Term
Units of charge for electrostatics |
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Two kinds of electrical charges in an object |
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Repulsion- Attraction Law |
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Definition
Like charges repel and unlike charges attract |
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Force between 2 charges is directly proportional to the product of their magnitudes and inversly proportional to the square of distance between them |
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Definition
Greatest concentration of charge will be on the surface where the curvature is the sharpest |
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(Only negative charges move along soild conductors)
Protons tighly bound inside nucleus but electrons are outside nucleus and move easily along conductors |
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3 Methods of generating static electric charges |
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Definition
Friction
Contact
Induction |
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4 classifications of conductors |
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Definition
Superconductors
Conductors
Insulators/ No conductors
Semi-Conductors |
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Ex of Insulators/ No Conductors |
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Descriptors of current flow |
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Definition
Quanity of electrons
Force of move current
Amount of Opposition (Resistance)
Direction of Travel |
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Term
Quanity of electrons is contorlled by ? and mesured in ? |
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Definition
controlled by mAs
Measured in Ampere (amps) |
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Term
How is force of move current described?
Controlled by? |
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Definition
Potenital Difference
(EMF)
Controlled by kVp |
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Term
How is the amount of opposition (resistance) measured? |
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Definition
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Term
Factors affecting Resistance |
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Definition
Ability to conduct
Length of conducter (directly prop)
Cross-sectional diameter (inversely prop)
Temp (directly prop) |
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Term
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Definition
Suppiles less total current
Supplies greater total voltage
Suppiles greater total resistance |
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Term
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Definition
Suppiles greater total current
Supplies lower total voltage
offers less total resistance |
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Term
Disadvantage to parallel circuit |
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Definition
when the circuit has more resistance added, the current can short circuit the entire system, which make the wires hot and may cause a fire |
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Term
Saftey devices to prevent overload of circuits
Which can we change? |
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Definition
Circuit breakers and Fuses
Can Change Fuses |
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Term
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Definition
Voltage: V=IR
Current: I= V
R
Resistnace: R= V
I |
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Definition
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Definition
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Definition
Higher resistance= less current
Lower resistance = more current
(inveresly prop) |
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Term
If you increase resistance it does what to heat? |
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Definition
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Term
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Definition
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Definition
- in a form of heat
P=I2R |
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Term
What does Voltmeter measure? |
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Definition
measures potential difference (EMF) (ACV and DVC) between any two points in a circuit |
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Term
What does Ammeter measure? |
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Definition
Amps current in AC and DC |
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Term
What does Ohmmeter measure? |
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Definition
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Term
If you half the distance to the pt what happens to Mag. Strenght? |
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Definition
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Term
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Definition
| invisblie force produced by electic charges in motion |
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Term
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Definition
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Term
| Two Kinds of motion contibute to magnetism |
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Definition
Orbital Magnetic Moment
Spin Magnetic Moment |
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Term
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Definition
| spinning electrions on theier own axis |
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| Ex of spinning magnetic moment |
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Definition
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Term
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Definition
| groups of magnetic atoms with thier dipoles aligned |
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| 3 Princple types of magnets |
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Definition
Natural Magnets
Artifical Permanent Magnets
Electromagnets |
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Definition
| Earth, Ore called Lodestones |
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Term
| Ex. Artifical Permanent magnet |
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Definition
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Term
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Definition
| current carrying coil wire wrapped around an iron core |
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Term
| Electromagenets can only me magnetic if...... |
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Definition
| Current is added (can be turned off) |
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| More loops of wire prodcudes greater # of magnetic field lines and magnetic field intensity |
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Definition
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Term
| What are the two behaviors that are brought into a magnetic field? |
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Definition
Magnetic permability
Magnetic retentiviy |
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Term
| What is the relationship of magnetic permeability and magnetic retentivity? |
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Definition
inversely prop
Ex. Soft iron= high permeability and low retentivity
Hard steel= low permeability and high retentivity |
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Definition
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Definition
| ability to stay magnetized or resist demagnetization |
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Definition
| easily magnetized (Highest) |
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Definition
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Term
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Definition
-Two types of electric charge (+) & (-).
–Like charges repel; unlike charges attract.
–Electric Force between charges depend on
the magnitude of the charges & the distance
of magnets between them.
–Some materials conduct electric charges; other do not
–Electric fields exist around electric charges |
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Term
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Definition
–Two types of mag. poles - N & S
–Like mag. poles repel; unlike attract.
–The mag. force between magnets depends on the strength & the distance between
–Some materials can be easily mag. (ferromagnetic) others cannot.
–Mag. fields exist around magnets. |
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Term
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Definition
| a current flowing in a conductor (wire) creates a magnetic field around the conductor; Increase current= increase magnetic field |
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Term
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Definition
| coiling the current carrying conductor (wire) will increase magnetic field strenght in the center of the coil |
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Term
| Strenght of the current is determined by..... |
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Definition
Number of turns or current:
increase the current or number of turns in the coil; increase magnetic field stregth in the center of the coil |
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Definition
| affect of compass with and without current flow in wire |
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Term
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Definition
remote control devices in circuit breakers
Detent button on Rad. Equip.
