Formaulating x-ray techniques Ch 12

47 terms by DebraTerry

Create a new folder

Advertisement Upgrade to remove ads

A technique chart provides the following information

1. MA
2. kVp
3. source-image distance (SID)

Manual technique charts are based on patient part measurements obtained using an x-ray caliper

thickness, in centimeters

The kVp that is sufficient to penetrate the body part adequately without excess exposure to the patient is called

Optinmum kVp

What factors need to be considered when selecting the mA station

Exposure time and focal spot size

When selecting a low mA station (100 mA) you should use

the small focal spot.

The advantage of using a variable kVp technique chart are

Lower overall image contrast. Improved visibility of detail. ability to make small incremental changes in exposure technique.

Why should a small focal spot be used as much as possible.

It provides better image sharpness

How should a exposure factors be adjusted when there is the likelihood of motion?

increase mA , decrease exposure time

A satisfactory radiograph is made using 5 mAs with an image receptor relative speed (RS) of 400. How many mAs would be necessary to produce a radiographih of similar density if an RS 100 screen is used?

20 mAs

Which mA station can be used for the most average size patients to take advantage of the small focal spot?

200

If 10 mAs produces satisfactory results with a 5:1 ratio grid, what mAs would be needed if a 16:1 ratio grid is used?

20mAs

Radiography of a wet plaster cast will require an increase in mAs of how much?

3x

A fiberglass cast will require an increase in mAs of how much?

No change is required.

What x-ray projections can benefit from the use of compensating filters?

Ateroposterior (AP) thoracic spine
axiolateral hip

Indicates the need for increased techniue

Paget disease
Edema
Hemorthorax
Bronchiectasis
Atelectasis
Matastases
Pleural effusion

Indicates a decrease technique

Chronic obstructive pulmonary disease (COPD)
Gout
Degenerative arthritis
Advanced age
Pneumothorax
Sarcoma
Bowe; obstruction

Which tool and which unit is used to measure body part thickness for radiography?

caliper - centimeters

Optimum kVp range for AP projection of the cervical spine

70 to 80 kVp

Optimum kVp for AP projection of the thoracic spine

80 to 90 kVp

Optimum kVp range for AP projection of the lumber spine

74 to 88 kVp

mA setting setting for Elbow

50 or 100 mAs with small focal spot

mA setting lumber spine

200 mAs

mA setting for chest

300 mAs with the shortest time possible involunteer movement

4 factors primary radiographic

1. mA
2. Time
3. kVp
4. distance SID

4 primary factors responsible for density

1. mA
2. Time
3. Distance
4. kVp contrast

TOD

target object distance

Make change in mAs you need to go at least

25 - 35 %

Record detail

refers to image clarity

Record detail - image clarity affected by

motion
quantum mottle
focal spot size
intensifying screen and film speed
film/screen contact

Also refered to as resolution

sharpness, definition, or detail

Detail

how much information you get

Gemetric Factors

SID
OID
Focal spot size

density

overall blackness

compensating filter

devices that can be placed between the radiographic tube and IR to compensate for variations in tissue density. (attenuating devices)

Fixed kVp chart

optimum KvP vaule is established for each projection and the mAs is varied according to the patient/part thickness

optimum kVp

the highest kVp setting that produces sufficient contrast for acceptable image quality.

Technique Chart

A listing of varies radiograp[hic examinations performed in the facility. It provides exposure factors for each body part according to its thickness.

variable kVp chart

Chart based on a specific mAs vaule for each projection and to vary the kVp by 2 to 3 kVp/cm for changes in the patient/part size.

High contrast

Is called short scale contrast

High kVp

Is called long scale contrast

Long scale

Is called low contrast.

Small focal spot

provides better image sharpness for all body parts.

200 mA station and small focal spot

Can be used for nearly all small to average size patients

To decrease contrast

increase kVp by 15% and divide the mAs by 2

compensaring filter

attenuating device

short exposure time

highest mAs is used.

Exposure times

are determine by calculation, based on the required mAs and the desired mA.

Please allow access to your computer’s microphone to use Voice Recording.

Having trouble? Click here for help.

We can’t access your microphone!

Click the icon above to update your browser permissions above and try again

Example:

Reload the page to try again!

Reload

Press Cmd-0 to reset your zoom

Press Ctrl-0 to reset your zoom

It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.

Please upgrade Flash or install Chrome
to use Voice Recording.

For more help, see our troubleshooting page.

Your microphone is muted

For help fixing this issue, see this FAQ.

Star this term

You can study starred terms together

NEW! Voice Recording

Create Set