Cluster 1 Radphysics Flashcards
anything that occupies space. It is the material substance with mass of which physical objects are composed. The fundamental, complex building blocks of __ are atoms and molecules.
Matter
the scientific unit of mass, is unrelated to gravitational effects. The prefix kilo stands for 1000; a __ (kg) is equal to 1000 grams (g).
Kilogram
__ is measured in kilograms (kg), This occurs because of the mutual attraction, called gravity, between the Earth’s __ and Although __, the quantity of matter, remains unchanged regardless of its state, it can be transformed from one size, shape, and form to another.
Mass
is the ability to do work by virtue of position. A guillotine blade held aloft by a rope and pulley is an example of an object that possesses __. If the rope is cut, the blade will descend and do its ghastly task.
Potential energy
the energy of motion. It is possessed by all matter in motion: a moving automobile, a turning windmill wheel, a falling guillotine blade. These systems can all do work because of their motion.
Kinetic energy
is the energy released by a chemical reaction. An important example of this type of energy is that which is provided to our bodies through chemical reactions involving the foods we eat. At the molecular level, this area of science is called biochemistry.
Chemical energy
represents the work that can be done when an electron moves through an electric potential difference (voltage). The most familiar form of __ is normal household electricity, which involves the movement of electrons through a copper wire by an electric potential difference of 110 volts (V). All electric apparatus, such as motors, heaters, and blowers, function through the use of __.
Electrical energy
the energy of motion at the molecular level. It is the kinetic energy of molecules and is closely related to temperature. The faster the molecules of a substance are vibrating, the more __ the substance has and the higher is its temperature.
Thermal energy (heat)
the energy that is contained within the nucleus of an atom. We control the release and use of this type of energy in electric nuclear power plants.
Nuclear energy
is perhaps the least familiar form of energy. It is the most important for our purposes, however, because it is the type of energy that is used in x-ray imaging. In addition to x-rays, __ includes radio waves; microwaves; and ultraviolet, infrared, and visible light.
Electromagnetic energy
Energy emitted and transferred through space is called __.
radiation
is any type of radiation that is capable of removing an orbital electron from the atom with which it interacts. __ occurs when an x-ray passes close to an orbital electron of an atom and transfers sufficient energy to the electron to remove it from the atom.
Ionizing radiation
The orbital electron and the atom from which it was separated are called an __.
ion pair
These sources of ionizing radiation can be divided into two main categories
natural environmental radiation and man-made radiation.
results in an annual dose of approximately 3 millisieverts (mSv). onsists of four components: cosmic rays, terrestrial radiation, internally deposited radionuclides, and radon.
Natural enviromental radiation
__are particulate and electromagnetic radiation emitted by the sun and stars. On Earth, the intensity of __ radiation increases with altitude and latitude.
__ results from deposits of uranium, thorium, and other radionuclides in the Earth.
Cosmic rays
Terrestrial radiation
is a radioactive gas that is produced by the natural radioactive decay of uranium, which is present in trace quantities in the Earth. All Earth-based materials, such as concrete, bricks, and gypsum wall- board, contain __. __ emits alpha particles, which are not penetrating, and therefore contributes a radiation dose only to the lung.
Radon
__ results in 3.2 mSv annually. Diagnostic x-rays constitute the largest man-made source of ionizing radiation (3.2 mSv/yr). This estimate was made in 2006 by the National Council on Radiation Protection and Measurements (NCRP). Other sources of __ include nuclear power generation, research applications, industrial sources, and consumer items. Nuclear power stations and other industrial applications contribute very little to our radiation dose.
Man-made radiation
was an Englishman from a rather humble background who was a self-taught genius.
The crookes tube that bears his name was the forerunner of modern fluorescent lamps and x-ray tubes
William crookes
Discovered xrays using crookes tube with black photographic paper so he could better visualize the effects of the cathode rays in the tube. A plate coated with barium platinocyanide, a fluorescent material, happened to be lying on a bench top several meters from the Crookes tube in Nov 8, 1895
Wilhem roentgen
Demostrate the use of intensifying screen (IS) im 1896
Michael pupin
Found that by exposing 2 glass xray plates w/ emulsion surface together exposure time was halved
Charles l leonard
Discovered fluoroscopy using barium platinocyanide as the primary material and stopped his research in this area due __ suffered severe radiation burns that leads to his death
Thomas edison, clarence dally
Two devices designed to reduce the exposure of patients to x-rays and thereby minimize the possibility of x-ray burn were introduced before the turn of the 20th century by?
William rollins
__, and inserting a __ improved the diagnostic quality of radiographs. This first application of __ and __ was followed very slowly by general adoption of these techniques. It was later recognized that these devices reduce the hazard associated with x-rays.
