Lesson 9: Early Effects of Radiation Flashcards
Define Total Body Exposure
Total body including critical organs are exposed
- all body systems effected
Define Acute Exposure
Short term high level exposure
Chronic Exposure
Long term low level exposure
What do Acute and chronic Exposures cause
Somatic Effects: Biological damage from ionizing radiation to the body
Stochastic and non stochastic (deterministic)
the way the human body responds to radiation dose
What are Non Stochastic Effects
the severity of the effects varies with the dose which a threshold value exists
- no effect until a certain point
What is a stochastic effect
increased levels of exposure make these health effects more likely to occur but does not influence the type or severity of effect
- non threshold (any chance of effect)
typically occur with chronic radiation
- cancer, leukemia, genetic deficits
What are some early deterministic (non stochastic) effects
have a threshold
appear within minutes to weeks
when whole body is exposed to large dose over short time leads to acute radiation syndrome
Where does the research for ARS
Hiroshima
Marshall Islanders
Chernobyl
Radiation therapy patients
Radiation Poisoning
Alexander Litvinenko
Former Spy poisoned by Radioactive plutonium
What is Acute radiation syndrome
the sequence of events following high level radiation exposure leading to death within days/weeks
4 Stages of ARS
- Prodromal Period
- Latent Period
- Manifest Period
- Recovery or death
ARS - Prodomal Period
happens at doses of 1Gy (1000mSv) delivered to total body
signs of radiation sickness may appear
NVD - reduction in white blood count
- hours to a few days
ARS- Latent Stage
The patient looks and feels healthy for a few hours to weeks
recovery or lethal effects begin here
ARS - Manifest Stage
- symptoms of particular syndrome begin to appear dose dependent
- Hematologic Syndrome
- Gastrointestinal Syndrome
- CNS Syndrome
Hematopoeitic Syndrome
Whole body dose of 1-10Gy
- damage to bone marrow
- Predomal Stage: (NVD) like the flu - hours to days
- Latent Stage: cells declining in numbers (about 4 weeks)
- Manifest Stage: survival range 1-2Gy depletion of blood cells, NVD anorexia destruction of bone marrow causing hemmorage
- mean survival of 6-8 weeks
Gastrointestinal Syndrome
Whole body dose of 6-8Gy
- damage to GI and bone marrow (severe fluid loss)
- Prodromal Stage: within hours, lasts <1 day
- Latent Period: 2-5 days
- Manifest Period: 5th-10th day
- irreperable damage of the GI tract cause infection dehydration and electrolyte imbalance
- death occurs with 3-14 days
Cerebrovascular Syndrome
Whole Body dose of 50Gy
- damage to blood vessels increases intercranial pressures
-Death happens before other symptoms can occur
- Prodromal Stage: NVD lasts a few hours
- Latent Period: a few hours
- Manifest Period: 5-6 hours after exposure
convulsions, coma
- death within 3 days
Explain LD 50/30
Signifies the whole body dose of radiation that can be lethal to 50% of the population within 30 days
- for adults its 3-4GY without medical support
What is LD 100
6Gy without medical support
What dose have humans survived with medical support
8.5Gy
Explain Partial Body Exposures
- radiation therapy
- results from early radiography pioneers
- radiodermatitis - skin burning
- skin cancer on fingers and hands
What Local Tissue Damage Occurs due to Partial Body Exposure
- Significant cell death usually results after substantial partial body exposure
- atrophy of organs and tissues
- organs may lose their ability to function or they may recover
- radiodermatitis: reddening of the skin
What is required to determine if recovery is possible
the dose recieved and the type of tissue cells involved
Dependent on
- Radiosensitivity
- Reproductive characteristics
- Growth Rate
What local tissues suffer immediate consequences from high radiation doses
- skin
- reproductive organs
- bone marrow
Effects Of Ionizing Radiation on the Skin
- radiodedermatitis
- desquamation
- epilation/hair loss (3-7Gy)
Effects of Ionizing Radiation on Epithelial tissue
- body constantly regenerates, therefor highly
radiosensitive
Effects of Ionizing Radiation on Muscle Tissue
- Muscle tissue- highly specialized, relatively insensitive to radiation
Effects of Ionizing Radiation on Nervous Tissue
- Nerve tissue in the human adult: highly specialized
- Nerve tissue in the embryo-fetus: more radiosensitive, especially 8 to 15
weeks after gestation
Effects of Ionizing Radiation on Reproductice Cells
- Spermatogonia: doses as low as 0.1 Gy (100 mSv) can depress sperm count
- Ova: doses as low as 0.1 Gy (100 mSv) may delay or suppress menstruation
- Testes of males and ovaries of females do not respond in the same way to
radiation - can lead to genetic mutations
What is the most radiosensitive cells
Lymphocytes and spermatogonia
What dose will cause temporary sterility
2Gy may last up to 12 months
- could be chromosomal abnormalities
What dose will cause permanent sterility
- 5Gy in male or female
What is a pluripotential stem cell
- becomes lymphocytes, Granulocytes platelets or erythrocytes
- Hemopoetic System
