7. Biological Effectiveness of 12 C and 20 Ne Ions with Very High LET

Knowledge of radiobiological effects of heavy ions at the cellular and molecular level is of fundamental importance in the field of radiation therapy (for example C ions) and space radiation biology (for example Ne ions). One of the issues that require deeper investigations is a determination of RBE values for a wide range of LET, for all relevant doses, for many cell types and various kinds of radiations During recent years, the biological effectiveness of heavy ions has been widely investigated with the aim to identify physical characteristics relevant to biological actions. These investigations are pertinent to the use of heavy ions in radiosurgery and radiotherapy. What has not been investigated so thoroughly is the biological effectiveness of heavy ions at low energies and very high LET values. The LET, which is equal to the stopping power of heavy particles, increases sharply at the end of the particle's path, forming a so-called Bragg peak. The shape of the Bragg peak depends on the particle type. Because overlying beams with different energies and components of primary and secondary particles are used in radiotherapy, the knowledge of RBE values of very high LET radiation need to be well characterized. An experimental set-up designed for such investigations was constructed at the isochronic cyclotron in Heavy Ion Laboratory. A more detailed description of the set-up can be found in Ref. CHO-K1 cells have been used as a suitable biological system for our studies. The cell line is characterized by genetic stability, the ability to form colonies, a relatively rapid growth rate with a cell cycle of 12-14 hours. For exposure to ions the cells were seeded in specially designed Petri dishes, which were filled with medium, sealed by a parafilm cover and placed in a vertical sample holder mounted in an x-y-z table that was connected to a special stepping motor. The irradiated sample moved under the beam according to a planned route. Movement was initiated when the number of counts detected by the 20 o particle detector reached the preset value. When all fields have been exposed the sample holder returned to the start position. Stored information enabled to evaluate the beam stability and intensity. The whole set-up was surveyed by a digital camera. The total time of exposure per dish was between 1-5 min. depending on the dose and beam intensity. The dose rates were changed from 0.05 Gy/min. to 1 Gy/min depending on the dose. Cell survival was estimated according to standard procedure

Investigation of Gold Nanolayer Properties Using X-Ray Reflectometry and Spectroscopic Ellipsometry Methods

X-ray reflectometry and spectroscopic ellipsometry methods were applied for determination of physical properties of gold nonolayers. The nanolayers were prepared by sputtering of gold on different substrates: borosilicate glass, polished crystalline quartz and crystalline silicon. With X-ray reflectometry technique roughness of the substrates and density, thickness and roughness of gold layers were determined. The results showed decrease in density of the gold layers due to their nanometer thickness and that roughness of the underlayer affects roughness of the gold layer. In addition, thicknesses of the gold layers measured with spectroscopic ellipsometry turned out to be in agreement, within the experimental uncertainty, with results of the X-ray reflectometry method

X-ray Diffraction and Elemental Analysis of Medical and Environmental Samples

The results of the elemental and chemical composition analysis of human medical samples (blood, serum, hair, urine, tooth, kidney stones, gallstones) and environmental samples (slag, cereal, vegetables, flour, pork bones, pork meat, fish) are presented. The analysis were performed by application of the total reflection X-ray fluorescence, wavelength dispersive X-ray fluorescence and X-ray powder diffraction methods. With X-ray fluorescence methods the following elements were identified: O, Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, Mn, Fe, Ni, Cu, Zn, Se, Br, Rb, Sr, Zr, I, Ba, and Pb, whose concentrations were from a few ng/g to tens of percent. For some samples the elemental analysis was extended by X-ray powder diffraction measurements. With this method the chemical composition was determined. In the paper the experimental setups, methodology of samples preparation and methods of carrying out the measurements are described. As an example the X-ray spectra registered for gallstone sample are discussed in detail. Finally, the results of X-ray diffraction and elemental analysis for selected medical and environmental samples are summarized

X-Ray Fluorescence Techniques in Medical Applications: Reference Values of Elements in Human Serum, Urine and Hair

The aim of undertaken long-term studies of the elemental composition of human serum, urine, and hair is to define reference values of elements concentration. For this purpose the total reflection X-ray fluorescence method was applied to determination of several elements concentration in human serum, urine and hair (S, K, Ca, Fe, Cu, Zn, Br, P, Cr, and Rb in serum samples; Fe, Cu, Zn, Rb, Cr, Mn, and Sr in urine samples; S, K, Ca, Fe, Cu, Br, Zn, Cl, Ti, Cr, Mn, Ni, and Se in hair samples) in the range of concentration from ppb to several hundred ppm. The method of selection of the control group, the experimental setup and its calibration procedure are described. We also present sample preparation methods and procedure of measurements

Heavy Ion Beams for Radiobiology: Dosimetry and Nanodosimetry at HIL

Ionizing radiation induces a variety of DNA lesions, including single and double strand breaks. Large energy deposition precisely localized along the ion track that occurs in the case of heavy ion irradiation can lead to complex types of DNA double strand breaks in exposed biological material. The formation of nuclear double strand breaks triggers phosphorylation of histone H2AX, which can be microscopically visualized as foci in the γ-H2AX assay. Studies with a carbon ion beam are being carried out at the Heavy Ion Laboratory of the University of Warsaw. The γ-H2AX assay as a method of measuring the biological response of cells irradiated with $\text{}^{12}C$ ions as well as the frequency cluster size distributions obtained in the nanodosimetry experiment at HIL will be presented