Control Factors/ Line-Focus Principle

Question 1

What does mAs determine?

Answer 1

the number of electrons emitted from the filament and the rate in which these electrons (-) are attracted to the anode (-)

Question 2

Radiographically kV (kilovoltage) controls density but primarily controls?

Answer 2

Contrast

Question 3

Contrast provides what on a radiograph?

Answer 3

Various shades of gray on a radiograph

Question 4

When electrons strike the _______ of the anode and interact with the tungsten metal, x-rays are produced

Answer 4

Target

Question 5

What is the focus or focal spot?

Answer 5

Area of anode in which the electron beam converts to a x-ray beam

Question 6

X-rays are ___________ when electrons interact with the tungsten target. The metal housing absorbs most X-rays emitted in any direction other than the ______ or _______.

Answer 6

• emitted in all directions (Isotropic)
• window
• port

Question 7

What factors do we control?

Answer 7

mAs and kV

Question 8

The product of electrons being emitted from the filament and the rate in which they travel from cathode to anode is_____?

Answer 8

mAs

• higher mAs = more electrons
• more electrons = more x-rays
• Radiographically, more x-rays, the darker the x-ray film (density)

Question 9

The energy or penetrating ability of x-ray is controlled by ______?

Answer 9

kV

Question 10

Stronger x-rays due to kV produce?

Answer 10

• Shorter Wavelengths
• Higher Frequencies
• Greater Penetrating Abilities

Question 11

Weaker x-rays due to kV produce?

Answer 11

• Longer Wavelengths
• Lower frequencies
• Lesser Penetrating Abilities

Question 12

Useful kV ranges from __________?

Answer 12

40-150 kV

• 40 kV for smaller body parts
• 80 kV for larger body parts

Question 13

mAs and kV are used in conjunction to___________?

Answer 13

produce an acceptable radiograph

Question 14

What two concepts are applied in the Line-Focus Principle?

Answer 14

1. Actual focal spot (actual focus)
2. Effective focal spot (effective focus)

Question 15

What is an actual focus spot (actual focus)?

Answer 15

The area where the electron beam actually strikes the target

Question 16

What is an effective focal spot (effective focus)?

Answer 16

The same area on the target where electrons are converted into X-rays

Question 17

Why is the line focus principle important?

Answer 17

Important in formation of a sharper radiographic image

Question 18

___________ the angle of the anode minimizes the size of the (projected) x-ray beam (and the effective focal spot), therefore improving _________.

Answer 18

• Decreasing
• Detail

Question 19

The _______ (________) the target angle, the smaller the ___________, therefore the _______ the projected x-ray beam.

Answer 19

• smaller (steeper)
• effective focal spot
• tighter

Question 20

Even when a larger filament is used, the ________ result is that of a smaller focal spot meaning_________

Answer 20

• effective
• better detail