Chapter 8 Bushong The Imaging System

Front 1

What is the function of the xray system?

Back 1

To provide a controlled flow of electrons intense enough to produce an xray beam appropriate for imaging

Front 2

What are the three components of the imaging system?

Back 2

1) xray tube
2) operating console
3) high voltage generator

Front 3

What does the operating console control?

Back 3

1) the voltage applied to the xray tube
2) the current through the xray tube
3) the exposure time

Front 4

What major parts does the high-voltage generator contain?

Back 4

1) high-voltage step up transformer
2)rectification circuit

Front 5

What is the range of Voltage for most diagnostic xray imaging systems?

Back 5

Voltage Range
25 - 150 kVp

Front 6

What is the general range of tube current for most diagnostic xray imaging systems?

Back 6

Current Range
100 - 1200 mA

Front 7

What is Peak kilovoltage controlled by?

Back 7

A series of electric taps on the autotransformer.

Front 8

How many windings does an autotransformer have?

Back 8

One

Front 9

What modes can an autotransformer work in?

Back 9

Step-Up Mode or
Step-Down Mode

Front 10

Where does the power to the primary side of the high voltage tranformer come from?

Back 10

Secondary side of the autotransformer

Front 11

What is the relationship of output voltage from the autotransformer to the turns ratio?

Back 11

Proportional to the turns ratio

Front 12

What is the principial purpose of the autotransformer?

Back 12

to Increase Voltage

Front 13

What type of energy does the autotransformer convert?

Back 13

Electrical Energy

Front 14

What type of energy does the autotransformer convert electrical energy into?

Back 14

Electrical Energy

Front 15

What is the principal purpose of the high-voltage transformer?

Back 15

Increase Voltage

Front 16

The voltage supplied to an x-ray imaging system is 220V. What is used to supply the voltage used by the xray tube?

Back 16

the High Voltage Transformer

Front 17

In the design of the autotransformer how many coils serve as the primary and secondary coils?

Back 17

A single coil

Front 18

What requires that constant voltage be supplied to the autotransformer?

Back 18

Selection of kVp

Front 19

What is required to stablize voltage?

Back 19

Line Compensation

Front 20

What is used to determine voltage before exposure?

Back 20

An autotransformer

Front 21

What is directly connected to the autotransformer?

Back 21

the kVp meter

Front 22

What are the taps on the windings of an autotransformer used to select?

Back 22

Line Compensation

Front 23

Where is the meter that monitors xray tube current physically located?

Back 23

on the Control Console

Front 24

What effect does the filament transformer have on current?

Back 24

It INCREASES current

Front 25

Where is the filament transformer usually located?

Back 25

with the High Voltage generator

Front 26

Where does the filament circuit begin and where does it end.

Back 26

It begins at the filament transformer and ends at the filament.

Front 27

What is the turns ratio of the filament transformer?

Back 27

< 1

Front 28

By what unit is Xray tube current is usually measured?

Back 28

mAs

Front 29

What are exposure timers?

Back 29

Precision devices that start and stop xray production.

Front 30

What are the four basic types of exposure timers

Back 30

1) Mechanical
2) Synchronous
3) Electronic
4) mAs

Front 31

Describe a mechanical timer.

Back 31

1) Operates by spring action
like a hand wound alarm
2) not very accurate
3) not used in modern equipment

Front 32

Describe synchronous timers.

Back 32

1) use a synchronous motor that operates @ 60 rps
2) shortest possible exposure time 1/60 s

Front 33

Describe electronic timers

Back 33

1) operates on an electronic resistive-capacitive circuit based on the time required to charge a capacitor
3)timers are accurate
4) allow exposure as short as 1 ms
5) can be used for serial radiography

Front 34

Describe mAs timers

Back 34

1) electronic timers that monitor the product of mA and time
2) terminate exposure when proper mAs is reached

Front 35

What is AEC?

Back 35

Automatic Exposure Control

Front 36

Describe Automatic Exposure Control.

Back 36

A radiation measuring device that terminates the xray exposure when enough radiation reaches the image receptor.

Front 37

CONTROL of the EXPOSURE TIME is always on what side of the high-voltage transformer?

Back 37

PRIMARY side

Front 38

The exposure timer on a three-phase radiographic imaging system will be ..

Back 38

electronic

Front 39

What uses an ionization chamber between the patient and the image receptor?

Back 39

An automatic exposure control (AEC) device.

Front 40

What device requires a BACKUP TIMER?

