Week 3

Question 1

What is the relationship between anode heel effect and anode angle?

Answer 1

The relationship is inverse; as the angle decreases, the anode heel effect increases.

Question 2

What is the relationship between anode heel effect and SID?

Answer 2

The relationship is inverse; as SID decreases, the anode heel effect increases.

Question 3

What is the relationship between anode heel effect and field size?

Answer 3

The relationship is direct; as field size increases, the anode heel effect increases.

Question 4

What is beam divergence in x-ray production?

Answer 4

Beam divergence refers to the spreading out of x-ray photons as they travel from the tube, similar to light from a source.

Question 5

How does beam divergence affect image formation?

Answer 5

Beam divergence causes magnification and distortion of imaged structures and reduces beam intensity over distance.

Question 6

What principle explains the reduction in beam intensity over distance?

Answer 6

The Inverse Square Law states that intensity decreases proportionally to the square of the distance from the source.

Question 7

What happens to beam intensity when the distance is doubled?

Answer 7

When the distance to the receptor is doubled, the intensity is reduced to one-fourth of the original.

Question 8

How does the Inverse Square Law apply to radiography?

Answer 8

It helps radiographers adjust exposure settings when changing the Source-to-Image Distance (SID) to maintain image quality.

Question 9

What unit is used to measure radiation intensity in air?

Answer 9

Radiation intensity is measured in milligray (mGya) or microgray (uGya) in air.

Question 10

How does the Square Law differ from the Inverse Square Law?

Answer 10

The Inverse Square Law describes how beam intensity decreases with distance, while the Square Law adjusts exposure (mAs) to compensate for distance changes.

Question 11

Why is the Square Law important in radiography?

Answer 11

It ensures proper image brightness and quality when changing SID by adjusting mAs accordingly.

Question 12

What happens to mAs if SID is doubled?

Answer 12

If SID doubles, mAs must be increased by four times to maintain the same exposure.

Question 13

What is the purpose of the exposure maintenance formula (Square Law)?

Answer 13

The Square Law helps radiographers adjust exposure factors to maintain optimal x-ray beam intensity when the distance (SID) changes.

Question 14

What happens to magnification when OID increases?

Answer 14

Magnification increases as OID increases.

Question 15

What happens to magnification when SID decreases?

Answer 15

Magnification increases as SID decreases.

Question 16

What is shape distortion?

Answer 16

Shape distortion occurs when an object appears elongated or foreshortened due to beam divergence or positioning.

Question 17

What are the two types of shape distortion?

Answer 17

1. Elongation – Object appears longer than reality.
2. Foreshortening – Object appears shorter than reality.

Question 18

What causes elongation in radiographic imaging?

Answer 18

Elongation occurs when an object is positioned obliquely and opposite to the direction of the divergent beam.

Question 19

What causes foreshortening in radiographic imaging?

Answer 19

Foreshortening occurs when an object is positioned obliquely and aligned with the central beam.

Question 20

How can radiographers correct elongation?

Answer 20

Align the beam perpendicular to the object.

Question 21

How can radiographers correct foreshortening?

Answer 21

Adjust the object to be perpendicular to the beam.

Question 22

How can a flashlight be used to demonstrate magnification principles?

Answer 22

Moving the light source closer increases the shadow size (magnification).
Moving the light farther away decreases the shadow size (reducing magnification).

Question 23

What are the two main types of geometric distortion in radiography?

Answer 23

Size Distortion (Magnification) – Objects appear larger than their actual size.

Shape Distortion – Includes foreshortening (shortened appearance) and elongation (stretched appearance).

Question 24

How does Object-to-Image Distance (OID) affect magnification?

Answer 24

As OID increases, magnification increases, causing image blurring and reduced sharpness.

Question 25

How does Source-to-Image Distance (SID) affect magnification?

Answer 25

Decreasing SID increases magnification due to more beam divergence. Increasing SID reduces magnification and improves image accuracy.

Question 26

What are the standard SID values in radiography, and why are they used?

Answer 26

Standard SID values (122 cm & 180 cm) minimize and standardize magnification while reducing patient skin exposure.