Diaphragm, leather or aluminum filter, collimation and filtration
In 1907, __ introduced a substitute high-voltage power supply, an interrupterless transformer, for the static machines and induction coils then in use. Although the __ transformer was far superior to these other devices, its capability greatly exceeded the capability of the Crookes tube. It was not until the introduction of the Coolidge tube that the __ transformer was widely adopted
H.C. Snook
__ unveiled his hot-cathode x-ray tube to the medical community in 1913. It was recognized as far superior to the Crookes tube. It was a vacuum tube that allowed x-ray intensity and energy to be selected separately and with great accuracy. This had not been possible with gas-filled tubes, which made standards for techniques difficult to obtain. X-ray tubes in use today are refinements of the __ tube.
William D. Coolidge
1913, stationary grid (glitterblende in german) 2 months after applied for a patent for moving grid
Gustav bucky
probably unaware of Bucky’s patent because of World War I, also invented a moving grid. To his credit, Potter recognized Bucky’s work, and the Potter-Bucky grid was introduced in 1921
Hollis potter
Metal filters, usually aluminum or copper, are inserted into the x-ray tube housing so that low-energy x-rays are absorbed before they reach the patient. These x-rays have little diagnostic value
Filtration
__ restricts the useful x-ray beam to that part of the body to be imaged and thereby spares adjacent tissue from unnecessary radiation exposure.
Collimation
Today, most x-ray films are exposed in a cassette, with radiographic __ on both sides of the film. Examinations conducted with radiographic __ reduce exposure of the patient to x-rays by more than 95% compared with examinations conducted without radiographic __.
Intensifying Screens
Lead-impregnated material is used to make aprons and gloves worn by radiologists and radiologic technologists during fluoroscopy and some radiographic procedures.
Protective apparel
The same lead-impregnated material used in aprons and gloves is used to fabricate gonadal shields.
Gonadal shielding
Often, the barrier is lead lined and is equipped with a leaded-glass window. Under normal circumstances, personnel remain behind the barrier during x-ray examination.
Protective barrier
Distance between the 2 lines engraved on a platinum–iridium bar kept at the International Bureau of Weights and Measures in Paris, France.
Length
The kilogram was originally defined to be the mass of 1000 cm3 of water at 4° Celsius (°C). In the same vault in Paris where the standard meter was kept, a platinum– iridium cylinder represents the standard unit of mass— the kilogram (kg), which has the same mass as 1000 cm3 of water.
Mass
The standard unit of __ is the second (s). Originally, the second was defined in terms of the rotation of the Earth on its axis the mean solar day. In 1956, it was redefined as a certain fraction of the tropical year 1900. In 1964, the need for a better standard of __ led to another redefinition.
Time
__, sometimes called speed, is a measure of how fast something is moving or, more precisely, the rate of change of its position with time.
Velocity
The rate of change of velocity with time is __ . It is how “quickly or slowly” the velocity is changing. Because __ is velocity divided by time, the unit is meters per second squared (m/s2).
acceleration
states that if no force acts on an object, there will be no acceleration. The property of matter that acts to resist a change in its state of motion is called inertia. Also known as the law of interia
Newtons 1st law
law states that the force applied to move an object is equal to the mass of the object multiplied by the acceleration. __ is a definition of the concept of force. Force can be thought of as a push or pull on an object
Newton’s second law
states that for every action, there is an equal and opposite reaction. “Action” was Newton’s word for “force.” According to this law, if you push on a heavy block, the block will push back on you with the same force that you apply.
Newtons 3rd law
is a force on a body caused by the pull of gravity on it. Experiments have shown that objects that fall to Earth accelerate at a constant rate.
Weight
The product of the mass of an object and its velocity is called __, represented by p. The greater the velocity of an object, the more __ the object possesses.
Momentum
as used in physics, has specific meaning. The __ done on an object is the force applied times the distance over which it is applied.
Work
__ may be transformed from one form to another, but it cannot be created or destroyed; the total amount of __ is constant.
energy
is the rate of doing work. The same amount of work is required to lift a cassette to a given height, whether it takes 1 second or 1 minute to do so.
Power
Two forms of mechanical energy often used in radiologic science is?
Kinetic and potential energy
t is a form of energy that is very important to radiologic technologists. Excessive __, a deadly enemy of an x-ray tube, can cause permanent damage.
Heat
3 Ways to transfers heat
Conduction, convection, thermal radiation
is the transfer of heat through a material or by touching. Molecular motion from a high- temperature object that touches a lower-temperature object equalizes the temperature of both.
Conduction
is the mechanical transfer of “hot” molecules in a gas or liquid from one place to another. A steam radiator or forced-air furnace warms a room by
Convection
is the transfer of heat by the emission of infrared radiation. The reddish glow emitted by hot objects is evidence of heat transfer by radiation. An x-ray tube cools primarily by radiation.
Thermal radiation
normally is measured with a thermometer. A thermometer is usually calibrated at two reference point the freezing and boiling points of water. The three scales that have been developed to measure __ are Celsius (°C), Fahrenheit (°F), and Kelvin
Temperature
is the kinetic energy transferred from photons to electrons during ionization and excitation. Measured in j/kg
Air kerma
is the radiation energy absorbed per unit mass and has units of J/kg or Gyt. The units Gya and Gyt refer to radiation dose in air and tissue, respectively.
