1 X-Ray Astronomy to Resonant Theranostics for Cancer Treatment Sultana N. Nahar Abstract location of the object. Figure 1 is an example of an image of galaxy Centauras A with a black Atomic spectroscopy is fundamental to hole in the center. The falling particles spiral study of astronomical objects for their around the black hole, move faster close to it formation, evolution, composition, physical and release energy in the form of radiation, conditions etc. Information are extracted from mainly X-rays. The highly energetic super hot the spectral analysis of the electromagnetic atoms near the black hole are in a plasma state radiation emitted by these objects. This article and emit bright Kα (1s-2p transitions) X-rays. will focus on the study of X-ray radiation which One main evidence of presence of a black hole is used as a powerful diagnostic for is large amount of high energy X- rays, astrophysical plasmas, particularly those especially hard X-rays (wavelength range less surrounding black holes. There are space than 100 ˚) emission. A black often gives out observatories, such as Chandra, XMM-Newton, jets of particles, formed by the conservation of dedicated in measuring the X-ray emissions in energy and angular momentum of the falling astronomical objects. The knowledge of X- ray particles, on the opposite sides. astronomy is very similar to that used in cancer treatment in medical facilities. Using this connection, we have formulated a new method, Resonant Nano-Plasma Theranostics or RNPT, which gives indication for one most efficient way for destruction of malignant cells. Introduction The brightness and width of spectral lines from the plasmas of an astronomical object or environment carry important information on elemental composition, physical and chemical Figure 1: Image of galaxy Centaurus A showing the processes, abundances of various ionic states, presence of a black hole and its jets at the center plasma temperature, density etc. The detection (Observed by X-ray space observatory Chandra). In itself of various broad and narrow band the image: red indicates low-energy X-rays. Toward radiation provide considerable knowledge of the the center, the green represents intermediate- energy object. X-rays, and blue that of the highest energy X-rays. The dark green and blue bands are dust lanes that Astronomical objects can be studied in a absorb X-rays. A jet of a billion solar-masses few ways, such as, imaging, photometry, and extending to 13,000 light years is seen being blasted spectroscopy. Images of an astronomical object out from the black hole. can be formed either by broad-band spectrometer or by superposition of low Photometry gives some more resolution pictures of various emissions. It gives information on the elemental composition that general information on the high-low can be used to categorize the astronomical temperature regions, shapes and sizes, and object, such as, a carbon star which produces dominant carbon lines. Figure 2 shows the 2 photometric image of the supernova remnant element and width of the spectral lines indicate Cassiopia A created from observations by three other effects such plasma broadening due to space observatories, Spitzer, Hubble, and collisions, Stark effects etc. Figure 3 shows the Chandra. well-known Kα (1s-2p) transition array lines of iron near a black hole in Seyfert I galaxy MCG- Various colors indicate production of 6-30-15 6 observed by Advanced Satellite for various types emissions, infrared, visible, and Cosmology and Astrophysics (ASCA) and X-rays from the remnant. They provide Chandra. The maximum energy for a 1s-2p information on activities in various regions of transition in iron is 5.4 keV. However, the large the remnant. Supernova explosions introduce extension of the lines toward low energy means elements heavier than iron or nickel in space. In that the escaped photons have lost energies in a star, nuclear fusions create elements from the black hole. X-rays are powerful diagnostics helium to iron and nickel. In the universe the and there are space observatories dedicated in most abundant element, up to 90% is hydrogen. measuring X- ray emissions. Helium is the next with 7%. The rest of the elements which combined together is called the Radioative Atomic Processes metals, consist mainly of Li, Be, B, C, N, O, F, Ne, Na, Mg, Al, Si, S, Ar, Ca, Ti, Cr, Fe, is about 3%. The existence of heavier elements in our solar system indicates that the system was created from the debris of supernova explosions. Figure 3: The Kα (1s-2p) transition array lines of iron around 6.4 keV observed by ASCA and Chandra. The asymmetric stretching toward lower energy to about 5 keV indicates presence of a black hole nearby. The Kα photons lose energy due to gravitational potential of the black hole. Figure 2: Photometric image of supernova remnant Cassiopia A observed by three space observatories, Several atomic parameters relevant to Spitzer shows infrared (red) emission, Hubble shows the