final quiz 1

Describe the anatomy of the x-ray tube. What is a cathode? What is an anode?

Cathode and anode are housed in glass or metal tube surrounded by oil to absorb heat Electrons from the cathode collide with anode which results in 99% heat and 1% x-rays X-rays leave through window and enter the aluminum filter Cathode = negatively charged Anode = positively charged

List important safety rules that should be kept in mind while exposing an x-ray film:

Lead shielding Increase distance from primary beam Use good technique (less repeat radiographs) Collimate to reduce scatter radiation

We can think of mA as approximating the

# of x-rays

A fetus should not receive more than__during the entire gestation.

0.5 rem

Give examples of how we can reduce scatter radiation:

1) Aluminum filter (weed out low energy x-rays), 2) collimator (reduce size of primary beam), 3) grids (filter out scatter radiation)

To double the density of your radiograph, you can increase the kVp by:

20% more

The National Council on Radiation Protection and Measurements recommends that the dose for occupationally exposed persons not exceed__per year

5 rem

A radiograph that you have just developed appears dark. You note that even the bones are gray. You are best to do what for the next radiograph?

Decrease mAs

Where do we set the caudal border of the collimation beam for a VD of the pelvis?

Distal to the stifles

Which of the following choices is ordered from lowest subject density to greatest subject density?

Gas, water, bone, metal

Where do we center the vertical line of the collimation beam for a lateral pelvic view?

Greater trochanter of the femur

Scatter will be more noticeable if there is a thicker patient and:

Higher kVp and larger collimation field size

We can improve the contrast on a radiograph by doing all of the following EXCEPT:

Increase the mAs

What types of electromagnetic radiation can cause cancer?

Ionizing radiation like UV light, x-rays and gamma rays

What is the most common cause of loss of detail on a radiograph? What can we do to limit loss of detail?

Patient motion is the most common. Options to limit loss of detail: low mAs (short exposure time) or use sedation

How do we check for straightness on a lateral view of the abdomen?

Superimposition of transverse processes of the lumbar vertebrae

How do we check for straightness on a VD of the pelvis?

a. Caudal lumbar vertebrae spinous processes are end on b. Obturator foramina are symmetrical and the same size c. Femurs are parallel

List four causes of film fogging:

a. Heat b. Light c. Chemical fumes d. Scatter radiation

List the required personal protective equipment for helping in the radiology room:

a. Lead gloves b. Lead apron c. Thyroid shield d. Lead glasses e. Dosimetry badge

Place the following steps in processing films in the correct order from 1-5:

a. ___2_ Rinse tank b. ___4_ Wash tank c. ___5_ Drying d. ___3_ Fixer e. ___1_ Developer

What four factors affect the scale of contrast on radiographs:

a. subject density b. kVp level c. film quality d. fogging

What does radiographic density mean?

darkness

To double the density of your radiograph, you can increase the mA by:

double

Denser tissues such as bone absorb_or lesser amounts of x-rays and appear_or black on a radiograph. Less dense tissues such as lung tissue absorb greater or_amounts of x-rays and appear white or black on a radiograph.

greater,white,lesser,black

as Kvp__or decreases, the contrast increases.

increases

The quality of the beam refers to:

kVp

For most studies, a short or _ scale of contrast is desirable.

long

Radiographs that have a_or short scale of contrast have a few black and white shades with many shades of gray. A long or_scale of contrast has black and white shades with few shades of gray in between.

long,short

We can think of kVp as approximating the

strength of x-rays.