1.Conversions of x-rays to light photons

   Input phosphor - cesium iodide CsN2.

2.Conversion of light photons into electrons.

   Photo cathode

3.Acceleration/focusing of electrons.

   Focusing/electronic lenses.

4.Conversion of electrons into light photons.

   Output phosphor - zinc cadmium sulfide ZnCd

   (Called Electron Graveyard)

B.G. = F.G. X M.G.

FLUX GAIN X MINIFICATION GAIN

• mA
• kVp
• collimation
• filtration - less scatter remove soft rays
• exposure time
• SID
• TPD -Patient to II tartget/panel distance 12" or more.
• sensitivity to II conversion factor - loses 10% a year.

• Collimate to area of interest.
• Use last frame hold. save re-exposure.
• Minimize patient-detector distance.
• Use highest kV and lowest mA. (optimal limits).
• Use non magnified mode. Less dose.

F.G.= Energy of e striking the output phosphor

       Energy of e emitted from photocathode

M.G.=  (Area of input window)²

           (Area of Output window)²

Dose increase =

(Original mode)²

(Magnification mode)²

(9)² = 81 = 2.25

(6)²    36            .

More line pairs per mm gives better resolution.

True or False.

True

100% Brightness Gain.

90-80=10, (10)²= 100%

What do you call it when the lens is out of whack?

Unsharpness.

Lack of resolution                    noise

  Unsharpness                

Contrast   Blurring                  Anatomy

               Geometric               Artifact              

Recording  Monitor                  Mottle(increase mA)

Medium     Receptor

Subject

A TV system that works through a cable. 

Does not go out anywhere.

Vidicon

Not for angio.

The tiny electrical impulses collected from the target compose the video signal.

The resulting electronic image on its target is the exact reproduction of the image from the output window.

Plumbicon

The gold standard.

A variable gain television camera that translates the image from the output window into the final image on a TV monitor.

Used in Cath Lab...

Low Resolution/High Lag

High Resolution/Low lag

Vidicon

Plumbican

Which is the variable gain TV Camera?

a. Vidicon

b. Plumbicon

b. Plumbicon

What is Synchronization?

The coordination of the shutter opening to the

exposure of film or digital recording.

• When the frames in the film time with the shutters on the tube.

Frame rate.

Which is the fixed gain TV Camera?

a. Vidicon

b. Plumbicon

a. Vidicon

What is the Kell Factor?

Ratio between the vertical

and horizontal resolutions.

Best resolution TV has a KF close to 1

Kell Factor equation?

K.F. = Vertical resolution

             Horizontel resolution

            (# of scan lines)

What is Bandwith?

A range of frequencies used to transmit information, such as picture and sound.

Bandwith Information:

The monitor bandwith:

higher is better resolution.

• is a speed at which the electronic beam can be turned on and off. Measured in MHz.
• To meet the requirement for refresh rate, the bandwidth should be faster than the pixel speed and the refresh rate of the electronic beam.

How do you measure Bandwith?

The pixel speed x 1.5.

• 1024 X 768 @ 60 Hz
• Bandwidth = 1024 X768 X 60 X 1.5 = 70.78 MHz

• 1024 X 1024 @ 60 Hz
• Bandwidth = 1024 X1024 X 60 X 1.5 = 94.37MHz.

640 X 480

• 640 dots/row
• 480 row - top to bottom
• 640 x 480 = 307200 pixels

What is the optimal viewing distance?

12" to 18" for binocular vision.

Define: Lag.

• Persistance of the image after the cessation of the signal.
• bothersome in dynamic studies.
• Helpful in the visualizationof low contrast and stationary objects.
• Vidicon present significant lag.

How much filtration is required for the table top and other material @ 80 kV?

Must be 2.5mm Al equivalent.

At 125kV must be 3mm Al Equivalent.

What is Focal Length?

The focal length of a lens determines the size of the image-image magnification.

The longer the focal length, the greater the mag.

Frame Rate?

The number of exposures per second.

Higher Frame Rate =

Higher Dose.

What is the maximum rate for High Level Fluoroscopy?

