Physics: Flouroscopy (Formulas, Doses And Stuff To Memorize)

Front 1

How many rads for a 2 minute upper GI

Back 1

5-15 rads (question answer is 6 roetgens)

Front 2

Normal amount of mA for flouro

Back 2

0.5 – 5 mA
Usually 1 – 3 mA

Front 3

Normal amount of mA for spot films

Back 3

100 mA or higher

Front 4

If the tube is operated above 125 kVp, what size Al eq is required

Back 4

3mm

Front 5

Source to table top distance

Back 5

Cannot be less than 12” and should be 18”
Mobiles are required to be at least 12”
Fixed units, 15”

Front 6

protection of the table top

Back 6

Less than 1 mm Al eq at 100 kVp

Front 7

The primary protective barrier

Back 7

The II is the primary barrier and must have 2 mm Pb eq for systems operating above 125 kVp

Front 8

Lead equivalent of the bucky slot cover

Back 8

Automatically covered, 0.25 mm Pb eq
(protects penis)

Front 9

Lead equivalent of protective curtains

Back 9

0.25 mm Pb eq

Front 10

Amount of scatter at 1 ft

Back 10

Scatter at 1 foot can reach 500 mrad/hr

Front 11

Amount of exposure rate

Back 11

Cannot exceed 5 rad/minutes

Front 12

types of artifacts

Back 12

Distortion
Size, shape, pincushion
Lag
Vignetting
Less bright at the edges than center of image
Magnification tubes, Multi-mode
Variable FoV

Front 13

Photospot camera dose

Back 13

½ to 1/3 dose of convent. Cass

Front 14

Cine camera dose

Back 14

Per frame basis 10 x the dose than fluoro

Front 15

dosage with change of II FOV

Back 15

Front 16

Advantages of medium/high frequency generator

Back 16

Relatively high mA
Higher effective kVp
Near constant potential
Less ripple

Front 17

How many photons/ray from input screen

Back 17

1 X Ray photon creates  3,000 light photons

Front 18

What percent of light rays are converted into electrons

Back 18

only 10 to 20% of light photons are converted into photoelectrons

Front 19

brightness gain

Back 19

BG is the product of minification gain and flux(electronic) gain

Front 20

flux gain

Back 20

Caused by the conversion efficiency of the output phosphor and the acceleration of the electrons across the II

Front 21

How much is the flux gain

Back 21

Flux gain is usually between 50 and 150.

Front 22

What is minification gain

Back 22

Minification Gain
Input phosphor dia.2/output phosphor dia2

Front 23

How much does brightness gain deplete annually

Back 23

Brightness gain will deteriorate 10% annually

Front 24

What percent of the light goes to the video camera

Back 24

10% of the output light goes to the vidicon (video camera) the remainder goes to the photospot device

Front 25

ABC

Back 25

Increase mA increase brightness; direct relationship
Increase kVp 10% double brightness

Front 26

Places where brightness is sensed for the abc

Back 26

II photocathode current
Television camera signal sensing
Lens coupled phototube sensing

Front 27

types of abc settings

Back 27

Variable mA, preset kVp
Set the kVp and the unit adjusts mA
Variable mA with kVp following
If the mA range is exceeded the unit will automatically adjust the kVp to compensate
Variable kVp, preset mA
Set the mA and the unit adjusts kVp
Variable kVp, variable mA

Front 28

horizontal resolution

Back 28

Bandwidth or bandpass
Increase frequency bandwidth increase horizontal resolution

Front 29

vertical resolution

Back 29

Determined by number of scan lines
Kell factor
Ratio of vertical resolution and scan lines

Front 30

cinefluoroscopy

Back 30

Synchronization
Camera shutters open at the same rate as x-ray pulses

Front 31

pulsed flouroscopy

Back 31

Variable frame rates are possible with a corresponding decrease in patient dose

Front 32

Spot film

Back 32

Dose 20 – 50 X higher per frame than fluoro because of higher mA

Front 33

Boost fluoro

Back 33

10-20 mA usual 40 mA potentially
Increase patient dose 2-10 times reg. Fluoro
10-50 rads per minute
Limited to 20 rad/minute unless recording the image

Front 34

Rads per minute with boost

Back 34

10-50

Front 35

What is the limit

Back 35

Limited to 20 rad/minute unless recording the image

Front 36

collimation

Back 36

A border needs to be visible when the II is 14 inches above the tabletop and the collimator is fully opened

Front 37

filtration

Back 37

2.5 mm Al eq < 125 kVp
3.0 mm Al eq at 125 kVp and above

Front 38

exposure rate

Back 38

Exposure rate should be less than 2.2 rads/min at 80 kVp

Front 39

exposure rate

Back 39

Limited to 5 rads per minute
If the unit has ABC/ABS then 10 rads/minute is allowed
However, if the unit has ‘boost’ then the limit is 5rads/minute

Front 40

inspection

Back 40

ABC/ABS units have to be checked by a physicist annually
Also have to have weekly fluoro checks of mA and kVp
No ABS 3 year check by physicist

Front 41

increased distance from II

Back 41

TPD increases from 12 to 18 inches
Pt. Dose decreases by 30%

Front 42

gonad shielding

Back 42

0.5 mm Pb eq
97% effective at 100 kVp and 3 mm Al filtration

Front 43

scatter radiation at different angles

Back 43

45 degrees is the worst

Front 44

scatter radiation at different distance

Back 44

Front 45

ssd for mobile equipment

Back 45

SSD has to be at least 12 inches

Front 46

immediate notification

Back 46

Total dose 25 rems
Eye dose 75 rems
Skin or extremity dose of 250 rems

Front 47

24h notice if

Back 47

Total dose 5 rems
Eye dose 15 rems
Skin or extremity 50 rems

Front 48

somatic effects of radiatin

Back 48

Somatic dose indicators
Injuries to superficial tissue
Induction of cancer
Cataracts, fertility issues, life-span shortening
Injuries to developing fetus
Based on dose at specific locations or points

