final exam image acquisition

what factor impact IR exposure

mAs,KVP, SID, grids, tube filtration, beam restriction, anode heele, patient factors

what is the law of reciprocity?

different mA and seconds have same amount of exposure

how can reciprocity law be used with the ma and time setting?

reduce motion and unwanted anatomy can be blurred

if increase exposure time in seconds, how should mA be adjusted?

decrease

25 ma x .80 seconds = 20 mAs

500 ma x .04 seconds = 20 mAs

which one for best control of motion?

500 ma x .04 seconds = 20 mAs

25 ma x .80 seconds = 20 mAs

500 ma x .04 seconds = 20 mAs

which one for breathing technique?

25 ma x .80 seconds = 20 mAs

how does kVp impact quality and quantity of X-rays?

increases energy and IR exposure

how does the 15 % rule effect a rise in kvp?

half the mAs

a longer SID will result in _____ IR exposure and may require _____ mAs.

less; more

a shorter SID will result in _____ IR exposure and may require _____ mAs.

more; less

if the exposure rate 1 m from source is 9 mR/hr, what is the exposure rate 3 m from the source?

1mr/hr

optimal IR exposure is achieved as an SID of 40 inches using 25MAS. The SI must be increased to 56 inches. With what adjustment in mass is needed to maintain radiographic IR exposure.

49 mAs

What is the purpose of a grid? Why does using a grid improve contrast?

Reduce a scatter

What exposure factor should you increase when using a grid

MAS

Which grid ratio would require the most exposure technique or MAS?

16:1

Define filtration

Remove removes low energy x-rays from the beam

How does filtration impact the IR exposure in the average energy of the beam?

Decreases IR exposure increases average of the beam

How does changing from a 14 X 17 fuel size 2 a 10 X 12 field size impact the factors of an IR exposure and contrast?

Decrease IR exposure and increase in contrast

If the same amount abbreviation is sent through two types of the same type, but different thickness the most, or largest amount of radiation will emerge from

Thin tissue

Increase in SID(receptor exposure)

Decrease

Increase in KVP (receptor exposure)

Increase

Increase mAs (ir expsoure)

Increase

Increase part thickness (ir exposure)

Decrease

Increase beam filtration (ir exposure)

Decrease

Which of the following factors could lead to an underexposed radiograph?

SID smaller than necessary

MMA is set too high

KVP is set too low

Focal spot size is large

KVP is set too low

Which of the following modifications were change in technical factors is most likely to result in decreased image receptor exposure?

Increased grid ratio

Decreased beam restriction

Increased focal spot size

Decrease source to image receptor distance

Increased grid ratio

What x-ray beam characteristic is reduced by aluminum filtration to the tube?

Energy of the x-ray beam

Quantity of x-ray

X-ray beam quality

Half value layer

Quantity of x-ray

Which three of the following will provide an increase in image receptor exposure?

Decrease SID

Decreased KVP

Increased MAS

Decreased vocal spot size

Decrease tube angulation

Increased grid ratio

Decrease filtration

Decreased SID, increase mAs decreased filtration

Which of the following body components would display the most radiographic IR exposure on the radiograph?

Air

Muscle

Fat

Bone

Air

Which of the following techniques would produce the highest IR exposure?

25 mA, 1/10 seconds, .6 mm FSS

80 mA, 50 ms, 1.6 mm FSS

200 mA, 1/5 sec, .6 mm FSS

40 mA,400 msec, 1.2 mm FSS

200 mA, 1/5 sec, .6 mm FSS

Define radiographic contrast

The difference in shades of grey between two areas in an image

Describe how a high or short scale contrast image would appear

A few shades of gray, but great difference among them

Describe how a low contrast or long scale contrast image would appear

Many grays low amount of difference

How can contrast of the radiograph be improved by the technologist during the procedure?

collimation and beam restriction

How does increasing collimation impact contrast?

Increases

Using a higher grid ratio 12 to one increase contrast more than using a low grid ratio such as five to one?

12:1 clean up scatter

Which two of the following will increase reduction in scatter radiation?

increase grid ratio

radiograph a thicker part or anatomy

use of smaller focal spot size

increase SID

increase the mAs

use a smaller field of view

increase grid ratio and use a smaller field of view

define differential attenuation

how different tissues and density effect the intensity of the beam

what does attenuation of the beam mean?

decreases the intensity

why does the beam attenuate differently with various areas of the body?

density, different atomic numbers, thickness

will low Kvp have a high or low attenuation?

high

will high KVP have a high or low attenuation?

low

chest = _______ subject contrast

high

abdomen = _______ subject contrast

low

what influences detail?

