chapter 8 Early Tissue Reactions and Their Effects on Organ Systems

Identify what early tissue reactions depend upon and the time frames in which these reactions appear

duration of time after exposure to ionizing radiation

substantial dose of ionizing radiation is required to produce biologic changes very soon after irradiation, and the severity of these changes is dose

Time frames

• Minutes • Hours • Days • Weeks

List and describe several possible high-dose consequences of ionizing radiation on living systems

• Severe nausea

• Vomiting

• Diarrhea Other signs and symptoms that may occur

include:

• Fever (as in hematopoietic syndrome)

• Fatigue • Loss of appetite • Lethargy • Anemia • Leukopenia (decrease in the number of white blood cells) • Hemorrhage (GI tract bleeding because the body loses its bloodclotting ability) • Infection • Electrolyte imbalance • Emaciation

Describe acute radiation syndrome and what dose it occurs at (ARS), and list three separate dose-related syndromes that occur as part of this total-body condition.

Acute Radiation Syndrome

radiation sickness, occurs in humans after whole-body reception of large doses of ionizing radiation delivered over a short period (from several hours to a few days).

occurs: When the whole body is exposed to a dose of 6 Gyt of ionizing radiation

• Hematopoietic syndrome

• Gastrointestinal syndrome

• Cerebrovascular syndrome

Identify and describe the four major response stages of ARS

• Prodromal-occurs within hours after a whole-body absorbed dose of 1 Gyt or more within few days or months

• Latent period- approximately 1 week follows during which no visible signs occur.

• Manifest illness-period when signs and symptoms

involving the hematopoietic, GI, and cerebrovascular systems become visibl

• Recovery or death

Explain why cells that are exposed to sublethal doses of ionizing radiation recover after irradiation, and discuss the cumulative effect that exists after repeated radiation injuries.

Because of repair enzymes surviving cells will be able to divide and thereby begin to repopulate in the irradiated region.

cumulative effect that exists after repeated radiation injuries--cumulative effect that exists after repeated radiation injuries.

Describe local tissue damage that occurs when any part of the human body receives high radiation exposure

atrophy-shrinkage of organs and tissues,

What are the downside of atrophy in organs

can lose their ability to function, or they may possibly recover. If recovery does occur, it might be partial or complete, depending on the types of cells involved and the dose of radiation received.

IF there is no recovery death/ necrosis occurs

List three factors on which organ and tissue responses to radiation exposure depend.

• Radiosensitivity

• Reproductive characteristics

• Growth rate

Describe radiation-induced skin damage from a historical perspective.

William Herbert Rollins began investigating the potential hazards of radiation exposure. This led to his becoming the first known determined advocate for radiation protection

Differentiate among the three layers of human skin, and identify other related accessory structures

• Epidermis, or outer, layer • Dermis, or middle, layer composed of connective tissue • Hypodermis, a subcutaneous layer of fat and connective tissue

State the single absorbed dose of ionizing radiation that can cause radiation-induced skin erythema within 24 to 48 hours after irradiation, and describe how this dose first manifests.

A single absorbed dose of 2 Gyt can cause radiation-induced skin erythema within 24 to 48 hours

Explain the difference between moderate and large radiation doses with regard to epilation.

Moderate doses of radiation generally produce temporary hair loss,

large radiation doses can result in permanent hair loss.

State the energy range of grenz rays, and give a historical example of their use in treating disease

(x-rays in the energy range of 10 to 20 kVp).

very low energy photons were adequate to cure the disease

Discuss the concept of orthovoltage radiation therapy treatment, and identify how this radiation energy range affects human skin.

orthovoltage radiation therapy (x-rays in the range of 200 to 300 kVp)

used for oncology patients who underwent such treatments in earlier years for deep-seated tumors

Discuss the impact on human skin when high-level fluoroscopy is used for extended periods of time during cardiovascular or therapeutic

Exposure rates -

high-level fluoroscopy for extended periods, the effects of ionizing radiation on the skin are significant

100 to 200 mGya/mi

Define cytogenetics, and explain how cytogenetic analysis of chromosomes

study of cell genetics with an emphasis on cell chromosomes.

