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Carol's Final Review

Carols final RA221

The most abundant molecule in the body is water
The 2 nucleic acids in the cell are DNA and RNA
What is the function of DNA? Heredity, chromosomes, genes, directs protein synthesis, tells the cell what protein to make
The significance of the sequence of the bases on the DNA molecule is critical or a mutation can occur or wrong protein made
What are the 4 stages of mitosis? Prophase, metaphase, anaphase, telophase
What occurs in Prophase? chromosomes begin to appear
What occure in metaphase? chromosomes line up at equator of the cell. At this stage can be studied.
What occurs in anaphase? Move to opposite poles (away)
What occurs in telophase? Dont see chromosomes, closes off and forms 2 daughter cells
Which phase is most radioresistant? "S" stage (DNA synthesis)
Which phase is most radiosensitive? Mitotic stage (division phase)
How does meiosis differ from mitosis? Meiosis is reduction (46 to 23). Mitosis duplicates
Mitosis occurs with somatic cells (nonreproducing)
Meiosis occurs with Germ cells (sperm and egg)
How many chromosomes are in human somatic cells? 46 chromosomes (23 pairs)
How many chromosomes are there in germ cells 23
Law of Bergonie and Tribondeau states Radiosensitivity of tissues varies with maturation and metabolism. 1. Age of cell (younger more sensitive) 2. Mitotic rate. (faster they divided more sensitive) 3. Degree of differentiation of cell ((more specialized less sensitive)
Define LET Linear Energy Transfer is the rate which energy is deposited into the tissue.
What is the LET is diagnostic radiology? 3 KeV per micrometer of tissue
Define RBE Relative biologic effectiveness. The biological effect of radiation what does it do to the body and how badly does it do it.
The formula for RBE is Dose of standard rad necesary to produce an effect/dose of test radiaiton necessary to produce an effect
How does LET relate to RBE? The higher the LET the greater the RBE because its going tobe more damaging.
Define protraction Dose delivered over a long period of time (low dose rate/low exposure rate)
Protraction and effect on the body Protects healthy tissue low dose rate over longer period of time allows time for tissue to recover
Define fractionation Dose deliverd in increments seperated by time
Fractionation and effect on the body Less tissue damage Lower dose rate separated by time
Explain OER Oxygen Enhancement ratio Degree that oxygen enhances cell sensitivity to radiation
How does oxygen influence radiaiton on the body? Makes the tissue more sensitive to radiation, it increases its affect
What period of life is individual most radiosensitive? Before birth
What period in life is an individual most radioresistant? Middle age, but as age more become more radiosensitive again
Define threshold dose Minimum dose needed for response to occur
Define non threshold No minimum dose is known
What is a stem cell? baby cell, immature cell, precursers
List 5 types of damage radiation can inflect on DNA molecule 1. Cell death; 2. Reproductive failure. 3. Interpherence with function (cell doesnt work right 4. Mitotic delay 5. Mutations
Direct effect Damage done directly to molecule
Indirect effect Radiation hits something else first. Most common effect
Define free radical Single unpaired orbital electron. Highly reactive, mobile damage other tisues
What 2 free radicals are produced during radiolysis of water? hydroxyl and hydrogen
What toxic compound is formed as result of combo of 2 hydroxyl radicals? Hydrogen peroxide
Stem Cells high radiosensitivity
Muscle cells low radiosensitivity
spermatogonia High radio sensitivity
Osteocytes (bone cells) Low radiosensitivity
Rapidly dividing cells High radiosensitivity
Highly differentiated cells Low radiosensitivity
Nerve cells low radiosensitivity
mature cells low radiosensitivity
Factors necessary to produce acute radiation lethality are Whole body dose, short period of time, high dose of 6 gray or more
Prodromal Diahrrea, vomiting, nausea
Latent period No symptms
Manifest illness See symptoms (3 stages, Hemopoetic, GI, CNS)
recovery or death Recover only from hemopoetic,rest are fatal
Exposure level to produce hematologic syndrome 200 to 1000
Exposure level to produce GI syndrome 1000 to 5000
Exposure level to produce CNS syndrom over 5000
Explain LD 50/30 50% of population will die in thirty days
Early effects of radiation Somatic not genetic. Appear right away or shortly after exposure, i.e., erythema
Late effects of radiation Life of individual appear much later i.e. cataracts, some cancers, genetic
Gonadal dose to produce a reduction in sperm count 10 rads
Gonadal dose to produce delay of menstruation 10 rads
Gonadal dose to produce temp sterility 200 rads
Gonadal dose to produce permanent sterility 500 rads
Three early effects of radiation to skin are Erythema (redness), Epilation (hair loss), desquamation (loss of skin cells, dry)
What is the threshold exposure for cataract formation? 2 gray single or 10 gray fractionated
Expected life span shortening for humans exposed to radiation is Lose 10 days per rad of exposure. This is accelerated aging. Normal conditions just appear earlier.
