Flashcards in RadBio Study Guide Deck (118):
The shedding of the outer layers of skin?
Who was Clarence Daily and did he do?
Thomas Edison's assistant , he helped prove the dangers of radiation.
4 Laws of Bergonie and Tribondeau?
1. Stem or immature cells are more radiosensitive than mature cells
2. Younger tissues and organs and more radiosensitive than older tissues and organs
3. The higher the metabolic cell activity, the more radiosensitive it is.
4. The greater the proliferation and growth rate for tissue, the greater the radio sensitivity.
What is the Law of Bergonie and Tribondeau?
Concludes that compared to a child or adult a fetus is most radiosensitive.
Believed it was best to give a large dose at one time for the best results from treatment.
Gave second treatment at smaller dose over longer period of time.
The ability of normal tissues to replenish themselves following injury.
Define as the time during which a course of radiation is given.
Symbol is R
It is a measure of the ionization of air.
Symbol is rad
Considered the unit of absorbed dose.
Symbol is Rem
Unit of dose equivalent or occupational exposure.
Rad = ?
Rem = ?
Roentgen = ?
Makes recommendation, not laws or requirements.
Set an occupational exposure limit of 5 Rem per year.
Occupational exposure is what per year?
Basic unit of a structure and function of all living things.
Water makes up how much of a persons body weight?
Cells can be?
Spherical, rectangular, or irregular.
What is radiobiology?
Branch of science concerned with the methods of interaction and the effects of ionizing radiation on living systems.
Building blocks of proteins.
Function is to store energy.
Outside; prevents the cell from bursting.
Inside the cell; prevents the cell from collapsing.
Takes place in the cytoplasm.
The process of of converting a complex substance into a simpler substance.
The building up if a body's substance.
Nicknamed suicide bugs.
What is a germ cell?
Chromosomes and genes are not paired.
What is a somatic cell?
All other cells within the body that arnt germ cells
Have at least two of each kind of gene situated on two different chromosomes.
Cell division can be divided into two parts (dividing of nucleus/cytoplasm)
Has G1, S, G2
Includes the four major steps.
Deals with formation of germ cells.
Cell divides twice in succession but chromosomes are duplicated only once
What is the most radiosensitive part of the cell?
Most radiosensitive phase?
M phase of mitosis.
Most radioresistant phase?
Late S phase of mitosis.
What does LET stand for?
Linear Energy Transfer.
What does RBE stand for?
Relative Biologic Effectiveness.
What does OER stand for?
Oxygen Enhancement Ratio.
A measure of the rate at which energy is deposited as a charged particle travels through matter.
A comparison of a dose to test radiation to a dose of 250 keV X ray that produces the same biological effect.
The does of radiation that produces a given biologic response under anoxic conditions divided by the dose of radiation that produces the same biologic response under aerobic conditions.
What happens as LET increases?
More oxygen = more radiation.
What is direct interaction?
Radiation interacts with a macromolecule.
What is indirect interaction?
Radiation interacts with water or a non critical molecule then transfers to a critical molecule.
What is a critical molecule?
What is the most critical target of radiation?
Assumes that there is a radiation level reached below where there are no effects observed.
Assumes that any radiation will produce an effect.
The observed effect is proportional to the radiation dose received.
The observed effect is not proportional to the radiation dose received.
Linear on a graph?
Nonlinear on a graph.
Threshold on a graph.
Line begins above zero.
Nonthreshold on a graph.
Line behind at zero.
Diagnostic radiography normally deals with what in the normal dose curve?
1 Rem = ?
6 mrem = ?
.006rem = .006rad.
The LD 50/60 is how many rads?
What are the 4 response stages?
Death and recovery.
Describe prodromal stage.
Nausea, vomiting, diarrhea
Can happen with 100 rads.
Describe latent stage.
Appear symptom free
Changes lead to death and recovery.
Mistaken for early recovery.
Describe manifest stage.
After latent stage.
Symptoms of which organ system has been damage.
Describe death and recovery stage.
Patient will either recover if die depending on this dose and which organ system was damaged.
Describe bone marrow syndrome.
No one has lived 1000R
Death would happen within 2 weeks caused by destruction of bone marrow.
100-300R = bone marrow can repopulate
300-500 death will occur within 4-6 weeks.
Describe gastrointestinal syndrome.
Death can occur between 4-10 days
Death is caused by severe damage to the stem cells lining intestines.
Describe central nervous system syndrome.
Can occur over 5000R
Will occur 10,000R
Death usually within hours (0-3 days)
Cause of death is elevated fluid content of the brain.
What are the 5 radiation interactions?
Describe coherent scattering.
The incident X-rays interact with a target atom causing it to be excited
Target atom releases the excess energy as scattered X-ray.
