3. Radiation Physics

Question 1

What is electricity in the context of X-ray production?

Answer 1

Flow of electrons through a conductor.

Question 2

What does current measure, and what is its unit?

Answer 2

Amount of electrons flowing per second, measured in amperes (A).

Question 3

What is voltage and how is it measured?

Answer 3

Difference in electrical potential energy between two points, measured in volts (V).

Question 4

What is an impulse in alternating current (AC)?

Answer 4

Alternating current switches direction 60 times per second; X-rays are produced in the positive half of the cycle.

Question 5

What is half-wave rectification in X-ray production?

Answer 5

Produces X-rays during one half of the current cycle; less efficient, 60 bursts per second.

Question 6

What is full-wave rectification in X-ray production?

Answer 6

Produces X-rays during both halves of the cycle; more efficient and continuous beam.

Question 7

How can the efficiency of X-ray production be improved?

Answer 7

Convert AC to DC, use full-wave rectification and high-frequency power supply.

Question 8

What are the benefits of using constant potential and direct current in X-ray production?

Answer 8

Shorter exposure times and consistent beam intensity with higher mean energy and reduced radiation dose.

Question 9

How are X-rays produced?

Answer 9

By deceleration of high-speed electrons upon interaction with high atomic number material like tungsten.

Question 10

What are the two mechanisms of X-ray formation?

Answer 10

Bremsstrahlung radiation and characteristic radiation.

Question 11

What is bremsstrahlung radiation?

Answer 11

Radiation produced by electrons slowing down or stopping near a tungsten nucleus.

Question 12

What are the two types of bremsstrahlung interactions?

Answer 12

Near miss: Electron deflected, losing energy as X-rays. Head-on collision: Electron stops, producing maximum energy X-rays.

Question 13

What happens in characteristic radiation?

Answer 13

An electron ejects an inner-shell tungsten electron; vacancy filled by higher shell electron releasing X-ray energy.

Question 14

What is a key feature of characteristic radiation?

Answer 14

Depends on atomic number of tungsten and shells involved, with discrete energy levels.

Question 15

What percentage of diagnostic X-ray beams is made up of characteristic radiation?

Answer 15

0.3

Question 16

What are the key differences between bremsstrahlung and characteristic radiation?

Answer 16

Bremsstrahlung is continuous and increases with kV and Z number. Characteristic is discrete, specific to tungsten.

Question 17

What are the benefits of full-wave rectification and constant potential in X-ray production?

Answer 17

Efficient production with shorter exposure times and decreased radiation dose.

Question 18

What is the primary source of X-rays in dental imaging?

Answer 18

Bremsstrahlung radiation.

Question 19

What contributes 30% to the overall X-ray beam?

Answer 19

Characteristic radiation.

Question 20

What determines the energy levels of characteristic radiation?

Answer 20

The difference in binding energy between electron shells.