Back 40

An automatic exposure control (AEC) device.

Front 41

What measurement expresses xray tube current?

Back 41

coulombs/second

Front 42

What is required when designing an mA station?

Back 42

Precision resistors

Front 43

What does the control of focal spot size depend on?

Back 43

the ENERGIZED filament

Front 44

mA is a unit of ...

Back 44

electric current

Front 45

mAs is a unit of ...

Back 45

electric charge

Front 46

What is in the high-voltage SECTION of the xray imaging system.

Back 46

1) high voltage transformer
2) filament transformer
3) rectifier circuit

Front 47

Describe the function of the high voltage transformer.

Back 47

converts low voltage from the autotransformer to the required kVp

Front 48

Describe function of the filament transformer.

Back 48

reduces the voltage from the autotransformer to about 10V for heating the filament. At the same time the filament current is regulated to the range of 4 - 10A.

Front 49

Describe the function of the rectifier circuit.

Back 49

converts the alternating voltage into a direct voltage before use by the xray tube.

Front 50

What type of rectifier is contained in a typical high-voltage generator?

Back 50

Diode rectifier

Front 51

Pulses per second for Half-wave

Back 51

6o

Front 52

Pulses per second for Full-Wave

Back 52

120

Front 53

Pulses per second for Three-phase, 6 pulse

Back 53

360

Front 54

Pulses per second for Three phase, 12 pulse

Back 54

720

Front 55

Pulses per second for High Frequency

Back 55

up to 1000

Front 56

Percentage Ripple for Half-wave

Back 56

100

Front 57

Percentage Ripple for Full-wave

Back 57

100

Front 58

Percentage Ripple for Three-phase, 6 pulse

Back 58

13

Front 59

Percentage Ripple for Three phase, 12 pulse

Back 59

4

Front 60

Percentage Ripple for High Frequency

Back 60

1

Front 61

What does a change in voltage waveform from the primary side to the secondary side of the high voltage transformer produce a change in?

Back 61

Amplitude

Front 62

What control is used to raise or lower the VOLTAGE in the high voltage circuit?

Back 62

kVp Selector

Front 63

What level of voltage flows through the filament of the xray tube?

Back 63

low voltage

Front 64

What selector controls the filament circuit?

Back 64

mA selector

Front 65

Which side of the step-up transformer has more windings?

Back 65

the secondary circuit side

Front 66

The rectifiers are part of whih xray circuit?

Back 66

the secondary circuit

Front 67

The xray tube current is controlled by the ...

Back 67

Filament current

Front 68

The changing of alternating current to direct current is known as

Back 68

rectification

Front 69

What is the name of the closed path over which electric curret flows.

Back 69

Circuit

Front 70

What controls the incoming voltage to the autotransformer?

Back 70

Main breaker switch

Front 71

Which type of rectification will supply the xray tube with the greatest power?

Back 71

Full Wave

Front 72

What is the voltage supplied to the autotransformer called:

Back 72

Line Voltage

Front 73

WWhat is the most accurate timer?

Back 73

Electronic

Front 74

If the line voltages changes because of demands by other users, adjustments must be made in the ....

Back 74

voltage compensator

Front 75

What is the current indicated by the milliammeter?

Back 75

tube current

Front 76

Tapping the windings of the autotransformer to supply voltage to the stepup transformer is the pulse of ...

Back 76

the kVp Selector

Front 77

What is an advantage of three phase equipment over single-phase equipment?

Back 77

can achieve shorter exposure times

Front 78

Where in the xray circuit is the timer located?

Back 78

between the autotransformer and the step-up transformer.

Front 79

What type of current suppplies the xray tube?

Back 79

Pulsating direct current

Front 80

What is placed in a circuit in case the current surges during the exposure?

Back 80

Breaker Switch

Front 81

What test can be used to determine the accuracy of the rectification circuit and/or timer circuit?

Back 81

Spinning Top Test

Front 82

Examination tables and the xray tube can be angles and moved in various ways to allow..

Back 82

1)easy positioning of the patient
2) very controlled exposure of the desired body areas

Front 83

A suspension systems that holds the tube on one end of the arm and the image receptor on the other is called

Back 83

C-Arm

Front 84

The operating console contains circuits that are

Back 84

Low Voltage only

Front 85

Most mammography units operate with .... generators

Back 85

High Frequency

Front 86

The main function of the primary circuit is to ...

Back 86

Step up the AC volatage to the secondary circuit.