atomic processes emitting or absorbing the visible (yellow), and Chandra shows X-ray (green photons are needed to study the astronomical and blue) emissions of the remnants. While the star objects. Interaction between an atomic species elements are from H though Fe, some Ni, the heavy X+z of charge z and a X-ray photon or any elements, beyond Iron, are created through nuclear other photon usually lead to two processes, fusion during supernova explosions and are photo-excitation (inverse is de-excitation) and scattered into interstellar medium. photoionization (inverse is electron-ion recombination). In photoexcitation an electron Spectroscopy of an astronomical object absorbs the photon and jumps to a higher gives the most detailed information on physical excited level, conditions of temperature, density, abundances, etc. and the chemical composition. The brightness of the line indicates abundance of the 3 but remains bound to the ion. The asterisk (*) denotes an excited state. Its strength is (2) determined by the oscillator strength (f). The atomic parameter for de-excitation is the radiative decay rate or Einstein‟s A- coefficient. and relativistic one-body terms are, In photoionization/ photo-dissociation/ the mass correction photo-electric effect an electron absorbs a photon and exits to continuum or a free state: the Darwin term and the spin- orbit interaction This direct ionization gives the background feature of the process. Photoionization often occurs via an intermediate The rest of the terms are weak interaction two- state, the doubly excited autoionizing state, as body terms. shown below. The wave functions and energies of the atomic system are obtained by solving HBPΨ = EΨ. The solutions are bound states with E < 0 and continuum states with E >0. They are used An electron collides with the ion and goes to the to calculate the transition matrix elements with doubly excited autoionizing state. The state photon interaction, < Ψf ||D||Ψi > where the leads either to autoionization (AI) when the dipole operator D = ∑i ri and the sum is over all electron goes free or dielectronic recombination electrons, and the corresponding line stregnth (DR) when a photon is emitted. The inverse of S.. The oscillator strength (fij), radiative decay DR is photoionization. The photoionization rate (Aji), and photoionization cross section (σPI) are then obtained from the line strength as cross section σPI give the measure of ionization probability. (3) Theoretical Treatment (4) The atomic parameters (f, A, σPI) can be obtained from atomic structure calculations or the R-matrix method. In relativistic Breit-Pauli approximation the Hamiltonian is written as The useful quantity mass attenuation (e.g. [1]) coefficient for a photon absorption by an atomic species with atomic weight WA is same as σPI except by a constant factor, (5) (1) where u is 1 amu=1.66054e-24 g. where HNR is the nonrelativistic Hamiltonian 4 Resonant Nano-Plasma Theranostics for addition to more effective treatment, the Cancer Treatment experiment showed that with gold nanoparticles less intense radiation was needed for the The physics of X-ray spectroscopy for a malignant cell destruction. black hole is very similar to that of X-ray sources in medical facilities, especially for cancer treatment. The main difference is in the atomic species. Medical facilities typically use heavier elements because of their characteristic absorption or emission of high energy X-rays. The absorption or emission occurs largely through the inner shell transitions. These transitions can be used as the source of radiation or electrons productions in biomedical applications. Using these facts we have Figure 4: Cancer treatment with gold nanoparticles developed a new method called Resonant Nano- and X-rays [5]. Plasma Theranostics [2, 3, 4] (RNPT) or in short Top left: radiograph of mouse hind leg before and Resonant Theranostics. Theranostics stands for after injection of gold nanoparticles (1.35g Au/kg) in the two words, therapy and diagnostics the tumor. (imaging). Through RNPT we show how Top right: tumor growth reduction in 30 days with monochromatic X-rays, targeted at resonant only gold, only radiation, and with gold and energies, can be used for most efficient radiation (30 Gy). treatment of cancer with elimination or grossly Bottom right: Mice survival treating with only gold, only radiation, radiation and two concentrations of reducing the harmful side effects due to gold. overexposure in irradiation. The objective has to deal with several factors which are described below. Studies are being carried out with many different nanoparticles as gold is expensive. Cancer Treatment with Nanoparticles There are a few criteria to meet by the nanoparticles. Toxicity is one most important Experiments on mice have shown that a issue to resolve since most of the nanoparticles cancerous tumor can be treated more effectively become toxic in vivo.
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