Question 27

What are the two main functions of the anode angle?

Answer 27

Increases the area for electron interaction, reducing heat load. Reduces the effective beam width, improving image quality.

Question 28

What is the Line Focus Principle?

Answer 28

The Line Focus Principle allows a large actual focal spot for heat dissipation while maintaining a small effective focal spot for better image resolution.

Question 29

How does anode angle affect the effective focal spot?

Answer 29

A larger angle results in a larger effective focal spot. A smaller angle results in a smaller effective focal spot, improving image sharpness.

Question 30

What happens if the anode angle is too small?

Answer 30

If the anode angle is too small, electrons are absorbed at a higher rate, reducing x-ray photon production.

Question 31

What is the Anode Heel Effect?

Answer 31

The Anode Heel Effect occurs because x-ray photons on the anode side must pass through more material, reducing their energy and intensity.

Question 32

How does the Anode Heel Effect impact image exposure?

Answer 32

The anode side produces lower intensity x-rays. The cathode side produces higher intensity x-rays.

Question 33

How can radiographers use the Anode Heel Effect to their advantage?

Answer 33

Position thicker body parts under the cathode side to take advantage of the more intense x-ray beam.

Question 34

How does SID affect the Anode Heel Effect?

Answer 34

Shorter SID = More pronounced Heel Effect. Longer SID = Less noticeable Heel Effect.

Question 35

What is Focal Spot Blur?

Answer 35

Focal Spot Blur occurs because x-rays are emitted from a rectangular area rather than a single point, causing a blurred region on the periphery of the image.

Question 36

How does focal spot size affect image detail?

Answer 36

Small focal spot (0.5mm - 1.0mm) → Improves detail but is limited to low exposure values. Large focal spot (1.0mm - 2.0mm) → Used for higher exposure values but increases blur.

Question 37

How does focal spot blur vary across the image?

Answer 37

Blur is more pronounced on the cathode side. The anode side has a smaller focal spot, reducing blur.

Question 38

How can a technologist minimize focal spot blur?

Answer 38

Use the smallest focal spot possible for fine detail. Minimize OID to reduce blur.

Question 39

Why can’t the small focal spot be used for large exposures?

Answer 39

Using a small focal spot for large exposures can cause anode damage due to excessive heat load.

Question 40

What is attenuation in x-ray imaging?

Answer 40

Attenuation is the reduction in both quantity and quality of the x-ray beam due to interactions with matter. It is essential for creating a diagnostic image through differential absorption.

Question 41

What are the four types of photon interactions with matter?

Answer 41

1. Coherent Scatter 2. Compton Scatter (affects image quality) 3. Photoelectric Effect (affects patient dose & image contrast) 4. Photon Transmission (creates the image)

Question 42

What is Coherent Scatter?

Answer 42

Occurs with low-energy photons. Causes atomic excitation and emission of a photon in a different direction. Has minimal impact on image quality due to low energy.

Question 43

What is Compton Scatter?

Answer 43

Occurs when a photon interacts with an outer-shell electron, ejecting it and losing some energy. Causes ionization and scatter radiation. Reduces image contrast, contributing to radiation fog. Increases with part thickness, high kVp, and larger field size.

Question 44

What is the Photoelectric Effect?

Answer 44

Occurs when a photon interacts with an inner-shell electron, completely absorbing the photon’s energy. Causes ionization and photoelectron emission. Increases patient dose but improves image contrast.

Question 45

What is Photon Transmission?

Answer 45

Some x-ray photons pass through matter without interaction. These photons reach the receptor with full energy and contribute to image contrast.

Question 46

How do Compton Scatter and the Photoelectric Effect contribute to imaging?

Answer 46

Compton Scatter → Decreases image contrast due to radiation fog. Photoelectric Effect → Increases image contrast but also increases patient dose. Only transmitted photons create the actual image.

Question 47

How does kVp affect scatter?

Answer 47

Higher kVp → More Compton Scatter → More fog, less contrast. Lower kVp → More Photoelectric Absorption → Higher contrast, but more patient dose.