Rad Tech: Technique and Exposure

How much do you increase by to double?

100%

How much of a change do you need to see a visible difference in density?

30%

How much do you decrease by to half something?

50%

What controls density? Resulting in how much of a change in density?

AEC (...-2, -1, N, +1, +2..), 25%

Positive side of the xray tube is called?

Anode

Negative side of the xray tube is called?

Cathode

What is black on an image called?

Density

What is mAs related to?

Density

What is the most common cause for repeat radiographs?

Exposure Error

How does exposure time (mAs) affects recorded detail?

Exposure time (mAs) doesn't affect recorded detail

Reciprocity Law

as long as the product remains the same the mA and time can be altered and can create the same total exposure ex: 2mA x 1s = 2mAs 1 mA x 2s = 2 mAs

Where are the AEC photons located?

between the patient and image receptor

Exposure time does not affect what but can be a contributing factor?

does not directly affect patient's motion (and thus recorded detail) and however is considered a contributing factor

To see a darker image you do what?

double mAs

What does electrons do as they flow through the filament circuit?

electrons will boil off at the filament

Exposure Time (s)

expressed in seconds

To see a lighter image you do what?

half mAs

Wide Exposure Latitude

high kvp with long scale of contrast

mAs is the primary controller of what?

image density

Quantum Mottle

insufficient mAs when you use a very low mass; you will have a very low quantity of xrays, which results in a grainy appearance on image.

mAs and time is what to each other when what is maintained?

is indirectly proportional to each other when the total exposure density is maintained.

What is Exposure Time?

is the amount of time which the xray beam is activated and exposure occurs

What is mAs?

is the total exposure or the total quantities produced after the exposure

What happens when AEC receives the right amount of exposure?

it terminates

When you hear exposure latitude you should think of?

kvp

The higher the _________ the wider the ________.

kvp, latitude

The lower the ______ the smaller the ________.

kvp, window

Narrow Exposure Latitude

low kvp with short scale of contrast

higher the _________ the higher the __________.

mA, current

increase in the ________ increases the _______ where electrons boil off at the filament.

mA, quantity

Things that affect density.

mA, time, mAs

mA x s =

mAs

How does mAs affect contrast?

mAs is directly proportional to density. You can change density but have the same contrast ratio. mAs is not a variable that affects contrast.

Optimal mA

maximum mA setting for a given focal spot size

Kilovoltage Peak (kvp)

measure of electrical force in the xray tube

Motion

one way that you can create an blur on an image

Thermionic Emission

the boiling off of electrons of the filament

Milliamperage (mA)

the flow rate of electrons from the xray tube

What is directly proportional to mA?

the intensity of the xray beam

Where are the current of the electrons going to flow to?

they going to flow to the positive side of the xray tube. (anode)

Density on a film is directly proportional to what?

to the total exposure (mAs)

Space Charge or Electronic Cloud

where electrons are in the focusing cup and they stay together as they boil off