The Physical and Clinical Aspects of Radiation Therapy in Skin Cancer and Subcutaneous Tissue Neoplasm

Cancers, malignant melanoma and sarcomas of the skin represent the most common group of malignancies in humans. The main treatment method of almost all skin cancers and subcutaneous tissue tumours is surgery, which consists of complete removal of a neoplastic lesion, with an adequate margin of healthy tissue. Radiotherapy plays an adjuvant role in this process, meaning complementing of the surgical procedure. This study compared four methods of irradiation treatment of cancer located in the skin or in subcutaneous tissues: contact brachytherapy, conventional orthovoltage therapy, electron beam conformal teleradiotherapy and IMRT dynamically shaped photonic beams conformal teleradiotherapy. In order to compare the methods and techniques of surface radiotherapy, following specific objectives were formulated. At the beginning in order to compare the scopes of the absorbed doses at different tissue depths, an analysis of parameters describing particular beams or radiation source has been performed—the curves for the absorbed-dose depth drop-offs. Doses distribution in tissue-like phantoms stimulating homogeneous cuboidal tissue block has been determined. A quality comparison of dose distribution in 2D and 3D treatment planning system for contact brachytherapy application has been made. The dose distribution for electron beam in the system has been determined. Conformal plannings for electron beam treatment, contact brachytherapy applicator treatment and 4 photon beams treatment optimized in IMRT technology have been performed. Dose distribution has been performed for the irradiated female patient within the well chest—the target included the recurrence area in the post-operative scar. The radiation therapy with X-rays has actually been completely eliminated from skin cancer and subcutaneous tissue radiotherapy by the electrons generated in linear accelerators, contact brachytherapy HDR and by high-energy photons used in conformal techniques, ex. IMRT. It is because the residual dose beyond the target is the highest for single X-ray beam. Although in brachytherapy HDR a rapid dose drop-off is observed, 5 cm from its normalization level for the target the residual radiation remains at the level of several percent. So, both X-rays beam radiation and brachytherapy in skin cancer treatment is connected with the administration of the dose with a high gradient in the health tissues. The dose distribution for photon conformal techniques IMRT or for electron radiation looks different. There with the dose normalization at the level of 90% or 85% we deal with the dose layer, the division does not exceed 15% of heterogeneity.

Studies on Physiological Radiation Spectrum and Fruit Quality of Sweet Cherry in Different Canopies

[ Objective] The physiological radiation spectrum and fruit quality in different canopies of sweet cherry tree were studied. [ Method] Opti- cal fiber spectrum was applied to determine the physiological radiation spectrum in different canopies of sweet cherry tree. The fruit quality in differ- ent canopies was determined. [Result] The results showed that from the top part to the lower part and from the outer part to inner part of sweet cherry canopy, Me physiological radiation intensity and ratio of short wave light reduced significantly, while ratio of long wave light increased. Fruit mass, Vc, TSS and total sugar content were significantly decreasing, while organic acid content increasing, but the fruit edible percent was similar. Furthermore, the physiological radiation intensity was strong, fruit mass, TSS, Vc and total sugar content increased, but organic acid content re- duced. [ Condusion] The higher and bigger canopy of sweet cherry, the poor and lower physiological radiation intensity, photosynthesis accumula- tion and fruit quality. The study provided theoretical foundation and reference for the trim of sweet cherry.

EFFECT OF TOTAL IRRADIATION DOSE ON MOSFETs/SOI

The MOSFETs are built on SIMOX material, the chide positive charge, interface state, threshold voltage and leakage current of MOSFETs/SOI after 60Co-rirradiation are measured with I-V technique. The results indicate that the accumulation rate of chide charge density is more than that of interface state density in dose range of 0-3×104Gy (Si), and the 'on' radiation bias is worst case for NMOSFET and PMOSFET.

Numerical simulation of radio signal from extended air showers

The burst of radio emission by an extensive air shower provides a promising alternative for detecting ultra-high energy cosmic rays. We have developed an inde- pendent numerical program to simulate these radio signals. Our code is based on a microscopic treatment, with both the geosynchrotron radiation and charge included. Here we give the first presentation of our basic program and its results. When the time-domain signals for different polarizations are computed, we find that the pulses take on a bipolar pattern and the spectrum is suppressed towards the lower frequencies. We investigate how showers at different heights in the atmosphere contribute to the total signal, and examine the signal strength and distribution at sites with different elevations. We also study the signal from showers with different inclination angles and azimuth directions. In all these cases we find the charge excess effect is important.

A Comparison between Neutron Activation Analysis and X-Ray Fluorescence Methods in Analyzing the Granite Samples

This study focused on the performance of where elements analysing techniques were used to detect the elements in granite stones. These techniques are NAA （neutron activation analysis） and XRF （X-ray fluorescence）. They were applied to detect the elements in samples which had been chosen from different areas of Pulua Penang in Malaysia collected by geophysics group which helped to describe and identify the elements found in the granite stone that were used in the study procedures to control the analytical results. The integration of both methods has enabled the researcher to determine 40 elements in the samples. The numbers of elements detected by XRF analysis method are 12 elements （Ar, K, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn）; while, the elements detected by NAA method have three folds of elements with XRF analysis method were 35 elements （Na, AI, Si, K, Ca, Sc,Ti, Mn, Fe, Co, Ga, Ce, As, Br, Rb, Zr, Sb, I, Cs, Ba, La, Nd, Sm, Eu,Tb, Dy, Yb, Lu, Hf, Ta, W, Au, Pa and Np）. Seven common elements were detected in both techniques： K, Sc, Ti, V, Mn, Fe and Co. Si has a higher concentration in NAA technique which is 331.8 ppm. Sc has a lower concentration in XRF technique which is 0.25 ppm. Nd has a lower concentration in NAA technique which is 3.09 - 10-5 ppm. Finally, it is found that the NAA is better to detect the elements than XRF.

Galactic center research:manifestations of the central black hole

This review summarizes a few of the frontiers of Galactic center research that are currently the focus of considerable activity and attention. It is aimed at pro- viding a necessarily incomplete sketch of some of the timely work being done on phenomena taking place in, or originating in, the central few parsecs of the Galaxy, with particular attention to topics related to the Galactic black hole （GBH）. We have chosen to expand on the following exciting topics： 1） the characterization and the im- plications for the variability of emission from the GBH, 2） the strong evidence for a powerful X-ray flare in the Galactic center within the past few hundred years, and the likelihood that the GBH is implicated in that event, 3） the prospects for detecting the ＂shadow＂ of the GBH, 4） an overview of the current state of research on the central S-star cluster, and what has been learned from the stellar orbits within that cluster, and 5） the current hypotheses for the origin of the G2 dust cloud that is projected to make a close passage by the GBH in 2013.

Electrical and γ-ray energy spectrum response properties of PbI_2 crystal grown by physical vapor transport

Lead iodide single crystal was grown by physical vapor transport method.Two radiation detectors with different configurations were fabricated from the as-grown crystal.The electrical and y-ray response properties at room temperature of the both detectors were investigated.It is found that the dark resistivity of the detectors are respectively 3×10^（10）Ω·cm for bias electric field parallel to crystal c-axis（E//c） and 2×10~8Ω·cm for perpendicular to crystal c-axis（E⊥c）.The energy spectrum response measurement shows that both detectors were sensitive to ^（241） Am 59.5 keVγ-rays,and achieved a good energy resolution of 16.8%for the E⊥c-axis configuration detector with a full width at half maximum of 9.996 keV.