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Oral Radiography > Radiation Biology pt. 2 > Flashcards

Radiation Biology pt. 2 Flashcards

1
Q

Fukushima Daichi,
March 11, 2011

A

An 8.9 magnitude earthquake and subsequent tsunami
overwhelmed the cooling systems of an aging reactor along
Japan’s northeast coastline. The accident triggered
explosions at several reactors at the complex, forcing a
widespread evacuation in the area around the plant

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2
Q

San Onofre Nuclear Power Plant, San Diego County

A

San Onofre is at the northwest
corner of San Diego County and
is surrounded by Camp
Pendleton and San Onofre
State Park. Interstate 5 passes
right by.

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3
Q

ACUTE RADIATION SYNDROME
(2)

A
  • A collection of signs and symptoms
    following acute whole-body radiation
    exposure
  • Information derived from animal
    experiments, patient therapeutic
    radiation exposures, atomic bombings
    and radiation accidents.
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4
Q

ACUTE RADIATION SYNDROME
* Sub-lethal exposure
* Lethal exposure
* Supralethal exposures

A

< 2 Gy (200 Rads)
~ 2 –8 Gys (~ 200 to 800 Rads)
> 8 Gys (800 Rads)

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5
Q

Higher dose, — latent period and —
onset of severe symptoms

A

shorter
rapid

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6
Q

Acute radiation syndrome
periods (4)

A
  1. Prodromal period
  2. Hematopoietic syndrome
  3. Gastrointestinal syndrome
  4. Central nervous system and
    cardiovascular syndrome
    (CNS/CVS syndrome)
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7
Q
  1. Prodromal period
A

(<200 R; <2Gy)

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8
Q
  1. Hematopoietic syndrome
A

(200- 1,000R; 2-10 Gy)

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9
Q
  1. Gastrointestinal syndrome
A

(1,000 – 10,000R; 10 – 100 Gy)

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10
Q
  1. Central nervous system and
    cardiovascular syndrome
A

(>10,000R; >100 Gy)

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11
Q

PRODORMAL SYNDROME

A
  • Shortly after exposure to whole-body
    radiation, an individual may develop
    nausea; vomiting;
    diarrhea; anorexia;
    Causes general malaise, fatigue,
    drowsiness and listlessness
    Symptoms resolve after several weeks
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12
Q

ACUTE RADIATION SYNDROME
Lethal exposure range
Supralethal exposures

A

~ 2 – 8 Gys
(~ 200 to 800 Rads)
> 8 Gys
(> 800 Rads)
short latent period and rapid onset of severe symptoms

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13
Q

HEMOPOIETIC SYNDROME

A
  • irreversible injury to the proliferative
    capacity of the spleen and bone
    marrow with loss of circulating
    peripheral blood cells
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14
Q

HEMOPOIETIC SYNDROME
* infection from the
(2)

A

lymphopenia and
granulocytopenia
* hemorrhage from thrombocytopenia
* anemia from the erythrocytopenia
* Death within 10 - 30 days.

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15
Q

GASTROINTESTINAL SYNDROME
(2)

A
  • extensive damage to the GI system (in
    addition to the hemopoietic system)
  • There is extensive injury to the rapidly
    proliferating basal epithelial cells of the
    intestinal villi which leads to atrophy and
    ulceration.
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16
Q

GASTROINTESTINAL SYNDROME
(5)

A
  • loss of plasma and electrolytes
  • hemorrhage and ulceration
  • diarrhea, dehydration, weight loss
  • Infection
  • Death in 3 - 5 days
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17
Q

CARDIOVASCULAR
and
CENTRAL NERVOUS SYSTEM
SYNDROME
(3)

A
  • radiation induced damage to neurons and fine vasculature of brain
  • Intermittent stupor, incoordination, disorientation, and convulsions from extensive CNS damage
  • irreversible damage with death in a few minutes to 48 hours.
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18
Q

RADIATION TREATMENTS TO THE
ORAL CAVITY

A
  • Combined surgical, radiation and chemotherapy
    often provides the optimum treatment
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19
Q

RADIATION TREATMENTS TO THE ORAL
CAVITY
* Oral tissues are subjected to high doses of
radiation during the treatment of malignant
tumors of the (5)

