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Chapter 1-Production & properties of x-ray beam
Question | Answer |
---|---|
What is the device that creates the x-ray beam? | x-ray tube |
What is another name for X-ray tube? | x-ray insert |
What is used to define the size of the x-ray beam to the area or body part being irradiated? | Collimator box |
What, contained within the collimator box, blocks the portion of the beam that is not needed? | lead plates, shutters |
What is the only useful part of the x-ray beam? | The part that is projected toward the patient |
-electric current running through the stator, that produces a magnetic field that turns the metal rotor | electromagnetic induction |
Cathode contains ___ filaments and has a ____ charge. | 2 ; negative |
How many of the two filaments is heated during a exposure? | only one |
The filament is heated in order to do what? | to liberate electrons |
What is the process of heating filament in order to liberate electrons called? | thermionic emission |
What is filament made from and why? | tungsten bc of its high melting point |
What controls the degree of filament heating? | mA - milliampere |
As the temp increases, the rate of emission will ? | increase |
What repels and contains the electrons in a small space so that they can be accurately focused on the anode disk? | the focusing cup |
- "prep" the tube by heating one of the filaments so that electrons are emitted and hover in the tube in an electron cloud | Boost-and-hold stage |
The boost is considered the _______. | thermionic emission |
The time before the exposure is made? | The hold |
The tungsten layer of the tube inhibits? | Heat dissipation from the tube |
The __________ allows for better heat distribution over the face of the disk when the disk is bombarded by electrons during an exposure. | rotating anode |
The area on which the electrons bombard the anode disk is called _______. | focal spot |
The flow of electrons from cathode to anode constitutes the _____________. | Tube current |
Tube current is measured in? | mA, milliamperes |
What determines the speed at which the electrons move from cathode to anode ? | kV, kilovolt |
Raising the kV will make the electrons travel? | Faster |
The energy of the x-rays produced within the disk depends what? | the speed or kinetic energy of the electrons |
Thicker anatomical parts require what kind of kV setting? thinner parts? | thicker = higher thinner = lower |
The nucleus of an atom contains what? | protons & neutrons |
the electrons of an atom still feel an electrostatic attraction to the protons in the nucleus, this is called _________________ | binding energy |
Inner-most shell has higher or lower binding energy? | higher |
What is the binding energy for level K? | 69 kV |
The sudden deceleration causes release of kinetic energy in the form of x-radation, known as: | brensstrahlung radiation, brems radiation. |
_______ occurs when a neutral atom either loses or gains an electron. | Ionization |
________ occurs when a neutral atom loses one of its electrons. | Positive ionization |
_________ occurs when a neutral atom gains an electron. | Negative ionization |
Why is the x-ray beams considered to be heterogeneous or polyenergetic? | bc it contains many different energies ranging from low to high |
Doing what to the beam will protect the patient by absorbing the lower energy x-rays? | filtering |
What are the two types of radation are x-ray beams made of? | Brems & Characteristic |
Name the 4 conditions necessary for the production of x-ray: | 1. boiling/separation off of electrons 2. production of high speed electrons 3. concentration of electrons 4. sudden slowing or stopage of electrons |
The boiling or separation of electrons is a process known as? | thermionic emission or the edison effect |
The controling factor of thermionic emission is? | mA |
What effect on density does thermionic emission have? | increases it |
increasing the heat in the filament, what effect does that have on the # of electrons being boiled off? | increases them |
What controls the quantity of photons? | mA |
What starts the boiling process? | hitting the rotor switch |
How do you overcome the negative effect of space charge? | increase kVp |
What is the controlling factor of the speed and strength of the photons? | kVp |
increase the speed, will do what to the kinetic energy produced? | increase it |
What handles the concentration of electrons? | focusing cup |
What is the difference between photon speed and electron speed? | Electron speed can vary; photon speed is constant |
What controls the sudden slowing or stopping of electrons? | target or anode |
What will determine the amt of projectile electrons? | mA |
What makes up the majority of the x-ray beam? | brems radiation |
The more energy the projectile electron loses per interaction, the _________ the brems photon will be. | stronger |
What are the 3 courses of action an electron can take that is characteristic of Brems radiation? | -attracted to proton and curved - repelled & curved -direct hit on neclues, stopped and all is kinetic energy |
If the photon is stopped instantly, it will be weak?strong? | strong |
In order for (K) Characteristic radiation to be produced, the projectile electron has to have energy that is __________________ than the binding energy of the k-shell. | greater than or equal to |
What type of characteristic radiation is the only one that is strong enough to be useful? | K-characteristic |
If kVp is able to produce k-characteristic radation, atom is _________ because electron is moved out of K shell. | ionized |
What are the 3 regions of electromagnetic spectrum? | Visible light, radio frequency, x-radiation |
List the following in order from lowest/longest to shortest/highest according to the electromagnetic spectrum; gamma, radio, infra-red, x-ray | radio, infra-red, x-ray, gamma |
What are the 3 reasons for reduced intensity of x-ray emission at low energies? | 1.electrons dont all reach peak kinetic energy 2.brems radiation may happen many times getting weaker each time 3.filters remove the low energy photons |
- how often the crests of a wave occur | frequency |
What is the symbol of frequency? | Nu |
What is the unit of measurement of frequency? | Hz |
The higher the frequency the _______ the photon is. | stronger |
Increaseing kVp will have what effect on the kinetic energy of the electron? | increases the kinetic energy |
Increasing the kVp will have what effct on the strength of the x-ray photon created? | increase the strength |
increasing the kVp will do what to the speed of the projectile electron that is traveling from the (-) to (+) | increases the speed |
Increasing the kVp will have what effect on the frequency of the photon? | increases the frequency |
Increasing the kVp, will have what effect on the wavelength of the photon? | decreases the wavelength |
-the distance between the crests of a wave | wavelength |
What is the symbol of the wavelength? What unit of measurement is used? | Lambda Angstrom |
The longer the wavelength the ______ the photon. | weaker |
-refers to the strongest photon in the beam of radiation | minimum wavelength |
What effect on wavelength does increasing the kVp have? | shortens the wavelength |
Strong photon has what frequency and wavelength characteristics? | high frequency short wavelength |
What is the symbol of the speed of light? | C |
What is the speed of light? | 186,000 miles/sec |
What is the formula that shows the relationship of frequency and wavelength to light? | C= nu(lambda) |
What is the wave particle duality phenomena? | A photon (pure energy) acts as tho it has the characteristics of matter |
Increasing the kVp will have what effect on the projectile electron's kinetic energy? | increase it |
Increasing the kVp will have what effect on the efficiency of x-ray production? | increase it. |