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What are the prime exposure factors?
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Prime exposure factors are variables controlled by ________________.
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Exam 4 Rad 102
Chapters 11, 13 & 14 - Prime Factors, Minimizing Pt Dose, Vision and Perception
| Question | Answer |
|---|---|
| What are the prime exposure factors? | Distance, mAs, kVp |
| Prime exposure factors are variables controlled by ________________. | the technologist |
| What is the product of tube current and exposure time? | mAs |
| Quantity of the beam is measured in _____________. | Roentgen |
| Which factor controls quantity? | mAs |
| mAs, distance and filtration directly affect ________________. | quantity |
| Which factor control quality? | kVp |
| X-ray quality is numerically represented by ______________. | Half-value layer (HVL) |
| Reducing x-ray beam intensity (Quantity) by half its original value is _________________. | Half-value layer (HVL) |
| Milliamperage (mA) is the measurement of ______________________. | tube current |
| What does X-ray tube current measure? | # of electrons crossing the tube from cathode to anode per second. |
| As mA increase, the number of electrons that are able to cross the tube to reach the x-ray target __________________. | Increase |
| The penetrating ability of the x-ray beam refers to ________________. | quality |
| Which systems provide the highest beam quality and quantity? | High-frequency |
| What are the quantitative factors affecting x-ray emission? (4) | mAs, kV, Distance, filtration |
| What are the qualitative factors affecting x-ray emission? (2) | kV, filtration |
| What is the focal spot size (range) of an x-ray tube? | 0.5 - 1.0 |
| Large focal spot size has a beam of high __________________, but unchanged _______________. | quantity (more x-rays produced) quality (looks the same) |
| Focal spot size is associated with ________ of an x-ray. | detail |
| What is the unit of current? | ampere |
| 1 ampere (A) equals? | 1 coulomb (C)/sec |
| What happens to the number of electrons passing from the cathode to the anode by doubling the mA? | Increase 2 fold |
| Exposure time is directly proportional to _______________________. | intensity of the beam |
| Short exposure times help in reducing _____________________. | motion artifacts |
| What is the shortest time by a single phase system? | 8ms |
| What does mAs control? (5) | Quantity, radiographic film density, patient dose, intensity, x-ray output |
| By doubling the mAs, the dose is ___________. | doubled |
| Increase in mAs causes a(n) ___________________ in beam quantity. | increase |
| What will increasing the kVp on the control panel cause? | an increase in speed and energy of the electrons |
| What does the Reciprocity Law state? | the density on an x-ray film should remain unchanged as long as intensity and duration of x-ray exposure remains unchanged |
| Which factor controls quality? | kVp |
| Change in kVp affects ____________. | contrast |
| As kVp double, the amount of x-ray photos will increase approximately? | 4 times |
| Amount of silver deposited on hard copy film image | density |
| Intensity and density increases as SID __________________. | decreases |
| What does the Inverse Square Law state? | The intensity of radiation at a given distance from a point source is inversely related to the square of the distance between the object and the source. |
| What is the Inverse Square Law formula? | |
| What is the function of the human eye? | Gather light, focus it, convert it to nerve impulses and transmit it to the brain for processing. |
| What are the 2 retinal cells that transform light into a nervous signal? | Rods and Cones |
| What is the aspect of the visual anatomy that transmit nervous signals to the brain? | Optic Nerve |
| What is the primary location of rods in the eye? | Retina cells |
| What is the primary location of cones in the eye? | Fovea centralis |
| What is another name for nearsightedness? | Myopia |
| What is another name for farsightedness? | hyperopia |
| What do rods and cones do when stimulated by light? | emit neurologic impulses |
| Daylight vision, color, processed by cones | photopic vision |
| Which color of light are cones most sensitive to? | yellow |
| Part of the eye that improves contrast perception? | cones |
| Name for night vision which is sensitive to low light levels | Scotopic Vision |
| Term for the visual phenomenon associated with viewing extremely small objects | Threshold Detection |
| What is boundary effect? | Difficulty is perceiving contrast difference at a distance |
| Neurologic basis for boundary effect. Some situations prevent neurological impulses from being transmitted by retina. | Mach Effect |
| When intense light from view box hits the eye directly, bright light scatters inside the eye (compton effect) and decreases contrast perception... | Veil Glare |
| Rule for views to be made in radiography, in order to perceive depth | Must have two (2) 90° opposing views |
| What radiographs produce the highest ESE? | Lumbar spine, pelvis and hip |
| Which radiographs produce the lowest ESE? | Extremities |
| Ways to reduce patient does? | Positioning Communication Technical Factors Filtration Field Size Gonadal Shielding |
| How do we reduce pt dose with technical factors? | high kVp, lowest possible mAs, increase SID and SOD, highest generator efficiency |
| What is entrance skin exposure (ESE)? | Maximun exposure to body |
| What is roentgen (R) in SI units? | air kerma |
| What is rem in SI units? | sievert |
| What is rad is SI unit? | gray |
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