פוטוגרפיה מצגת 24 23

Front 1

What is the advantage of fleuroscopy?

Back 1

• images internal organs in real time
• dynamic, taken over time
• shows movement
• can use contrast (drink or injection)

Front 2

When do the colors switch in a fluoroscopy?

Back 2

When recording

Front 3

How do the colors appear in a fleuroscopy?

Back 3

• Image appears positive--parts are dark
• bones (absorb most radiation) appear black
• parts that absorb less radiation (lungs, tissue) appear white
• recording it flips the colors to make it negative

Front 4

What are the eye sensors?

Back 4

• cones for seeing light
• rods for seeing dark

Front 5

How do the cones work?

Back 5

In daylight we can react to a wide range of light (strong light doesn't bother us)

Front 6

How do the rods work?

Back 6

Start to work in dark, pupil widens, we become sensitive to low levels of light

Front 7

What are the two main jobs of fluoroscopy?

Back 7

• show dynamic movement (heart beating...)
• navigate organs (change positions during imaging to see a specific organ)
  

Front 8

What type of radiation is used in fluoroscopes?

Back 8

xrays

Front 9

How do fluoroscope images appear?

Back 9

displayed on tv screen that shows several pictures/second (video), image as positive opposite of reality (bones show dark, lungs white)

Front 10

Because radiation is given over time, fluoroscopes must use ___ MA and ___ ___ ____.

Back 10

low, KV as needed

Front 11

Quality of fluoroscope images are ____ than xrays.

Back 11

worse (bc MA is low)

Front 12

What unit measures the light given off in fluoroscopes?

Back 12

lumens (.02 lumens we use rods, take a while to see)

Front 13

What type of screens are used in fluoroscopes?

Back 13

zinc cadium sulfide

Front 14

What is the mean source of exposure to staff in a fluoroscope?

Back 14

direct beam, NOT patient

Front 15

What is used to improve the light in fluoroscopes?

Back 15

image intensifiers

Front 16

What parts make up a fluoroscope?

Back 16

(from bottom up)

• tube
• collimator
• (patient)
• image intensifier
• Cine camera (for recording)
• TV camera (for displaying)
• Video output

Front 17

How does the image intensifier work in a fluoroscope?

Back 17

Made from glass vacuum tube, one part wider, has four parts:

1. input window: a) phosphor screen from CSI (x>light) b) photocathode (light>e-)
2. Electron lenses: direct e- toward output
3. output anode
4. output phosphor screen (e->light>ADC)

Front 18

In a fluoroscope, the photocathode produces e- based on the ___ of the ___ and not the ___ of the ___.

Back 18

power of the light, not the amount of photos (since MA is low)

Front 19

In fluoroscope, one xray may may ___ photo-electrons.

Back 19

50

Front 20

In a fluoroscope, the ___ must be close to the ___.

Back 20

image intensifier, patient

Front 21

Adding light to a fluoroscope image is known as the _____ _______.

Back 21

brightness gain

Front 22

The brightness gain can be achieved in what two ways?

Back 22

• flux gain (more electrons, 1 xray>50 e-)
• minificaiton gain (reducing the size of the output screen compared to the input screen)

Front 23

What is the calculation for the flux gain?

Back 23

# photoelectrons/#xrays

(=x50)

Front 24

What is the calculation for the minification (optic) gain?

Back 24

[diameter of input screen/diameter of output screen]squared

(can be =x144, for ex.)

Front 25

How does magnification work in fluoroscopes?

Back 25

small FOV>magnified image

large FOV>less magnified image

(xrays come through pt first before hitting image intensifier)

more magnification=more radiation to pt+darker image

Front 26

collimation -

magnification ?

Back 26

collimation -

magnification+

Front 27

If the FOV is too big in relation to the output screen, only the e- in the center are read, and ____ occurs.

Back 27

distortion and darkness around edges

Front 28

What is 6" mode?

Back 28

magnification

Front 29

If not enough e- come to the image intensifier, the ___ kicks in.

Back 29

ABC automatic brightness control

Front 30

What happens when the ABC kicks in?

Back 30

When less radiation is received, ABC compensates by generating more x-rays (more more exposure) and making them more penetrating (reduces contrast)

Front 31

What is SNR?

Back 31

signal to noise ratio (measures noise. we want this to be high)

Front 32

If collimation is good:

? quality

? SNR

? radiation

? scatter

Back 32

If collimation is good:

+ quality

+ SNR

- radiation

- scatter

Front 33

What helps improve resolution in fluoroscopes?

Back 33

collimation, centering, image intensifier close to body

Front 34

What types of distortion occur in fluoroscopes

Back 34

• pin cushion
• vignetting (darker on edges)

(can reduce both by moving ii close to body)

Front 35

How can we improve the noise in a fluoroscope image?

Back 35

raise MA

Front 36

What is continuous fluoroscopy?

Back 36

giving radiation for a long time, uses MA .5-5 depending on size of organ and ability of system, will beep after 5 min

Front 37

What is pulsed fluoroscopy?

Back 37

Used to reduce radiation and improve resolution, can set how many pulses per second