RT 210 FILM SCREEN IMAGE ACQUISITION, PROCESSING, AND IMAGE ANALYSIS

RT 210 FINALS TOPIC 1 FLASHCARDS BY YUL VICTORIA

TIME

TEMPERATURE

CHEMISTRY

PROCESSOR CONDITION

ENUMERATION: PROCESSING CONDITIONS

ANATOMY

PHYSIOLOGY

PATHOLOGY

WHAT IS TO BE IMAGED?

ENUMERATION: PATIENT

FILM

SCREEN FILM

SCREEN FILM CONTACT

ENUMERATION: IMAGE RECEPTOR

kVp

mA

Time

Focal Spot Size

Exposure

ENUMERATION: TECHNIQUE VARIABLES

ROOM LIGHT

VIEWBOX LIGHT

ENUMERATION: VIEW CONDITIONS

PATIENT

TUBE

IMAGE RECEPTOR

ENUMERATION: MOTION

TARGET FILM DISTANCE

OBJECT FILM DISTANCE

GEOMETRIC DISTORTION

OBJECT DISTORTION

ENUMERATION: GEOMETRIC VARIABLES

RADIOGRAPHIC IMAGE QUALITY

is the exactness of representation of the patient’s anatomy on a radiographic image.

High-quality images

are required so that radiologists can make accurate diagnoses

Chest X-ray

bread and butter of radiology department

common and frequent

Chest x-ray is the most _____ and _____procedure in the radiology department

clavicles, ribs

During chest x-rays, ______ should be aligned and all _____ must be seen.

image quality

The term __________ refers to the FIDELITY with which the anatomical structure that is being imaged is rendered on the radiograph.

high quality radiograph

A radiograph that faithfully reproduces structure and tissues is identified as a ________

1. Spatial Resolution

2. Contrast Resolution

3. Noise

4. Artifacts

Most Important characteristics of radiographic image quality:

Density

Contrast

Speed

Latitude

Film Factors of Radiographic Quality: Characteristic Curve:

Time

Temperature

Film Factors of Radiographic Quality: Processing:

Distortion

Magnification

Blur

Geometric Factors of Radiographic Quality:

Contrast

Motion

Subject Factors of Radiographic Quality:

Thickness

Density

Atomic Number

Subject Factors of Radiographic Quality: Contrast:

Film Factors

innate; how the film was constructed

Size Distortion

magnification

Shape Distortion

foreshortening and elongation

Foreign object

general term of an artifact caused by objects

Identification marker

very important to identify who owns the radiograph

Resolution

it is the ability to image two separate objects and visually distinguish on from the other.

Spatial Resolution

refers to the ability to image small objects that have high subject contrast (short scale), such as a bone-soft tissue interface, a breast microcalcification, or a calcified lung nodule.

Screen-film radiography

It has an excellent spatial resolution and it utilizes an intensifying screen

Contrast Resolution

refers to the ability to distinguish anatomical structures of similar subject contrast such as liver-spleen and gray matter-white matter.

high subject contrast, low subject contrast

The actual size of objects that can be imaged is always smaller under conditions of __________ than under conditions of __________

different shades of gray (long-scale contrast)

Contrast resolution is used to distinguish __________

Phantom

test object that is exposed to test contrast resolution

Radiographic noise

is the RANDOM FLUCTUATION in the optical density of the image

Adjusting technical factors

Using grids

Noise is removed by:

DECREASE, DECREASE, INCREASE, DECREASE, DECREASE

Fast Image Receptor: _____ radiation dose, _____ patient dose, _____ noise, _____ spatial resolution, ______ contrast resolution

INCREASE, INCREASE, DECREASE, INCREASE, INCREASE

Slow Image Receptor: _____ radiation dose, _____ patient dose, _____ noise, _____ spatial resolution, ______ contrast resolution

Density

It is the overall blackness of the film

mAs

SID

Optical Density can be controlled by two major factors:

TRUE

TRUE OR FALSE: It is not enough to say that optical density is the degree of blackening of radiograph or that a clear area of the radiograph represents low optical density and a black area represents high optical density

0

Sensitometric curve (s-curve) or H & D curve or characteristic curve never starts at _ because there is an innate density added in the base of the radiographic film

mAs, quantity

Density is _____. mAs is _____ because of the number of xray photons

Radiographic Contrast

defined as the percentage of difference between the extreme blacks and whites in the radiograph

kVp

Major factor used in controlling radiographic contrast:

more visible

The function of contrast in the image is to make anatomy ________

Contrast

is the difference in optical density between adjacent anatomical structures, or the variation in optical density on a radiograph.

important factor

Contrast is the most ________ in radiographic quality because it gives us more detail

specific term for detail

Resolution

high contrast (short scale)

Spatial Resolution

different shades of gray (long scale)

Contrast Resolution

Image contrast

is necessary for the outline or border of a structure to be visible.

differences in attenuation

Image contrast is the result of __________ of the x-ray beam as it passes through various tissues of the body.

