Make Up Flashcards
Amplitude
1/2 of the range from crest to valley
Wavelength
Is the distance from one crest to another, from one valley to another, or from any point on the sine wave to the next corresponding point.
Frequency
Is the number of wavelengths that pass a point of observation per second.
Rectifier
Allows current flow in one direction. x-ray tubes must be provided with direct current. X-rays are produced by the acceleration of electrons from the cathode to the anode.
Rectification
is accomplished with diodes. A diode is an electronic device that contains two electrodes. they are made by solid-state rectifiers made of silicon.
Single Phase Power
Single phase power results in a pulsating x-ray beam. This is causes by the alternate swing in voltage from zero to maximum potential 120 times each second under full-wave rectification. The x-rays produced when the single-phase voltage waveform has a value near zero are of little diagnostic value because of their low energy; such xrays have low penetrability.
Three Phase Power
Multiple voltage wave forms are superimposed on one another, resulting in a waveform that maintains a nearly constant high voltage. There are 6 pulses per 1/60s compared with the two pulses characteristic of single phase power.
High frequency Generator
High frequency generators produce a nearly constant potential voltage waveform, improving image quality at lower patient radiation dose.
Single Phase
HU=kVp x mAxS
3 phase, 6 pulse
HU=kVp x mAxs =1.35….35%
3 phase, 12 pulse
HU=kVp x mAxs=1.41…41%
To see significant increase in density
increase mAs 30%
kVP 4%
To see Double density: must
double mAs, or increase kVp by 15%
Lumbar
Intervertebral Foramina 90 degrees Lateral (right or left)
Zygaphophyseal Joints 45 degrees obliques Posterior Obliques--downside RPO--Right joints LPO--Left joints Anterior obliques--upside RAO---left joints LAO--right joints
Cervical
Intervertebral Foramina 45 degrees oblique
CR 15 degrees cephalad–upside visualized
LPO—right foramina
RPO– left foramina
CR 15 degrees caudad–downside visualized
LAO —left foramina
RAO—right foramina
Thoracic
Intervetebral Foramina 90 degrees (right or left lateral)
Zygaphphyseal joint 70 degrees oblique
Posterior Oblique—upside
LPO —right zygopophyseal
RPO—Left zygapophyseal
Anterior Oblique–downside
LAO–left zygaphophyseal
RAO—right zygaphophyseal
Bodies center of gravity
S2
Radiographic Rating Chart
is most important indicates safe/unsafe techniques
x-axis: exposure time
y-axis: Kvp
Below mA line is safe
Anode cooling chart
Shows how long to wait to make more exposures after anode has rached max capacity (HU)s
x-axis: time (minutes)
y-axis: HU
curve line: cooling curve
XR Emission Spectrum
x-axis: energy (keV) quality
y-axis: quantity
filtration
inherent filtration 0.5mm
added filtration 1.0mm
mirror 1.0mm
total: 2.5mm
CR uses IP:
- Protective layer
- Phosphor layer—BFH coated with Europium (PSP) photostimulable phosphore (active layer)
- light reflective—sends light forward (some detail lost)
- conductive —absorbs static electricity.
- support—-semi-rigid, gives IP strength
- light shielding
- backing—protects back
Solid State lasers
less diameter—-better spatial resolution
Laser Scanning
Blue light is emitted
Grid frequency
Number of grid lines per cm/m
typically 150 + lines/inch
Exposure Indicator
Fuji: S# target 200-400 (inverse) high S# means underexposed
Kodak/Carestream: Ei Target 2000 (direct)
Agfa: log mean target =2.2 (direct)
Spatial Resolution
in DR is pixel limited
DR
uses flat panel direct capture detector (then temporary stored in TFT’s or thin silm transistors)
Indirect conversion System
X-ray absorbed by cesium iodide –light
light interacts with Amorphous silicon
Photodiode–electric charge
Direct Conversion System
Amorphous Selenium (a-Se) electric charge
Sensitivity speck
Electrons traps in conductive layer
increasing filtration
primary purpose rad protection
lowers patient dose
increases beam energy by removing weak beams
decreases beam quantity by removing weak beams
Most scatter results from Compton
Filtration does affect image contrast by affecting the differential absorption (reduces subject contrast)
Volvulus
Twisting of intestines on its own mesentery–beak sign cork-screw look.
Hallux
big toe
Annual limit for techs
5 rem=0.05 Sv
Normal Cretinine
0.6-1.5mg/100ml
Geometric Factors
magnification, distortion, focal spot blur
XRs transmitted w/o interaction
rad imaging
visibility of detail
is affected by contrast and OD
Sella Turcica
3/4 superior and 3/4 anterior to EAM
Waters
OML is at 37 degrees to IR
MML is perpendicular to IR
CR at acanthion
Petrous Ridges below maxillary sinuses
Modified Waters
OML 55 degrees to IR
Orbits shown w/o distortion (orbital floors perpendicular to IR)
Best for orbital fractures
Haustra
normal pouches/sacs along LG intestines
Principle function of grid
improve image contrast
The ? is the source of radiation in the x-ray tube.
focal spot
Because of the line focus principle, the effective focal spot size decreases with ? decreasing.
target angle
The negative side of the x-ray tube holds the
filament
what is the most common cause of tube failure?
tungston vaporization
The filament is made up of
tungsten
Thermionic emission at the filament creates
space charge
The rotating anode is turned by a
magnetic field
When electrons bombard the target, ?% of their kinetic energy is converted to heat.
99%
The target of the rotating anode is usually coated with a ? alloy.
tungsten
The ? is the source of radiation in the x-ray tube.
focal spot
Because of the line focus principle, the effective focal spot size decreases with decreasing
target angle
High capacity tube rotors revolve at
10,000 rpm
The x-ray intensity is lower on the anode side of the tube because of the ?
heel effect
Tube failure can occur from
long exposure times
The filament in an x-ray tube is about ?cm in length
1 to 2
A dual focus tube has two
filaments
Each tube has its own tube rating chart to show
maximum exposure times
The ? are outside the glass envelope
stators
Extrafocal or off focus radiation is produced from
rebounding electrons
