radiographic screens and digital imaging

Question 1

What is a cassette

Answer 1

the device that provides a light tight film holder and rigid support for film, as well as an intensifying screen

Question 2

The cassette contains two intensifying screen, one on each side of the inside of the cassette. What is their purpose?

Answer 2

this doubles the film exposure obtained with a given x-ray exposure, thus reducing the amount of exposure to the patient

Question 3

What type of film is used inside an X-ray cassette?

Answer 3

dual emulsion

Question 4

What is the function of the padding in the pack of a cassette?

Answer 4

it ensures that there is a light positive pressure exerted on the film when the cassette is closed so that there is optimal film/screen contact at all points on the film

Question 5

How do intensifying screens double the film exposure obtained with a given x-ray?

Answer 5

They are coated with phosphors, which are fluorescent crystals that give off light when exposed to x-rays
this is the property of luminescence that creates 99% of the x-ray image

Question 6

The process of glowing only while being excited (such as during ionizing radiation) that will cease glowing at completion of exposure

Answer 6

fluorescence

Question 7

luminescence that demonstrates afterglow (continues to flow for a period of time after the exposure to radiation has ceased)

Answer 7

phosphorescence

Question 8

the emission of light from a substance bombarded by radiation

Answer 8

luminescence

Question 9

what does the term radio parent mean?

Answer 9

does not have a habit of absorbing X-rays

Question 10

What is radioparent in the X-ray cassette?

Answer 10

the cassette face

Question 11

What is the reflective layer of screens in a cassette made of?

Answer 11

titanium oxide

Question 12

What is the function of the reflective later of cassette screens?

Answer 12

it redirects light created during exposure back towards the film

Question 13

Edison discovered calcium tungstenate to be able to glow efficiently when exposed to radiation. This material was the gold standard in X-ray technology for a long time, but has been replaced with what rare earth phosphors?

Answer 13

gadolinium
lanthanum
yttrium

Question 14

The base layer of screens in mostly made of

Answer 14

polyester or cellulose triacetate, which are radioparent, chemically inert, tough and flexible

Question 15

What creates “faster” screens?

Answer 15

thicker phosphor layers and larger crystals in the phosphor

Question 16

thicker phosphor layers and larger crystals in the phosphor result in

Answer 16

lower detail than thinner phosphor layers and smaller crystals but greater speed of x-ray exposure

Question 17

the portion of electromagnetic spectrum the film is most sensitive to?

Answer 17

spectral sensitivity

Question 18

Spectral sensitivity should match what?

Answer 18

the spectral emission of the screens used in the film

Question 19

What is the formula for adjusting mAs for changing screen speed

Answer 19

(speed1/speed2) x mAs1 = mAs2

Question 20

What is spectral emission

Answer 20

the color of light emitted by a phosphor

Question 21

What is the protective layer of the screen

Answer 21

a thin transparent supercoat consisting of gelatin that protects the the emulsion of the phosphor on the film

Question 22

How often should screens be cleaned?

Answer 22

monthly if films are taken every day

quarterly if films are taken once a week

Question 23

What is screen speed?

Answer 23

the efficiency of a screen in converting x-rays to light

Question 24

greater screen efficiency =

Answer 24

less exposure = faster screen

Question 25

A screen with a speed of 200 would be twice as fast as a 100 speed screen and require _____ as much exposure

Answer 25

half

Question 26

What screen speed is used for general purpose radiography?

Answer 26

400-600

Question 27

What screen speed is used for extremity or other detailed radiography?

Answer 27

100

Question 28

big crystals in thick layer =

Answer 28

fast exposure, lower detail

Question 29

small crystals in thin layer =

Answer 29

slow exposure, greater detail

Question 30

How do you calculate the change in technique needed to create a film of equal density on two different system speeds?

Answer 30

(system speed 1/system speed 2) x mAs 1 = mAs 2

Question 31

Components of a film emulsion:

Answer 31

- gelatin (support medium) - silver halide micro crystals (active ingredient, 90% silver bromide and 10% silver iodide) - silver sulfide (sensitivity center)

Question 32

Why is film screen contact important?

Answer 32

it prevents loss of detail

Question 33

film screen contact is negatively affected by:

Answer 33

- foreign material in the cassette or on screen - dents due to objects dropped on screen or closed inside the cassette - damage due to improper mounting - deterioration of padding - warping of screen from getting wet

Question 34

What is a latent image?

Answer 34

the image that has been created after exposure but before development, so it cannot be seen yet

Question 35

What are some causes of undesired exposure of film?

Answer 35

- unintended light exposure - scattered x-rays - heat - chemicals or fumes - pressure - age

Question 36

film speed is directly proportional to what?

Answer 36

mAs

Question 37

slower film speed = _____ detail

Answer 37

more detail

Question 38

faster film speed = _____ detail

Answer 38

less detail

Question 39

How should film be stored?

Answer 39

vertically oriented in a light proof case that is kept cool, clean, dry and ventilated

Question 40

The rules and best practices established by the American college of radiology (ACR) and the national electronic manufacturing association (NEMA) to ensure standard and protocols for image and communications formatting

Answer 40

DICOM (digital imaging and communications in medicine) standards

Question 41

Sets standard for what can and cannot be disclosed without the patient's consent to provide for confidentiality, safety, and protection of health information

Answer 41

HIPPA (health insurance probability and affordability act)

Question 42

Establishes rules and incentives for transition to digital health record management and rules regarding digital acquisition, sharing, storage, safe keeping and privacy in the digital universe

Answer 42

HITECH (health information technology for economic and clinical health) act

Question 43

What are the three digital imaging platforms?

Answer 43

- analog films converted to digital images - computer radiography - direct (digital) radiography

Question 44

computed radiography uses a ______ instead of film

Answer 44

detector plate (aka photostimulateable phosphor plate, PSP)

Question 45

The digital plate that is used in digital radiography is a(n) _______ consisting of millions of indexical semiconductor elements deposited onto a substrate material

Answer 45

active matrix liquid crystal flat panel display - AMLCD

Question 46

What is PACS?

Answer 46

picture archival and communication system - the software that stores, organizes and allows for seamless integration of images from storage to terminal interface

Question 47

All images subject to compression for storage purposes must have _____

Answer 47

reversible compression without loss of original data

Question 48

Can imaged being exported for interpretation or review be partial studies?

Answer 48

no, they must be complete studies

Question 49

Which is more expensive: direct or computed radiography?

Answer 49

direct radiography