-observe the chromosomes of each human cell have greatly contributed to advancing genetic analysis and the understanding of the influence of radiation on genetics

Explain the process of karyotyping, and identify the phase of cell division in which chromosome damage caused by radiation exposure can be evaluated.

chromosome map called a karyotype. This map consists of a photograph, or photomicrograph

Metaphase is the phase of cell division in which chromosome damage caused by radiation exposure can be evaluated.

List two types of chromosomal aberrations that can be caused by exposure to ionizing radiation, and explain what determines the rate of production of these aberrations

Chromosome aberrations (deviation from normal development or growth)

chromatid aberrations have been observed at metaphase

The total radiation dose given to a somatic or genetic cell and the period of time in which that dose was delivered determine the rate of production of chromosome aberrations.

acute radiation syndrome (ARS).

What is and dose

radiation sickness, occurs in humans after whole-body dose of 6 Gyt of ionizing radiation

biologic dosimetry

A method of dose assessment in which biologic markers or effects of radiation exposure are measured and the dose to the organism is inferred from previously established dose-effect relationships.

cytogenetics

study of cell genetics with an emphasis on cell chromosomes.

Desquamation

shedding of the outer layer of skin, occurs at higher radiation doses.

Early tissue reactions

Epilation, or hair loss

r hair loss (also called alopecia

Early Tissue Reactions

Appear within

• Minutes • Hours • Days • Weeks

Genetic effects

effects upon future generations due to irradiation of germ cells in previous generations.

genetic mutations

Changes in the genetic material of cells that passes from one generation to another. in future generations

Note Effects on the Reproductive System

grenz rays

Used to treat and cure

X-rays in the energy range of 10 to 20 kVp

photons were adequate to cure the disease

karyotype

chromosome map that is taken of the human cell nucleus during metaphase, when each chromosome can be individually demonstrated.

ARS presents in four major response stages

• Prodromal • Latent period • Manifest illness • Recovery or death

prodromal stage

what does

occurs within hours

latent period

Importance:

approximately 1 week which no visible signs occur.

period that either recovery or lethal effects begin.

manifest illness

period when signs and symptoms

involving the hematopoietic, GI, and cerebrovascular systems become visible.

Recovery or death

Most patients who do not recover will die within several months of exposure. The recovery process lasts from several weeks up to two years.

Metaphase relations radiation

phase of cell division in which chromosome damage caused by radiation exposure can be evaluated

pluripotential stem cell

A single precursor cell from which all cells of the hematopoietic system develop

radiodermatitis

significant reddening of the skin caused by excessive exposure to relatively low-energy ionizing radiation that eventually led to cancerous lesions on the hands and fingers.

Soma

body

somatic tissue reactions

If the consequences include cell killing and are directly related to the dose received,

1. Although early tissue reactions are not common in diagnostic radiology, what type of diagnostic imaging procedure could possibly produce a radiation dose sufficient to cause such a reaction?

Fluroscopy

2. In what do unacceptable high x-ray exposures in radiology primarily result?

Skin effect

3. How can a cytogenetic analysis of chromosomes be accomplished?

Through the use of a chromosome map called a karyotype (constructed by cutting out the individual chromosomes and pairing them on the map with their sister chromosomes)

4. What are genetic effects?

Biological effects from radiation on future generations

5. How have scientists become aware of radiation-induced skin damage in early pioneers?

They have developed radiodermatitis (significant reddening of the skin caused by excessive exposure to relatively low-energy ionizing radiation that eventually led to cancerous lesions on the hands and fingers).

6. What are the three separate dose-related syndromes that occur as part of acute radiation syndrome, and what are the four major response stages?

