Radiation Safety

Question 1

Although dental radiographs use a very small amount of radiation, can harmful effects still occur?

Answer 1

Yes, It is important to understand the risks and address them with patients

Question 2

All ionizing radiation is — and produces — changes in living tissues

Answer 2

Harmful, biological

Question 3

Ionization can cause disruption, which leads to?

Answer 3

temporary and/or permanent damage

Question 4

Direct theory

Answer 4

radiation damages the protein, lipid, carbohydrate, and DNA molecule of a cell and causes cell death

• accounts for 1/3 of radiation-induced biological damage

Question 5

Indirect theory

Answer 5

radiation interacts with the cells’ water content (H2O) and produces free radicals

• accounts for approximately 2/3 of radiation-induced biologic damage, proportional to the body’s water content (60-80% water)

Question 6

Free radicals are mostly which elements? Are they stable?

Answer 6

H and OH; they are highly unstable

They interact with each other and produce toxins such as hydrogen peroxide (H2O2)

Question 7

Latent period

Answer 7

time between radiation exposure and observed clinical effect

Question 8

Acute exposure

Answer 8

occurs when a large dose of radiation is absorbed in a short period (e.g., nuclear exposure)

(high doses of radiation to the whole body may result in nausea, diarrhea, fever, hair loss, and death)

Question 9

Chronic exposure

Answer 9

occurs when small doses of radiation are absorbed over time

• the effects may not be visible for an extended amount of time
• low doses of radiation received over a long period may result in cancers

Question 10

Exposure of the entire body results in?

Answer 10

more severe biological effects

Question 11

Long-term effect

Answer 11

may occur months, years, or decades following exposure

Question 12

Cumulative effects

Answer 12

exposure to radiation has a cumulative effect over a life time

some tissues can repair themselves but some will stay damaged

Question 13

Recovery period

Answer 13

repair period

Most injuries from low-dose radiation are repaired naturally

Question 14

Somatic effect

Answer 14

injury to the person being affected

Question 15

Genetic effect

Answer 15

injury to the future generation

Question 16

Stochastic effect

Answer 16

probability of the occurrence increases with dose, but the severity is not dependent on the dose (e.g., cancer)

(all or nothing - a person either has or doesn’t have the condition)

Question 17

Non-stochastic effect (deterministic)

Answer 17

severity of the damage is dependent on the dose (e.g., loss of hair)

Question 18

Highly-sensitive cells

Answer 18

immature cells, quickly-dividing cells, younger person’s cells

Question 19

Less-sensitive cells

Answer 19

highly-specialized cells, mature cells, slowly-dividing cells

Question 20

Cell types in order of most sensitive to least sensitive

Answer 20

• Small lymphocytes, blood-forming (bone marrow) cells, reproductive cells, intestines

-Skin, lens of eye, oral mucosa

-Connective tissue, immature bone, blood

-Mature bone, salivary gland, thyroid, kidney, liver

-Muscle, nerve

Question 21

Most sensitive parts of a cell

Answer 21

DNA and Chromosomes

Question 22

Critical organs

Answer 22

organs that are more sensitive to radiation

Question 23

CO: Thyroid

Answer 23

adult thyroid glands are fairly resistant to radiation while children’s thyroid glands are sensitive

Question 24

CO: Bone Marrow

Answer 24

exposure to a large amount of radiation can cause leukemia

Question 25

CO: Skin

Answer 25

radiation can cause erythema (redness)

Question 26

Background radiation

Answer 26

radiation encountered in daily living arising from natural and artificial sources

Question 27

natural sources of radiation

Answer 27

radon cosmic radiation, terrestrial radiation, etc. - Accounts for most of background radiation exposure - 20-images full-mouth survey taken with F-speed films and rectangular collimation is equivalent to 1-2 days of background radiation

Question 28

Radon

Answer 28

a gas released from the ground and decaying material that releases radiation energy that penetrates every aspect of our environment (house, soil, etc.) and combines with dust, which can be inhaled

Question 29

Artificial sources of radiation

Answer 29

Majority come from from medical assessments (not dental assessments) CT scans emit 100 times more radiation energy than a dental radiograph Other sources include: television sets, smoke alarms, building materials, etc

Question 30

Dental radiation is responsible for — of the total exposure from medical imaging

Answer 30

1-5%

Question 31

Dental exposure is similar to?

Answer 31

doses received during a cross-country airplane flight

Question 32

What are the two systems used to measure the amount of radiation?

