radiation biology Flashcards by Jacob Amato

why are patients afriad of radiation

found all over in the news, from reputable sources

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Ionizing radiation leads to what

Formation of free radicals

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what types of effect can free radicals have

Direct effects (33%)
Indirect effects (67%)

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what are the direct effects of free radicals

Free radical action directly on biological moleucles

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what are the indirect effects of free radicals

Radiolysis of water which then affects biological mocules

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What are the possible outcomes of ionizing radiation on Cell DNA

Cell Death
Heritable mutation
Carcinogenesis

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what dose is needed for Deterministic effects

Clinical symptoms appear at any dose above the threshold dose

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what defines severity for deterministic effects

Proportional to dose

caused by high radiation

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what does Deterministic effects leads to

Increased cell death

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what dose is needed for stochastic effects

No threshold, an all or none response

greater dose increases probablitiy though

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what does Stochastic effects lead to

Cell DNA injury

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what is the Law of Bergonie and Tribondeau

Radiosensitivity is different for different tissues

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what defines the radiosensitivity of different tissues

Amount of undifferentiated cells (undifferentiated more susseptible)
Mitotic activity (greater activity greater risk(
Length of active proliferation(greater is more likely)
also OOcytes and Lymphocytes very susseptible

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what non tissue based factors for radiation injury

Age(young more susseptible)

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what organs have high radiosensitivty

Lymphoid ttisues/organs
Bone marrow
Testes
Ovaries
Small intestine

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What organs have fairly high radiosensitivity

Skin 
Cornea and lens of eyes
Esophagus
Stomach
Rectum

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what organs have moderate radiosensitivity

growing cartilage
Growing bone
Vasculature

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what organas have fairly low radiosensitivity

Mature cartilage
Mature bone
Lungs
Kidney
 liver
Pancrease
Adrenal gland
Pituitary gland

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what organs have low radiosensitivy

Muscle
Brain
Spinal cord

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what are the modifying factors in radiation injury

Radiation source (medical and background)
Dose distribution (whole body vs local)
Dose rate (high rates worse)
linear energy transfer (LET)

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what is linear energy transfer

The rate at which the energy from photons is imparted as they travel through matter

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The measure of the total energy transferred from any type of radiation to matter

Absorbed dose (rad or Gy)

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what is 1 Gy

1 Gy=100 rad

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A measure of how different types of radiation affect various tissues

Equivalent dose (Sv=Gy)

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Calculating equivalent dose

equivalent dose= radiation weighting factor x absorbed dose

A measure of the estimate risk in hmans

Effective dose

calculating effective dose

sum of tissue weighting factor x equivalent dose

Weighting factor for Effective and Equivalent

Effect: tissue Equivalent: radiation

what causes acute radiation syndrome

Whole body irradiation

onset of acute radiation syndome

Onset is more rapid and severe with greater dose

Managing accute raditation syndome

depends on stage

Stage of acute radiation syndrom depends on

The level of dose

dose and symtoms of prodromal acute radiation syndrom

``` 1.5 grays Anorexia Nausea Comiting Diarrhea weakness fatigue ```

dose of latent acute radiation syndrom

2 gray

dose and symptoms of Hematpoietic acute radation syndrome

2-7 gray Infections (immunosuppression Hemorrhage (decreased clotting) Anemia

Dose and symptoms of Gastrointestinal acute radiation syndrom

``` 7-15 gray Dehydration Diarrhea weight loo Septicemia ```

dose and symptoms of acute radation syndome for Cadiovascular and CNS

``` 50 gray Hypotension Cardiac muscle necrosis Stupor Incoordination Disorientation Convulsions ```

High radiation dose effects can be

Cataracts in eyes Shortened life expectange (2 months to 2.6 years) Impaired growth in children

what causes shortened life of high radiation dose patients

Increased heart disease Stroke Non-cancerous disease of digestive, respiratory, and hematopoietic systems

what does it take for radition to affect children in utero

.1 grays

what are some abnormalities in children boen after radiation exposure in utero

``` Microcephaly Microphthalmia Cataracts Mental impairment Small birth size and reduced growth throughout life Genital and skeletal malformations ```

how to differentiate radiation cancer from other cancers

Indistinguishable

how do we study radiation induced carcinogenesis

Japanese atomic bomb survivors

why did people die in two months in 1945

Burn injuries and acute radiation system

how was the study conducted to look at radiation

Systematic studies on suriviors and offspring (120,000 people) to see that they got leukemia, esophageal, salivary gland, and thyroid gland tumors

do the unexposed offspring of atomic bomb surviors have mutations

no (also true for the children of parents who have had radiotherapy)

what is the linear nonthreashold (LNT) hypothesis

Increased risk for carcinogenesis above 100,000 microGy | exposures are addative

when doing dental X-rays what are also are exposed

``` Red Bone Marrow Esophagus Thyroid Bone Brain Salivary glands Skin Lymph nodes muscle Oral mucosa ```

what is the most common oral cancers from radiotherapy

Squamous cell carcinoma (2-3%) - Tongue, floor of mouth, gingiva, lip, palate

what type of radiotherapy is found in the oral cavity

fractionated radiotherapy reaching 60-70 Gy

what can oral radiotherpay be combined with

Surgical intervention and/or chemo

when is mucositis found

2nd wek of therapy

what does Mucositis lead to

Erythematous mucosa( sloughing of irradiated tissue ans a white yellow pseudomembrane)

problems with Mucositis

Painful Secondary infection Difficulty consuming food

healing of mucositis

Heals within 2 months after leading to atrophic, thin, avascular tissues

why does Xerostomia occure

Parenchymal cells of salivary glands are radiosensitive leading to reduced salivary flow

what does Xerostomia lead to

Reduced buffering potential decalcifaction of enamel Pain/tenderness Difficulty chewing and swolling

when does XXerostomia heal

6-12 months

how does Xerostomia heal

heals, but persistent reduced flow occures after 1 year

when does taste loss cure

Second/third week of therapy

how much does taste loss occure

Acuity decreased by a factor of 1000 to 10000

what may also lead to taste loss

Reduced salivary flow

Healing taste loss

Recovery in 60-120 days

what is trismus

Inflammation and fibrosis of musculature, usually the medial and lateral pterygoid muscles and masseter muscles

when do you get trismus

limited opening 2 months after completion of radiation therapy

how does one fix trismus

Physical therapy

why does radiation caries lead to rempant caries

due to salivary changes and direct effect on teeth

how does radiation effect on salivary gland change shit to lead to caries

``` Reduced saliva flow Decreased saliva pH Reduced saliva buffering increased salivary viscosity Altered bacterial flora debris accumlation ```

how does radiation directly effect teeth

Flake enamel

How to fix radiation caries

Good oral hygeine Daily fluoride varnish Restricted cariogenic foods Restorations

what happens to children receiving radiotherapy

Incomplete formed teeth (root) Malformed teeth Tooth bud destrcution Microdontia

how to fix impeded tooth development in kids

Resotorative pocedures

how much radiation does it take for Osteoradionecrosis

50-60 Gy

what does Osteoradionecrosis lead to

Reduction of blood supply, bone remodeling capacity (brittle), and mineralization breakdown of mucosa with bone exposure

what part of the mouth is most exposed to osteoradionecrosis and why

Mandible less vasculature

what is done to fix osteoradionecrosis

Debridement Resection restoration

what is done to minimize the effects of osteoradionecrosis

Pre-radiotherapy clearance when possible

what are most mutations from radiation

Deletorous

what gender is more radioselective

Males

ways to reduce the effect of radiation

Low dose | Low dose rate

radiation biology Flashcards

(80 cards)