1. hematopoietic syndrome

2. Gastrointestinal syndrome

3. Cerebrovascular syndrome

1. prodromal

2. latent period

3. Manifest illnes

4. recovery or death

7. What is radiodermatitis?

a significant reddening of the skin caused by excessive exposure to relatively low-energy ionizing radiation that eventually led to cancerous lesions on the hands and fingers.

8. After the reception of a single absorbed dose of 2 Gyt of radiation, approximately how long will it take to cause radiation-induced skin erythema?

24 to 48 hours

9. How has information on the gonadal response to radiation exposure been acquired?

• Patients who have undergone radiation therapy

• Radiation accident victims

• Volunteer convicts

10. How significant is the chance of causing sterility in imaging personnel who perform routine procedures?

Depressing sterility-

Temporary sterility-

Permenant sterility -

0.1 Gy can depress the sperm population and possibly cause genetic mutations in future generation; and 0.1 Gy may delay or suppress menstuation

Depressing sterility-0.1gy

Temporary sterility- 2gy for as long as 12 months

Permenant sterility -6gy

11. What are the somatic effects of radiation exposure?

classified as either early or late reactions

12. From where does the term somatic originate?

greek means body

acute radiation syndrome (ARS) whole body is exposed to a dose of

6 Gyt

Symptoms of acute radiation syndrome

Three separate dose-related syndromes

• Hematopoietic syndrome

• Gastrointestinal syndrome

• Cerebrovascular syndrome

manufactures the corpuscular elements of the blood and is the most radiosensitive vital organ system in humans

. The hematopoietic system

Hematopoietic syndrome.

occurs when people receive whole-body doses of ionizing radiation ranging from

1 to 10gy

Hematopoietic syndrome.

Function of the hematopiietic system

manufactures the corpuscular elements of the blood and is the most radiosensitive vital organ system in humans

Hematopoietic syndrome.

Radiation exposure to hematopoietic system will cause

the number of red blood cells,

white blood cells, and

platelets in the circulating blood to decrease

Hematopoietic Symptoms

Nausea; vomiting; diarrhea; decrease in number of red blood cells, white blood cells, and platelets in the circulating blood; hemorrhage; infection

Hematopoietic syndrome.

hematopoietic syndrome and relationship with survival time and why does this occur

shortens as the radiation dose increases.

additional bone marrow are being destroyed and the body becomes more susceptible to infection. (mostly from its own intestinal bacteria)

Hematopoietic syndrome.

When death occurs it is because?

excessive bone marrow destruction causing anemia and little or no resistance to severe infection.

Hematopoietic syndrome.

Death occurs in what time span after irradiation?iWhat is the whole body dose of these very sensitive subjects

6 to 8 weeks after irradiation

receive a whole-body dose just exceeding 2 Gyt

Hematopoietic syndrome.

How can the 6 to 8 week time span of death be shortened

t as the whole-body dose increases from 2 to 10 Gyt, all irradiated individuals will die and in a shorter period

Hematopoietic syndrome.

In dose and time span can recovery happen? bone marrow cells will eventually repopulate to a level adequate to support life in most individuals.

1 to 2 Gyt

3 weeks to 6 months

Hematopoietic syndrome.

How can survival propability be enchanced in patients with hematopoietic syndrome

intense supportive care and special hematologic procedures

ex:bone marrow transplants from appropriate histocompatible donors

Gastrointestinal syndrome.

the gastrointestinal (GI) form of ARS appears at a threshold dose of approximately?

What is the peak dose

6 Gyt and peaks @ 10gy

Gastrointestinal syndrome.

How long does it take the prodromal stage to appear

few hours after the dose Severe nausea, vomiting, and diarrhea persist for as long as 24 hours.

Gastrointestinal syndrome.

How long does it does the latent period last

lasts as long as 5 days

Gastrointestinal syndrome.

manifest illness stage symptoms

Severe nausea, vomiting, diarrhea, fever, fatigue, loss of appetite, lethargy, anemia, leukopenia, hemorrhage, infection, electrolytic imbalance, and emaciation

Gastrointestinal syndrome.

