X-ray Emission Spectrum Ch 7 Flashcards Preview

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Flashcards in X-ray Emission Spectrum Ch 7 Deck (39):
1

The primary beam is characterized by...

Quantity and Quality

2

What is the quantity of the beam?

The number of x-rays in the beam

3

What is the quality of the beam?

The penetrability of the beam

4

Quantity is also known as...

Intensity and radiation exposure

5

What is quantity measured in?

Roentgens or milliroentgens

6

Quantity is ______ proportional to mAs.

Directly

7

What is the ratio of x-ray quantity and mAs?

I1 = mAs 1
_________
I2= mAs2

8

If you double the mAs, what happens to the intensity?

You double the intensity

9

What is the ratio of x-ray quantity and kVp?

I1= (kVp1)2
_________
I2 = (kVp2)2

10

Quantity is proportional to the _____ of the ratio of the kVp.

Square

11

What is used to determine how kVp affects the quantity?

15% rule

12

What is the 15% rule?

If you increase the kVp by 15% you will double the mAs/ density on the image

13

What would happen to the density if you decrease the kVp by 15%?

You would half the mAs/ density

14

Quantity varies _____ as the square of the distance from the target.

Inversely

15

What is the square law?

mAs1 = (SID1)2
____________
mAs2 = (SID2)2

16

To maintain a constant exposure to the image receptor when SID changes, _____ must be increased by the SID2.

mAs

17

What are factors that affect quantity?

1. mAs
2. kVp
3. Distance
4. Filtration

18

What does filtration do to x-rays?

The quantity is reduced by removing low energy x-rays.

19

Why would you want to remove low energy photons?

Because they only increase pt. dose

20

What factors affect quality?

1. kVp
2. Filtration

21

Factors that affect x-ray beam quality also influence radiographic ________.

Contrast

22

______ and mAs do not affect quality.

Distance

23

In radiography the quality of x-rays are measured in _____.

HVL

24

The HVL of an x-ray beam is the thickness of absorbing material necessary to reduce the x-ray _____ to 1/2 of its original value

Intensity

25

A diagnostic x-ray beam usually has an HVL in the range of _____ AL or 3-6 cm of soft tissue

3-5mm

26

Quality is increased as ___ is increased.

kVp

27

An increase in ______ will effect the x-ray emission spectrum to shift to the high energy side (to the right of the curve) indicating an increase in the effective energy of the beam.

kVp

28

An increase in kVp also causes an increase in ____.

HVL

29

Quality is increased with increased _______.

Filtration

30

What is the primary purpose of filtration?

To remove low energy photons

31

Why is aluminum primarily used?

1. Efficiency- Photoelectric effect
2. Availability
3. Cost

32

What are the types of filtration?

1. Inherent filtration
2. Added filtration
3. Compensating filters
4. Total filtration

33

What is inherent filtration?

Glass or metal enclosure of the tube

34

The tube starts with ____ AL equivalent filtration.

.5mm

35

Inherent filtration will increase with age due to...

Sunburning

36

What is added filtration?

Something that is placed between the tube and the collimator (usually AL)

37

What are compensating filters?

Used to produce a uniform intensity on the image receptor when imaging body parts of varying thicknesses

38

How is total filtration found?

By adding the thicknesses of the filters in the tube, collimator housing and compensating filters

39

What is the most common compensating filter?

Wedge