RADT 151 RADIOGRAPHIC EXPOSURE

What is the ART and SCIENCE radiographic exposure

is selecting technical factors in order to produce optimal diagnostic medical images while minimizing radiation exposure to the technologist and patient

in radiographic what to you have to balance and why do you have to do this

Radiation balance and radiographic exposure in order to have optimal diagnostic

what are the optimal setting to use

current, voltage and distance

to get optimal results what to you have to do

manipulate factors

what are the knowing condidtion for compensating

1.body part : are we talking about finger

2.patient size: if it is a child pt or larger pt or elderly

3.desired outcomes ( sometimes looking for bumb,fluid or air )

4.Pathology( if a pt has pneumonia,tech will have to adjust technical factor)

what are the nature of x ray radiation

• Electromagentic spectrum

• characteristics of x-ray radiaiton

• wave particle duality

• principle of ionizing radiation

what is the importance of optimal exposure

• Image quality-diagnostic values

• patient radiation exposures

• technologist radiation exposures

what are the characteristic of radiation

•Bundle of light energy –invisible light

•Electromagnetic radiation

•No charge (electrically neutral) ; not affected by electric or magnetic fields(not negative or positive)

•Highly penetrating

•Travel at the speed of light

•Travel in waves

•Travel in straight lines

•Cannot be detected by human senses

•Can ionize matter

•Causes fluorescence

•Cannot be focused by lens

•Affects photographic film

•Produces biological and chemical changes in matter

•Produces secondary and scatter radiation

•Releases very small amounts of heat upon passing through matter

what is the formula for speed of light

(3 x 10⁸ meters/sec in vacuum)

in x-radiation No charge ( electricity neutral) means

it is not affected by electric or magnetic fields(not negative or positive)

what is the white powder called

Barium platium

Man who discovered x-ray On November 8,1895

Wilhelm Conrad Roentgen

the first xray Wilhem conrad Roentgen he took

his wife hand-clara Roentgen

postivie image means

were you can clearly see white image

the Target is made out of and it does what

Rhenium alloid/tungstang coating it is were xray is produce

negative image means

more black coloring image

Name this

Stator electromagnets

name this

Armature

name this

Rotating portion

Name this

molybdenum neck and base

Name this

x-ray beam

name this

electron beam

name this

filament circuit

name this

glass envelope

name this

tungsten anode

name this

bearing

what is pyrex

strong, heat-resistant glass used to form the tube envelope.

what is the degree for the tube to heat up

2,200 C degree in less then 3 sec

negative side of x ray tube is called

-cathode

positive side of x ray tube is called

anode

in the filament what specific dense metal is called

tungsten

C shape in the filament is called

focusing cup

what does focusing cup do

confined,directs and concentrate electrons towards focal (cathode side)

the focusing cup is made out of

Molybdenium(a type of metal)

Tungstan energy releases what

heat

what makes up the anodes to spin and what is it called

Roder and Stator and they are both called Induction motor

what is Rhenium

metal added to tungsten in the anode target of many X-ray tubes.

what is Rhenium main job

make the target stronger and more resistant to heat damage.

what are the two dual filament

small filament and large filament

what is the purpose of filament

to heat up and release electrons

small body parts uses what type of filament (ex: finger hands)

small fillament

large body part uses(ex: chest or abdomen)

large filament

current always travel

negative to positve

what is target angle average

12 degree

what is the melting point of tungsten

74,3422 c

what are the sizes for small filament

.1mm-.6mm

what are the sizes for large filament

.4mm-1.2mm

Anodes has two rotators

Stationery and Rotating

is an older units and mammography uses it

Stationery

how fast does rotating spin

3,400-10,000rpm

radiography uses what type of metal

Tungsten/rhenium

copper is used in

mammography

the metal molybdenum Rhodium is used in

Mammography (2)

material that carries heat away from the X-ray tube. (heat dissipation) has a larger surface area and longer life

Thermal conductor

what is the angle for radiography

5-15 degree

what angle is CT

12-20 degree

which x-ray will have a stronger side

Cathode (-)

which side will have a weaker side

Anode (+)

area anodes(+) where electrons hit is called

Actual Focul

anode heel effect is

not equally strong on both side

WHAT ARE THE STAGES OF X RAY PRODUCTION

prep satge and exposure stage

In the prep stage what typeof emission is being used

Thermionic emmision

Line focus principle uses

Anode heel effect and target angle

what is the purpose of Line focus principle

the idea angle the target to direct beam out of the tube

In the prep stage how many sec does iot take

2-4 sec

In the Prep stage RT are responsible for what

Set exposure factor, depresses prep/exposure button

In the prep stage what is applied to the induction motor(stator)

Current

Rotator starts spinning @ what rmp

3,400-10,000 rmp

when rotator start spinning what to do target start to do

the target starts to spin.

when thermionic emission reaches to 2,200 what happens with electrons

Tungstan electrons are boiled off the filament meaning more mA, more electrons

In the prep stage what does the focusing cup force

the electron beam to coverage

one the space is charged what does electron create

electron clouds

In the exposure stage small rise of current is applied to the tube creates a larger potential difference in charge from cathode to anode what is it callled

tube current

what does tube current do

push electrons to other side

in the exposure stage the difference drive electrons across the tube to target surface is called

tube potentil

when electrons bombard tungstan atoms, the interaction and dislodging tungsten electrons creating what

heat and photons

the % of heat is

98%-99.8%

what is the % of photons

.2to 2% photons

what are the 3 element with tungstan

Coherent ,photoelectric interaction, Compton scatter

Coherent scattering occurs below what keV

below 20 keV

what happen with the electrons in Coherent scattering

electrons enter,atoms and get pulled into forces field of nucleus

does the elctron slow down or move fast in Coherent scattering

slowed down

when electrons slows down what happens in Coherent scattering

gets pushed out of atom in different direction

the term “ breaking radiation or loose charge is called

Bremsstrahlung radiation.

Photoelectric Interaction occurs between what keV

50-150 keV

electrons bombards what And what shell is it called

inner shell tungsten electron and is called K shell

when tungsten electrons knock out what does it create

it create vacancy

Tungsten electrons becomes

photoelectrons

K shell is filled by

the outer shell

once L shell fills the vacancy it has what impact

greater energy

When M shell move in and is filled in the L shell what does it hold

hold more energy than L shell

when N shell fill M shell what does it have

has excess energy

Compton scattering occurs predominately over what keV

100 keV

During Comptom scattering x ray photons primary interacts with which electrons shell electrons

electrons interact with the outer shell

what happens to the incoming x ray photons energy during Compton scattering

the incident electrons energy is partially absorbed

after Compton interaction what happens to scattered x ray photons

incident electrons ejects tungsten creating a Compton electrons

After Compton interaction what happens to the scatter x ray photons

continues in different direction

why is compton scatter undesirable in radiographer imagining

can reduce image contrast and contribute radiaiton

what is the purpose of Primary beam

existing tube and traveling through air to patient bot yet been alter

Attenuated radiation purpose

to be absorbed or scattered radiation is going to pass pt