How much is the occupational dose per quarter?

1,250 mRem

What is the occupational dose for pregnant techs?

500 mRem/term

In a radiology department, what is the amount needed to make an area restricted?

Any area that emits 100mRems per hr at 1ft

In terms of somatic effects, if you give 300 to 500 rads what will the patient have?

erythema

How many rads will give you sterility?

500 rads or 5 Gy

Genetically Significant Dose

If received by all individuals, produces the same total genetic effect on the entire population.

What factors are important in biological effects?

• Dose rate to which the tissue is exposed
• Total dose received by the tissue
• Type of cells irradiated

What determines a cell's sensitivity?

• the number of undifferentiated cells within
• degree of mitotic activity
• length of proliferation time

Law of Bergonie and Tribondeau

• Immature or young cells and tissues have increased radiosensitivity
• High metabolic rate increases radiosensitivity
• High proliferation and fast growth rate increases the radiosensivity

Which cells are most radiosensitive?

Which cells are the least radiosensitive?

In order from most sensitive to lease:

lymphocytes, red blood cells

epithelial, endothelial cells

connective tissue cells

bone cells

nerve cells

brain cells

muscle cells

Look for most fluid= increased sensitivity

Decreased fluid= decreased sensitivity

How can you tell if cataracts is radiation induced?

It appears on the posterior lens of the eye

Stochastic effects def?

Is it likely to be threshold or non-threshold?

The probability of an effect occuring, rather than its severity.

Likely to be threshold, non-linear

Nonstochastic Effects definition?

Threshold vs Nonthreshold?

Deterministic effect. When severity varies with dose until it reaches a threshold for a symptom to occur.

Cataracts, skin damage, bone marrow disorder.

Likely a linear, non-threshold

If you receive a dose of 500mr/hr at 1ft, how much would you recieve at 2 ft?

100mr/hr

if you double your distance, you will decrease your dose by a 1/4

At what angle of scatter do you recieve the most radiation?

135 degrees, gonad level strength

What is an example of an acceptable fluro phantom?

7.9" lucite

9" of water

What personnel monitoring device provides a permanent record?

Film badges

Does the maximum permissive dose include radiation that may be recieved from other non-work sources?

No it does not include radiation from other non-work sources such as background and dental and medical exams.

What is the timeline for checking your dosimeter?

Recommended change/checking once a month.

Must NOT exceed a calendar quarter.

What is the difference betweena high radiation area and a radiation area?

High radiation area= 100 mRems/hr at 1 ft

Radiation area= 5 mRems/hr at 1 ft

How do you calculate your maximum permissable dose?

5(n-18)rems

n= your age

5(26-18)rems= 40 rems

Does air produce scatter radiation?

Yes

Kerma

Measured in?

Kinetic Energy Released in Matter

Measured in Gy, same as Air Kerma

Dose in air is recorded in?

Occupational dose is recorded in?

Absorbed dose is recorded in?

Dose in air= roentgens

occupational dose= rems or sieverts

absorbed dose= rads or grays

What is the optimal viewing distance?

12-15"

Rods vs Cones

What do they look like?

Photopic vs Scotopic?

Daylight vs Night time vision?

Rod looks like a candle. Cone looks like umbrella.

Rod uses scotopic vision. Cones use photopic vision.

Rod responsible for nightime vision. Cones use daylight.

Rods and Cones can be found in the...?

Rods are located where?

Cones are located where?

Rods and cones can be found in the retina.

Rods are located on the periphery?

Cones are located in the fovea centralis?

What is the integration time?

.2 seconds

20/20 vision

Cones vs Rods

Cones: 20/20 vision

Rods: 20/200 visions

Spatial Resolution is measured in?

Line pairs per mm

Mammography needs highest line pairs, pixels, and resolution.

FOr my info :)

At 80 kv and 1 mA radiation exposure should not exceed what?

2.2 rads/min

Beam intensity at tabletop should not exceed 2.2 rads/min for every mA at 80 kVp.

Occupational dose for radiation workers is?

Occupational dose for pregnant techs?

5000 mRem/year

500 mRem/term

What is the shielding for a bucky slot cover?

Atleast .25 mm Pb equivalent

Gonadal shielding should be?

.5 mm Pb equivalent!!

Watch for the equivalent. He will likely have answers without the equivalent on it.

What is the best gonadal support for men?

Shaped contact shield with an athletic support

Room lighting in fluro should allow for _________ vision.