Max rate is 20 rads/minute of fluoro.

except when image recording.

What is the exposure for high level Fluoro?

a. 5 - 10 rads/hr

b. 5 - 10 rads/min

c. 10 - 50 rads/min

d. 10-50 rads/hr

c. 10 - 50 rads/min

High level Fluoro does not require a loud signal.

True or False?

False.

High level fluoro requires an audible signal the must be heard in the exam room.

It requires special activation with an additional person.

In interlaced mode how many

fields are there in a video frame?

Two.

1. odd lines

2. even lines

mA in fluoro:

Is dose directly proportional to mA used?

Yes.

Reducing from 5mA to 3mA,

dose is reduced by how much?

a. 20%

b. 30%

c. 40%

d. 50%

c. 40%

mA

Brightness is proportional to mA.

True or False?

True

What size is the output phospor?

a. 1/2 inch

b. 1 inch

c. 2 inches

d. 1/4 inch

b. 1 inch   

Using peak/optimal kV will not yield maximum

differential absorption by the tissue.

True or False

False.

Using peak/optimal kV will yield maximum

differential absorption by the tissue.

Lower mA can be used.

There will be some scatter or noise is slight excess.

What is one of the most important measures

you can take to reduce unnecessary radiation?

Collimation.

Down to the area of interest.

What is the total quanity of energy imparted to an irradiated object from ionizing radiation?

Integral Absorbed Dose

is the radiation quanitity that is equal

to the total energy absorbed by the body.

Or

Total absorbed energy.

What does the F stop equal?

F stop = focal length/aperture diameter

40 mm lens/20mm aperature = F2

40 mm lens/10mm aperature = F4

On iris set up F stop,

is a higher # a smaller or larger spot?

Higher # is a smaller spot.

F16

F11

F8

F5.6

F4

F2.8

F16 is the smallest.

What does the F stop control?

How much light passes through the aperature.

What is the requirement for Collimation?

You must see 4 borders on the

image display at any distance?

Is 1 Rem of x-ray radiation as powerful

as 1 Rem of Gamma radiation?

No, Gamma is a more powerful.

What is Integral Absorbed dose?

The total quanitity of energy imparted to

an irradiated object from ionizing radiation.

or the radiation quantity that is equal to

the total energy absorbed by the body.

In what unit is the total integral absorbed

dose measured?

It is measured in Gram-rads.

Integral Dose:

What is 1 gram-rad = to?

1 gram-rad = 100 ergs

If a 10 gram volume of tissue is given an

absorbed dose of 3 rads.

The integral does is 30 gram-rads.

Dose x volume.

Define virtual image.

A type of image that exists as a result of

a projection of a true object.

It is reflected through a lens and is not a true image.

What is a true image?

The object or part of interest.

How much beam intensity is allowed at the tabletop?

Fro every mA at 80 kVp the beam

intensity should not exceed 2.2 rads/min.

For Routine fluoro what is the allowable exposure Rate?

• Not to exceed 5 rads/min

• 2.2 rads/min/mA at 80 kVp

• Shall not exceed 10 rads/min.

What is an acceptable phantom to test fluoro?

A bucket with a minimum of 9" of water

or

a 3.4 cm of acceptable material  or an alloy phantom.

How often much the fluoro beam be testED.

Once a week with record kept.

What is the normal viewing distance for the monotor?

12" to 15" for normal viewing distance.

Vision integration time is 0.2 seconds.

How long is vision integration time?

Time for brain to register image is 0.2 seconds.

Normal viewing distance is 12 to 15"

What is the requirement for gonad shielding?

0.5 mm Pb equivalent reduces 99.9%

What is the shielding requirement

of the bucky slot cover?

Must be at least 0.25 mm Pb equivalent.

Lead on this one not Aluminium.

Why shield slot?

Protects the user.

Name those old cardinal rules?

• Time

• Distance

• Shielding

How can you practice ALARA in fluoro?

• Use last frame hold

• Min ON time

• Use the manual-resent timer (5 minutes)

• Use low mA

• Use non-mag mode when possible

• Collimate

Where does the table bucky belong

during a fluoro procedure?

