RAD 208 EARLY TISSUE REACTIONS AND THEIR EFFECTS ON ORGAN SYSTEMS

Biologic effects of radiation that occur relatively soon after humans receive high doses of ionizing radiation

Early effects (deterministic)

Produced by a… of ionizing radiation

Substantial dose

Are effects upon the body that was irradiated

somatic effects

Are effects upon future generations because of irradiation of germ cells in previous generation

Genetic effects

Depending upon the length of time from the moment of irradiation to the first appearance of symptoms of radiation damage, the effects are classified as either

Early or Late effects

Amount of biologic damage a human undergoes as a
result of radiation exposure depends on several factors

1. The amount of ionizing radiation to which the subject is exposed

2. The ability of the ionizing radiation to cause ionization of human tissue

3. The amount of body area exposed

4. The specific body part exposed

The amount of biologic damage for Early effects depends on ?

The actual absorbed dose of ionizing radiation

A point at which symptoms begin to appear and below which they are absent

Threshold

As the radiation dose increases, the severity of these effects also

Increases

What’s the threshold of Hematologic depression

25 rad or 0.25 Gyt

What’s the threshold of Skin erythema?

200 rad or 2Gyt

what’s the threshold of Gonadal Dysfunction?

10 rad or 0.1 mGyt

The threshold for Death by radiation is 200rad/0.25 just as skin erythema how come they differ?

B/c for death to occur the whole body was exposed while skin erythema only the a certain area was exposed

Occurs in humans after whole-body exposure of a large doses of ionizing radiation delivered over a short period of time

Acute Radiation Syndrome

Hematopoietic syndrome (bone marrow syndrome) is a syndrome of ARS which has a threshold of what?

1-10 Gyt

Gastrointestinal syndrome is a syndrome of ARS which has a threshold of how much?

6Gyt-10Gyt

Cerebrovascular syndrome is a syndrome of ARS which has threshold of how much?

50Gyt or more

What is the ARS syndrome that a person can possible survive depending on the amount absorbed of radiation and if blood transfusion is involved?

Hematopoietic syndrome

The average amount of life expectancy after whole body radiation exposure

Mean Survival time

As whole body radiation doses increase, the average time between exposure and death

Decreases (more likely to die)

The mean survival time for mammals after a single whole body dose of radiation is

Dependent on dose (2 – 10Gy)

ARS presents in four major response stages

Prodromal, or initial stage

Latent period

Manifest illness

Recovery or death

The first stage of acute radiation syndrome, which occurs within hours after a whole body absorbed dose of 1 Gy t or more; characterized by nausea, vomiting, diarrhea, fatigue, and leukopenia.

Prodromal, or initial stage

The period of about 1 week after the prodromal stage of acute radiation syndrome, during which no visible symptoms of radiation exposure occur.

Latent period

The stage of ARS when symptoms that affect the hematopoietic, gastrointestinal, and cerebrovascular systems become visible again after a latent period.

Manifest illness

ARS is actually a collection of symptoms associated with

Exposure to high level radiation

Signifies the whole-body dose of radiation that can be lethal to 50% of the exposed population within 30 days

LD 50/30

For adult humans the estimated LD 50/30 dose is

3.0 to 4.0 Gyt. (3.5 Gyt)

A more accurate measure for Humans that signifies the whole-body dose of radiation that can be lethal to 50% of the exposed population within 60 days due to medical intervention

LD 50/60

Repair and recover can occur when cells are exposed to … doses of ionizing radiation

sublethal

Approximately how much of the radiation-induced damage will be irreparable

10%

How much of the remaining irradiated cells will be repaired over time

90%

Cells that are more… are more likely to repair b/c they receive more nutrients

Oxygenated

When cells are exposed to sublethal doses of radiation, repair and recovery may occur because cells

Contain repair enzymes

Organs and tissues sustaining such damage may lose their ability to function, or they may recover If recovery occurs, it may be

Partial or Complete

If organ and tissue recovery fails to occur… of the
irradiated biologic structure results

Necrosis or death

Organ and tissue response to radiation exposure depends on

Radiosensitivity (Wt)

Reproductive characteristics

Growth rate

What are the 3 layers of the skin

Epidermis (outer)

Dermis (middle)

Hypodermis (subcutaneous)

Accessory structures of skin include

Hair Follicles

Sensory receptors

Sebaceous glands

Sweat glands

Epilation or loss of hair (alopecia) is a effect on the skin due to radiation if moderate doses are receive what is the result? and if Large doses are received what is the result?

Moderate→ temporary hair loss

Large→ permanent hair loss

What are some medical procedures that can cause radiation effects on the skin?

Oncology (receiving orthovoltage radiation therapy treatment)

Cardiovascular or therapeutic interventional procedures (high-level fluoroscopy)

Gonadal dose of … depress the male sperm population or
cause a genetic mutation in future

0.1 Gyt

Gonadal dose of …may delay or suppress menstruation in the female

0.1Gyt

Gonadal dose of ionizing radiation that will cause
temporary sterility in the male and in the female

2 Gyt

Gonadal dose of ionizing radiation that will cause
permanent sterility in the male and in the female

5-6 Gyt

HOW MANY MATURE OVA ARE PRODUCED, MATURED AND MADE AVAILABLE FOR FERALIZATION
DURING A WOMAN'S REPRODUCTIVE LIFE

400-500

WHEN ARE HUMAN OVARIES MOST RADIOSENSITIVE?

During the fetal stages of life and during early childhood

Consists of: bone marrow, circulating blood, and lymphoid organs (lymph nodes, spleen, and thymus gland)

Hematopoietic System

Hematopoietic System cells of this system all develop from a single precursor cell, the….

pluripotential stem cell

When lymphocytes, granulocytes, thrombocytes (platelets) and erythrocytes are damaged by radiation exposure, which of the following are possible consequences?

Increased susceptibility to aggressive infectious organisms, high risk of hemorrhage and anemia