intro to rad tech (exam 3)

List the three major classifications of diagnostic image production:

1. Film/Screen Radiography

2. Computed Radiography (CR)

3. Digital Radiography (DR)

Primary radiation is rays that exit the X-ray tube and travel through the ________ before it interacts with a patient.

air

X-rays are bits or packets of ________ called photons or quanta.

energy

Secondary radiation is rays that interact with atoms within the patient and continue in a different direction. It is made up of two types which are: __________________ and_________________.

Scatter and Leakage

Define Attenuation:

process whereby the primary radiation is partially absorbed as it travels

BONE or SOFT TISSUE (circle one) attenuates more of the X-ray beam.

Bone

____________________ materials allow x-ray photons to pass easily, which will produce black on a radiograph. An example of this type of material is:

Radiolucent Material; Lungs- Gas/air

____________________ materials do not allow X-ray photons to pass through as easily and will produce white on a radiograph. An example of this type of material is:

Radiopaque Material; bone

Remnant radiation is rays that exit from the patient and reach the image receptor. It is made of ____________, _________________, and ________________ radiation.

primary, secondary, and scatter radiation

CR stands for _____________________ and is also known as PSP which stands for_______________________________.

Computed Radiography; Photostimulable Phosphor

CR is cassette-based with an imaging plate inside coated with______________________ phosphors to capture trapped energy within F traps or______________ centers of the conduction band.

photostimulable phosphors; phosphor

An invisible image recorded on a PSP before it is put into the reader is called:

latent image (cant see it yet)

A CR imaging plate that is processed and converted into a visible image is called:

manifest image (can finally see it)

DR stands for ____________________ and is cassette-less.

Digital Radiography

There are two types of DR which are __________________ and ________________.

Direct and Indirect

TFT stands for _______________ which stores an _________________.

Thin Film transistor which stores the electronic signal

Direct capture converts X-rays into:

electrionic signal

Indirect capture converts X-rays into __________ and then _________________.

Light and then the electronic signal

List the four prime factors of exposure and define each:

1. MilliAmperage (mA)

2. Time (s)

3. Kilovoltage Peak (kVp)

4. Source to image distance (SID)

Who controls the primary factors of exposure?

radiographer

Define IR exposure:

the amount of IR exposure striking the image receptor

How does IR exposure differ from brightness?

Brightness is the measurement of luminance of an area in an image, IR exposure measures the actual radiation

Define contrast:

the visible difference between any two selected areas of brightness levels within a displayed radiographic image

Define Spatial Resolution:

(detail) (structure of lines) the sharpness of the structural edges recorded in the image

Define Distortion:

the misrepresentation of the size and shape of a structure recorded in the radiographic image

The higher the atomic number of a tissue the EASIER or HARDER it is to penetrate with X-rays?

Harder

What is the major controlling factor for IR exposure?

mAs

What is the formula to calculate mAs?

mAs = mA x time

How would you adjust mAs if you needed to double the IR exposure?

double mAs

_____________ is the penetrating ability of the beam. If a photon has a short wavelength it is said to have LOW or HIGH (circle one) energy or penetrating power.

kVp; short wavelength= High kVp

When kVp increases by 15%, how will IR exposure be affected?

equivalent to doubling IR exposure

Define SID:

the distance from the x-ray tube (anode) to the image receptor

Define the Inverse Square Law:

the intensity of the beam of radiation is inversely proportional to the square of the distance from the source

increase in distance, decrease in intensity

According to the inverse square law if the distance is doubled how will the intensity of the x-ray beam be affected?

If the distance is doubled, the intensity of the x-ray beam will decrease to one-fourth (1/4) of its original intensity.

What is the relationship between SID and mAs?

If you increase the distance you must increase the mAs to compensate and vice versa. Direct Proportion

______________________ alters the primary beam by removing the low energy (LONG or SHORT) wavelengths to decrease patient dose.

Filtration; long wavelength

What does a collimator or beam restrictor do to the primary x-ray beam?

adjusts the size and shape of the beam to the size of the IR or smaller. This decreases pt exposure and increases the quality of the beam by limiting the field so less scatter radiation is produced in the body

Increasing collimation will INCREASE or DECREASE the production of scatter within the patient's body.

Decrease

A __________________ is made up of lead strips that absorb scatter radiation before it reaches the image receptor.

Grid; decreases the IR exposure

Where is the grid placed?

between the patient and the IR

Define exposure latitude

range of exposure that can be used for a diagnostic image

The dynamic range of a digital receptor is _______% to _________%.

-50% to +200%

List the four current exposure indicators in digital radiography.

1.Sensitivity Number (S#)

2.Exposure Index (EI)

3.Logarithm of the mean of the histogram (IgM)

4.Deviation index (DI)

A short scale of contrast (LOW or HIGH contrast) consists mainly of blacks and whites and is referred to as decreased gray scale in digital.

High Contrast

A long scale of contrast (LOW or HIGH contrast) consists of many shades of gray and is referred to as increased gray scale in digital.

Low contrast

What technical factor controls subject contrast?

kVp

Increasing collimation will create a SHORT or LONG scale of contrast.

Short scale of contrast

A grid will create a SHORT or LONG scale of contrast.

