Chapter 3 Interaction With Matter Flashcards
The highest energy level of photons in the x-ray beam, equal to the highest voltage established across the X-ray tube?
Peak kilovoltage (kVp)
The produce of electron tube current and the amount of time in seconds that the X-ray tube is activated?
Milliampere-second (mAs)
Controls the quality, or penetrating power, of the photons in the X-ray beam and to some degree also affects the quantity, or numbers of photons in the beam?
KVp
Is the X-ray tube current and time (in seconds) during which the X-ray tube is activated and is the main determinant of how much radiation is directed toward a patient during a pre selected X-ray exposure?
MAs
Xrays are carriers of?
Human made electromagnetic energy
If X-rays enter a material such as biologic tissue they may?
1) interact with the atoms of biological material in the patient and be absorbed
2) interact with the atoms in the biologic material and be scattered, causing some indirect transmission
4) pass through without interaction
Happens when electromagnetic energy is transferred from the X-rays to the atoms of the patients biologic tissue?
Absorption
Amount of energy absorbed per unit mass is referred to as?
Absorbed dose (D)
Who also benefits when the patients dose is minimal because less radiation is scattered from the patient?
The radiographer
The anode is made of tungsten or an alloy of tungsten and rhenium, these materials have?
High melting points
High atomic numbers (tung 74 Rhen 75)
Permits passage of all but lowest energy components of the X-ray spectrum? Therefor acts as a filter by removing diagnostically useless, very low energy X-rays.
The glass window.
A certain thickness of what is placed within the collimator assembly to intercept the emerging X-rays before they reach the patient
Aluminum
Combination of the X-ray tube glass wall and the added aluminum placed within the collimator is called
Permanent inherent filtration of the X-ray unit.
The filtered X-ray photon beam is collectively referred to as?
Primary radiation
Photons that interact with atoms of the patient but only surrender part of their energy and will continue to exist but will emerge from the interaction at a different angle these photons are said to be?
Scattered
X-rays sometimes interact with atoms of a patient such that they give up all of their energy and cease to exist, these photons are said to be?
Absorbed
Photons that strike the image receptor?
Transmitted photons
Are photons that have undergone either absorption or scatter and do not strike the image receptor are called?
Attenuated photons
If a person were counting photons that were emitted from the X-ray tube, the total number of photons _______ would equal the total number of photons ______ plus the total number that _____ away from the IR
- attenuated
- absorbed
-scattered
If photons pass through the patient without interacting with atoms of the patient is referred to as?
Direct transmission photons
If photons interact but still happen to strike the IR they are termed?
Indirect transmission photons
What type of transmission is always the result of scatter?
Indirect transmission
Before the four photons produced by the X-ray source enter the human tissue are referred to as?
Primary photons
If only two photons emerge from the tissue and strike the X-ray detector below it they are referred to as?
Exit, or image formation photons
The two photons that miss the detector are classified as?
Attenuated
Refers to both absorption and scatter process that prevent photons from reaching a predefined location
Attenuation
If photon 2 reaches the IR, it is part of the exit, or image formation, radiation but the bending of its path represents what?
Small angle scatter
Interferes with the radiologist ability to distinguish different structures in the image?
Radio graphic fog
Radiographer can confine or collimate the X-ray beam as much as possible to include only the region of interest is the best way to reduce what?
Fog
Five types of interaction with X-ray radiation and matter?
1) coherent scattering
2) photoelectric absorption
3) pair production
4) Compton scattering
5) photodisintegration
Of the five types of interaction between X-ray radiation and matter, only two are important in diagnostic radiology?
1) Compton scatter
2) photoelectric absorption
Coherent scatter is also called what? And is simply a process of what?
-classic scattering
- elastic scattering
-unmodified scattering
It is a simple process that results in no loss of energy as X-rays scatter.
Is an interaction between an X-ray photon and an inner shell electron (usually in the K or L shells).
Photoelectric absorption
To dislodge an __________ from its atomic orbit, the incoming X-ray photon must be able to transfer a quantity of energy as________ or ________ that the amount of energy that holds the electron in its orbit
- inner-shell electron
- large or larger
Unbound orbital electron and possesses energy equal to the energy of the incident photon minus the binding energy of its electron shell
Photoelectron
Promotion of electrons from lower energy shells to higher energy shells
Excitation
Complete ejection of the electron from an atom
Ionization
As a result of _________ a vacancy is created in an inner shell of the target atom, for the ionized atom this represents an unstable energy situation
Photoelectric interaction
Released energy is carried off in the form of a photon in photoelectric absorption called a________, because it’s energy is directly related to the shell structure of the atom from which it was emitted.
Characteristic photon, or characteristic X-ray
Process of photoelectric interaction, when an inner electron removed from an atom in a photoelectric interaction, thus causing an inner shell vacancy, the energy liberated when this vacancy is filled can be transferred to another electron, instead of emerging from the atom as characteristic radiation
Auger effect
What a process does not include any X-ray emission
Radiationless effect
Like the Auger effect
Number of X-rays emitted per inner shell vacancy
Fluorescent yield
The less a given structure attenuates radiation the _________ it’s appearance will be on a raw digital detector image, and the more it absorbs radiation, the less radiation will be received by the detector and a _________ shade of gray it will display as a raw image.
Brighter
Darker
Is most likely to occur at less than 10 keV?
Coherent scattering
