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03 - pathology radiation


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3 types of Radiation
1. Electromagnetic Waves
2. Energetic Charged Particles
3. Neutral High Energy Particles
2 Electromagnetic Waves

Gamma rays
3 Energetic Charged particles
Neutron radiation = __1___ particles that are a type of ___2____ radiation
1. uncharged
2. non-ionizing
Neutron radiation is produced in large amounts by _________
nuclear explosions

*accounted for ~2-20% of radiation dose at Hiroshima
Neutron High Energy Particle
Neutrons accounted for 2-20% of the radiation dose at _________
Alpha radiation = release of ____1___ and _____2__ from a __3_____
1. 2 protons
2. 2 neutrons
3. fissioning nucleus
Alpha particles travel only a few ___1__ in air, but are __2___
1. mm
2. ionizing
emission of electrons = ?
Beta radiation
Beta radiation: All electrons possess a ___1__ charge so they ___2___matter that they interact with. Beta particles travel several meters in ___3__, several cm in __4__, but only mm through __5___
1. negative
2. ionize
3. air
4. tissue
5. aluminum
Quantity of X or g rays which give rise to 2.09 X 10^9 ion pairs/ cm3 of AIR.
R (Roentgen)
Roentgen is not applicable to _______
particulate radiation
RAD = ?
Radiation absorbed dose
Radiation absorbed dose = a method of estimating radiation effects absorbed by ___________
substances other than air
1 RAD = ?
100 ergs of energy absorbed per gram of any substance
the new international unit replacing the RAD
Gy (Gray)
1 Gy = ?
100 RAD
Infrared radiation = a __1__ wavelength form of __2__ radiation that is __3__. Its effects are commonly experienced as __4__
1. long
2. electromagnetic
3. non-ionizing
4. heat
Gamma radiation = a __1__ wavelength, __2__ energy form of __3__ radiation that has high __4__ qualities.
1. short
2. high
3. electromagnetic IONIZING
4. penetration
X rays = identical to __1__, except that they originate from __2__ the atomic nucleus. They are a __3__ form of radiation.
1. gamma rays
2. outside
3. ionizing
REM = ?
RAD equivalent (Man)

*man = humans*
REM multiplies RAD times a quality factor (Q), to approximate absorption of energy by _____
For humans, the quality factor is assumed to be 1 for _1_ and _2_ rays. So 1 REM = __3__ RAD
gamma rays
New international unit replacing REM
Si (Sievert)
1 Si = ?
joules of energy absorbed per kg
__1__ REM = 1 Sievert
1 __2__ = 1 Sievert
1. 100
2. Gray
Explain Fission
nucleus of an atom splits into 2 or more smaller nuclei and by products.
It is induced by a thermal neutron being absorbed by the nucleus of Uranium-235 atom
Explain Fusion
process in which multiple nuclei join together to form a heavier nucleus accompanied by release or absorption of energy
depending on the masses involved.

Nuclei lighter than Iron and Nickel will cause release of energy
Fallout occurs only after _______
Explain "Local Fallout"
Coarse particles caught in the explosion are contaminated with Fission products and "fallout" of the air near the site of the blast
Explain "Worldwide Fallout"
Smaller debris carried into the Stratosphere by the heat of the explosion that may not return to earth for years.
5 Radionuclides that are of greatest concern
1. Strontium-90
2. Strontium-89
3. Cesium-137
4. Carbon- 14
5. Iodine-131

Strontium-90 half-life
28 years
Strontium-89 half-life
51 days
Strontium-90 is a major hazard due to these two properties
1.incorporated into BONE
2. long half-life
Sources of Strontium-90
1. Dairy products
2. surface contamination of fruits and vegetables
Produces the greatest internal exposure in the weeks following a nuclear explosion
Iodine-131 is deposited on the surface of __1__, which is then eaten by __2__, where it is secreted in __3__
1. vegetation
2. meat animals
3. milk
When ingested in animals, Iodine-131 concentrates in the ____
Iodine-131 half-life is __1__, and is therefore only a threat in __2__
1. 8 days
2. local fallout
* Iodine-131 in the stratosphere will decay harmlessly before it falls to earth
Cesium-137 half-life is __1__. It localizes in __2__ and can represent a genetic hazard from __3__ exposure.
1. 30 years
2. soft tissue
3. gonadal
Why is Cesium-137 a lesser risk than Strontium-90
Cesium is gradually eliminated from the body over several months
Cesium is used as a source for _________
modern radiotherapy equipment
Carbon-14 is formed by __1__ activation of stable __2__ following a nuclear explosion. It is familiar to most people as an isotope used in __3__.
1. neutron
2. Carbon-12
3. radiocarbon dating
Carbon-14 half-life = ?
5800 years

*dangerous component of nuclear fallout
Cells most subject to radiation damage
rapidly proliferating cells
Body systems most vulnerable to radiation
1. Hematopoietic (bone marrow, spleen, lymph nodes)

2. GI system

3. CNS
> 100,000 RAD
Molecular Death
>2000 RAD
CNS syndrome
500-2000 RAD
GI syndrome
50-500 RAD
Hematopoietic Syndrome
Late effects
GI syndrome: death results in a few days from ________
Circulatory Collapse
GI syndrome: no treatment except for those with lower doses that might benefit from _______.

3 symptoms associated with GI syndrome.
Bone Marrow Transplant

Nausea, vomiting, diarrhea = NVD Syndrome
Severity of NVD correlates with ________
radiation dose
Hematopoietic Syndrome: has __1__ symptoms that resolve in 1-2 days.
Treatment = __2__
1. NVD symptoms
2. Bone Marrow Transplant
Possible late effects of Hematopoietic Syndrome
Post-radiation cancers - Leukemia
Only this Radiation Syndrome can be effectively treated
Hematopoietic Syndrome
Hematopoietic Syndrome treatment consists of __1__, plus early __2__
1. supportive care
2. HLA typing for BMT
If HLA is not typed right away, the radiation may _____
eliminate all white cells (Pancytopenia) and even with transplant survival is poor
Short-term effects of radiation on Skin:
First seen within __1__ and peak effects at __2__ post-irradiation

5 Symptoms
1. 2-3 days
2. 2-3 weeks

Hyper/Hypo pigmentation
Epidermal Atrophy
Telangiectasia (spider veins)
Long-term effect of radiation on Skin
Squamous Cell Carcinoma
Soft Tissue has long term risk of ________
Sarcoma (angiosarcoma, osteosarcoma, etc.)
Direct Effect of radiation
disruption of DNA covalent bonds and linkages
Indirect Effect of radiation
H2O electrolysis --> oxygen free radicals --> lipids, enzymes, nucleic acids
Tissue injury is dependent on these 4 factors
1. dosage
2. rate of dose delivered
3. LET (linear energy transfer) of the radiation
4. vulnerability to radiation effect

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