SID, OID, FSS

which of the following set of factors will produce decreased detail?

80 kvp 300 mas .10 sec .6 mm

60 kvp 500 mA .9 sec 2.00 mm

50 kvp 300 mA .2 sec .8 mm

100 kvp 200 mA .5 sec 1.2 mm

60 kvp 500 mA .9 sec 2.00 mm

spatial resolution can be improved by reducing which of the following?

SID

SOD

focal spot size

grid ratio

filtration

FOV

focal spot size

what are the 2 controlling factors of size distortion?

SID and OID

will decreasing SID increase or decrease magnification?

increase

if you decrease OID, will that increase or decrease magnification?

decrease

the SID is 72”. the OID is 4”. AN object measures 40 cm. what is the size of the image?

42.4 cm

if the SID is 40", the OID is 2. and the image size 6'“ what is the object length

5.7”

what is the two types of shape distortion?

enlongation and foreshortening

what are the 3 factors involved in shape distortion?

angled anatomy, angled receptor, angle the tube

examples of using shape distortion to help

wrist, inlet pelvis

what determines the quality of the xray beam?

KVP

increasing the kvp does what to the average photon energy

increases

which of the following exposure techniques would provide the most penetrating xray beams?

60 kvp 30 mas 72 SID

70 kvp 20 mas 40 sid

80 kvp 10 mas 30 SID

90 kvp 20 mas 55 SID

90 kvp 20 mas 55 SID

what is the purpose of moving (oscillating) grid?

absorbs scatter radiation

what type of radiological exams would you use a stationary grid?

mobile X-rays

what sid can be used with a parallel liner grid?

any

what factor should increase when using a grid?

mAs

higher ratio grids will _______ patient rad dose

higher

lower ratio grids will _______ patient rad dose

lower

what is the grid ratio formula?

height/ distance

what is the grid ratio when the lead strips are 3.2 mm high and separated by .2 mm?

16:1

what is the GCF for a 6:1?

3

which grid ratio provides the best image contrast?

16:1

which grid ratio would require the most exposure technique or mAs?

5:1

which grid ratio provides the least patient dose?

5:1

if a radiographer performed a routine portable abdomen exam using 30 mAs with a 6:1 ratio grid, what mAs should be used if a 12:1 ratio grid is substituted?

50 mAs

what is grid cutoff?

occurs when useful part of beam is absorbed

what is off level grid error?

angling the tube across grid lines

what is the off center grid error?

central beam is not aligned side to side with the focus grid

what is the focus grid error?

when using wrong sid

when is the upside down error?

placing a focus grid upside down

In a fixed kVp/variable mAs chart, what happens if you increase the patient thickness by 4-5 CM?

Every 4-5 CM increase, the mAs should be adjusted by a factor of 2 (doubled).

if a part measures 18 cm and requires the use of 70 kvp, how much would a part measuring 16 cm require when using a variable kvp-fixed mAs technique chart?

66 kvp

if the fixed kvp, variable mAs technique chart states a 14 cm knee should be taken at 16 mAs and the patient’s knee measures at 8 cm what mAs should be used?

8 mAs

what technique change would be made taking an abdomen xray on patient with osteoporosis ?

increase exposure

which of the following would have the highest kvp setting using an optimum Kvp chart?

PA hand

l-spine AP

double contrast barium enema

single contrast barium enema

intravenous urogram

tib/fib AP

single contrast barium enema

what type of cast would require an increase in exposure factor?

plaster

what technique change would be made when taking a chest xray on a patient with pneumothorax?

decrease exposure

accurate patent measurement is most crucial for which of the following of the technique charts?

variable kvp/ fixed kvp

what kind of chart uses a kvp value that is high enough to adequately penetrate the part?

fixed kvp/ variable mAs

what is automatic programmed technique?

cheat sheet that pops up with the automatic presets

how would you adjust your technical factors to compensate for a patient with a large BMI?

increase mAs and kvp

what kvp is recommended for barium sulfate iodine?

100-120 kvp

what kvp is recommended for barium sulfate single barium contrast?

90-110 kvp

what kvp is recommended for barium sulfate double contrast?

90 kvp

what are the two types of AEC?

phototimer and ionization chamber.

what is phototimer?

located after the IR

what is ionizing chamber?

located before IR

what specific exposure factor does AEC control?

exposure time

What is the minimum response time for AEC?

the time it takes AEC to work

What is the purpose of AEC density control?

increase or decrease IR exposure

What is an example of technologist error when using AEC?

wrong chamber and not correct center

Decrease KVP in exposure time

increase

Decrease MA in exposure time

increase

increase sid from 40 to 72 while using AEC (exposure time)

increase exposure time