Negatively charged electrode. Coiled wire that is a source of electrons
Cathode/Filament
Surrounds the cathode/filament to focus stream of electrons onto the focal track of the anode
Focusing Cup
2 filaments and 1 anode
dual focusing cup
positively charged electrode. Stationary or rotating.
Anode
A rotating anode can rotate at
3,000-10,000 RPM
This can withstand a great amount of heat and is a big makeup of the anode
Tungsten
- A rotating motor consists of ______ & ______
2. And these make up a ____ motor. Speeds can change.
- rotor and stator
2. induction
Moving energy
Kinetic energy
When electrons strike the anode, Kinetic Energy is converted to __1__ heat and __2__ energy
- 99%
2. 1%
X-ray tube is made of _______ because it can withstand a great amount of heat.
pyrex glass
The xray tube is ______ to provide unobstructed path for electrons
vacuumed
The xray tube is insulated with
lead and oil
Leakage radiation cannot exceed
100mR/hr @ a distance of 1 meter
German word for braking
Brehmsstrahlung
Forms 85-90% of the beam. Occurs when the electrons rapidly decelerate and loop around nucleus on surface of anode.
Brehmsstrahlung
10-15% of the beam. Occurs when electrons on face of anode drop to fill hole in inner shells
Characteristic
used in fluro, positive pressure switch.
“Deadman Switch”
Tube current displays only during ______
exposure
Quantity, number, amount
controlled mAs
Quality, energy, penetrating ability
controlled by kV
least ripple 3-5% and is most efficient
High frequency transformer
No practical amount of __1__ can ever compensate for inadequate __2__
- mA
2. kVp
Recorded detail (spatial resolution) is controlled by 3 geometric factors
- focal spot size
- OID
- SID
projected or effective focal spot is smaller than the AFS
Blooming
over 100 mAs, use _____
large FS
The steeper the anode, the _____ the FS
smaller
Intensity of beam is greater on the cathode side of the tube
Anode heel effect
“FAT CAT”
Ways to enhance AHE (3 ways)
- steep anode
- large IR
- short SID
Main purpose of the filtration
to decrease patients skin dose
If a tube operates at __1__, you must have __2__ filtration
- 70 kVp
2. 2.5 mm Al
amount of metal that cuts intensity to half its initial output.
Half Value Layer (HVL)
*Thicker HVL=stronger beam
thick part of filter at thin part of anatomy
wedge filter
Cut SID in half
4x greater radiation intensity
Double SID
1/4 radiation intensity
attenuation = _______ + _______
absorption + scatter
total absorption of incoming photon
photoelectric effect
xray gives up all of it’s energy-knocks out an inner shell electron
Photoelectron
released as electrons drop down to fill holes in shells.
Characteristic radiation
White or Clear on radiograph
photoelectric effect/characteristic radiation
less than 30 kV (not in diagnostic)-TOO LOW
Classical/Coherent/Unmodified/White Scatter
Modified scatter. Wray gives up some but not all of it’s energy to knock out an outer shell electron.
Compton
Compton makes it’s presence known through
SCATTER
Scatter is _____ on the radiograph
GRAY
Are Pair Production and Photodisintegration in diagnostic?
No, too high
when xrays pass through without interacting with the atoms in the body. Shows up black
Remnant/Transmission/Exit Radiation
picture element that makes up the Matrix
pixel
larger matrix & greater number of pixels=
improved spatial resolution
Increasing pixel density and decreasing pixel pitch ________ spatial resolution
INCREASES
A. OD of 1=
B. OD of 2=
C. OD of 3=
A. 1/10
B. 1/100
C. 1/1000
COUNT THE ZEROS
Density (Screen Film)=
Brightness (Digital)
Recorded detail (Screen Film)=
Spatial Resolution (Digital)
Contrast (Screen Film)=
Grayscale/dynamic range (Digital)
utilizes a plate that is put in a reader to retrieve image
CR
utilizes a digital plate or digital bucky that sends image directly to computer
DR
Main advantage of CR/DR
Post processing (window and leveling)
- overall darkness on radiograph
2. controlled by
- Density
2. mAs
To double density you must…
Double mAs
To cut density in half you must…
cut mAs in half
kVp controls _________
SCATTER
Scatter is _______
DENSITY
Above 90 kVp:
if you add 15 kV, you must ______
mAs in half
Above 90 kVp:
if you take away 15 kV, you must ____
Double mAs
Below 90 kVp:
if you add 10 kVp, you must
cut mAs in half
Below 90 kVp:
If you subtract 10 kVp, you must _______
double mAs
As collimation decreases then density __1__. As collimation increases then density __2__.
- Increases (b/c larger field size)
2. Decreases (smaller field size)
part density and IR density are _____ proportional
inversely
Automatic Processor
developer, fixer, washer, dryer
90 seconds to process film
Main controlling factor of contrast
kV
High kV= \_\_1\_\_ scale \_\_2\_\_ contrast \_\_3\_\_ latitude \_\_4\_\_ scatter \_\_5\_\_ penetration \_\_6\_\_ colors
- long
- low
- wide
- increased
- increased
- many
Low kV=
- scale
- contrast
- colors
- latitude
- scatter
- penetration
- short
- high
- few
- narrow
- decreased
- decreased
increased grid ratio = ______ contrast
increased
increase collimation= ________ contrast
increased
First step in protection
OPTIMUM COLLIMATION
T B M F G
Hardest to penetrate to easiest
teeth, bone, muscle, fat, gas
Contrast medias:
A. Adds density
B. Takes away density
A. Positive (ex: barium and iodine)
B. Negative (air and CO2)
Additive pathology (ex: edema, atelectasis)=_____ kVp
increase
destructive pathology (ex: emphysema, osteoporosis)=_______ kVp
decrease
Three ways to overcome motion
- clear instructions
- Immobilization devices
- short exposure time
Magnification is AKA
size distortion
Increase SID and Decrease OID to prevent
size distortion (AKA magnification)
Shape distortion is AKA
true distortion
This is caused by mal-alignment of tube, part, and/or IR. Usually elongated or foreshortening. Can be done accidently or on purpose
Shape distortion
AKA true distortion
if “S” number is too high then the IR is __1__ and image has excessive __2__.
if “S” number is too low then the IR is __3__ and patient maybe ultimately __4__ due to __5__.
- underexposed
- Quantum Mottle/Noise
- Overexposed
- overdosed
- dose creep
Invisible image
Latent
Visible image
Manifest
Film Screen»Digital Term
- Density/Receptor Exposure
- Contrast
- Recorded Detail
- Brightness
- Grayscale/dynamic range
- spatial resolution