Death of exposed persons occur within how many days and from what key factors

3 to 5/3-10 days from a combination of infection, fluid loss, and electrolytic imbalance

Gastrointestinal syndrome.

How can survival propability be enchanced in patients with Gastrointestinal syndrome.

Survival time does not change with dose in this syndrome.

Gastrointestinal syndrome.

Fatality occurs primarily because

catastrophic damage to the epithelial cells that line the gastrointestinal tract.

Cerebrovascular syndrome

cerebrovascular form of ARS results when the central nervous system and cardiovascular system receive doses

50 Gyt or more of ionizing radiation.

Cerebrovascular syndrome

Death of exposed persons occurs within?

few hours to 2 or 3 days after exposure.

Cerebrovascular syndrome

Symptoms

Same as hematopoietic and gastrointestinal, plus excessive nervousness, confusion, lack of coordination, loss of vision, burning sensation of the skin, loss of consciousness, disorientation, shock, periods of agitation alternating with stupor, edema, loss of equilibrium, meningitis, prostration, respiratory distress, vasculitis, coma

Major response stages of acute radiation syndrome

Doses

• Prodromal

occurs within hours after a whole-body absorbed dose of

• Latent period

what happens here

• Manifest illness

Signs and symptoms

• Recovery and death

after receiving a whole-body near-lethal dose such as _________

death exposed persons pass through the first three stages but display less severe symptoms than those seen with highly lethal doses of 6 to 10 Gyt? What dose might recovery happen at and in how much time might recovery happen?

1. 1 Gyt or more

dose related; the higher the dose, the more severe the symptoms.

2.period that either recovery or lethal effects begin

3. • Apathy and confusion • Fluid loss and dehydration • Epilation • Headaches and exhaustion • Vomiting and severe diarrhea • Fever and infection • Decreased numbers of red and white blood cells and platelets in the circulating blood • Hemorrhage • Cardiovascular collapse

4. 2 to 3 Gyt, recovery may occur in approximately 3 months.

Lethal Dose LD 50/30.

signifies?

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

The lethal dose (LD 50/30) of radiation for humans is estimated to be

3.0 to 4.0 Sv

Whole-body doses greater than______ will cause the death of the entire population in 30 days without medical support.

6 Gyt

Repair and Recovery

How does repair and recovery occur

cells contain a repair mechanism inherent in their biochemistry (repair enzymes

Repair and Recovery

repair and recovery can occur when cells are exposed to____________ doses of ionizing rad

After this level of irradiation, surviving cells will be able to divide and thereby begin to repopulate in the irradiated region. What is the importance of this process

sublethal doses

organ is able to regain some of its most useful abilities beacuse damage was only functional damage

Repair and Recovery

What type of cells are best for recovery and why?

What type of cell are worst for recovery and why

cells that are oxygenated- receive more nutrients, have a better prospect for rec

cells that are hypoxic, or poorly oxygenated-receive fewer nutrients

Repair and Recovery

When both cell categories are exposed to a comparable dose of low-LET radiation, the oxygenated cells are

more severely damaged, but those that survive can repair themselves and recover from the injury. Even though they are less severely damaged, the hypoxic cells do not repair and recover as efficiently.

Repair and Recovery

Research has shown that repeated radiation injuries have a cumulative effect. Hence a percentage _____________ of the radiation-induced damage will be irreparable, whereas the remaining_____________ may be repaired over time.

10%

90%

Local Tissue Damage

What is the type of effect occurs as a result of the human body receiving high radiation

atrophy

Local Tissue Damage

How can atrophy cells recover

Organ and tissue response to radiation exposure depend on factors such as

partial or complete, depending on the types of cells involved and the dose of radiation received. Should this not happen, then necrosis, or death, of the irradiated biologic structure results.

• Radiosensitivity

• Reproductive characteristics

• Growth pattern

Effects on the Skin

Whi pion