Date post: | 30-May-2018 |
Category: |
Documents |
Upload: | johntobler |
View: | 226 times |
Download: | 0 times |
of 26
8/14/2019 Radiation Saftey Series 4
1/26
Radiation Safety Series 4
Radiation Hazards
8/14/2019 Radiation Saftey Series 4
2/26
Human Exposure to Radiation
Annual DoseSource mrem/yr
Exposure from natural backgroundCosmic rays (sun and outer space) 28Building materials 4
Human body 25The earth 26
Approximate total annual exposure 100
8/14/2019 Radiation Saftey Series 4
3/26
Human Exposure to Radiation
Annual DoseSource mrem/yr
Exposure from man made sourcesMedical (mostly diagnostic x-ray) 90Fallout from atomic bombs 5
Consumer products (mostly color TV) 1__ Approximate total annual exposure 100
8/14/2019 Radiation Saftey Series 4
4/26
Human Exposure to Radiation
Occupation radiation source averagesRadiography company workers 440Gamma Radiographers 1,000
CNRP Report No. 45, 1975 and NCRP Report No. 45, 1977
8/14/2019 Radiation Saftey Series 4
5/26
Radiation vs. Contamination
RadiationThe emission of waves or fast moving
particles through spaceRadioactive Contamination
Material that is radioactive anduncontrolled. It may soil surroundingareas and become airborne
8/14/2019 Radiation Saftey Series 4
6/26
Ionization of Body Tissue
X-ray, gamma andneutron penetrate the
body to differentdegrees
Through the ionization process energy isabsorbed by the tissue
This causes damage tothe bodys complexsystemshttp://www.ratical.org/radiation/NRBE/NRadBioEffects.html
8/14/2019 Radiation Saftey Series 4
7/26
8/14/2019 Radiation Saftey Series 4
8/26
Biological Effects
How much physical energy does this largedose of ionizing radiation represent?
Since all forms of energy interconvert, wecan use heat units as a basis of comparison
A CALORIE is (by definition) the amount
of heat needed to raise the temperature of one gram of water by one degree Celsius.The conversion from ergs to calories is:
8/14/2019 Radiation Saftey Series 4
9/26
Biological Effects
1 erg = 2.39 x 10 -8 calories. Now since 1 rad (of ionizing radiation)
deposits 100 ergs of energy per gram,400 rads will deposit
40,000 = 4 x 10 4 ergs per gram,
which is equivalent to (4 x 10 4) x (2.39 x 10 -8) = 9.56 x 10 -4
calories per gram
8/14/2019 Radiation Saftey Series 4
10/26
Biological Effects
This amount of energy would raise thetemperature of one gram of water by lessthan 0.001 o C !
(That is, less than one one-thousandth of adegree Celsius!) It is an imperceptible
amount of heat
8/14/2019 Radiation Saftey Series 4
11/26
Biological Effects
This calculation highlights the enormousdifference between energy in the form of heat and
energy in the form of ionizing radiation. An amount of energy which is absolutely
inconspicuous in one form can be lethal inanother. When a radioactive material gives off anydegree of perceptible heat, it is capable of killingthousands of people.
8/14/2019 Radiation Saftey Series 4
12/26
What is the reason for the
difference?It is because the energy of ionizing radiation is notuniformly distributed among all the molecules of agram of tissue, the way thermal energy is. Instead,ionizing energy is transferred to just a fewelectrons in a relatively few molecules, therebydisrupting the molecular basis of living cells. Thatcellular damage is then multiplied and amplified
by normal -- and abnormal -- biological processes.
http://www.ccnr.org/ceac_B.html
8/14/2019 Radiation Saftey Series 4
13/26
Radiation Damage
Cell damage due to radiation Exposure: Increases as cell reproduction rates
increases Decreases as the degree of cellular
differentiation increases Decreases as cells mature
8/14/2019 Radiation Saftey Series 4
14/26
Human Cell Sensitivity
1. White Blood Cells2. Immature Red Blood Cells3. Digestive System Lining Cells4. Cells of the Gonads
5. Blood Vessel Cells6. Bone, Muscle and Nerve Cells
Lowest number has the highest sensitivity
8/14/2019 Radiation Saftey Series 4
15/26
Nature of Cell Damage
Cell damage due to radiation exposure canoccur in the following ways:
2. Mitosis delayed or stopped (cell division)3. Cell Injury may be temporary or
permanent
4. Cell death5. Chromosome Breakup6. Temporary or permanent cell dysfunction
8/14/2019 Radiation Saftey Series 4
16/26
Categories of damage
Somatic effectsthe physical effects to the body resultingfrom cell damage
Genetic effectsmutations caused by damage to the germline (inheritance)
8/14/2019 Radiation Saftey Series 4
17/26
Radiation Damage Factors
Rate the dose is administered5 rem per quarter for 40 years = 200rem. 200 rem in one dose may be fatal. Damaged cells are replaced quickly.
2. Extent the body is exposedA large dose over the whole body may cause death. A large dose on a small part of the body will damage that partand not cause death.
5. Part of the body exposedHands, forearms, feet and ankles are allowed 18.75 rem per quarter. Whole body is only allowed 1.25 rem.