Front 49

genetic

Back 49

50 rads temp male sterility
30 rads temp female sterility

Front 50

high bone marrow exposure

Back 50

BE, UGI, abdominal angio

Front 51

radiation effects

Back 51

25 rads or less demonstrate no effects

Front 52

embryologic effects

Back 52

As little as 10 rads demonstrates effects in animal models
50 rads can cause spontaneous abortion

Front 53

bone marrow coverage

Back 53

Aprons cover 80% of the bone marrow

Front 54

film badge detector

Back 54

10 mrad to 700 rads

+- 25% accuracy

Front 55

maximum dose over 18

Back 55

Whole body - head, trunk, arms above the elbow, and legs above the knee
5 Rem

Front 56

maximum dose over 18

Back 56

Skin and extremities
50 rem

Front 57

maximum dose over 18

Back 57

Lens
15 Rem

Front 58

maximum dose under 18

Back 58

Occupational dose for people under 18 y/o 10% of adult dose

Front 59

occupational exposure

Back 59

Front 60

At 80kVp the intensity of X-ray at the the table top should not exceed

Back 60

2.2R/min

Front 61

Doubling the distance from the Xray tube to the II will

Back 61

decrease the output to 1/4

Front 62

The normal viewing distance for binocular vision is

Back 62

4-8 inches

Front 63

Scatter radiation exposure at 1 hr

Back 63

500mR/hour

Front 64

magnification is switch to 6 inch field of view

Back 64

exposure rate has increased by 150%

Front 65

300ergs for 3 grams is

Back 65

1 rads

Front 66

Gonadal shield

Back 66

.5 pb equiv

Front 67

What film size in spot film has the greatest dose

Back 67

105

Front 68

time it takes to recognize an object

Back 68

0.2sec

Front 69

flourescent material and minification will result in

Back 69

brighter image at the output phosphorus

Front 70

What is a virtual line

Back 70

image created by actual intersection of light rays

Front 71

plumicon TV

Back 71

least exposure

Front 72

electronic intensification

Back 72

electrons are moved at high speed from the photocathode to the output intenisfier

Front 73

What happens to a centrally located image on the input window

Back 73

If the center of the image intensifier has better resolution and less geometic distortion it follows that
a sma'' 'mage 'ntensifier, that encompasses only the central, more accurate'y focused e'ectrons,
produces a better-qua,,ty ,mage than a ,arge un,t

Front 74

Cause of increased radiation with magnification

Back 74

Concurently, the collimator must
automatically reduce the X-ray ield to the useable input phosphor area. The 6-inch mode has a
reduced miniication gain with ewer photoeectrons incident on the output phosphor. A dimmer image
J is the result With automatic bightness control (ABC) the mA is automaically increased when the
y\V\V v( unit is used in the 6-inch node o compensate for the decreased bightness. Thus, paient dose also increases

Front 75

Moving from 9 to 6 will

Back 75

more than double the dose

Front 76

What controls the mottle

Back 76

mA

Front 77

Does a smaller tv have better resolution

Back 77

yes

Front 78

Last image hold decreases flouro by 80%

Back 78

yes

Front 79

The speed of any given camera sysem depends on the abifty of its lens o concentrate light on a
given area and is denoted by the lens*
"f-number.

Back 79

as F decreases less light needed by worse quality

Front 80

High level fluoroscopy refers to a "special activation' capability of a luoroscopy system to provide
significantly higher tube currents, from 10 to 20 mA, and in some instances to even 40 mA. The
coresponding entance dose rate o the patient is 2 o 10 times higher than conventional luoroscopy,
from 10 to 50 rads per minute at the tabletop

Back 80

yes

Front 81

maximum tabletop dose rate o 20 rads per minute when acquiring
images without recording devices such as videotape.

Back 81

yes

Front 82

During digital flouroscopy, how does the under-table x-ray tube operate?

Back 82

it operates in the radiographic mode. Tube current is measured in hundreds of mA instead of less than 5 mA, as in image-intensifying fluoroscopy.

Front 83

If the flouro has AEC the max exposure rate is

Back 83

10R/min

Front 84

The linear nonthreshold curve

Back 84

the most conservative type of dose effect cuvrve and also the curve upon which radiation protection guides and regulatory requirements are based on

Front 85

Several hundred rads will result in cataractses

Back 85

yes

Front 86

risk to fetus for malformation is significantly increased if

Back 86

above 15 rads

Front 87

high radiation area

Back 87

greater than 100mrem

Front 88

radiation area

Back 88

greater than 5mrem

Front 89

cardiac catheterization bone marrow dose

Back 89

110 mrads

Front 90

dosage a pt would recieve for 5 minutes of flouro

Back 90

10-30

Front 91

dose to fetus from 5 R

Back 91

100milirad

Front 92

Cine with 33 mm film at 30frame sec exposure rate

Back 92

10-20 R/min

Front 93

5 rems to the skin of the whole body

Back 93

notify state within 24h

Front 94

If an occupational worker is exposed to 2 Rems in a calendar quater

Back 94

notify within 30 days

Front 95

red bone marrow

Back 95

most sensitive tissue

Front 96

0.25 pb

Back 96

decrease exposure by 97%

Front 97

stray radiation from x-ray tube

Back 97

leakage radiation

Front 98

material in TLD

Back 98

lithium flouride

Front 99

5 rems a year

Back 99

occupational 18 and over

Front 100

special procedure examination or pregnant

Back 100

can wear a 2nd device