Short scale of contrast

LUT stands for ______________________, which is a reference table of luminance values used to correct or fix an image.

Look-Up-Table

List the three types of unsharpness:

1. Motion Unsharpness (pt)

2. Geometric Unsharpness (tube, pt, IR)

3. Material Unsharpness (devices)

What is the most common type of unsharpness?

Motion unsharpness

Voluntary motion is motion that a patient CAN or CANNOT control. List an example of voluntary motion:

CAN control; breathing during exposure; pt. movement

Involuntary motion is motion that a patient CAN or CANNOT control. List an example of involuntary motion:

CANNOT control; heartbeat, disease

Geometric unsharpness is affected by what three factors?

1. Focal Spot Size

2. SID (source-to-image distance)

3. OID (object-to-image distance)

For the greatest degree of detail (sharpness) how would those three factors be adjusted?

small focal spot- increased sharpness

increase in SID- increased sharpness

a decrease in OID- increased sharpness

Material unsharpness refers to four factors, match the following terms to the appropriate definition:

a. Point Spread Function: _______ 1. Lack of sufficient incoming data

b. Quantum Mottle: _______ 2. Undesirable background information

c. Noise: _______ 3. Light spread causing unsharp edges

d. Modulation Transfer Function: 4. Information lost btwn part and image

a. Point spread function =

3. light spread causing unsharp edges

b. Quantum Mottle =

1. Lack of sufficient incoming data

c. Noise =

2. undesirable background information

d. Modulation Transfer Function =

4. information lost between part and image

DEL stands for:

detector element

Size distortion is affected by what two factors?

SID and OID

What are the two types of shape distortion?

Elongation and foreshortening

Fluoroscopy produces a _______________ image, which is known as dynamic, while general radiography produces a ____________ image, which is known as static.

moving; nonmoving

The tube housing is lined with

lead

The glass envelope contains the ______________ and ______________ and is in a vacuum.

cathode and the anode

The _________________ is the negative electrode

cathode

It contains a filament that when it is heated produces electrons. This process is known as __________________________.

Thermionic Emission

The ________________ is the positive electrode, which is known as the target.

anode

What does a filter do?

filters out the soft x-rays that have long wavelengths that cause an increase in the dose of radiation to the pt.

A collimator is a beam-limiting device that controls ____________ of the x-ray field.

size and shape

What does PBL stand for and what does it do?

positive beam limiting. automatic collimation to the size of the IR

List the four different types of tube movements and how they move in relationship to the table.

1. Longitidunal

2. Transverse

3. Vertical

4. Tube angle

What does AEC stand for?

automatic exposure control

What does AEC control?

automatically adjusts the exposure time according to patient thickness

contains ionization chambers

What does the Bucky tray hold?

holds a portable digital detector or a CR cassette

What types of controls will you find on a control panel?

main power

kVp

mA

timer

rotor-exposure switch

There may be two steps of an exposure button. The first step starts the ____________ spinning and the second step initiates the __________________.

1st: anode spinning (rotor)

2nd: x-ray (exposure button)

In fluoroscopy the X-ray tube is located ABOVE or UNDER the X-ray table.

Under

What is the purpose of an image intensifier (II)?

increases brightness of the image

Mobile or portable equipment allows x-rays to be taken?

bedside, cart side, or in surgery

The operator for the mobile x-ray should stand atleast?

at least 6 feet away

A ___________________________ is a fluoroscopic piece of equipment that is used in surgery or special procedures.

C- Arm or Mini C-Arm

Milliamperage (mA)

amount of e- that are boiled off cathode= quantity

Time (s)

it takes for e- to pass from cathode to anode mAs is the quantity of e0 and time it takes to pass from cathode to anode

Kilovoltage peak (kVp)

energy it takes to send e- from cathode to anode. Affects the quantity and quality of the beam

pushes e- across

an increase in kVp leads to shorter wavelength photons

Source-to-image distance (SID)

distance between the x-ray tube and the image receptor. It affects the intensity of the radiation

Photographic Properties

1. IR exposure

2. Contrast

Geometric Properties

1. Spatial Resolution

2. Distortion

Atomic number of Soft tissue

7; attenuates the least

Atomic number of Bone

14

Atomic number of Barium

56

Atomic Number of Lead

82; attenuates the most

Tumor (easy or hard to penetrate)

hard; more attenuation

Fluid (pneumonia) (easy or hard to penetrate)

hard; more attenuation

Emphysema (trapped air) (easy or hard to penetrate)

easy

Does a fat person need more or less IR exposure

less IR exposure (i think its more)

Does a skinny person need more or less IR exposure

more IR exposure (i think it is less)

Increased IR exposure (less or more bright)

less brightness; because x-rays pass through the part easily

Decreased IR exposure (less or more bright)

more bright; because x-rays have a more difficult time passing through because they were absorbed by the part

Grid=height over distance

No grid = 1 (uno)

5:1 = 2 (dos)

6:1 = 3 (tres)

8:1 = 4 (quatro)

10:1 & 12:1 = 5 (cinco & cinco)

16:1 = 6 (seis)

define longitudinal tube movement:

moves the rube the length of the table

define transverse tube movement:

moves the tube across the width of the table

define vertical tube movement:

moves the tube up and down