Filtration and Collimators

Question 1

Collimation

Answer 1

blocks unnecessary radiation outside of the desired exposure field

Question 2

Increasing collimation ___________ patient dose and ___________ image quality

Answer 2

decreases; increases

Question 3

Collimation reduces _________ ___________.

Answer 3

scatter radiation

Question 4

Define Beam Restrictor & give example

Answer 4

restricts size of beam without options of adjustment

Aperture Diaphragm

Question 5

Define Beam-limiting Device and give example

Answer 5

device that restricts the size of x-ray field with options of adjustment

Variable-Aperture Collimator

Question 6

Aperture Diaphragm

Answer 6

beam restrictor that has a lead or lead-lined metal diaphragm attached to x-ray tube head

designed to cover just less than size of IR

Question 7

Cones and cylinders

Answer 7

modifications of the aperture diaphragm

restricts useful beam to the required size

Question 8

Variable-Aperture Collimator

Answer 8

most common type of beam-limiting device used in radiography

2 different stages of shuttering blades to control beam

Question 9

What is the first-stage shuttering blade control?

Answer 9

1. blades protrude from top of collimator into the x-ray tube housing

helps control off-focus radiation

Question 10

What is the second-stage shuttering control?

Answer 10

2. shutters work in pairs and are independently controlled, allowing for rectangular and square fields (knobs)

Question 11

What do Positive Beam-Limiting (PBL) devices do?

Answer 11

automatically adjusts the collimation to match the detector size

Question 12

How much kVp is required to have 2.5 mm Aluminum equivalent of filtration

Answer 12

70

Question 13

Filtration

Answer 13

process that removes low energy photons from the x-ray beam

Question 14

Filtration decreases _________ and increases _________.

Answer 14

quantity; quality

Question 15

Inherent filtration

Answer 15

actual glass part of the tube that is 0.5 mm Al equivalent

Question 16

Added filtration

Answer 16

filtration outside of the x-ray tube

mirror is 1.0 mm Al equivalent and reflects collimator light onto patient
addition 1.0 mm Al equiv between tube housing and collimator

Question 17

An additional 1 mm Al filter is inserted between what?

Answer 17

x-ray tube housing and collimator

Question 18

Total Filtration

Answer 18

Inherent filtration (0.5 mm) + Added filtration (2.0 mm) = 2.5 mm Al equivalent

Question 19

What is the primary purpose of using filtration?

Answer 19

to decrease patient dose