Physics - Chapter 6 Flashcards by Gracie Costello

What kvp do imaging systems usually operate between?

25-150 kvp

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What is the tube current in an imaging system?

100-1200mA

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What shape is an xray couch/table?

Flat or curved

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How far can a fluoroscopy table tilt toward the feet?

90 degrees

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How far can a fluoroscopy table tilt toward the head?

30 degrees

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What is a common material for an xray table to be made of?

Carbon Fiber

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What are the 3 principle part of an xray imaging system?

Xray tube
Operating console
High voltage generator

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What does Theo operating console allow technologists to control?

Xray tube current and voltage

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What is xray quantity?

Intensity (mAs)

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What is xray quality?

Penetrability (kvp)

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How many volts are xray imaging systems designed to operate at?

220V
Some can operate at 110V or 440V

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What percent can the voltage vary by in a hospital? Why?

Up to 5%
Electric power companies are not capable of providing 220V accurately and continuously

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What part of the operating console measure the voltage provided to the xray imaging system and adjusts that voltage precisely to 220V?

Line compensator

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Has only one winding and one core

Autotransformer

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Designed to supply a precise voltage to the filament circuit and to the high voltage circuit of the xray imaging system

Autotransformer

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T/F
The primary voltage and the secondary voltage in an Autotransformer are directly related to the number of turns of the transformer enclosed by the respective connections

True

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What does the major kvp selector do?

Gives a broad selection of kvp technique

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What does the minor kvp selector do?

Fine tunes the selected technique

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What is the filament current measured in?

Amperes (A)

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What current do filaments usually operate at?

3-6A

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Tube current

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Tube voltage

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Line compensation

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Lower the voltage for safer use and manipulation

Autotransformer

What is the full name for a filament transformer?

Filament heating isolation step-down transformer

What does the filament transformer step the voltage to?

Approx. 12V

What is the current and voltage in the primary windings of a filament transformer?

0.5A - 1A 150V

What is the current and voltage in the secondary windings of a filament transformer?

5A - 8A 12V

What are the most accurate type of timer?

Electronic

Uses synchronous motor as timing mechanism Minimum exposure time = 17 ms

Synchronous

Monitors the product of mA and time Terminates exposure when specific mAs is obtained

Milliampere-second timer

Measures quantity of radiation that reaches the IR Exposure automatically terminates when required intensity has reached IR

AEC

What are the 3 parts of a high voltage generator?

High voltage transformer Filament transformer Rectifiers

The process of converting AC to DC

Rectification

What type of transformer is the high voltage transformer?

Step up

What is the turns ratio of a high voltage transformer usually between?

500:1 and 1000:1

What is responsible for increasing the output voltage from the autotransformer to the kvp necessary for xray production?

High voltage generator

What is the oil primarily used for in a high voltage generator?

Primarily used for electrical insulation

What is the primary voltage in a high voltage transformer measured in?

Volts

What is the secondary voltage measured in in a high voltage transformer?

Kilovolts

What is the primary current measured in in a high voltage transformer?

Amperes

What is the secondary current measured in in a high voltage transformer?

Milliamperes

What type of current is required for an xray tube?

What is required to ensure that electrons flow from cathode to anode only

Voltage rectification

What results from single phase power?

Pulsating xray beam

What is a disadvantage of a single phase power supply?

Xrays produced during the lower part of the voltage cycle have low penetrability

Multiple voltage waveforms are superimposed on one another, resulting in a waveform that maintains a nearly constant high voltage

Three phase power supply

What are the limitations of three phase power supply?

Initiation time and extinction time

Generator producing a nearly constant potential voltage waveform, improving image quality and lowering patient dose

High frequency

What is the converted frequency in a high frequency generator?

500-25 000 Hz

Variation between minimum and maximum voltage

Voltage ripple

T/F Less voltage ripple leads to better beam quality/quantity

True

100% voltage ripple

Single phase

14% voltage ripple

Three phase, six pulse

4% voltage ripple

Three phase, twelve pulse

1% voltage ripple

High frequency

High voltage generator power(kW) = maximum tube current (mA) at 100kvp and 100ms

Power rating

What is the power rating for basic radiography?

30-50kW

What is the power rating for interventional radiography?

Up to 150kW