Photopic vision

Is it possible to exceed 5rads/min

Yes

Notes state "May not exceed 5rads/min"

Is it possible to exceed 10rads/min?

No

Notes state "Shall not exceed 10rads/min"

Half Value Layer

Characterizes the quality of the beam.

We want 1/10th value layer.

Filtration

At 80 kV, must be __________

At 125 kV, must be __________

80= 2.5 mm Aluminum equivalent

125= 3 mm Aluminum equivalent

T/F

Virtual image exists in all units of fluoroscopy.

True

If a 10 gram volume of tissue is given an absorbed dose of 3 rads, what is the integral dose?

30 gram-rads.

The integral dose is the total dose given to that tissue.

A patient receives a skin dose of 5 rads/slice in CT. 10 slices are performed.

What is the absorbed dose?

What is the integral dose?

Absorbed= 5rads

Integral dose= 50 rads

Integral dose= surface x dose   or    dose x volume

Integral absorbed dose

mGy= amount ________ by patient

cGycm²= amount ______ by patient

Which is the integral exposure?

The amount absorbed by a patient is recorded as mGy.

Th amount GIVEN to the patient overall is recorded as cGycm²

cGycm² is the integral dose

Low Fstop #= _____ light

                    _____ aperature

High Fstop #= _______ light

                     _______ aperature

Low= more light, large aperature

High= less light, small aperature

The higher the frame rate, the _______ the dose.

higher

Frame Rate

The number of exposures per second

If you have 525 lines, will increasing the size of the tv improve the image?

No

640 x 480

What does the 640 represent?

What does the 480 represent?

How many dots/row?

How many rows from top to bottom?

How many pixels?

640= Horizontal

480= Vertical

640 dots/row

480 rows from top to bottom

640x480= 307,200 pixels

Definition of Plumbicon

A variable gain tv camera

Plumbicon vs Vidicon

Plumbicon                              Vidicon

Variable Gain                          Fixed Gain

No Lag                                   Lag

Definition of Vidicon

A fixed gain tv camera. Operates at 60 hz.

What is the diameter of a vidicon camera?

1".

The exact size of the output phosphor window.

What is the most common tv tube in fluoroscopy?

Vidicon

What is it called when you have a montoring system that operates through internal connections tube.

Closed circuit tv

Vignetting

(Know exact definition)

Decrease of brightness at the periphery, and increase of brightness at the center of the image.

Which of the following units represent resolution?

1.) Line pair per cm

2.) kV

3.) Line pair per mm

4.) mAs

3.) Line pair per mm

What is the term used in measuring the dose rate?

Roentgen (air)

What is the formula to measure the dose increase?

                  Dose increase= (Original mode)²

                                        (magnification mode)²

At the original mode of 9", you switch to 6". What is the dose increase?

A.) 1/2

B.) x2

C.) x3

D.) x4

                             x= 9²= 81= 2.25 Dose increase

                                 6²   36

Answer B.) x2

Focusing lens are _____ charged.

Positively

What is it called when the electrons leave the photo cathode and move to the output phosphor?

Minification

Minification Gain formula

                      MG= (Area of input window)²

                             (Area of output window)²

Area of output window is always 1"

If an image intensifier has a flux gain of 50 and you are using a 9" diameter mode, what is the brightness gain?

BG= FG x MG

                                 x= 50 x 9⁽²⁾

                                            1 ⁽²⁾

                                x= 4050

Choose one

The (mA  or   mAs) is controlled by the machine?

mA

(mAs does not apply)

In fluorscopy, the xray output dose is diectly proportional to ______ used

mA

Fluoroscopy uses a min of _ __ mA and a max of ___ mA.

Radiography uses ______ mA

Fluoro= .5 mA to 5mA

Radiography= 100mA or higher

Brightness Gain

definition and formula

Combined effect of flux gain and minification gain

BG= FG x MG

Grid ratio in fluoroscopy is always ______.

8:1

Input layer/phosphor is made of ________

Output layer/phosphor is made of ________

Input= Cesium Iodide

Output= Zinc Cadmium Sulfide

Image intensifier increases light ________

3-5,000 x more light

Name where the location is for each action:

• Conversion of xrays into light
• Conversion of light photons into electrons
• Accleration/focusing of electrons
• Conversion of electrons into light

Xrays to light= input phosphor

light to electrongs-= photocathode

speed up electrons= focusing or electronic lenses

electrons into light= output phosphor

The dstance from target (xray anode) to panel (patient) shall not be less than ___________.

12"