A

soft palate, tonsils, floor of the
mouth, nasopharynx, and hypopharynx

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20
Q

RADIATION TREATMENTS TO THE ORAL
CAVITY
* Total radiation doses to treat malignant
tumors ranges from

A

6,000 - 8,000 Rads. Or
60 -80 Gy

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21
Q

Previous Radiation Therapy for Cancer
* Dose
– Solid tumors =
– Lymphomas =
– Intraoral cancer =

  • 1 Gy =
A

60 –80 Gy
20 –40 Gy
50 Gy

1 million μSv

22
Q

Single intraoral — μSv
FMX (20 images) — μSv
Panoramic radiograph — μSv

A

1.3
35
9

23
Q

RADIATION TREATMENTS TO THE ORAL
CAVITY
* Fractionation of the total dose into multiple
small doses provides

A

greater tumor destruction
than a single large dose
* Fractionation also increases cellular repair of the
normal tissues

24
Q

Mucosa: -

A

mucositis
- 20 infections

25
Q

Taste Buds: -

A

loss of taste

26
Q

Salivary Glands: -

A

xerostomia

27
Q

Teeth:

A
  • lack of or retarded development
  • radiation caries
28
Q

Bone: -

A

osteoradionecrosis

29
Q

Muscle: -

A

fibrosis

30
Q

Hypoguesia
(2)

A
  • Epithelial atrophy,
    xerostomia and
    mucositis all result in
    loss of taste
    (hypoguesia) by the 2nd
  • 3rd week of treatment
  • recovery of taste
    sensitivity will occur in
    2 - 4 months following
    treatment
31
Q

SALIVARY GLANDS
There is marked and
progressive loss of

A

salivary secretion

32
Q

Adult teeth are very resistant to the

A

direct
effects of radiation exposure

33
Q

There is no discernible effect on the

A

crystalline
structure of enamel, dentin, or cementum

34
Q

Radiation does not increase the —- of
teeth

A

solubility

35
Q

When teeth are irradiated during the
developmental stage, their growth may be

A

severely retarded

36
Q

If the radiation precedes calcification, the
tooth bud may be

A

destroyed

37
Q

Irradiation after initiation of calcification,
teeth may demonstrate

A

malformations and
arresting general growth

38
Q

Generally, if some portion of the salivary gland
has been spared, the dryness of the mouth
subsides in

A

6 month to 1 yeAR

39
Q

However, xerostomia may persist without any

A

significant return of salivation

40
Q

Major salivary glands are often exposed
unavoidably to radiation during

A

treatment
for carcinoma of the oral cavity or
oropharynx

41
Q

Parenchymal cells (especially of the parotid
glands) are very sensitive to X-rays and are
replaced by

A

fibrosis and adiposis with
parenchymal degeneration and loss of fine
vasculature

42
Q

The scanty saliva makes the mouth

A

dry
(xerostomia) and tender. Swallowing is difficult
and painful

43
Q

The residual saliva has a lowered pH (from 6.5
to 5.5), which is acidic enough to initiate

A

decalcification of enamel

44
Q

The buffering capacity of saliva is reduced

A

40 -
45%

45
Q

Children may show defects in the permanent
dentition, such as

A

retarded root development,
dwarfed teeth, or failure to form one or more
teeth

46
Q

A dose as low as 200 R at the age of 5 months
has been reported to cause

A

hypoplasia of the
enamel.

47
Q

Although irradiation may retard or abort tooth
formation, the — mechanism is much
more radiation resistant

A

eruptive

48
Q

Irradiated teeth with —
will still erupt

A

altered root formation

49
Q

RADIATION CARIES
* A rampant form of decay that

A

may affect
individuals who received a course of
radiation therapy that include exposure of
the salivary glands

50
Q

BONE
Osteoradionecrosis
The primary damage to bone is from
irradiation to
(2)

A

– fine vasculature
– marrow –affecting vascular and hemopoietic
elements.

51
Q

Radiation Effects –Oral Tissues
– Musculature
* Inflammation and fibrosis –results in

A

contracture and
trismus in the muscles

Oral Radiography (24 decks)

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