Meaghan Piretti X-ray Production/Equipment Flashcards by Madison moss

Incoming Power Supply

A/C supply
220 Volts

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Master Power Switch

Single Throw Double Blade Switch
Big switch on wall

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Fuses (circuit breaker) job/location:

Protects equipment from excessive current
Located on primary side

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Line Voltage Meter (compensator) job/location

Primary or low circuit
Measuring incoming line voltage
Detects a surge or drop
Maintains 220 volts to auto transformer

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Auto transformer job/location:

Operates on self induction
Works off A/C
Low voltage/primary circuit side
KV selection (not production)
Determines line voltage sent to step up transformer

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MA selector (Rheostat) (variable resistor) job/location

Regulates amperage/regulates thermionic emission
Think thermostat
Think Dimmer on a light switch
Location:low voltage- filament circuit

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Step up transformer job/location:

Mutual Induction (2 wires)
More turns on secondary side
Works off AC
Increases Volts to Kilovolts
We need high Volts to produce x-rays

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Step-Down Transformer job/location:

Filament transformer
Mutual Induction
More turns on primary side
2 jobs!
1. Decreases Voltage
2. Increases Amperage

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Rectifier job/location:

Changes AC to DC
Solid state semiconductor
4 diodes

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Single phase voltage ripple:

100% (the worst)

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3 phase, 6 pulse voltage ripple:

14% (old equipment bad)

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3 phase, 12 pulse voltage ripple:

4% (not as bad but aril not the best)

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High frequency voltage ripple:

Less than 1% or 1
(Best) (newest equipment)

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Place the voltage ripple in order:

Half wave, full wave, three-phase six pulse, three phase twelve pulse, high frequency

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What voltage ripple is preferred?

High frequency (1% or 1)

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Heat Units Definition:

Calculation of the total heat produced during an x-ray exposure

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Heat Units Calculation for High Frequency:

kVp x mA x s x 1.45 (1.44)

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Falling Load Generator Definition:

Provides extremely short exposure times by taking advantage of tube heat loading potential

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4 things needed to produce x-rays:

Source of free electrons
-thermionic emission-filament heats up-mA
-cathode side-negative
A means of accelerating electrons
-potential difference (EMF/Voltage) kVp
A way to focus the electrons
-focusing cup (focuses the electrons toward the anode)
-molybdenum or Nickle
A means to decelerate these electrons
-rapidly stopping sudden deceleration
Anode- positive side made of Tungsten Rhenium

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What is the focusing cup made of?

Molybdenum or Nickel

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Anode is made of?

Tungsten Rhenium

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The cathode is what charge?

Negative

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The anode is what charge?

Positive

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Source of electrons is a _________ at the __________ side of the tube.

Filament; cathode end

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The filament consists of a:

Small coil of tungsten wire

As it is heated up the increased energy enables electrons to be released from the filament through:

Thermionic emission

The __________ provides the electron source for x-ray production.

Electron cloud

If you _____________, you increase the ____________; which in turn ___________ this leads to more x-ray photons being created.

Increase the mA, Increase the filament current, increases the tube current

The free electrons must be accelerated through the x-ray tube from _______ to _______.

Cathode to Anode

__________ forces the electrons across the tube giving them kinetic energy.

Voltage, Kilovoltage Peak (kVp) (tube potential)

The higher the kVp the more/less energy the accelerating electrons will have?

A _________ houses the filament wires

Focusing cup

When the kVp is applied the electrons are focused in a ________ beam.

Narrow

The focusing cup holds the released electrons in a tiny cloud sound the filament wires called the:

Space Charge

Electrons are directed from the:

Cathode toward the anode to the area of the focal track

_____ of elections are absorbed as heat.

99%

____% of electrons are created into x-ray photons through target interactions

The electrons _______ when they strike the anode.

Decelerate

The anode is a Tungsten disk which has a:

High atomic number 74 and a high melting point

The Anode heel effect refers to:

The lower field intensity toward the anode in comparison to the cathode due to lower x_ray emissions from the target material at angles perpendicular to the x-ray beam

The anode surface is:

At an angle

Decreasing anode angle (smaller angle degree) =

Increased heel effect

Anode Angle and Anode Heel effect have a _________ relationship:

Inverse

Decreasing the anode heel effect (steeper)=

Increase anode heel effect

Decreasing SID: __________ anode heel effect

Increases anode heel effect (not as present at 72”)

Increasing the field size= _________ anode heel effect

Increases

Define Line focus Principle:

The relationship between the actual focal spot on the anode surface and the effective focal spot size

Actual focal spot size location:

Where electrons interact with the anode (target)

Effective focal spot size location:

Is what exits the tube and interacts with the patient

What size is the effective focal spot compares to the actual focal spot:

Smaller

What size is the actual focal spot size compared to the effective?

Larger

Decrease anode angle= ______ effective focal spot

Decrease

Increase anode angle= __________ effective focal spot

Increase

Two types of interactions that occur at the target (anode):

Bremsstrahlung and Characteristic

Target interactions both start with a _______ and end with a _________ that will exit the tube.

Electron, x-ray photon

90% of all production, (100% below 70 kVp):

Bremsstrahlung

The incident electron brakes before the nucleus and bends direction, the closer the nucleus the harder the break the higher energy of the photon

Bremsstrahlung

What is the K-Shell binding energy of tungsten?

69.5 keV or 70 keV

Can you identify the bremsstrahlung interaction on a video?

Yes or no

Can you identify the circuit in a picture?