Result is changed direction with no change in energy.
Describe Compton effect (Compton scattering)
Incident X-ray interacts with outer shell electron and ejects it from atom therefor ionizing atom.
One of two primary forms of X-ray interactions for diagnostic ranges.
Describe photoelectric effect (photoelectric absorption)
X-ray interacts with an inner shell electron and its completely absorbed.
Inner shell electron that was interacted with is then ejected from atom.
One of two primary X-ray interactions in diagnosis ranges.
Describe pair production.
X-ray has enough power to interact with nuclear field of atom it hits.
Incident X-ray disappears and two electrons appear. (Positive,Negative)
Describe photo disintegration.
Xray is absorbed directly by nucleus of atom it interacts with.
Causes atom to become excited and release nuclear fragment.
What are 4 populations that are used as sources of data on the incidence of radiation induced cancer.
1. Atomic bomb survivors.
2. Medically exposed patients
3. Occupationally exposed personnel
4. Populations that receive high natraj background exposure.
What are the 6 radiation induced malignancies?
2. Skin carcinoma
3. Thyroid cancer
4. Breast cancer
5. Osteosarcoma (bone cancer)
6. Lung cancer.
What did Russell conclude?
Radiation is a powerful mutagenic agent
Radiation induced he tic damage can occur as a result of a single mutation.
Why are the three stages of development of the fetus?
Fetal or growth stage.
Describe the preimplantation stage.
From conception to 9days
Radiation damage during this stage can cause prenatal death.
Describe major organogenesis stage.
2nd - 8th week of pregnancy.
Congenital abnormalities is more frequent in this stage
Describe the fetal growth stage.
End of major organogenesis-until birth.
Involve the nervous system and sense organs.
Damage caused may not show up until later in life.
Symptoms include behavior changes, reduced IQ, and cancers.
The theory that ionizing radiation is benign at low levels of exposure, and that doses at the level of natural background radiation can be beneficial.
What does TLD stand for?
(Worn by nuc med techs on finger)
Describe film badges.
Measure occupational radiation exposure.
Shallow and deep doses can be calculated.
Advantages of TLD?
Can be very small
Response to X-rays up to 4R
Less sensitive to heat
Can be worn for 3 months.
Disadvantages of TLD?
Cannot be stored as a permanent record
More expensive then film badges.
What does OSL stand for?
Optically Stimulated Luminescence.
(Used for pregnant workers as it can measure as small as 1mrem)
Advantages of OSL.
Bimonthly readout offered
Not effected by heat
Disadvantage of OSL?
More expensive than film badges and TLD.
Describe pocket dosimeters.
Can provide instantaneous read outs, but recalibrate daily
Used in emergency situations.
Advantages of pocket dosimeters.
Sensitive to exposures up to 200mR
Can be reset to record individual exposure readings
Provides an immediate exposure reading.
Disadvantages a of pocket dosimeters.
Does not provide a permanent record of exposure.
Bumping or shock to unit can cause false high readings.
What is the dose limit for whole body?
What is the dose limit for whole body cumulative (life)
Age X1 Rem (age X 10 mSv)
Why is the dose limit of a fetus ( one month )
0.05 Rem (0.5 mSv)
What is the dose limit for a student under the age of 18?
0.1 Rem (1mSv)
Skin dose and mean marrow dose for PA chest?
Skin and mean marrow dose for AP Abdomen?
Skin and mean marrow dose for lumbar spine?
Skin and mean marrow dose for pelvis?
SD - 150mrad
How far away should you be away from X-ray source during a mobile exam?
How much minimum of lead should lead aprons have in thickness?
What is the most effective means of protecting the radiographer from radiation exposure?
Inverse square law!
What happens to patient dose when mAs is decreased?
Increase film speed what happens to patient dose?
Approx 95% of density on a film is what?
Result from light from the screen.
Increase in grids does what to patient dose?
What produces the greatest patient radiation exposure?
What do proteins do?
Assist in cellular growth and repair.
What do carbohydrates do?
Provide energy in the cell.
Mitosis process of cell division is what?
The nucleus and the cytoplasm divide to form two identical cells.
Meiosis process of cell division is what?
The purpose of reproduction.
What is main-chain scission?
Macromolecule is reduced in size and thickness.
What is cross linking?
Spurs on ma macromolecules adhere to other macromolecules, enlarging and thickening the original.
What is a point lesion?
Slight molecular changes occur that cause the cell to function incorrectly.
When do stochastic effects occur?
Randomly, the probability of being affected increases with the dose.
Responsible for maintaining the protection of personnel, monitoring personnel exposures, testing for radiation leaks, developing shielding apparatus, responding to emergencies involving radiation exposures and coordinating the decontamination of radiation spills.
Radiation safety officer.