Absorbed dose (Gy)
which is used to express the quantity of radiation received by radiation workers and populations.
Sievert (Sv)
is the unit of quantity of radioactive material, not the radiation emitted by that material.
Becquerel (Bq).
John Dalton, an English school teacher, published a book summarizing his experiments, which showed that the elements could be classified according to integral values of atomic mass. According to Dalton, an element was composed of identical atoms that reacted the same way chemically. For example, all oxygen atoms were alike. They looked alike, they were constructed alike, and they reacted alike. They were, however, very different from atoms of any other element. The physical combination of one type of atom with another was visualized as being an eye- and-hook affair
Dalton atom
Some 50 years after Dalton’s work, a Russian scholar, __, showed that if the elements were arranged in order of increasing atomic mass, a periodic repetition of similar chemical properties occurred. At that time, about 65 elements had been identified. __ work resulted in the first periodic table of the elements.
Dmitri Mendeleev
After the publication of Mendeleev’s periodic table, additional elements were separated and identified, and the periodic table slowly became filled. Knowledge of the structure of atoms, however, remained scanty. Before the turn of the 20th century, atoms were considered indivisible. The only difference between the atoms of one element and the atoms of another was their mass. Through the efforts of many scientists, it slowly became apparent that there was an electrical nature to the structure of an atom.
Thomson atom
In the late 1890s, while investigating the physical properties of cathode rays (electrons), __ concluded that electrons were an integral part of all atoms. He described the atom as looking something like a plum pudding, in which the plums represented negative electric charges (electrons) and the pudding was a shapeless mass of uniform positive electrification. The number of electrons was thought to equal the quantity of positive electrification because the atom was known to be electrically neutral.
J.J. Thomson
Through a series of ingenious experiments, __ in 1911 disproved Thomson’s model of the atom. __ introduced the nuclear model, which described the atom as containing a small, dense, positively charged center surrounded by a negative cloud of electrons. He called the center of the atom the nucleus.
Ernest Rutherford
In 1913, __ improved Rutherford’s description of the atom. __ model was a miniature solar system in which the electrons revolved about the nucleus in prescribed orbits or energy levels. For our purposes, the __ atom represents the best way to picture the atom, although the details of atomic structure are more accurately described by a newer model, called quantum chromodynamics (QCD). Simply put, the __ atom contains a small, dense, positively charged nucleus surrounded by negatively charged electrons that revolve in fixed, well-defined orbits about the nucleus. In the normal atom, the number of electrons is equal to the number of positive charges in the nucleus
Niels Bohr
3 fundamental particles
Electron proton neutron
Because an atomic particle is extremely small, its mass is expressed in __ (amu) for convenience.
atomic mass units
When precision is not necessary, a system of whole numbers called __ is used. The __ of an electron is zero.
atomic mass numbers
The nucleus contains particles called __, of which there are two types: protons and neutrons. Both have nearly 2000 times the mass of an electron.
Nucleons
Atoms that have the same number of protons but differ in the number of neutrons are __; they behave in the same way during chemical reactions.
isotoPes
Electrons can exist only in certain __, which represent different electron binding energies or energy levels. For identification purposes, electron orbital shells are given the codes K, L, M, N, and so forth, to represent the relative binding energies of electrons from closest to the nucleus to farthest from the nucleus. The closer an electron is to the nucleus, the greater is its binding energy.
shells
Made of atoms
Matter
Central core contains nearly all the mass nucleons (proton + neutron)
Nucleus
Contains electron a negatively charged particle
Orbits or shell
electron-
neutron-
Lightest
Heaviest
Smallest chemical unit of an element or compound
Molecule
Any atomic specie
Nuclide
Outermost electron, unstable, unpair
Valence e-
A-
Z-
atomic mass
atomic mass number
Determine max number of electrons in each shell
Pauli exclusion formula
Energy possesed by an electron in the shell, energy required to cause ionization, energy required
Electron binding energy
Atomic nuclei that have the same atomic mass number but different atomic numbers are?
isobArs
Atoms that have the same number of neutrons but different numbers of protons are?
IsotoNes
__ have the same atomic number and the same atomic mass number.
IsomErs
is the emission of particles and energy in order to become stable.
Radioactivity
Many factors affect nuclear stability. Perhaps the most important is the number of neutrons. When a nucleus contains too few or too many neutrons, the atom can disintegrate radioactively, bringing the number of neutrons and protons into a stable and proper ratio. In addition to stable isotopes, many elements have radioactive isotopes or?
radioisotopes
Some atoms exist in an abnormally excited state characterized by an unstable nucleus. To reach stability, the nucleus spontaneously emits particles and energy and transforms itself into another atom.
Radioactive disintegration or radioactive decay
Radioactive matter is not here one day and gone the next. Rather, radioisotopes disintegrate into stable iso- topes of different elements at a decreasing rate so that the quantity of radioactive material never quite reaches zero.
Radioactive Half-life