Answer 32

Standard (traditional) and Systeme Internationale (newer)

Question 33

Standard units include:

Answer 33

Roentgen Rad: Radiation absorbed dose Rem: Roentgen equivalence in man

Question 34

SI units include:

Answer 34

C/kg: Coulombs per kilogram Gy: Gray Sv: Sievert

Question 35

Both units follow these specific conversions

Answer 35

1 Sv = 100 rem 1 Gy = 100 rad Milli (m) is equal to 1000, therefore 1000 mrem = 1 rem

Question 36

Exposure

Answer 36

**quantity** of ionization in the air * the measurement is taken at the skin surface before radiation penetrates the tissues * measured in Roentgen (Standard system) or Coulomb (SI system)

Question 37

Absorbed dose

Answer 37

amount of radiation **absorbed** by an object * depending on the material, the amount of radiation absorbed will vary * measured in Rad (Standard system) or Gray (SI system)

Question 38

Dose equivalent

Answer 38

absorbed dose “**adjusted**” to the biological damage potential of the particular type of radiation * some types of radiation produce greater effects than others * measured in Rem (Standard system) or Sievert (SI system)

Question 39

Maximum Permissible Dose (MPD)

Answer 39

Defined by the National Council on Radiation Protection and Measurements (NCRP)

Question 40

Is the dose of radiation expected to produce any significant radiation effects?

Answer 40

No

Question 41

What is the MPD for an occupational person?

Answer 41

**5 rem/year** (5000 mrem), or **50 mSv/year** * 00 rem = 1 Sv; 1 rem = 0.01 Sv; 5 rem = 0.05 Sv = 50 mSv

Question 42

MPD for a non-occupational person

Answer 42

**10%** of worker amount, or 0.5 rem (500 mrem), or 5 mSv/year

Question 43

Maximum accumulated lifetime dose

Answer 43

5 rem x N - 18 (N = age)

Question 44

For pregnant patients, use?

Answer 44

non-occupational dose

Question 45

ALARA (As Low As Reasonably Achievable)

Answer 45

exposure should be kept to a minimum and benefits should outweigh the risks for the patien

Question 46

Dental radiographs should be carefully prescribed depending on?

Answer 46

the patient’s age and risk level for oral diseases

Question 47

Should "routine" radiographs be taken?

Answer 47

No

Question 48

Dosimeter

Answer 48

receptor badge that measures exposure to radiation ## Footnote Worn at **waist** level

Question 49

# New Patient Primary dentition

Answer 49

**selected** periapical/occlusal views and/or posterior bitewings if proximal surfaces cannot be visualized or probed

Question 50

# New PT Which type of patients may **not** require a radiographic exam?

Answer 50

Patients **without** evidence of disease and with open proximal contacts * child dentition is more spread out, which usually allows the probe to detect the interproximal surfaces

Question 51

# New PT Mixed dentition (after eruption of first permanent tooth)

Answer 51

posterior **bitewings** with panoramic exam; or posterior bitewings and **selected** periapicals

Question 52

# New PT Adolescent

Answer 52

posterior **bitewings** with **panoramic** exam; or posterior bitewings and **selected** periapicals

Question 53

# New PT A full-mouth intraoral radiographic exam is preferred when?

Answer 53

the patient has clinical evidence of generalized dental disease or a history of extensive dental treatment

Question 54

# Recall PT T/F: Radiographs should be taken every 6 months regardless of the patient’s condition

Answer 54

False; should not Examine the patient’s **caries risk** and determine the interval

Question 55

# Recall PT Radiographs should be taken?

Answer 55

only if the *interproximal surface* **cannot** be examined with an instrument or visually

Question 56

# Recall PT High caries risk

Answer 56

posterior bitewing examination at **6 to 12-month** intervals for children and adults

Question 57

# Recall PT Low caries risk

Answer 57

posterior bitewing examination at **12 to 24-month** intervals (children), 18 to 36-month intervals (adolescents)

Question 58

Periodontal Diseases & Growth Development

Answer 58

Clinical judgment should determine the need for and type of radiographic images

Question 59

If adolescents are developing **3rd** molars?

Answer 59

**panoramic** examination may be needed

Question 60

Clinical Positioning

Answer 60

* Never stand in the line of the primary beam * Clinician should stand behind a protective wall * If a wall is not available, stand at least **6 feet** from the source of radiation, at a **90-135°** angle from the beam * Clinician should **never** hold the tube head or receptor in the patient’s mouth during exposure. If assistance is required, a parent or guardian should be shielded and allowed to help the patient

Question 61

Dosimeter

Answer 61

* Measures the amount of occupational exposure * Most commonly worn as a badge that contains a receptor package * The badge should be worn at all times by the professional at work. * Every 3-4 weeks, the badge is sent for review

Question 62

Equipment Monitoring

Answer 62

Dental radiographic machines should be inspected regularly to identify leakage

Question 62

Digital radiography requires a -- amount of radiation compared to receptor and is therefore considered --

Answer 62

lesser; safer