Radiation Protection & Legal Aspects

Question 1

~73% of the background radiation is from

Answer 1

radon

Question 2

• Decay of uranium-238
• One of the most naturally ocurring radioactive element
• Second cause for lung cancer
• Releases alpha particles
• ~73% of the background radiation

Answer 2

Radon-222

Question 3

What kind of space radiation:

Composed of subatomic particles

Large quantity is blocked by
terrestrial electromagnetic shield

Harmful to astronauts

Answer 3

Primary

Question 4

What kind of space radiation:

Affects living beings on Earth

Interaction of primary radiation with the atmosphere

Increases with the altitude

~11% of background exposure

Answer 4

Secondary

Question 5

~9% of background exposure is from

Answer 5

internal radionuclides

Question 6

What kind of radiation:

Radioactive nuclides in the soil

Potassium-40 and decay products of uranium-238 and thorium-232

~7% of background exposure

Answer 6

terrestrial radiation

Question 7

Cigarette smoking
* Building materials
* Air travel
* Combustion of fossil fuels
* ~4% of non-background exposure

Answer 7

Consumer products

Question 8

The principal risk of oral and maxillofacial radiography is the unlikely chance of

Answer 8

radiation-induced cancer

Question 9

In general, these studies demonstrate reasonable evidence that cancer risk
increases linearly with radiation exposures greater than

Answer 9

100 mSv

Question 10

linear relationship between dose and the risk of inducing a new cancer, even at very
low doses

no threshold or “safe dose” below which there is no added cancer risk

Answer 10

Linear no-threshold (LNT) hypothesis

Question 11

The ___ model is currently accepted as the approach to develop radiation protection
guidelines

Answer 11

LNT

Question 12

Which guiding principle?

Benefit of the diagnostic exposure exceed the Risk of harm

Answer 12

justification

Question 13

Which guiding principle?

Dentists should use all possible means to reduce unnecessary exposure to their patients, staff and themselves

Answer 13

optimization

Question 14

The radiation dose to the patient should be kept as
low as possible

Answer 14

Optimization - ALARA (as low as reasonably achievable)

Question 15

The radiation dose to the patient should be kept as
low as diagnostically acceptable

Answer 15

Optimization - ALADA (as low as diagnostically achievable)

Question 16

The individual effective dose shall not exceed the limits recommended by the International Commission on Radiation Protection (ICRP)

Answer 16

Dose limitation

Question 17

Good performance of Dentistry → Average dose of ____ mSv (1% of the limit)

Answer 17

0.2

Question 18

Is there a defined dose limit for patients?

Answer 18

No

Question 19

Rectangular collimation can reduce the effective dose by as much as 80 % and it improves image quality by reducing _____

Answer 19

scatter

Question 20

Rectangular collimation of the x-ray beam shall be used routinely for ____ and _____ radiography

Answer 20

periapical ; bitewing

Question 21

_______ limits the amount of radiation, both primary and scattered, to which the patient is exposed

Answer 21

collimation

Question 22

An added benefit of rectangular collimation is an
improvement in contrast as a result of a reduction in fogging caused by _____ and _____ radiation

Answer 22

secondary ; scattered

Question 23

Since a rectangular collimator _____ the radiation dose by up to fivefold as compared with a circular one, radiographic equipment should provide
rectangular collimation for exposure of periapical and bitewing radiographs

Answer 23

decreases

Question 24

Which patient protection measure?

To filter out the photons with less energy

Answer 24

filtration

Question 25

Which patient protection measure? The most sensitive receptor compatible with indicated examination should be used

Answer 25

imaging receptors

Question 26

Film speeds available for dental radiography are D-speed, E-speed and F-speed, with D-speed being the ____ and F-speed the _____

Answer 26

slowest ; fastest

Question 27

Switching from D to E speed can produce a ______ percent reduction in radiation exposure

Answer 27

30-40%

Question 28

The use of F-speed film can reduce exposure ______ compared to use of E- speed film, without compromising diagnostic quality

Answer 28

20-50%

Question 29

Digital imaging provides an opportunity to further reduce the radiation dose by ______ percent

Answer 29

40-60%

Question 30

Image receptors of speeds slower than ANSI Speed Group E/F (AKA D-SPEED) shall not be used for _____ radiography

Answer 30

intraoral

Question 31

Which patient protection measure: The longer the distance, the less divergent the photons will be, and the lower the irradiated area

Answer 31

Source-to-skin distance

Question 32

Use of long source-to-skin distances of 40 cm, rather than short distances of 20 cm, decreases exposure by _______ percent

Answer 32

10-25%

Question 33

Which patient protection measure: They should be used whenever possible Reduce the number of repetitions

Answer 33

Receptor holding devices

Question 34

The ideal differential potential is between ____ and ____ kVp Factors should be adjusted to obtain a great quality image, avoiding over or underexposure **Proper exposure time is essential!**

Answer 34

60 and 70 kVp

Question 35

The optimal operating potential of dental x-ray units is between ___ and ____ kVp

Answer 35

60 and 70 kVp

Question 36

For a given beam, the intensity is _________ to the square of the distance from the source

Answer 36

inversely proportional

Question 37

The reason for the decrease in intensity regarding distance is that an x-ray beam spreads out as it moves ____ its source

Answer 37

from

Question 38

When shielding is not possible, the operator should stand at least ___ meters from the tube head and out of the path of the primary beam

Answer 38

2

Question 39

Maximum dose will generally be in line with the primary beam as it ___ the patient

Answer 39

exits