Relative Biological Effectiveness Studies Using 3 MeV Proton Beam from Folded Tandem Ion Accelerator: An Experimental and Theoretical Approach

Proton being the easiest light ion to accelerate and achieve desired beam profile, has been pursued as a popular particulate radiation for therapy applications. In the present study, Saccharomyces cerevisiae D7 strain was used to estimate the RBE values of the 3 MeV proton beam, and an attempt was made to derive mathematical formula for calculating RBE value with respect to the dose. Dosimetry studies were carried out using Fricke dosimetry and Semiconductor Surface Barrier detector to calibrate the absorbed doses of Gamma chamber-1200 and Folded Tandem Ion Accelerator respectively. Gold standard cell survival assay and gene conversion assay were used to compare gamma and proton radiation induced cell death and genetic endpoint. Multi target single hit model was used to derive mathematical formula for RBE estimation. The results show a linear survival-dose response after proton radiation and sigmoid survival-dose response after gamma radiation treatment. The calculated RBE value from the survival and gene conversion studies was 1.60 and 3.93, respectively. The derived mathematical formula is very useful in calculating RBE value, which varies from 3.61 to 1.80 with increasing dose. The estimated RBE value from the mathematical formula is comparable with the experimental values. With the help of the present mathematical formulation, RBE value at any dose can be calculated in the exponential and sigmoidal regions of the survival curve without actually extending the experiment in that dose region, which is not possible using conventional methods.

Proton Induced X-ray Emission Studies Using Folded tandem Ion Accelerator (FOTIA) at Bhabha Atomic Research Centre (BARC), Trombay, Mumbai, India

The Folded Tandem Ion Accelerator (FOTIA) at Van De Graaff was used to study PIXE (Particle-induced X-ray Emission) using protons of energy 3-5 MeV. It has been used for a variety of applications from studying intensity ratios, biological samples (blood), rare earth, materials (gold standards), geological samples (gemstones) pottery samples and forensic samples (ink). This article attempts to elucidate the preparation methods of the samples, the detectors used, the analysis and the findings therein for different applications.

CHARACTERIZATION OF A FEW GEM STONES BY X-RAY EMISSION TECHNIQUES (EDXRF AND EXTERNAL PIXE)

X-ray Emission Techniques (EDXRF) and External Proton Induced X-ray Emission Technique (PIXE) have been used to characterize 13 gem stones obtained from Gem Testing Laboratory, Jaipur, India. Radioisotope sources 109 Cd and 241 Am were used to excite the gem stones to generate K and L X-rays in the low and high Z region of the periodic table to investigate trace element inclusions besides the main matrix. A proton beam of 4 MeV energy and current of 8 nA intensity were extracted from the FOTIA (Folded Tandem Ion Accelerator) at VandeGaaff Accelerator, Trombay, Mumbai in air through a Kapton foil of 8 micrometer thick mounted on a Teflon cone. Gem stones such as Labradorite Feldspar, Moonstone Feldspar, Almandine Garnet, Tsavorite Garnet, Apatite, Natural Spinel, Natural Zircon, Spessartine Garnet, Natural Ruby (Lead filled), Natural Ruby were characterized for their elemental profile to see the differences in composition besides the main matrix differences. Elements such as Ca , Ti , V , Cr , Mn , Fe , Cu , Zn , Sr , Y and Zr were detected.

PIXE STUDIES USING THE VAN-DE-GRAAFF ACCELEARTOR AT BARC, TROMBAY – DIFFERENCES IN ELEMENTAL CONCENTARTIONS IN BLOOD SAMPLES OF CHILDREN

Metal monitoring is one of the major concern of biological and bio-medical research. The Proton Induced X-ray Emission (PIXE) which is a multi elemental and non-destructive technique for trace element analysis has been set up at the Folded Tandem Ion accelerator (FOTIA) at BARC, Trombay, Mumbai, India. A few of the bioscience applications carried out at the Van de Graaff Laboratory using PIXE will be summarized in this presentation. Tea leaves obtained from the eastern region of India were analyzed by PIXE using 2.5 MeV protons. Trace elements such K , Ca , Ti , Cr , Ni , Mn , Fe , Cu , Zn , Rb and Sr were present in varying concentration in the tea leaves. The soil analysis showed Ti , Y , Zr and Nb in addition to the elements shown in the leaves. Blood samples of children exposed to vehicular traffic exhaust were analyzed for its Pb content and it was seen that the concentrations of Pb in the blood of the children were high (6.0 μg/ml). Pb poisoning of air due to vehicular exhaust is a major concern and cause for air pollution leading to high blood lead levels in children.

PIXE STUDIES ON GOLD STANDARDS BY PROTONS OF ENERGY 3.3 MeV

Proton Induced X-ray Emission Technique (PIXE) has been used in analyzing Gold standards of 22, 20, 18, and 14 karats with a proton beam of Energy 3.3 MeV at the newly commissioned Folded Tandem Ion Accelerator (FOTIA) at B.A.R.C, Trombay. Well resolved Au and Ag X-rays were detected at a current of 3 nA . Percentage values of gold and silver were calculated and were checked with those obtained by Energy Dispersive X-ray Fluorescence (EDXRF) Method and were found to be in agreement with the certified values as well as those obtained by XRF.