Ch. 1 Concepts of radiologic science Flashcards
All things can be classified as…
matter or energy
Define matter
anything that occupies space and has mass
All physical objects are composed of…
matter
All matter is composed of foundational building blocks called
atoms
Define mass.
A primary, distinguishing characteristic of matter that is the quantity of matter contained in any physical object
Define weight
the force exerted on a body under the influence of gravity
Mass is measured in..
kg
What are the fundamental, complex building blocks of matter?
atoms and molecules
1 kg is equal to…
1000 grams
What is the unit of energy in radiology?
eV (electron volt)
Define energy
the ability to do work
Define chemical energy
energy released by a chemical reaction
Name an example of chemical energy
biochemistry..the type of energy is provided to our bodies through chemical reactions involving the foods we eat.
Define electrical energy
the work that can be done when an electron moves through an electric potential difference (voltage)
What is electric potential difference?
voltage
Define thermal energy
the energy of motion at the molecular level. It is the kinetic energy of molecules and is closely related to temperature.
What is nuclear energy?
the energy that is contained within the nucleus of an atom
What is an example of the uncontrolled release of nuclear energy?
the atomic bomb
Define electromagnetic energy
Oscillating electric and magnetic fields that travel in a vacuum with the velocity of light. Includes x-rays, gamma rays, and some nonionizing radiation (such as ultraviolet, visible, infrared, and radio waves.)
What is the least familiar form of energy?
electromagnetic energy
What kind of energy is used in x-rays?
electromagnetic energy
What are types of electromagnetic energy?
x-rays, radio waves, microwaves, ultraviolet light, infrared light, and visible light
Can energy be transformed from one type to another?
yes
Explain how energy can be transformed in the production of an x-ray.
electrical energy produces electromagnetic energy in the machine which is converted to chemical energy in the film or electrical signal in a digital image receptor.
What is the mass-energy equivalence equation?
E=mc2
Energy emitted and transferred through space is called…
radiation
Visible light, a form of electromagnetic energy, is radiated by the sun and is called…
electromagnetic radiation
Matter that intercepts radiation and absorbs part or all of it is called….
exposed or irradiated
When a patient is exposed to radiation, they are said to be…
irradiated
Define ionizing radiation
any type of radiation that is capable of removing an orbital electron from the atom with which it interacts.
Interaction between radiation and matter is called…
ionization
Ionization 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
What is an ion pair?
the orbital electron and the atom from which it was separated. The electron is a negative ion, and the remaining atom is a positive ion.
What is the transfer of energy?
radiation
What is the removal of an electron from an atom called?
ionization
What are the only forms of electromagnetic radiation with sufficient energy to ionize?
x-rays, gamma rays, and ultraviolet light
Other than electromagnetic radiation, what can also ionize?
Some fast moving particles (particles with kinetic energy)
What are examples of particle type ionizing radiation?
alpha and beta particles
What are the 2 categories of ionizing radiation?
natural environmental radiation and man made radiation
What is the annual dose of natural environmental radiation?
3 mSv
What is the annual dose of man made radiation?
3.2 mSv
What is the unit of effective dose?
mSv
What does the unit dose mSv express?
it is used to express radiation exposure of populations and radiation risk in those populations.
What are the 4 components of natural environmental radiation?
cosmic rays, terrestrial radiation, internally deposited radionuclides, and radon
What are cosmic rays?
particulate and electromagnetic radiation emitted by the sun and stars
On Earth, how do cosmic rays intensify?
with altitude and latitude
Where does terrestrial radiation result?
deposits of uranium, thorium, and other radionuclides in the Earth.
What does the intensity of terrestrial radiation rely on?
the geology of the local area
What is the largest source of natural environmental radiation?
radon
What is radon?
a radioactive gas that is produced by the natural radioactive decay of uranium that is present in trace quantities in the Earth.
All Earth based materials contain…
Radon
What does radon emit?
alpha particles
Alpha particles are penetrating..T or F?
F, they are not penetrating so they only contribute dose to the lung
Natural environment radiation results in how much microgray/hr?
0.02 to 0.1 microgray/hr at waist level which equals 0.2 milligray/yr at the gulf elevations and 1 mGy/yr in the Rocky Mountains.
What makes up the largest man made source of ionizing radiation?
diagnostic x-rays at 3.2 mSv/yr
Why was there such an increase in man made ionizing radiation between the years 1990-2006?
It was caused because of CT and high level fluoro
What is the currently accepted approximate annual dose that results from medical applications of ionizing radiation?
3.2 mSv
What % of our annual average radiation dose is attributable to medical imaging?
51%
cathode rays are also called…
electrons
When did Roentgen discover x-rays?
November 8, 1895
What was the plate coated with when Roentgen discovered the rays?
barium platinocyanide
What type of material is barium platinocyanide?
fluorescent
Who received the first Nobel Prize in physics?
Roentgen in 1901
In 1896 Roentgen published the 1st medical x-ray. What was it?
His wife’s hand
What are the 3 types of x-ray examination?
radiography, fluoroscopy, and CT
To provide an x-ray beam that is satisfactory for imaging, you must supply the x-ray tube with a high what?
voltage and electric current
How are x-ray voltages measured?
in kVp
How are x-ray currents measured?
mA
Who invented the fluoroscope?
Thomas Edison in 1898
Radiology emerged as a medical specialty because of…
the Snook transformer and the Coolidge x-ray tube
What were the early reports of radiation injury?
skin damage, hair loss, and anemia
What does ALARA stand for?
