X-ray Production And The Tube Head

Question 1

What is an atom?

Answer 1

A particle of matter with a nucleus containing protons and neutrons, surrounded by electrons.

Question 2

What particles are found in the nucleus of an atom?

Answer 2

Protons and neutrons.

Question 3

What is the charge of protons and neutrons?

Answer 3

Protons are positively charged; neutrons are uncharged.

Question 4

What is the charge of electrons?

Answer 4

Electrons are negatively charged.

Question 5

What does it mean if an atom loses an electron?

Answer 5

It becomes positively charged.

Question 6

What does it mean if an atom gains an electron?

Answer 6

It becomes negatively charged.

Question 7

What is an ionised atom?

Answer 7

A charged atom resulting from the loss or gain of electrons.

Question 8

What is the basic method of X-ray production?

Answer 8

When moving electrons are slowed down or stopped, energy is converted into X-rays, with the rest lost as heat.

Question 9

What percentage of energy is typically converted into X-rays during production?

Answer 9

Less than 1%.

Question 10

What percentage of energy is lost as heat during X-ray production?

Answer 10

99%.

Question 11

What is the first stage in the production of X-rays?

Answer 11

Production of electrons through thermionic emission from a heated tungsten wire filament.

Question 12

What happens in the second stage of X-ray production?

Answer 12

Electrons are repelled by a huge negative charge (cathode) and accelerate towards a huge positive charge (anode).

Question 13

What is the role of the anode in an X-ray tube?

Answer 13

It is given a huge positive charge to attract and accelerate electrons.

Question 14

What occurs in the third stage of X-ray production?

Answer 14

Electrons are stopped abruptly at the anode, releasing energy as heat and X-rays.

Question 15

How is heat dissipated in an X-ray tube?

Answer 15

Quickly dissipated by copper, which is a good conductor of heat, to cooling fins set in an oil bath.

Question 16

What is the target area at the anode set at?

Answer 16

20’ to the vertical

Question 17

What does the effective focal spot represent?

Answer 17

The X-ray beam appears to have come from as small an area as possible

Question 18

Why is it important for the effective focal spot to be small?

Answer 18

To produce a sharp radiographic image

Question 19

What does fine focus produce?

Answer 19

A smaller actual and effective focal spot

Question 20

What is fine focus good for?

Answer 20

Small areas such as the limbs

Question 21

What are the limitations of using fine focus?

Answer 21

There are limitations to the exposure factors due to concentrated heat

Question 22

What does coarse or broad focus produce?

Answer 22

Larger actual and effective focal spots

Question 23

What is coarse focus good for?

Answer 23

Larger areas such as the abdomen

Question 24

What is the trade-off when using coarse focus?

Answer 24

Higher settings can be used, but the overall image is less sharp

Question 25

Fill in the blank: A smaller filament produces a smaller beam, resulting in a smaller _______.

Answer 25

[actual and effective focal spot]

Question 26

What is the primary beam in X-ray generation?

Answer 26

The primary beam is the X-ray beam produced through a window in the casing, while X-rays traveling in other directions are absorbed by the casing.

Question 27

Why are low energy or 'soft' X-rays considered potentially harmful?

Answer 27

Low energy or 'soft' X-rays are not powerful enough to penetrate through the patient and may be absorbed or scattered.

Question 28

What material is used as a filter across the window of the primary beam?

Answer 28

Aluminium is used as a filter to absorb low energy X-rays.

Question 29

What is the function of the rotating anode in X-ray tubes?

Answer 29

The rotating anode spreads the heat produced over a wider area, allowing for higher X-ray output without overheating.

Question 30

At what angle is the target set in a rotating anode X-ray tube?

Answer 30

The target is set at 20 degrees to the vertical.

Question 31

What is the range of speeds at which the disc in a rotating anode X-ray tube rotates?

Answer 31

The disc rotates at speeds of 3,000 to 10,000 revs per minute.

Question 32

What is the significance of molybdenum in the construction of a rotating anode X-ray tube?

Answer 32

Molybdenum is a poor conductor used to prevent the motor from overheating.

Question 33

How is heat lost in a rotating anode X-ray tube?

Answer 33

Heat is lost by radiation through the vacuum to the oil bath.

Question 34

In which type of X-ray machines are rotating anode X-ray tubes typically found?

Answer 34

Rotating anode X-ray tubes are found in more powerful machines.

Question 35

What does altering the milliamperage (mA) control affect?

Answer 35

Altering the mA control affects the current through the tungsten filament, which influences the degree of heating and the quantity of X-rays produced.

Question 36

Fill in the blank: Increasing the mA leads to _______.

Answer 36

increased heat

Question 37

Fill in the blank: Increased heat means more _______.

Answer 37

electrons

Question 38

What does kilovoltage control (kV) affect?

Answer 38

The potential difference between the anode (+ve end) and cathode (-ve end) ## Footnote Increasing kV means electrons have more energy to penetrate tissues more effectively.

Question 39

How does increasing kV impact x-ray quality?

Answer 39

It improves the quality (penetrating power) of the x-rays ## Footnote Higher kV allows for better penetration through thicker tissues.

Question 40

What does the timer (s) control in x-ray machines?

Answer 40

The amount of time the kV is applied ## Footnote This affects the duration the anode is positive and the cathode is negative.

Question 41

How does increasing the timer impact x-ray production?

Answer 41

More electrons have the chance to cross the tube head, resulting in more X-rays produced ## Footnote Longer exposure times lead to increased x-ray output.

Question 42

What are the two stages of most modern exposure buttons?

Answer 42

1. Half-way depression heats the filament 2. Full depression applies the kV ## Footnote This design helps manage exposure safely.

Question 43

What is a characteristic of older machines' exposure buttons?

Answer 43

They have single stage exposure buttons that apply the kV ## Footnote Older machines heat the filament fully once switched on.

Question 44

What should be done with older machines after use?

Answer 44

They should be switched off immediately after use ## Footnote This prevents burnout of the filament.