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Physics - Test 5
Chapters 7 & 10
32
Anatomy
Undergraduate 1
11/16/2017

Additional Anatomy Flashcards

 


 

Cards

Term
Incident electrons
Definition

Electrons accelerated from the thermionically emitted cloud toward the anode.

 

** Represented by a straight arrow on diagrams

Term
How are x-ray photons represented on diagrams?
Definition
With a wave line and arrow
Term
Describe Target Interactions
Definition
  • The greater the quantity of electrons =             greater quantity of x-ray photons produced(mAs)

 

  • The greater the kinetic energy of electrons =      greater quality of photons produced (kVp)
Term
Describe heat production as it relates to target interaction.
Definition

99% of kinetic energy produced by target interaction results in heat production.

 

** as kinetic energy of photons increases, so does efficiency; by the time therapeutic machines reach MeV's, most of energy is actually photons.

 

99% Heat, 1% X-Ray photons

Term
Give another name for Bremsstrahlung
Definition
Brems or Breaking
Term
What is the primary product produced from the electron cloud striking the anode?
Definition

Heat

 

99% heat, 1% x-ray photons

Term

Which way do incident electrons travel? 

From what to what....

Definition
Cathode to Anode
Term
At what kVp range do characteristic photons begin to comprise the useful beam?
Definition

70 kVp or more

 

(or 69.5)

Term
Where is an x-ray photon produced?
Definition
Anode
Term
Define Inherent Filtration
Definition
Found within the glass envelope.  Most tubes have inherent filtration of 0.5-1.0mm al eq.
Term
What does Al eq. stand for?
Definition
Aluminum Equivalent
Term
What is added filtration and list several types?
Definition

Any filter added between the tube and the patient.

 

  1. Collimator
  2. Compound
  3. Compensating (wedge, trough)

* made of aluminum or sometimes clear lead, which allows you to see the collimator light

Term
Describe a compensating filter
Definition
Used for objects with unequal densities to try to provide a more uniform density on the film.
Term
Describe a trough filter
Definition

(double-wedge)

Used for differences in mediastinum and the lungs

Term
Define Characteristic Interactions
Definition

Occur when incident electron interacts with an inner shell electron (k shell)

 

* Only the k shell characteristic photon has sufficient energy to be a part of the useful beam

Term
List the 3 recommended minimum total filtration levels
Definition

1. Below 50kVp, 0.5mm al eq

 

2.  From 50-70kVp, 1.5mm al eq

 

3.  Over 70 kVp, at least 2.5mm al eq

Term

True or False

 

When the amount of filtration increases,

the % of attenuated photons increases

Definition

True

 

(direct relationship)

Term
State and describe HVL
Definition

Half Value Layer

 

Amount of absorbing material required to reduce the intensity of the beam to half its original value

Term
If kVp is increased, what needs to happen to the HVL?
Definition

Increased

 

* HVL will increase as kVp increases

Term
Describe the filtration process and why filtration is used
Definition

The process of eliminating the undesirable low-energy x-ray photons by the insertion of absorbing materials into the primary beam.

 

* increasing the quality of the beam, hardening the beam

Term
Define Bremsstrahlung Interactions
Definition

Electron passes close enough to the nucleus to allow its force field to alter its course, causing the electron to brake or slow down.

 

note: this lost energy is converted to an x-ray photon (brems photon).  The energy of the brems photon is exactly the difference between entering and exiting kinetic energy of the electron.

 ex: enters at 100 kev's and exits at 70 kev's = 30 kev's

Term
At what level of kVp do brem rays get generated?
Definition
Brem rays can happen at any kVp
Term

What kind of rays make up the majority of

useful x-ray beam?

Definition
Brems Rays
Term

Characteristic Interactions

Projectile electrons must have a potential of at least ____ or ____ kVp to contribute to the useful beam.

Definition
69.5 or 70
Term
How could you double the number of incident electrons produced?
Definition
Double the mAs???
Term

List the energy levels for the following generators:

 

single phase

3-phase, 6-pulse

3-phase, 12-pulse

Definition

Single phase = ?

3-phase, 6-pulse = 35% more than single phase

3-phase, 12-pulse = 41 % more than single phase

Term
How does the emission spectrum change when mA is the only thing that is increased?
Definition
An increase in amplitude
Term
How does the emission spectrum change when kVp is the only thing that is increased?
Definition
An increase in amplitude, as well as a shift to the right (indicating higher average energy)
Term
Describe the x-ray emission spectrum
Definition

A way of graphically observing the different x-ray energies present in a particular beam

 

note:  also allows us to see how certain factors affect the overall beam

Term
What two types of interactions are x-rays created from?
Definition
Characteristic and Brems
Term
At what kV will characteristic x-rays begin to be produced for diagnostic purposes?
Definition
69.5 or 70
Term

List the # of -e and EB (keV) for the shells

 

K

L

M

N

O

P

Definition

K      2     69.5 or 70

L      8     12.1

M    18     2.8

N     32     .6

O     12     .08

P       2     .00

 

** the further away from the nucleus, the better the energy!

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