Electromagnet relays on contorol console to protect the RT from Hi-voltage circuit |
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Definition
| a current carrying coil/helix of wire |
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| Factors affecting effectiveness of solenoids and electromagents |
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Definition
diameter
length
current passing along wire |
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Term
| Strength of solenoids & electromagnets |
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Definition
numbers of loops/ turns of wires
current strength
permability of core |
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Term
| Electromagnetic induction |
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Definition
| production of current in a conductor by using a changing magnetic field near the conductor |
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Term
| Require compoents of electromagnetic Induction |
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Definition
magnetic field
conductor
relative motion |
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Term
| 3 ways to induce current in electromagnetic induction |
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Definition
1. Move conductor through a stationary unchanging strength mag. field; more practical – generators do this.
2. Move mag. field of magnet near a stationary conductor with an unchanging strength mag. field.
3. Vary the mag. flux strength from a stationary magnet through a stationary conductor by ↑ or ↓ the current in the wire; |
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Term
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Definition
1. Strength of mag. field
2. Speed of motion between lines of force & conductor
3. Angle between mag. field & conductor
4. Number of turns / loops in the conducting coil |
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Term
| the angle between the direction of magnetic field and the conductor |
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Definition
| — As the angle approaches 90º, the spaces between the lines of force become smaller, progressively more flux lines are cut per sec., larger induced current |
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Term
| Strength of te magnetic field in electromagnetic induction |
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Definition
| stronger the magnetic firld the hight the induced voltage |
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Term
| Flemings right hand thumb rule |
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Definition
| When the right hand is positioned so the thumb points in direction of conventional current flow, the fingers indicate the direction of the induced magnetic field |
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Term
| Right hand generator rule |
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Definition
| When the thumb points in the direction the conductor is moving and the index finger points in the direction of the magnetic lines of force field, the middle finger indicates the direction of conventional current flow. Fleming’s left hand generator rule does the same for actual electron flow. |
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Definition
| occurs when there is an AC that opens its own flow |
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Term
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Definition
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Term
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Definition
Two coils=
1st coil: primary coil
2nd coil: Secondary coil |
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| Generators are also called..... |
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Definition
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Definition
| device that converts mechanical energy of motion (input) to electrical energy (output) |
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Term
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Definition
armature
electromagnet
set of slip rings
Brushes |
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Term
| Fleming's Right hand generator rule |
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Definition
• Thumb – direction of the conductor
• Index Finger – direction of the mag field
• Middle Finger – direction of Induced Current |
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| How is frequency measured? |
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Definition
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Definition
| device that converts electrical to mechanical energy |
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Term
| What part does a DC motor have? |
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Definition
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Term
| What parts does a AC motor have? |
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Definition
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Term
| Fleming's Left hand motor rule |
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Definition
• Index Finger– direction of the mag field
• Middle Finger – direction of induced current in conductor
• Thumb – direction that Conductor will move |
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Term
| Ex. of a synchronous motor |
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Definition
| timing devices (AEC device) |
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Term
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Definition
| AC motor which operates at a fixed synchronous speed prop to the frequency of the appiled AC power |
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Term
| Synchronous motor must be with the speed of what generator? |
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Definition
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Term
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Definition
useful with x-ray tube designs with rotating anodes
(very powerful Motor) |
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Definition
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Definition
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Definition
solenoid AC
100% ripple
Conversion efficiency 1.00
180 degree from positive to negative |
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| Single phase full wave generators |
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Definition
| changes the negative half of the cycle to positive |
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Term
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Definition
uses 3 out-of-phase AC cycles sepreated by 120 degrees from each other (1/3 cycle)
Ratings up to 2000 mA for 150 kVp
Exposure time as short as 1 msec. |
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Term
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Definition
efficiency factor 1.35
13.5 % ripple |
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Definition
efficiency factor 1.41
4% ripple
-more efficient than single or 3-phase 6 pulse |
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Term
| High frequency Generators |
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Definition
| provides nearly a constant voltage potiental less than 1-2 % ripple |
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Term
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Definition
| designed to prodcue exposure in the shortest possible time by operarting the x-ray tube beginning at the highest mA settings and then allowing it to fall during the exposure |
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| Method of falling load generators |
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Definition
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| Disadvantage of falling load generator |
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Definition
| can shorten tube life due to constant use of high mA |
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| disadvantage Battery powered mobile unit |
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Definition
| cordless x-ray unit must be re-charged |
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Term
| disadvantage Capacitor-discharge mobile unit |
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Definition
residual charge can remain on electrodes after completion of exposure and eletric shock is possible
-kVp will not be consistent
-must be recharged
-no increase mAs techniques |
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