Genetic effects follow what dose response relationship? Nonthreshold, linear
In addition to leukemia what malagnancies have been directly related to radiation exposure? Thyroid, bone, skin, breast, lung, liver cancers
What is difference between genetic and somatic effects? Somatic occur during life of individual. Genetic affects future generations
3 stages of fetal development are Preimplantation, Major organogenesis, fetal growth
Preimplantation stage is 1st 2 weeks of implantation. egg fertilized but not implanted in urerine wall. pregnancy is unknown. Safest exposure period cuz pregnancy is unknown. common effect spontaneous abortion.
Major organogenesis stage is 2nd to 10th week. major organs developing. common effects of radiation exposure are congenital abnormalties, abnormal functioning kidneys, mental retardation, skeletal or muscular systems damaged. iIf dose high enough result in neonatal death.
Fetal growth stage is 10th week to birth.Primarily growth stage. Most organ systems are developed,cells differentiated. Effects of radiation are late effects i.e. cancer and potential genetic affects (when child reproduces later in life)
Doubling dose is Radiation dose that causes the number of spontaneous mutations occurring in a given generation to increase 2 times their normally occuring number
Genetically significant dose is (GSD) Measures impact of radiation on gene pool Dependent on age sex and reproductive potential
Are genetic effects of radiation dominant or recessive? Recessive
What are the 3 cardinal principles Time shielding distance
What is max time film badge should be worn 30 days
What crystal is used in a TLD? Lithium flouride
Where should film badge be worn during flouroscopy Collar
What is best method/principle of radiation protection Distance
The occupational exposure should be kept below what percent of effective dose limit? 10%
What is occupancy factor? Use of room adjacent to x-ray room. Greater use greater shielding
What is workload factor? How often is the room used. mA minutes per week
What is use factor? Percent of time beam is on and aimed at a particular wall. Walls = 1/4, Floors = 1 (overhead table)
What is a controlled area? Area occupied by radiographers. Max exp. 100 mrem per week
What is an uncontrolled area? Occupied by general population. 2 mrem per week
When should gonald shielding be used? If the gonads lie within or close to (5 cm) of the beam, doesn't interfere with anatomy examined and has a reasonable reproductive potential. (Page 31 V1 Merrills)
When should gonaldal shield not be used? When it interferes with the anatomy being examined
What is the guideline as to who should receive personnel monitoring device? Anyone who will receive 25% of dose limit.
What technical factors would be used to reduce skin exposure to the patient? Increase kVp
How does collimation affect patient exposure? Collimate decrease exposure, don't collimate increase exposure
How does beam filtration affect patient dose? Decreases,because it removes unnecessary soft x-ray from the beam
What is the useful (primary) beam? Radiation that comes out of the tube and interacts with the body
What is scatter radiation? Radiaiton that has changed directions but still the primary incoming photon.
What is leakage radiation? Radiation that leaks out of the tube
How to keep patient exp low and reduce unnecessary radiation exposure avoid repeats, time,shield,distance
Way to protect tech from radiation Dont hold patients, time shield , distance
Describe photoelectric effect Results in total absorption, body absorbs all energy. Creates image absorption and ionization (damage to patient) must have enough energy to knock out inner shell electron
Compton effect Produces scatter X-ray photon comes in and changes direction and loses energy
Unmodified scatter Also called Coherent, classical and thompson effect. Low energy photon collides with electron in atom. This occurs below 10kev. Vibrates electron
Pair production Interaction occuring in the nucleus. Way above level we use in diagnostic radiology. Incident photon collides with nucleus energy disappears but forms 2 new particles each having .51 mev of energy
Photodisintegration Interaction occuring in the nucleus. Way above level we use in diagnostic radiology.
What interaction is responsible for radiation to the patient? PE
What interaction is responsible for radiation exposure to the tech Scatter
What interaction is responsible for differential absorption? PE
What interaction results in complete absorption of incident photon? PE
What interaction at the diagnostic range is predominant at high kVp levels? Compton effect
What interaction is more predominant at low kvp levels? PE
What affect does atomic number have on PE occurring? Increase atomic number increase in absorption which is PE
What interaction results in the partial loss of energy and scattering of the incident photon? Compton
Define stochastic effect No threshold. Probability of occurence increases with increasing dose.
Define nonstochastic effect Have a threshold. Severity of damage increases with increasing dose. i.e. skin erythema
Gonadal shielding will reduce gonad exposure by 95% in males and 50% in females
Created by: bang1234