RADIATION SAFETY UPDATED COMPREHENSIVE
QUESTIONS AND ANSWERS GUARANTEE A+
✔✔Quality of x-ray beam - ✔✔Controlled by amount of voltage. Voltage provides
contrast to the film. Increasing voltage provides less contrast or more shades of gray.
✔✔Quantity of x-ray beam - ✔✔Controlled by amt of milliamperes. The more x-rays
(photons) in the x-ray beam the more dense (dark) the x-ray negative (radiograph)
becomes. By increasing milliamperes we increase the # of available electrons at the
cathode filament.
✔✔Inverse square law - ✔✔Radiation is inversely related to the square of the distance
from the source. If distance is doubled, intensity is reduced by 1/4, if distance is cut in
half the intensity is increased by 4
✔✔Photons are - ✔✔The measurement of electromagnetic energy
✔✔Photons - ✔✔Move at the speed of light, have no mass, and possess both electric
and magnetic fields.
✔✔Electromagnetic energy can be described by - ✔✔Velocity (speed), frequency, and
wavelength (velocity does not change)
✔✔Ionizing electromagnetic radiation is characterized by - ✔✔the energy contained in a
photon. Photons have higher frequency and shorter wavelengths than other
electromagnetic energy.
✔✔X-Ray's are produced __________the nucleus of excited atoms - ✔✔Outside
✔✔What are x-rays? - ✔✔High energy waves with very short wavelengths and travel at
the speed of light. They have no mass (weight), no charge (neutral) and they are
invisible. Travel in straight lines. Cannot be focused to a point. X-ray spreads out as it
travels toward and through a patient.
✔✔What are the 5 different ways photons interact with matter? - ✔✔Coherent
scattering, Compton scattering, photoelectric absorption, pair production,
photodisintegration
✔✔Compton effect - ✔✔Responsible for most of the scatter radiation produced during
radiologic procedures. Can occur in any direction. When incoming x-ray photons meet
up with electrons of irradiated object it knocks the electron from its orbit causing
ionization and freed electron is the Compton scattered electron. Can cause fog on
image.
, ✔✔*Photoelectric absorption - ✔✔*The most important interaction to produce useful
images. Interaction between x-ray photon and inner shell electron (K or L) upon
interaction in the orbit, the x-ray photon surrenders all of its kinetic energy to the orbital
electron and comes to and end. Electron that is hit is knocked from its orbit and called
photoelectron which may interact with other atoms until all of its kinetic energy has been
used.
✔✔Coherent scatter (Thompson scatter) - ✔✔Bad kind. No loss of energy as x-rays
scatter. Low-energy photon interacts with atom causing vibration and change in
direction. Causes fog on an image.
✔✔What is attenuation - ✔✔The reduction in the number of primary photons in the x-ray
beam through absorption and scatter. Density in body structure affects attenuation. The
more dense the more absorption. Bone is 2x as dense as soft tissue and will absorb 9x
as many photons
✔✔Z (atomic number) increases as the energy of the photon decreases - ✔✔Compact
bone has a Z 13.8
Calcium has a Z of 20
Soft tissue has a Z of 7.4
Air has a Z of 7.6
✔✔International system of units (SI) - ✔✔Coulomb
Kilogram
Gray sievert
Becquerel
✔✔Traditional units used - ✔✔Roentgen
Rad
Rem
Curie
✔✔Dosimetry - ✔✔the calculation of the absorbed dose in tissue resulting from
exposure to ionizing radiation
✔✔Quantity Si unit and traditional unit - ✔✔
✔✔Absorbed dose (AD) - ✔✔Amount of energy absorbed by the object
✔✔1 gray= - ✔✔100 rads
✔✔Physical dose - ✔✔Amount of energy deposited in a unit mass of human tissue or
medium
QUESTIONS AND ANSWERS GUARANTEE A+
✔✔Quality of x-ray beam - ✔✔Controlled by amount of voltage. Voltage provides
contrast to the film. Increasing voltage provides less contrast or more shades of gray.
✔✔Quantity of x-ray beam - ✔✔Controlled by amt of milliamperes. The more x-rays
(photons) in the x-ray beam the more dense (dark) the x-ray negative (radiograph)
becomes. By increasing milliamperes we increase the # of available electrons at the
cathode filament.
✔✔Inverse square law - ✔✔Radiation is inversely related to the square of the distance
from the source. If distance is doubled, intensity is reduced by 1/4, if distance is cut in
half the intensity is increased by 4
✔✔Photons are - ✔✔The measurement of electromagnetic energy
✔✔Photons - ✔✔Move at the speed of light, have no mass, and possess both electric
and magnetic fields.
✔✔Electromagnetic energy can be described by - ✔✔Velocity (speed), frequency, and
wavelength (velocity does not change)
✔✔Ionizing electromagnetic radiation is characterized by - ✔✔the energy contained in a
photon. Photons have higher frequency and shorter wavelengths than other
electromagnetic energy.
✔✔X-Ray's are produced __________the nucleus of excited atoms - ✔✔Outside
✔✔What are x-rays? - ✔✔High energy waves with very short wavelengths and travel at
the speed of light. They have no mass (weight), no charge (neutral) and they are
invisible. Travel in straight lines. Cannot be focused to a point. X-ray spreads out as it
travels toward and through a patient.
✔✔What are the 5 different ways photons interact with matter? - ✔✔Coherent
scattering, Compton scattering, photoelectric absorption, pair production,
photodisintegration
✔✔Compton effect - ✔✔Responsible for most of the scatter radiation produced during
radiologic procedures. Can occur in any direction. When incoming x-ray photons meet
up with electrons of irradiated object it knocks the electron from its orbit causing
ionization and freed electron is the Compton scattered electron. Can cause fog on
image.
, ✔✔*Photoelectric absorption - ✔✔*The most important interaction to produce useful
images. Interaction between x-ray photon and inner shell electron (K or L) upon
interaction in the orbit, the x-ray photon surrenders all of its kinetic energy to the orbital
electron and comes to and end. Electron that is hit is knocked from its orbit and called
photoelectron which may interact with other atoms until all of its kinetic energy has been
used.
✔✔Coherent scatter (Thompson scatter) - ✔✔Bad kind. No loss of energy as x-rays
scatter. Low-energy photon interacts with atom causing vibration and change in
direction. Causes fog on an image.
✔✔What is attenuation - ✔✔The reduction in the number of primary photons in the x-ray
beam through absorption and scatter. Density in body structure affects attenuation. The
more dense the more absorption. Bone is 2x as dense as soft tissue and will absorb 9x
as many photons
✔✔Z (atomic number) increases as the energy of the photon decreases - ✔✔Compact
bone has a Z 13.8
Calcium has a Z of 20
Soft tissue has a Z of 7.4
Air has a Z of 7.6
✔✔International system of units (SI) - ✔✔Coulomb
Kilogram
Gray sievert
Becquerel
✔✔Traditional units used - ✔✔Roentgen
Rad
Rem
Curie
✔✔Dosimetry - ✔✔the calculation of the absorbed dose in tissue resulting from
exposure to ionizing radiation
✔✔Quantity Si unit and traditional unit - ✔✔
✔✔Absorbed dose (AD) - ✔✔Amount of energy absorbed by the object
✔✔1 gray= - ✔✔100 rads
✔✔Physical dose - ✔✔Amount of energy deposited in a unit mass of human tissue or
medium
