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RADT 465: radbio/saf
BR: rad bio& physics
| Question | Answer |
|---|---|
| this can be discribed as wave like fluctuations of electric and magnetic fileds | electromagnetic radiation |
| refers to the distance between two consecutive wave crests | wavelenght |
| refers to the number of cycles per second | frequency |
| what is frequencys unit of measurement | hertz (Hz) |
| what is the velocity of electromagnetic radiations | 3 x 10^8 m/s |
| some radiations are energetic enough to rearrange atoms in the materials through which they pass, and they can therefore be hazardous to living tissue. this is known as | ionizing radiation |
| ionizing radiation has the potential to | break apart electrically neutral atoms |
| ___ photons are man-made infinitesimal bundles of energy that deposit some of their energy into matter as they travel through it. | xray |
| what are the 2 PRODUCTION xrays | Bremsstrahlung and characteristic |
| High speed electron is deflected from it path and the loss of kinetic energy is emitted in the form of an xray photon | bremsstrahlung |
| Bremsstrahlung comprises what percentage of the primary xray beam | 70-90 |
| A high speed electron ejects a tungsten K-shell electron, leaving a k-shell vacancy. An electron from the L-shell fills the vacancy and emits a ray | characteristic |
| When is the xray created in the bremsstrahlung | the energy loss is given up in the form of an xray |
| K-characteristic xrays from a tungsten target xray tube have ____keV evergy | 69 |
| what are the 3 INTERACTION xrays | Compton, photoelectric, coherent |
| The incoming (low-energy) photon releases all of its energy as it ejects an inner shell electron form the orbit | photoelectric |
| The photoelectric effect is more likely to occur in absorbers having what | high atomic number |
| what interaction significantly effects patient dose | photoelectric |
| incoming (high energy) photon uses part of its energy to eject an outer shell electron; in doing so, the photon changes direction (scatters) but retains much of its original energy | compton |
| what interaction do us technologists have to be concerned about | compton |
| an incident photon that does not have enough energy to remove an inner shell electron, due to low binding energy, it is deflected and turned into scatter radiation | coherent |
| relationships are those in which the response is directly proportional to the dose received, that is, id the dose is increased, the biologic response is increased | linear/straight line |
| the effects are not proportional to the dose | nonlinear |
| a dose must be received before a response can occur | threshold |
| responses that are proportional to the radiation dose received only after some particular dose is received. | linear, threshold |
| this effect occurs randomly and are "all or nothing" | stochastic or probabilistic |
| no safe dose- even one photon can cause a response | nonthreshold |
| is the SI unit of ionizing radiation absorbed in matter (absorbed dose) | Air kerma (kinetic energy released in matter) |
| The quantity that measures risk to human tissue is termed | effective dose (EfD) |
| the SI unit of effective dose to biologic tissue | Sievert (Sv) |
| SI unit of radioactivity; it's symbol is Bq | The Becquerel |
| he rate at which particulate or photon energy is transferred to the absorber. Because different kinds of radiation have different degrees of penetration in different materials, it is also a useful way of expressing the quality of the radiation | LET |
| the amount of material necessary to decrease the intensity of the beam to one-half | HVL |
| What 2 factors affect both the quality and the quantity of the primary beam? | Kv & HVL |
| Why are muscle and nerve tissue insensitive to radiation? | they do not divide; remember, the most sensitive tissues to radiation are tissues that are constantly dividing (mitosis) Epithelial cells |
| If the center photocell were selected for a lateral projection of the lumbar spine that was positioned with the spinous processes instead of the vertebral bodies centered to the grid, how would the resulting radiograph look? | The image would be underexposed. |
| when you want to make an exposure longer, you would decrease... | mA |
| A decrease in kilovoltage will result in | a decrease in receptor exposure & a shorter-scale, or higher/increased, contrast. |
| risks have a threshold, are nonlinear, includes all early effects, and includes some late effects | nonstochastic/deterministic |
| risks have no threshold, are linear, have genetic effets, cause cancer, and includes most late effects | stochastic/propbabilistic |
| effect occurs when the ioniziing particle (an electron) interacts directly with the key molecule (DNA) or another critical enzyme or protein | direct effect |
| radiation interaction with water; ionization water | radiolysis |
| the more frequent occurring effect happens when ionization takes place away from the DNA molecule, in cellular water | indirect effect |
| this effect creates free radicals | indirect effect |
| small doses delivered over a long period of time produce a lesser effect (the greatest effect of irradiation will be observed if a large quantity of radiation is delivered in a short time to the whole body | fractionation and protraction |
| the greater amount of what makes tissues greater in their radiosensitivity | oxygen // aerobic |
| during the first trimester, specifically the 2nd to 10th weeks of pregnancy what can appear | skeletal and/or organ anomalies |
| fetal irradiation during the first 2 weeks of gestation can result in | embryonic resorption or spontaneous abortion |
| what are 3 ways to reduce risk to recently fertilized ovum | elective scheduling/10 day rule, patient questionnaire, posting (posters) |
| the average annual gonadal dose to the population of childbearing age is estimated to be | 0.2 mSv (20mrem) |
| ____ effects are described as being early or late | somatic effects |
| are manifested within minutes, hours, days, or weeks of irradiation | early somatic effects |
| appear years after initial exposure and are caused by low, chronic exposures | late somatic effects |
| Acute radiation syndrome (3) | hematopietic, gastrointestinal, central nervous system |
| this ARS can cause nausea, vomiting, diarrhea, decreased blood count, infection and hemorrhage | hematopoietic |
| this ARS syndrome generally occurs between 10 and 100 Gy (1000 and 10,000 rad) & causes severe damage to the stem cells lining, resulting in nausea, vomiting, diarrhea, blood changes, and hemorrhage; death occurs within 2 weeks | GI syndrome |
| this ARS syndrome causes collapse of the circulatory system, as well as increased pressure in the crnial vault, vasculitis, atazia and shock. death occurs in 3 days | CNS |
| what are the 4 stages of acute radiation syndorme | prodromal (few hours following radiation), latent (symptoms fade), manifest illness (symptoms return), recovery or death |
| occupational: annual dose | 50 mSI (5 rem) |
| occupational: lens of the eye | 150 mSI (15rem) |
| occupational: skin, hands and feet | 500 mSI (50 rem) |
| occupational: cumulative radiation | 10x age for mSI or 1 x age for rem |
| Public: anual dose | 5 mSI (0.5rem) |
| Public: lens of the eyes, skin, hands and feet | 50 mSI (5rem) |
| minimum lead equivalent: lead aprons | 0.5 mm |
| minimum lead equivalent: gloves | 0.25 mm |
| minimum lead equivalent: thyroid shield | 0.5 mm |
| minimum lead equivalent: glasses | 0.35 mm |
| minimum lead equivalent: bucky slot covers | 0.25 mm |
| minimum lead equivalent: fluoroscopy drapes | 0.25 mm |
| minimum lead equivalent: clear lead plastic overhead protective barrier | 0.5 mm |
| minimum thickness of filtration requirement for operating kv: below 50 | 0.5 mm |
| minimum thickness of filtration requirement for operating kv: 50 - 70 | 1.5 mm |
| minimum thickness of filtration requirement for operating kv: above 70 | 2.5 mm |
| Embryo: radiation per month | 0.5 mSV (0.05 rem) |
| Embryo: entire gestation | 5 mSV (0.5 rem) |
| min SSD fixed fluoro unit | 15 in |
| min SSD mobile fluoro unit | 12 in |
| cumulative fluoro time | every 5 mins |
| primary barrier | 1/16 in |
| secondary barrier | 1/32 in |
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