As Low As Reasonably Achievable
What are metal filters usually made of?
aluminum or copper
The use of intensifying screens reduce patient exposure by how much vs. non use?
95%
What are the 3 base quantities of measure in physics?
Mass, length, and time
Secondary quantities of measure are also called
derived quantities
Why is the term derived quantities used?
Because they are derived from the 3 base quantities
In radiologic science, special quantities are considered…
exposure, dose, effective dose and radioactivity
The second (s) is based on…
the vibration of atoms of cesium
When working on problems or reporting answers, what should always be used?
the same system of units
Volume=?
V=lwh
The dimensions of a box are 30cm x 86cm x 4.2m. Find the volume
V = (0.3m)(0.86m)(4.2m) = 1.1m^3
Find the mass density of a solid box 10cm on each side with a mass of 0.4kg.
D = m/v change 10cm to 0.1m = 0.4 kg/(0.1m x 0.1m x 0.1m) = 0.4 kg/0.001m^3 = 400kg/m^3
A 9” thick patient has a coin placed on the skin. The SID is 100cm. What will be the magnification of the coin?
M = SID/SOD M = 100cm/100cm-9" M = 100cm/100cm - (9" x 2.54 cm/in) M = 100cm/100cm - (23cm) M = 100cm/77cm M = 1.3 The image of the coin will be 1.3 times the size of the coin
Define velocity
the measure of how fast something is moving or , the rate of change of its position with time
Velocity = ? (formula)
V = d/t
What is the velocity of a ball that travels 60m in 4s?
v = 60m/4s v = 15m/s
Light is capable of traveling 669 million miles in 1 hour. What is its velocity in SI units?
v = 6.69x10^8 mi/hr x 1609 m/mi/3600 s/hr v = 2.99 x 10^8 m/s
The velocity of light is constant and is symbolized by…
c
Average velocity = ?
Average velocity = initial velocity + final velocity/2
Define acceleration
The rate of change of velocity with time
acceleration = ? (formula)
a = final velocity - initial velocity/ time
What is Newton’s first law?
Inertia-a body will remain at rest or will continue to move with constant velocity in a straight line unless acted on by an external force
inertia is..
the property of matter that acts to resist a change in its state of motion
What is Newton’s second law?
Force-the force (F) that acts on an object is equal to the mass (m) of the object multiplied by the acceleration (a) produced.
Force = ? (formula)
F = ma
Find the force on a 55kg mass accelerated at 14 m/s^2.
(55kg)(14 m/s^2)
F = 770N
For a 3600 lb (1636kg) Mustang to accelerate at 15 m/s^2, what force is required?
F = ma F = (1636 kg)(15 m/s^2) F = 24,540 N
What is Newton’s 3rd law?
Action/reaction-for every action, there is an equal and opposite reaction
Weight is the product of…
mass and the acceleration of gravity on Earty
Weight = ? (formula)
mg
What is the unit for weight
N or lb
A student has a mass of 75 kg. What is her weight on the Earth? On the moon?
Earth = 9.8 m/s^2 Wt = mg Wt = 75kg (9.8 m/s^2) Wt = 735 N
Moon = 1.6 m/s^2 Wt = mg Wt = 75 kg (1.6 m/s^2) Wt = 120 N
Define momentum
The product of the mass of an object and its velocity
Formula for momentum?
p=mv
Work= ? (formula)
W = fd
What is the unit for work?
Joule (J)
Find the work done in lifting an infant patient weighing 90 N (20 lb) to a height of 1.5m.
W = fd W = (90 N)(1.5m) W = 135 J
Define power
The rate of doing work
Power = (formula)
P = work/t = Fd/t
What is the unit for power?
J/s which is also a watt (W)
A radiographer lifts a 0.8kg cassette from the floor to the top of a 1.5m table with an acceleration of 3 m/s^2. What is the power exerted if it takes 1.0 s?
Multistep problem:
P=work/t
W=Fd
F=ma
F=ma
=(0.8 kg)(3 m/s^2)
= 2.4 N
W=Fd
=(2.4 N)(1.5m)
= 3.6 J
P=work/t
= 3.6 J/1.0s
= 3.6 W
What is the formula for kinetic energy?
KE=1/2 mv^2
What is the formula for potential energy?
PE=mgh
Define heat
the kinetic energy of the random motion of molecules
What is the unit of heat?
calorie
Define calorie
the heat necessary to raise the temperature of 1g of water by 1 degree C
How is heat transferred?
By conduction, convection, and radiation
Define conduction
the transfer of heat through a material or by touching
Define convection
the mechanical transfer of hot molecules in a gas or liquid from one place to another
Define thermal radiation
the transfer of heat by the emission of infrared radiation
An x-ray tube cools primarily by…
radiation
Convert 77 degree F to Celsius
C = 5/9 (F-32)
= 5/9 (77-32)
=5/9(45)
= 25 degrees Celsius
Method to go from F to C and vise versa.
From F to C - subtract 30 and divide by 2
From C to F - double and then add 30
What is Air Kerma?
Kinetic energy transferred from photons to electrons during ionization and excitation
What is the unit of measure for Air Kerma?
Gy
1 J/kg is how many Gy?
1
What is absorbed dose?
radiation energy absorbed per unit mass and has units of J/kg or Gy
For a given air kerma, the absorbed dose depends on…
the type of tissue being irradiated.
Occupational radiation monitoring devices are analyzed in terms of….
Sv
Sv is used to express..
the quantity of radiation received by radiation workers and populations
