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D2: 621 Radiology > Principles of Radiology > Flashcards

Flashcards in Principles of Radiology Deck (46)
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1

Can xrays be focused on a single point?

No

2

What property of an xray allows it to penetrate

Short wavelength

3

What produces an x ray?

Two electrodes in a glass vaccum tube

4

Which is the positive Electrode?

Anode, the TARGET of negative electrons

5

Which is the negative Electrode?

Cathode, the expeller of negative electrons

6

What does the cathode consist of

Tungsten filament wound in molybdenum cup

7

How does the cathode make electrons?

When the tungsten is heated it boils off electrons

8

What is the process of "boiling off" electrons that the cathode goes through when heated?

Thermionic emission

9

What is the anode made of

Copper for heat conduction and tungsten to produce radiation

10

What percent of the xray kinetic energy produced by the cathode is turned into heat?

99%

11

What are the 3 ways an x ray can interact with a patient?

Scattered
Absorbed
Transmitted

12

Why are scattered x rays bad?

They produce fog on a film
They are a source of exposure for patients

13

What happens when an x ray scatters?

It changes direction and has its energy lowered

14

What is another word to describe an absorbed xray?

Attenuated

15

What determines an xray's absorbtion?

Wavelength/kilovoltage
Tissue thickness
Atomic Number
Density

16

What color does an absorbed x-ray produce on the film?

White

17

What measurement refers to the amount of x-rays being directed at the patient?

mA

18

What measurement is the penetrating power of the x-ray beam?

kVp

19

What is meant by the term "dead man switch"

It means you have to depress the button to make x-rays....you can't leave the switch on passively

20

What is the formula for the inverse square law?

I = 1/d^2

21

What is the inverse square law?

The intensity of the radiation varies inversely with the square of the source-film distance

22

What is SFD?

Source-Film Distance

23

According to the inverse square law, what happens to the intensity of the beam if the SFD is doubled?

Intensity decreases by 4x

24

Why does the intensity of the beam lessen as the SFD is increased?

There is more time for the x-rays to disperse which makes the beam less focused.

25

What happens that causes dark/black areas to develop on image?

Primary photons are transmitted through the tissue and are received by the film

26

Why are absorbed x-rays also called attenuated x-rays?

Because the intensity of the beam is reduced as it passed through tissues. Photons are absorbed by the tissue thereby removing them from the beam

27

What will result in full beam attenuation

Metallic restorations

28

What are the two most attenuating natural tissues

Enamel and Cortical bone

29

What is the letter designating the fastest speed film?

F

30

What determines the diagnostic quality of Radiographs

The balance between the visibility and sharpness of the image