Yes or no

The incident electron collides with a k shell electron crashing it out of orbit and causing a cascade of electrons to fall into each shell closer to the nucleus, each time the electron cascades it causes characteristic x-rays closer to the nucleus the higher the photon energy:

Cascading “hallmark” Cascade Effect

Select three properties of x-rays off of a list:

Travel in straight lines Electrically neutral (no mass) Heterogenous Travel at the speed of light (186,000 miles per second) (3 x 10^8 m/s) Capable of ionizing matter Cannot be focused by a lens Each photon carries its own energy (poly energetic)

Refers to the x-rays being produced by the x-ray tube and strike the patient

Primary beam

The primary beam is made up of:

Bremsstrahlung or Characteristic or both

Remnant means:

Remaining

Define remnant beam or exit radiation:

The remaining beam after it exits/leaves the patient

What is the remnant beam made up of?

Primary or secondary radiation

The type of secondary radiation that occurs when the beam intercepts an object causing the x-ray beam to be scattered

Scatter Radiation

Quality, energy, penetrability of the x-ray photons

kVp

kVp determines the:

Quality of the x-ray beam

Refers to the number, quantity of the x-ray beam:

mAs

Refers to the number of waves:

Frequency

Higher kVp= _______ energy

Higher

Higher kVp= _______ frequency

Higher

The distance between two successive peaks:

Wavelength

The higher the energy of the x-ray the ______ frequency

Higher

The distance between tops of the waves

Wavelength

High kVp= ____________ wavelengths

Short

Low kVp= __________ wavelength= ________ energy.

Long, less

Decrease wavelength, _________ frequency, _________ wavelength

Increase, increase

Frequency and wavelength have what type of relationship?

Inverse

kVp controls:

Subject Contrast Beam Quality Beam energy Beam Penetrability

Increasing kVp also _________ scattered photons reducing image quality

Increases

Increase kVp ______ electron energy, _______ x-ray energy

Increase, increase

The degree of density difference between two areas on a Radiograph

Subject Contrast

Short scale of Contrast (Short Gray Scale):

High Contrast Low kVp

Long Scale of Contrast (Long Gray Scale)

Low Contrast High kVp

Digital Image Contrast is controlled by the:

Look Up Table (LUT)

A processing algorithm built into the equipment that the technologist does not control:

LUT (Look up table) NOT controlled by kVp

Lower kVp settings use:

A long wavelength Lower Energy Lower Penetrating ability Less chance of scatter radiation Considered high contrast

______ kVp examinations penetrate fewer thicknesses and only have a few steps in between black and white (50-70 kVp)

Lower

Demonstrates fine bone markings and fractures better

Low kVp (small focal spot)

Low kVp Small focal spot High contrast

Short scale

Long scale of contrast have _______ shades of grey in between black and white.

Many (multiple)

Penetrate more thicker dense areas of anatomy

High kVp

Used for contrast barium

110 kVp Large Focal Spot High kVp

High kVp settings use:

Long scale of contrast A short wavelength Higher energy Higher chance of scatter radiation

Low contrast:

High kVp

Long scale of contrast:

Decreases image quality Increases patient dose Increases tech dose

Measurement of tube current

mAs

Increases the filament temperature which increases the electrons boiled off from thermionic emission

Increase mA

mA controls

Beam Quantity Receptor Exposure Patient Dose

What is the calculation for MA

mA x s = mAs

How many seconds are in each of the following milliseconds? 1,000 50 400

1,000 milliseconds = 1 second 50= 0.05 sec 400= .4 sec

Exposures made while the patient is breathing:

Orthostatic breathing techniques

If you don’t have enough mAs or have quantum mottle (Noise):

Double original mAs or increase by 30%

mAs will never have an effect on:

Contrast and Scatter

There are multiple ways to combine mA and seconds to equal the same mAs

mAs Reciprocity Law

The reciprocity law shows us that:

mA and time are inversely proportional

If seconds increases= ______ mAs

Decreased

If mA is doubled= _____ should be cut in half

Time

If mA is cut in half= _____ time

Double

An original exposure was made using 100 mA at .10 sec. A repeat exposure must be made using 200 mA while keeping the same receptor exposure. What is the new time required?

Original Exposure: 100 x .10= 10 mAs New exposure= 200 x ? = 10 mAs Double mA? Cut time in half! .05 seconds 200 mA x 0.5 seconds = 10 mAs

Most common beam retracting device used in radiography. It can be used for any field size

Variable-aperture collimator

Primary purpose of beam restriction is to:

Restrict the primary beam to the area of interest and decrease patient dose

The simplest type of beam restrict or, and is made up of lead-lined metal sheet attached to the x-ray tube head

Aperture diagram

These modifications are the aperture diagram. It had extended metal structure which produces a circular image

Cones and cylinders

Decrease collimation=

Light field is getting bigger

Increase beam restriction=

Increase collimation= decrease field of view= smaller light field

Increase Field of View=

Decrease collimation=larger light field

The size of your light field

Field of view

Light field that is limited to the IR placed in the Bucky tray

Positive Beam Limitation (PBL)

Increase in Patient Size=

Higher Absorption of the beam into the tissue

Used to control spatialize resolution:

Focal Spot Size

Produce less blurring and better visibility of detail (extremity work/ribs)

Small Focal Spot

Greater heat dissipating capacity

Large focal spot (chest and abdomen)

SOD equation

SID-OID

Increasing SID

Further away

Magnification of the part:

Size Distortion

For every _____ increase in OID a ______ increase in SOD should be used to compensate

1”, 7-8”

Meaghan Piretti X-ray Production/Equipment Flashcards

(130 cards)