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Carol's Final Review
Carols final RA221
| Question | Answer |
|---|---|
| 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 |
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