Ch. 13 Exposure Technique Selection Flashcards by Holly c

a system that controls the duration of the exposure, thereby controlling the amount of radiation that is used

AEC - automatic exposure control

How well did you know this?

Not at all

Perfectly

what are the 2 types of AEC radiation detector systems

phototimers
ionization chambers

How well did you know this?

Not at all

Perfectly

these use a fluorescent screen coupled with a photomultiplier (PM) tube or a photodiode

phototimers

How well did you know this?

Not at all

Perfectly

these convert light into electrical signal

photomulitplier (PM) tubes and photodiodes

How well did you know this?

Not at all

Perfectly

phototimer AECs are what type of devices

exit-type - radiation passes through the IR before it can be measure and used to terminate exposure

How well did you know this?

Not at all

Perfectly

what are most AEC devices now

ionization chambers

How well did you know this?

Not at all

Perfectly

a hollow cell filled with air, connected to a timer circuit via electrical wire

ionization chamber

How well did you know this?

Not at all

Perfectly

ionization chambers are what type of devices

entrance-type - positioned in front of the IR

How well did you know this?

Not at all

Perfectly

what do ionization chambers measure

DAP

How well did you know this?

Not at all

Perfectly

which AEC device is less sophisticated and less accurate

ionization chambers

How well did you know this?

Not at all

Perfectly

which AEC device is less prone for failure

ionization chambers

How well did you know this?

Not at all

Perfectly

AEC only controls this

quantity of radiation

How well did you know this?

Not at all

Perfectly

does AEC have an effect on contrast

How well did you know this?

Not at all

Perfectly

using a higher kVp with AEC will result in this

shorter exposure time

How well did you know this?

Not at all

Perfectly

using lower kVp with AEC will result in this

longer exposure time

How well did you know this?

Not at all

Perfectly

lower mA will result in this

longer exposure time

How well did you know this?

Not at all

Perfectly

this is the shortest exposure time that a system can produce

minimum response

How well did you know this?

Not at all

Perfectly

is minimum response time usually longer with AEC systems

yes

How well did you know this?

Not at all

Perfectly

maximum length of time an exposure can go when using AEC

backup time

How well did you know this?

Not at all

Perfectly

when setting a backup timer, the tech should set it to terminate the exposure at what percent of the desired exposure

150-200%

How well did you know this?

Not at all

Perfectly

exposure adjustment is also known as this

density controls

How well did you know this?

Not at all

Perfectly

AEC is designed to compensate for changes in this

patient thickness

How well did you know this?

Not at all

Perfectly

destructive pathologies may cause this (using AEC)

underexposure

How well did you know this?

Not at all

Perfectly

additive pathologies can cause this (using AEC)

overexposure

How well did you know this?

Not at all

Perfectly

a series of pre-built exposure techniques that a radiographer can quickly select from when preparing to image a patient

anatomic programming

exposures need to be able to be reproduced using the same technical factors that provide mR reading within ___% of each other, and with pixel brightness levels within ___% of each other

5%, 30%

how much is kVp increased for every cm increase in part thickness

mAs is adjusted by a factor of 2 for every how many cm change in part thickness

4-5 cm

do fiberglass casts require technique change

do plaster casts require technique changes

yes

do splints require a technique change

not unless stabilizing piece is over anatomy of interest

if the disease is an additive pathology what do you need to do to technique

increase

if the disease is a destructive pathology what do you need to do to technique

decrease

how does positive contrast show up on an x-ray

lighter

how does negative contrast show up on an x-ray

darker

what might you need to do to technique when using a positive contrast

increase

what might you need to do to technique when using a negative contrast

typically no change

what type of disease is an aortic aneurysm

additive

what type of disease is ascites

additive

what type of disease is cirrhosis

additive

what type of disease is hypertrophy

additive

what type of disease is a bowel obstruction

destructive

what type of disease is free air

destructive

what type of disease is atelectasis

additive

what type of disease is congestive heart failure

additive

what type of disease is malignancy

additive

what type of disease is pleural effusion

additive

what type of disease is pneumonia

additive

what type of disease is emphysema

destructive

what type of disease is pneumothorax

destructive

what type of disease is hydrocephalus

additive

what type of disease is metastases (osteoblastic)

additive

what type of disease is osteochondroma

additive

what type of disease is paget disease (late stage)

additive

what type of disease is gout

destructive

what type of disease is metastases (osteolytic)

destructive

what type of disease is multiple myeloma

destructive

what type of disease is paget disease (early stage)

destructive

what type of disease is an abscess

additive

what type of disease is edema

additive

what type of disease is sclerosis

additive

what type of disease is atrophy

destructive

what type of disease is emaciation

destructive

what type of disease is malnutrition

destructive

diseases or conditions that increase the absorption characteristics of the part, making it more difficult to penetrate

additive diseases

diseases or conditions that decrease the absorption characteristics of the part, making the part less difficult to penetrate

destructive diseases