Which of the following radiation is not emited by radio- active isotope?
Ans. A. X-rays.Alpha, beta and gamma rays are produced by radioactive isotopes, while x - rays are extranuclear in origin produced by bombarding fast moving electrons on the anode (target) of the x-ray tube (in X-ray machine or Linear acclerator).Ionization involves actual ejection of one or more electrons from the atom. Ionizing radiation is subclassified as electro- magnetic (photon) or particulate radiation. X-rays and gamma rays are examples of electromagnetic photon radiation; they differ only in their source. X-rays are produced mechanically, by making electrons strike a target, which causes the electrons to give up their kinetic energy as x-rays, while gamma rays are produced by nuclear disintegra- tion of radioactive isotopes.X-rays can be thought of as packets of energy, or photons. X-rays have no mass or charge, travel in straight lines, and attenuate continuously as they traverse tissue. X-rays differ from light in energy.Discussion:# Types of particulate radiation include electrons, protons, alpha particles, neutrons, negative pi-mesons, and heavy charged ions; these have discrete mass and charge (except for neutrons, which lack charge;- Alpha particles are helium nuclei, consisting of two protons and two neutrons. The mass and charge are great enough that these particles do not penetrate far through matter unless they have tremendous energy; even a piece of paper is enough to protect against most alpha particles. Because these particles are charged, they can be accelerated in electrical fields.- Electrons. or beta particles. are small and negatively charged and can be accelerated to close to the speed of light. They decelerate fairly rapidly in tissue and penetrate it to only a limited depth. Thus, electron beams are often used to treat superficial problems.- Protons are positively charged and have a mass about 2000 times that of an electron. Protons stop abruptly, depending on their energy; in the process of sudden deceleration, most of their energy is given up, which tends to cause ionization just before the proton stops. This region of enhanced ionization, sometimes called the Bragg peak, means that proton beams exert their effects in a relatively compact region. Therefore, protons may have advantages over other types of particulate radiation with respect to conforming the dose to the treat- ment volume.- Neutrons are similar in mass to protons (having an atomic mass of 1), but they are not charged and therefore cannot be accelerated in an electrical field. Neutron beams are produced by colliding charged particles into a suitable target or are emitted as a fission product of heavy radioactiveatoms. Heavycharged ions are nuclei of heavier elements that have a positive charge owing to the stripping away of some or all of the orbiting electrons.Additional Educational points:1Linear accelerator (Linac)Used to accelerate electrons, & produces X-ray beam2CyclotronProduces neutrons, photons3MicrotronIs an electron accelerator, combines principles of both linac + cyclotron4BetatronDevice for accelerating electrons used for production of electron beam for RT & an X-ray beam5SimulatorApparatus that uses a diagnostic X-ray tube but duplicates a radiation t/t. Main function is to display the t/t field to accurately deliver the dose.Some important Radioactive Sources# g - ray sources: Co-60, Cs-131, Tc-99m, Ra-226# Pure ss - particle emitters: Sr-90, Y-90, Phosphorous-32# Both ss & g rays emitter: 1-131 (mainly ss > g), Samarium-153 (), Ra, Au, etc# Neutron emitting Radioisotope: CaliforniumRADIOISOTOPESA radioactive substance is one which is unstable and spontaneously decays to form a more stable substance, giving out electromagnetic rays.RADIOACTIVE MATERIALS1. Naturally occurring radioactive materials# All naturally occurring radioactive materials have atomic number greater than 80 and are grouped in three radioactive families starting with uranium, thorium and actinum.# All elements with atomic no > 82 are radioactive.# It appears that as the no.of particles inside the nucleus increases, the forces that keep the particles together become less effective since chance of particle emission are increased.2. Radioactive 'Induced" bv neutron bombardmentAlso called n-g reaction. Here the neutron enters the nucleus and some energy is liberated in the form of gamma ray.3. Radioactive 'Induced" bv proton bombardmentAlso called p-n reaction and is caused by the proton bombardment of nucleus. The proton is positively charged. So there is increase in the electrostatic repulsion of the proton as it approaches the nucleus and the proton needs considerable energy to achieve the desired penetration. For this purpose the protons have to be accelerated in a CYCLOTRON.
X-rays
Alpha
Beta
Gamma
Fundamentals In Radiology