7. Age of individual18 years of age and younger are in a high cell growth stage9. Biological differences
Biological response is different from individual to individual
8/14/2019 Radiation Saftey Series 4
18/26
Effects of Radiation Dose
The minimum lethal dose of radiation exposure isapproximately 200 rem. By comparison,
background radiation exposure in the UnitedStates is about 360 mrem per year. Whenappropriate medical care is not provided, themedian lethal dose of radiation is estimated to be
350 rem. Modern medical therapy dramaticallyimproves the survivability of radiation injury.
8/14/2019 Radiation Saftey Series 4
19/26
Effects of Radiation Dose
The following probable outcomes depend on radiationexposure amounts:
For 1000 rem or more: Immediate death occurs . For 600-1000 rem: Weakness, nausea, vomiting, and
diarrhea are followed by apparent improvement. After several days, fever; diarrhea; hematochezia; hematemesis;hematuria; and hemorrhage of the larynx, trachea, bronchi,or lungs may occur. Death results in about 10 days .Autopsies show destruction of hematopoietic tissues,including bone marrow, lymph nodes, and spleen, andswelling and degeneration of epithelial cells of theintestines, genital organs, and endocrine glands.
8/14/2019 Radiation Saftey Series 4
20/26
Effects of Radiation Dose
For 250-600 rem: Nausea, vomiting, diarrhea, epilation (loss of hair),weakness, malaise, hematemesis, hematochezia, hematuria, epistaxis,
bleeding from gums and genitals, subcutaneous bleeding, fever,
inflammation of the pharynx and stomach, and menstrualabnormalities occur. Marked destruction of bone marrow, lymphnodes, and the spleen causes a decrease in blood cells, especiallygranulocytes and thrombocytes. Radiation-induced atrophy of theendocrine glands, including the pituitary, thyroid, and adrenal glands,occurs. From the third to fifth week after exposure, death is closelycorrelated with the degree of leukocytopenia. More than 50% of patients die in this time period . Survivors may develop keloids,ophthalmologic disorders, blood dyscrasias, malignant tumors, and
psychoneurologic disturbances.
8/14/2019 Radiation Saftey Series 4
21/26
Effects of Radiation Dose
For 150-250 rem: Nausea and vomiting occur on the firstday. Diarrhea and skin burns are probable. Apparentimprovement is noted for about 2 weeks thereafter. Fetal or embryonic death occurs in pregnant women.Symptoms of malaise are noted, as described above.
Persons in poor health prior to exposure or those whodevelop a serious infection may not survive. A previously
healthy adult recovers somewhat in about 3 months butmay have permanent health problems, may develop cancer or benign tumors, and will probably have a shortenedlifespan. Genetic and teratogenic effects have been noted.
8/14/2019 Radiation Saftey Series 4
22/26
Effects of Radiation Dose
For 50-150 rem: Acute radiation sickness and burns are less severe than at the higher exposuredose. Spontaneous abortion or stillbirth occurs.Tissue damage effects are less severe. Reductionin lymphocytes and neutrophils leaves theindividual temporarily vulnerable to infection.Genetic damage to offspring, benign ormalignant tumors, premature aging, andshortened lifespan are possible. Genetic andteratogenic effects have been noted.
8/14/2019 Radiation Saftey Series 4
23/26
Effects of Radiation Dose
For 10-50 rem: Most persons experiencelittle or no immediate reaction. Sensitive
individuals may experience radiationsickness. Transient effects
http://www.emedicine.com/emerg/topic934.htm
8/14/2019 Radiation Saftey Series 4
24/26
4 clinical stages of radiation
exposureEach of the acute radiation syndromes (ie, hematopoietic,
gastrointestinal, neurovascular) manifests 4 clinical stages.Depending on the dose of radiation absorbed, these stages
may be of varying lengths. The prodromal phase begins at the time of exposure and
lasts for approximately 1-4 days. The prodrome ischaracterized by a relatively rapid onset of nausea,vomiting, and malaise. Radiogenic vomiting may easily beconfused with psychogenic vomiting that often resultsfrom stress. In high-dose exposures, the length of the
prodromal phase may be considerably shortened andreplaced by the manifest illness phase. A very short to nolatent period may occur, as described below.
8/14/2019 Radiation Saftey Series 4
25/26
stages of radiation exposure
The latent period represents an interval of apparent well- being that lasts for 2-6 weeks but decreases markedly asthe dose rate and the total dose are increased. Cliniciansshould not be encouraged by this apparent improvement inclinical status.
Manifest illness is characterized by the clinical symptomsassociated with the major organ system injured (ie,
marrow, intestinal, neurovascular). Recovery or death follows.
http://www.emedicine.com/emerg/topic934.htm
8/14/2019 Radiation Saftey Series 4
26/26
Works Sited
Radiation Safety Training Series Part 1: Radiation, RudarmelEnterprises, inc. Lake Oswego, Oregon
CNRP Report No. 45, 1975 and NCRP Report No. 45, 1977http://www.ratical.org/radiation/NRBE/NRadBioEffects.htmlhttp://www.ccnr.org/ceac_B.htmlhttp://www.emedicine.com/emerg/topic934.htm