Attenuation

reduction of energy as it passes through an object

15% increase

A _________ in kVp accompanied by a half reduction in mAs results in the same optical density.

Optical Density

Image Density

Radiographic Density also known as:

Radiographic Density

It is defined as the overall amount of blackening on a radiographic image or a particular portion of the image. It provides the correct degree of background blackening for the anatomic image.

Brightness

In electrical/digital imaging, radiographic density is referred to as _______

Excessive density

can obscure image details

Insufficient density

can mask pathology

quantitative factor

Radiographic density is a _______; that is, it describes an amount of image blackening determined by the number of x-ray photons used to create the image.

exposure rate or number of photons

Thus, radiographic density is regulated by the _________ reaching the film emulsion or image receptor.

the amount of light incident upon the film image, the amount of light transmitted through the film image

Optical density can be described as the relationship between ____________ compared to ____________.

logarithm

Optical density is expressed as a ________, demonstrating the relationship between the amount of light transmitted through the film (It) compared to the amount of light incident upon (Io) the film.

0.2 to 2.5

The diagnostically useful range of optical image density is _______

Sensitometric curve

can be used to illustrate the relationship between the x-ray exposure given the film emulsion and the resulting density.

Sensitometry

The study of the film emulsion response to exposure

mAs

It is the product of milliamperes (mA) and exposure time (seconds)

mA and time

Technical factors are usually expressed in terms of mAs rather than _____ and _____. This is because there are a number of possible combinations of mA and time that will produce.

Reciprocity Law

is when the mAs is the same but the mA and time is different

quantitative factors, directly related

Radiographic density and mAs are ________ and are ________.

Doubling the mAs, halving the mAs

________ will double the radiographic density; _______ will reduce the density to half

30% change

At least a ________ must be made in mAs for there to be a perceptible change in radiographic density

mA x s

Computation for the mAs

more electrons

As kilovoltage is produced, _______ are driven to the anode with greater speed and energy.

more high-energy x-rays.

More high-energy electrons will result in production of

kV

affects both quantity and quality (energy) of the x-ray beam

not directly proportional

However, although kV and radiographic density are directly related, they are ___________; that is, twice the radiographic density does not result from doubling the kV.

effect of kV on quantity

The _________ is not proportional because an increase in kV produces an increase in photons of all energies.

Increased kV

________ produces more high energy x-ray photons; i.e., exposure rate increases

increase in radiographic image density

An increase in kV will result in an __________

decrease in radiographic/image density

a decrease in kV will result in a __________

True

TRUE OR FALSE: When mAs manipulation is not possible, radiographic/image density can be doubled or halved by using the 15% rule.

True

TRUE OR FALSE: As x-ray photons travel though a part, they either pass all the way through to expose the film/image receptor, or undergo interaction(s) that may result in their being absorbed by the part or deviated in direction. It is those that change direction (scattered radiation) that undermine and degrade the image

Grid

A ____ is a device interposed between the patient and image receptor that functions to absorb a large percentage of scattered radiation before it reaches the image receptor.

lead foil and radiolucent filler material

Grid is constructed of alternating strips of ________ and _______

Lead strips

X-ray photons traveling in the same direction as the primary beam pass between the ________

“cleanup”

X-ray photons, having undergone interactions within the body and deviated in various directions, are absorbed by the lead strips; this is referred to as _______ of scattered radiation

stationary or moving

a grid may be _________

Stationary grids

are the simplest type and usually consist of alternating vertical lead strips (i.e., a parallel grid) and radiolucent interspace filler material.

grid cassette

“slip-on” grid

“wafer” grid

examples of stationary grid:

mobile radiography and horizontal beam radiography

Stationary grids are useful in _____________ because they are usually low ratio

Visibility of grid lines

disadvantage of stationary grids

Grid Ratio

defined as the height of the lead strips compared to the distance between them

TRUE

TRUE OR FALSE: The height of the lead strips (H) to width of the interspace material (W)

Grid Ratio = H/W

CONVERSION FACTOR: 1

No grid

CONVERSION FACTOR: 2

5:1 grid ratio

CONVERSION FACTOR: 3

6:1 grid ratio

CONVERSION FACTOR: 4

8:1 grid ratio

CONVERSION FACTOR: 5

10 or 12:1 grid ratio

CONVERSION FACTOR: 6

16:1 grid ratio

grid conversion factor

The grid factor (G) is the ___________ and expresses the total amount of radiation striking the grid surface compared to the amount of radiation transmitted through the grid