A, German, Japan etc. These researches were related tightly to biology since beginning. Both of experiment and theory method were used, and the relationship between physical measurement and biological effects was related through various mathematical models, with which the phenomena of cell-death could be explained. The investigation of the micro-distribution of radiation energy deposition has been extended largely from micron level to nanometer level with the development of computer technology and the perfection of the measuring methods since 1970. The research region was enlarged to heavy ions accompanied by the development of space-flight and the running of many large heavy ion accelerator after then.The instantaneous or permanent changes in tissue were close depended on the spatial micro-distribution of energy deposition and energy transfer process of radiation. In this case, some dosimetry concepts such as LET, stopping power and mean energy imparted would not be capable to describe the progress of physics, chemistry and biological effects. New concepts must be established, so the energy deposition fashion and the energy deposition distribution of various particles in tissue must be studied. The ranges, cross sections of ionizing particles and radial dose distributions along particles' trace in targets should be given much more attention both in theory and in experiment. The physics basement of energy deposition micro-distribution in tissue will be recognized deeply after these research, and the biological effects of all sort of ionizing particles will be explained correctly, then the ionizing radiation action model and according physics action mechanism will be established also. Little has been done in our country in the region, no matter in theory calculation or in experiment aspects now. In our research we will do some theory calculations first, and give some results of energy deposition micro-distribution in tissue. This study will be the first step in our national research.we have done a lot of investigation to do the work. There is little clue about this research, so we find no papers in Chinese. We have obtained lots of knowledge on this study main from worldwide web, and formed ourselves framework doing the research. If the Monte Carlo method was accepted, charged particles energy deposition micro-progress and ionizing radiation spatial action will be simulated, then many physics phenomena such as energy loss fluctuation, delta ray produced and all of other forked track will be scribed particularly. The important thing is that some supposes about physics progresshappened in target will not be done. We give up mathematical calculation method and choice Monte Carlo method as our research means in this work.In our research progress, these problems have been resolved in turn: first, the tissue component was analyzed, and the rationality that liquid water (or water vapor-density is 1g/cm3) is the substitute of tissue equivalent material was made sure. Second, various cross section data on proton, alpha particles, electron and photon in water vapor were obtained, and these data were optimized. Third, the ESLOW3.1 code has been improved, and the new cross section data were adopted. The electron energy spectra from different energy photon (10keV~1.6MeV) in tissue equivalent materials were acquainted, and the electron mean energy was obtainted by this code also. Fourth, we acquainted energy deposition event position distribution, energy distribution from different energy electron (20eV~1.0MeV) in tissue equivalent material by the usage of ESLOW3.1 electron sub-code, and all sort of event type were analyzed. At the same time, according to DNA molecule diameter, the energy deposition cluster events were defined; the frequency distribution and energy distribution of cluster events were calculated. Fifth, neutron reaction types in body tissue were analyzed, and productions in these reactions were estimated. Sixth, using the latest code M0CA15 written by Wilson and Paretzke, we calculated track section of proton and alpha particle in the tissue equivalent material, and the energy deposition distribution, position distribution, energy distribution and radial dose distribution for second electron were all acquainted. The code-MOCA15 can dispose any proton and alpha particle with the energy region between 0.3MeV/u~5MeV/u. the wide particle energy region covers all energy proton and alpha particle we care about.Some energy deposition micro-distribution styles for different ionizing particles in tissue equivalent materials have been known thorough these researches. We have acquainted these particles energy deposition event distribution and dose distribution at nano-level also, and can recognized origin physics mechanism when various biological effects happen. This research will help us evaluated ionizing radiation latent physics injures in tissue at low dose. Meanwhile we can forecast the serious degree and happen probability of biological effects, and recognize ionizing radiation injure at molecule level. All these research are the physics base of ionizing radiation molecule biology.