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Safety
Certification Review
| Question | Answer |
|---|---|
| what is the function of the uppermost collimator shutter? | the eliminate off-focus radiation |
| the radiographer wears a lead apron to protect from what type of radiation? | Compton scatter |
| when trying to determine effective dose, what is used to account for the differences in the tissues that were irradiated? | tissue weighting factor |
| what is an x-ray photon's original intensity at 1 meter from the scattering object? | 1/1000 |
| an area occupied by only radiology personnel and patients | controlled area |
| areas occupied by anyone | uncontrolled area |
| occupancy factor | the amount of time the space beyond the barrier is occupied |
| workload | expressed in units of mA seconds/week or mA minutes/week |
| use factor | the percentage of time the primary beam is directed at a particular barrier |
| primary barriers | 1/16 inch lead thickness and 7 feet high - lead walls and doors of the room - any surface that can be struck by the primary beam |
| secondary barriers | 1/32 inch lead thickness and must overlap primary by 1/2 inch - includes control booth |
| when is radiation monitoring required for personnel? | when there is a chance to receive more than 10% of the annual dose (50mSv); 5 mSv |
| the size of the focal spot (does/does not) effect patient dose | does NOT |
| what kind of abnormalities can occur if the fetus is irradiated during the first trimester, specifically between weeks 2-10? | early part: skeletal and/or organ abnormalities latter part: neurological anomalies - mental retardation and childhood malignant disease may occur |
| what unit of measurement expresses the ionizing radiation dose to biologic material? | Sievert (Sv) |
| what type of radiation dose the annual occupational dose account for? | beta, x-rays, and gamma rays |
| what can the irradiation of macro molecules of a fetus result in? | cleaved chromosomes, cross-linking, and mutations |
| what dose curve response would leukemia and genetic effects fall under? | linear, nonthreshold |
| stochastic/probabilistic | late effects where dose is related and there is no threshold responsee |
| what tissue absorbs the largest amount of radiation? | bone |
| what interaction contributes significantly to patient dose? | photoelectric effect |
| half value layer describes what about the beam? | the beam quality |
| what is the effect on RBE as LET increases? | as the LET increases, so does the RBE |
| fractionation | equal doses of radiation that are delivered with time interval separations |
| protraction | radiation dose that is delivered continuously but at a lower dose rate |
| apoptosis | also known as interphase death --cell dies without attempting to divide |
| radiolysis | radiation interaction with water |
| what are the three stages of acute radiation syndrome (ARS)? | 1. hemopoietic syndrome 2. gastrointestinal syndrome 3. cerebrovascular syndrome |
| hemopoietic syndrome | -100 to 1000 rads (1-10 Gy) whole body dose - death occurs within 3 to 6 weeks following exposure |
| gastrointestinal syndrome | - 1000 to 5000 rads (10-50 Gy) whole body dose - death occurs one week following exposure |
| cerebrovascular syndrome | - over 5000 rads (50 Gy) - death occurs within hours or days following exposure |
| what are the 4 requirements for x-ray production? | 1. source of free electrons 2. acceleration of electrons 3. focusing of electrons 4. deceleration of electrons |
| what interaction has a continuous energy spectrum? | Bremsstrahlung |
| what interaction has a discrete energy spectrum | Characteristic |
| what are the 7 types of interactions? | 1. Bremsstrahlung 2. Characteristic 3. Compton 4. Photoelectric 5. Coherent 6. Pair Production 7. Photodisintergration |
| what two interactions occur at the anode? | - Bremsstrahlung - Characteristic |
| what three interactions occur at the patient? | - Photoelectric - Compton - Coherent (only contributes to dose or degrades image quality) |
| what two interactions occur outside of the diagnostic x-ray energy range? | - Pair Production (nuclear medicine) - Photodisintergration |
| what are the traditional units? | - rad - rem - roentgen - curie |
| what are the SI units? | - gray - sievert - columb/kg - becquerel |
| what is the oxygen effect? | defines the ability of aerobic conditions to enhance the effectiveness of radiation -- increasing the oxygenation, increase the cell's radiosensitivity |
| what is relative biologic effectiveness (RBE)? | defines the ability to produce biologic damage |
| what does your back-up timer need to be set to for an AEC? | 150% of the mass set or 600 |
| what are the minimum lead requirements? | aprons: 0.5 mm Pb gloves: 0.25 mm Pb thyroid shield: 0.5 mm Pb glasses: 0.35 mm Pb bucky slot cover: 0.25 mm Pb lead curtains: 0.25 mm Pb overhead plastic barrier: 0.5 mm Pb |
| what is the maximum exposure at the tabletop of a fluoroscopy unit? | 10R/minute or 2.1 R/minute for each mA at 80 kVp |
| what material is used in a thermoluminescent dosimeter (TLD)? | lithium fluoridee |
| pocket dosimeter | ionization chamber |
| the opically stimulated luminescent dosimeter (OLD) uses what material? | aluminum oxide |
| what are the occupational exposure limits? | - annual whole body: 50mSv (5 rem) - lens of the eye: 150 mSv (15 rem) - red bone marrow, breast, lung, gonads, skin, and extremities: 500 mSv (50 rem) - cumulative effect limit: 10mSv x age in years (1 rem x age in years) |
| what are the public exposure limits? | - annual effect dose: 5 mSv (0.5 rem) - lens of the eye, skin, and extremities: 50 mSv (5 rem) |
| what the exposure limits for an embryo/fetus? | 5 mSv (0.5 rem) for the entire gestational period, maximum of 0.5 mSv (0.05 rem) per month |
| what are the fundamental properties of x-rays? | - scatter in straight lines and cannot be focused - heterogeneous and polyenergetic - travels at the speed of light |
| what is the most common interaction? | compton scatter |
Created by:
fbarnett20
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