At the end of the table that is

not being used by the procedure.

On the c-Arm why is the spacer used?

to ensure a minimum of 12".

What is an acute exposure?

a. Large dose in short time period

b. Dose received over a long period of time

c. When Dr. McDreamy is doing the surgery.

a. Large dose received in a short period of time

What is chronic exposure?

Doses received over long periods.

What is 5,000 mrem/year?

The occupational limits.

or 1250 mrem/ 1/4 year.

What is 500 mrem/term?

Occupational limit for declared pregnant females.

What is the requirement for a restricted area?

Leakage radiation at 100 mR/hr @ 1foot

Somatic effect is?

a. effect to population and kids.

b. effect to individual.

c. no effect to anyone.

b. effect to individual.

How many rads to cause erythema?

500 rads to skin causes erythema.

What somatic effect will 2500 rads cause?

• Permanent tanning and hair loss

• damage to superficial vessels and sweat glands

• temporary ulceration

What dosage causes somatic effects of

permanent ulceration and increased risk of cancer?

5000 rads.

Gonadal irradiation:

What amount for

temporary sterility?

Temporary is 30 rads.

Permanent is 500 grays or 500 rads.

Define: Genitically significant dose

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

Hiroshima, Nagasaki

Define: Biological effects.

Dose rate to which the tissue is exposed.

(Concentaration)

Total dose received by the tissue

(Total Dose)

Type of cells irradiated.

Non-linear threshold effect is:

a. Directly porportional.

b. Porportional, but not direct.

c. Not porportional

b. Porportional, but not direct.

Linear Non-threshold effect is:

a. Directly porportional.

b. Porportional, but not direct.

c. Not porportional                

a. Directly porportional.

Which cells are the most sensitive to radiation?

a. Cells with hi mitotic activity

b. Cells with low mitotic activity.

c. Cells with long proliferation cycle.

d. Cells with short proliferation cycle.

d. a and d only

e. b and c only

d. a and d only

What is the law of Bergonie and Tribondeau?

Radiosensitivity:

• Immature or young cells are more radiosensitive.

• Cells with high metabolic rates are more sensitive.

• Cells with high proliferation and fast growth

rate are more senitive.

Cells with more fluid are more or

less sentive then cells with less fluid?

More fluid more sensitive,

more chance of a reaction.

List cells in order of radiosensitivity.

• Lymphocytes, red blood cells    

• Epithelial, endothelial cells

• Connective tissue dcells

• Bones cells

• Nerve cells

• Brain cells

• Muscle cells.

Which lens pole of the eye gets cataracts from radiation? 

a. Anterior

b. Posterior

Posterior pole.

Effect of irradiation to lens.

What is Stochastic effect?

Probability of an effect occurring,

rather than its severity.

When there is a predictable threshold

for a symptom to occur.

Fluoro operator exposure,

what is the exposure at 1 foot from the patient?

1 foot is 500 rems.

2 feet is 100 rems.

Which angle gives the most scatter?

Most scatter at 135° = 22mrems/hr.

Scatter during fluoro.

What is the highest?

What is the lowest?

•  30° = 15 mrems/hr

•  45° = 12 mrems/hr

•  60° = 12 mrems/hr

•  90° = 13 mrems/hr

• 120° = 20 mrems/hr

• 135° = 22 mrems/hr

What is the primary barrier in Fluoro.

The II.

What is Integration?

The time necessarey for an image to be

recoginzed by the brain.

Takes .2 seconds

Kerma is what?

Kinetic Energy Released in Matter (equilalent to absorbed dose) The amount of energy transferred from the xray beam to charged particles per unit mass in the medium of interest.

Measured in Gy or Rad.

What is air kerma?

The energy released per unit mass of a small volume of air when it is irradiated by an xray beam.

Measure Gray (Gy)

M.P.D.

Maximum permissable dose =

5(N-18) rems

N = your age.

Radiation area?

Any area with radiation levels greater than 5 mR or 0.05mSv in 1 hour 30cm from sourface through which the radiation penetrates.