Conventional Fluoroscopy

Question 1

What is fluoroscopy?

Answer 1

The viewing a temporary, moving image for the purpose of diagnosis and treatment

Question 2

What are the main reasons for using fluoro?

Answer 2

• observe antomy in motion
• locate or position anatomical structures

Question 3

What is the exposure rate in fluoroscopy?

Answer 3

Lower than in radiography for an infividual image, but in total its much higher than x-ray because of the lenth of the exams

Question 4

What is automatic brightness control?

Answer 4

A unit built into the system designed to automatically adjust the mA and/or kVp when the unit moves over different areas of the body

Question 5

What does the image intensification tube do?

Answer 5

Converts the x-ray image to a light which is bright enough to be received by a video camera or CCD

Question 6

What is the first step of the image intensifier tube?

Answer 6

The xray enters the cathode end of the II tube and interacts with the input phosphor, which converts it to a light image

Question 7

What is the input phosphor made of?

Answer 7

Cesium iodide

Question 8

What is the second step of the II tube?

Answer 8

The light is absorbed by the photoemissive material in the photocathode and converted to an electron image

Question 9

What happens after the electrons are available?

Answer 9

They are accelerated toward the anode (output end) by the KV difference in cathode and anode

Question 10

What happens in the output phosphor screen?

Answer 10

the electron image is focused on the screen and convertes it to a small, bright light image

Question 11

What is the output phosphor screen made of?

Answer 11

Zinc cadmium sulfide

Question 12

How does the output phosphor size differ from the input phosphor size?

Answer 12

It is mich smaller

Question 13

What helps the electrons travel toward the output phosphor?

Answer 13

A focusing lends that uses postive charges to pull the electron while narrowing it

Question 14

What is the narrowing function of the focusing lens called?

Answer 14

Minification

Question 15

What is the ratio of the number of light photons emitted by the output phosphor to the xrays stiking the input phosphor called?

Answer 15

Flux gain

Question 16

Once the image is intensified what happens?

Answer 16

The intensidied image passes thorugh a bundle of fiber optics to a CCD or CMOS camera

Question 17

What is a CCD?

Answer 17

Charge couple device

Question 18

What is a CMOS?

Answer 18

Compementary metal oxide semiconductor

Question 19

What is the ratio of the square of the input phosphor to the square of the output phosphor called?

Answer 19

Minification gain
= Diameter of input phosphor ^2/ Diameter of output phosphor ^2

Question 20

What does minification gain do?

Answer 20

Makes the output image 35-80 times as bright as the input phosphor

Question 21

What is the total brightness in a fluoro image?

Answer 21

Brightness gain = minification gain x flux gain

Question 22

What is a summary of the process of conventional fluoro?

Answer 22

• X-ray energy converted to light energy by input phosphor
• Light energy converted to electrons by photocathode
• Electrons converted to light energy by output phosphor
• Light energy converted into electrons in TV tube
• Electrons converted into light energy on video monitor

Question 23

What are the two modes II tubes can operate in?

Answer 23

regular mode
- magnification mode

Question 24

What does magnification mode use in an II tube?

Answer 24

A smaller area of the input screen (6” vs 9”) which makes patient dose higher

Question 25

What are image intensifiers that can do magnification called?

Answer 25

Multi field or dual field intensifiers

Question 26

What improves with magnification mode in II's?

Answer 26

Spatial resoltion

Question 27

How is the FOV changed with magnifiers in II?

Answer 27

By adjusting the charge of the electrostatic lenses

Question 28

What does going down in multi field number represent?

Answer 28

An increase in magnification

Question 29

What determines the image quality of fluoro images?

Answer 29

The number of photons absorbed by the image intensifier

Question 30

What is the quality of an image intensification system defined by?

Answer 30

Resolution Scintillation Contrast Distortion

Question 31

What is scintillation?

Answer 31

Various amout light given off by absorbing x-rays

Question 32

What does scintillation cause?

Answer 32

Small flaws in the distribution of the brightness of an image, which causes noise

Question 33

What two ways can contrast be reduced in fluoro images?

Answer 33

- By photons that don't get absorbed by the input phosphor, but strike the output phosphor - light photons generated by the output phosphor traveling backwards

Question 34

How are conventional fluoro machines setup?

Answer 34

Xray tube is inside the table and the II is mounted above the patient

Question 35

How is collimation done in conventional fluoro?

Answer 35

By remove controls on the fluoro carriage

Question 36

How are remote fluor machines setup?

Answer 36

Have the II inside the tbale and the x-ray tube above the patient

Question 37

What are the differences in operation between a conventional fluoro machine and remote fluoro machine?

Answer 37

In conventional the dr operates the equipment tableside and in remote the dr operates outside the room

Question 38

When are mobile fluoro units used?

Answer 38

Primarily in the operating room to allow a sneak peak of orthopedic appliances