Radiology

Question 1

Milliampere (mA)

Answer 1

AMOUNT or number of electrons

Measures the AMOUNT of current passing through the wires of the circuit

The AMOUNT of x-rays produced

Question 2

Kilovolt peak (kVp)

Answer 2

The power or speed of electrons

Determines the PENETRATING ability

Question 3

What is the yoke?

Answer 3

Connects extension arm and tube head

Can revolve 360 degrees

Question 4

High kVp vs low kVp

Answer 4

High kVp= long scale contrast(many shade of black and white)

Low kVp=short scale contrast (few shades of black and white)

Question 5

Direct current

Answer 5

Electricity continuously flows in one direction

*Good for DIGITAL radiography

Question 6

Alternating current

Answer 6

Changes direction of flow 60x/second

Question 7

What do most dental xray units operate on

Answer 7

110-120 V alternating current

7mA-15mA

65kVp-100kVp

Question 8

Voltage

Answer 8

The electrical pressure between two electrical charges

Question 9

Step-down transformer

Answer 9

Decreases voltage

Heats filament and produces electron cloud

Question 10

Step-up transformer

Answer 10

Increases voltage

Question 11

What percent of energy is converted to x-rays and what percent is lost in heat

Answer 11

1% converts to X-ray

99% loss is heat

Question 12

Ionizing radiation

Answer 12

Any radiation that produces ions

Question 13

Electromagnetic radiation

Answer 13

Movement of wave-like energy through space as a combination of electric and magnetic field

Question 14

How are wavelength and frequency related

Answer 14

Inversely

Long wavelength= low frequency

Short wavelength=high frequency

Question 15

Velocity

Answer 15

The speed of the wave

Question 16

Compton effect

Answer 16

Causes x-rays to scatter in all directions

Called Secondary radiation

Question 17

Coherent scattering is also known as

Answer 17

Thompson scattering

Question 18

What is the occupational exposure limit in one year

Answer 18

50 mSv (5rem)

Question 19

What is the occupational lifetime exposure limit

Answer 19

10mSv x age

Question 20

Pregnant Dental personnel occupational exposure limit is

Answer 20

0.5 mSv/month

Question 21

General public is permitted how much radiation in one year

Answer 21

5mSv (0.5rem)

Question 22

Organs with high radiosensitivity

Answer 22

Lymphoid organs, bone marrow, ovaries, small intestine, fetal cells

Question 23

Organs with low radiosensitivity

Answer 23

Muscle, brain, spinal cord

Question 24

ALARA

Answer 24

As low as reasonably achievable

Question 25

What is the single most effective method of reducing radiation to the patient

Answer 25

Rectangular collimator Reduces radiation up to 70%***

Question 26

Federal regulations state the X-ray beam needs to be how far from the skin surface

Answer 26

2.75 in or 7cm

Question 27

How thick is the added filtration (aluminum discs in the pathway of the X-ray beam)

Answer 27

0.5mm

Question 28

Is a longer or shorter PID more safe

Answer 28

Long PID= less radiation

Question 29

How much thickness of lead needs to be in the lead apron and thyroid collar

Answer 29

0.25 mm

Question 30

What is the second most effective method of reducing radiation to the patient

Answer 30

Film speed Faster film=less radiation needed to expose it

Question 31

What is the correct distance away from the x-ray beam for the operator

Answer 31

6 feet at 90° to 135° from the head of the patient

Question 32

The walls blocking the x-ray should be

Answer 32

2.5-3 in of drywall

Question 33

Silver halide crystals

Answer 33

Retain the latent image when exposed to X-ray beam larger the crystal=faster film speed*** Thicker emulsion= faster film speed

Question 34

Manual film processing steps

Answer 34

Develop, rinse, fix, wash, dry

Question 35

Automatic film processing steps

Answer 35

Develop, rinse, dry

Question 36

The Safelight should be a minimum of how far from the working area

Answer 36

4feet

Question 37

A white ceiling light may cause what to the film

Answer 37

Foggy film

Question 38

Inverse square law

Answer 38

I(1) D(2)^2 —— = ———— I(2) D(1)^2 I(1)=original intensity I(2)= new intensity D(1)= Original distance D(2)= new distance

Question 39

SLOB rule

Answer 39

Same=lingual | Opposite=buccal

Question 40

The size and shape of the focal trough is determined by

Answer 40

The manufacturer **Structures positioned outside of the focal trough will be blurred

Question 41

During a pano where should the tongue be placed

Answer 41

Roof of mouth

Question 42

On a panoramic x-ray if the chain is too low what will happen

Answer 42

Exaggerated smile appearance

Question 43

On a panoramic x-ray if the chin is too high what will happen

Answer 43

Frown appearance

Question 44

When the Patient’s chin is tipped too low on a panoramic x-ray the teeth on the anterior will be positioned how

Answer 44

Farther from the film

Question 45

What causes a black film

Answer 45

Light leaking

Question 46

An unexposed film will be what color

Answer 46

White

Question 47

What is the earliest clinical signs of radiation over exposure

Answer 47

Erythema

Question 48

If the kVp is set higher is there more or less scatter radiation

Answer 48

Less

Question 49

kVp effects what mA effects what

Answer 49

kVp= contrast mA=density

Question 50

If anterior teeth look short and fat, that means

Answer 50

The teeth were BEHIND the focal trough