Physics Review Flashcards
Which requires energy, movement of an electron from a lower to higher shell, or from a higher to lower shell?
movement of an electron from a lower shell to a higher shell requires energy input
Which is accompanied by emission of energy, movement of an electron from a lower to higher shell, or from a higher to lower shell?
What is this energy?
movement of electron from a higher to lower shell is accompanied by emission of energy
photons of electromagnetic energy (x-rays)
What occurs when transfer of energy to an orbital electron results in ejection of the electron from the atom?
ionization
What does EM energy stand for? What is it?
Electromagnetic Energy (“let the light shine”)
produced by 3 processes–> our focus = sudden deceleration of electrical charges
What is the smallest quantity of EM energy? What does it travel at?
the photon; travels at the speed of light
Which have a higher frequency, gamma rays or radio waves? What does this tell us?
Gamma rays–> a higher frequency, means more energy; and more energy increase the ability to pass through objects (like patients)
What are the two things that photons can act like?
a wave and particle
What are the two things we should remember about how photons travel?
travel at the speed of light in a:
- straight line and
- diverge from their source
What is the velocity of photons when they act as waves?
constant; speed of light
What is the number of wavelengths that pass a point of observation per second?
frequency (f)
How are wavelength and frequency related? What do they determine?
inversely related
determine the energy of the wave
How is frequency and the strength of an x-ray related?
frequency has direct/linear relationship with strength of x-ray
Do the inner or outer shell electrons produce higher energy x-rays? What does this allow?
inner shell electrons –> and have higher frequency–> therefore pass through patient
(outer shell electrons produce lower energy, w/ lower frequency, can cannot pass through patient easily–> cause tissue damage)
What refers to any form of energy that is transmitted through space?
Radiation
T/F. Only matter that completely absorbs the radiation is said to be exposed or irradiated.
False–BOTH matter that intercepts either completely or partially absorbs the radiation is said to be exposed or irradiated
What happens to the tissue what is stopping or deflecting x-rays?
What about if the x-rays are going through the tissue?
causes tissue damage
No tissue damage
What are three examples of Ionizing radiation?
- x-rays
- gamma rays
- UV light
Is ionizing radiation harmful to the body?
YES
What are the two sources for Ionizing Radiation?
- Natural Environment (radon)
2. Man-made
Where does the largest source of Ionizing Radiation come from? What disease is this a major cause of?
radon from Natural Environment–> major cause of lung cancer
What are some properties of X-ray photons?
- invisible and highly penetrating
- no mass or weight
- produce wide range of energies (high or low kVp)
- can damage tissues–> via ionization or free radicals
- no charge–>therefore unaffected by magnetic field
- scatters upon interaction w/ matter
- ionizes matter–> DAMAGE tissues
- NOT FOCUSABLE by a lens
- no charge
- have differential absorption by matter
T/F. We can focus x-ray photons by a lens.
FALSE— they are NOT focusable by a lens!!!
What type of current is it when electrons flow in a single direction?
Direct Current (DC)
What type of current is it when electrons flow in a bidirectional method, oscillating back and forth?
Alternating Current (AC)
When we plug in an x-ray machine, what type of current do we need to change it to? In order words, what is the type of current used in the x-ray tube?
change it from AC to DC
What is the term used for changing of the AC current coming out of the wall into DC current?
Rectification
What gives photons more energy? How does this change their ability to pass through patients?
Frequency (NOT speed); will be a decrease in wavelength, but will increase energy —> an increase in frequency allows them to pass through patients easier
What is the name of the equipment where x-rays are created?
The tube–> is lead lined cylinder w/ two circuits and electrons that are acclerated
What does the collimator do?
limits where the x-rays can travel, it trims/crops x-ray beam
(does NOT focus x-rays)
T/F. the collimator focuses x-rays
FALSE— it limits where x-rays can travel, but it does NOT focus them
What happens to the x-rays when we open up the settings on the collimator?
more x-rays are allowed to exit the colllimator and expose more of a patient
What happens to the x-rays as we close down the collimator (increased the collimation)?
less x-rays come out and less of the patient will be imaged
What do the wall buckyy or table bucky do?
hold the cassette and have a grid in front of them to remove useless x-rays (scatter x-rays)
What does the generator do?
power supply to operate the tube
What does the control panel do?
control show much power is sent from generator to tube in the form of current
What is the mAs the product of?
seconds(time) x mA (current)
What is the mA? What does it determine?
current that runs across cathode–> determines how many electrons made at cathode
What does the “ON” button on the control panel do?
forms electron cloud at cathode
What does the expose button on the control panel do?
sends electrons to the anode –> x-rays are then created
If we keep seconds the same, and we increase the mAs, what does this cause the mA to do?
causes an increase in mA—> and MORE x-rays are produced
What does an increase in kVp have on the frequency and wavelength of the x-rays?
higher frequency and shorter wavelengths
causes x-rays to race across the tube faster and energy of x-rays are higher
What will a lower kVp have on frequency and wavelength? How does this impact ability of the x-rays to pass through the patient?
travel slower–> decreased frequency and a longer wavelength—> so LESS energy and therefore decrease ability to pass through patient
What does an increase in mAs have on electrons and x-rays?
increases electrons and increases x-rays
therefore a decrease will decrease electrons and x-rays
What is the current that sends electrons from cathode to anode?
kVp
will increase frequency and penetrating power of x-ray photons
What are filters used for for taking an x-ray?
used to even out tissues of varying thickness
Ex: aluminum and glass
What type of measurement is used for the Calipers? What does this tell us?
cm
tells us how much kVp to use
increase tissue thickness need to increase x-rays used
What is SID or FFD?
Source-to-image Distance (preferred term)
Focal Film Distance
What is the distance from the tube to the film/image receptor called?
SID (source-to-image Distance)
What effect will a decreased SID have on the anatomy?
will magnify anatomy
we DO NOT want this
What effect will increased SID have on magnification?
will decrease magnification = GOOD and what we want
When we use an increase SID, what else shall we change in order to narrow in on the part of the anatomy we want to take a film of?
need to increase the collimation so we don’t have scattering x-rays
What is the OID/OF?
Object-to-image Distance (preferred term)
Object-to-Film Distance
What is the distance from the object we are imaging to the film/image receptor called?
OID (object-to-image distance)
What effect will an increased OID have on the magnification? Is this what we want?
will increase the magnification–> which we DO NOT want
Is magnification good or bad when taking an x-ray? Why?
BAD
- inaccurate measurements of anatomy/pathology
- distortion and blurry image (penumbra)
Will an increase or decrease in SID/FFD decrease magnification?
increased
Will an increase or decreased OID/OFD decrease magnification?
decreased
