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Exposure I Final
Radiology Exposure I Final
| Question | Answer |
|---|---|
| If a lower mA is activated on the generator panel, AEC will | use a longer time of exposure |
| AEC devices provide a diagnostic quality radiograph when the | part is positioned directly over the chamber |
| When an AEC detector sets over an area of increased fluid, exposure to the IR will | be higher |
| US Public law requires automatic termination of AEC exposure at _____mAs above 50kVp. | 600 |
| With an ionization chamber device, the electrical charge produced is in proportion to the amount of radiation received. True or False? | True |
| What will result in more exposure to the image receptor, but not alter the dynamic range when using AEC? | changing the density control to +2 |
| AEC devices operate by measuring | radiation transmitted through the patient |
| The purpose of the back-up timer is to | Set the maximum exposure time possible |
| The dectectors, cells or sensors can differentiate between secondary and scatter radiation | False |
| Your next KUB patient has Hyperstenic body habitus. Acknowledging that fact, you increase the density control to +2. How will the length of exposure change, as compared to density control at N? | Exposure time will remain the same |
| You are using AEC with the center sensor activated. If the centering point for an AP lumbar spine is set incorrectly over the liver, the radiograph will | be lighter in film density or show underexposure |
| Which one of these would assist in the control of motion in the AEC mode? | Increase the mA |
| Nsme four considerations with any AEC exposure | Patient position kVp level Focal spot size Sensor selector |
| Which statement is false concerning scattering radiation? | Scattering radiation does not contribute to image density |
| When kVp increases from 70 to 80 | more photons undergo interaction with matter |
| As the beam size of radiation changes from 10x12 to 14x17 inches, scatter production | will increase |
| Identigy the beam restriction device composed of a flat sheet of lead with a circular opening | Aperture diaphragm |
| A collimator device has how many sets of lead shutters? | 2 |
| You have produced a scout AP KUB (14x17 IR) using AEC mode. After fluorscopy, the radiologist requests an image of only the RUQ which requires only a 10x12 IR. The second image will | produce a higher mAs readout |
| Components of a collimator device are | light source, mirror and shutters |
| What collimator components must be an equal distance from the mirror? | Light source and focal spot |
| The collimator mirror is mounted at an angle of | 45 degrees |
| A visible sign of collimation to the necessary anatomical region is evidenced by the _____ around the radiographic image | unexposed area |
| A radiograph produced with AEC exhibits increased exposure/film density due to excess scattering radiation. A second image is produced, but with increased collimation. The second image will show what level of contrast? | No change in contrast scale occurs |
| If an uneven beam field is projected onto the patient's anatomy, it is due to | lead shutter(s) being misaligned |
| What happens to exposure time when kVp is decreased to reduce scattering radiation when in the AEC mode? | Exposure time increases |
| The source of off-focus radiation is | any point other than the focal spot |
| What would NOT be classified as a beam restriction device? | Port |
| What feature do secondary radiation and scattering radiation have in common? | Decrease in intensity of the beam |
| The principal factors that affect the amount of scatter produced are mAs and the type of irradiated material | False |
| A lead blocker or leaded rubber may serve as a beam restrictor | True |
| If the primary beam is collimated from an activated AEC sensor, the result would be a | change in exposure quantity to the IR |
| Automatic collimators are known as positive beam limitation devices. | True |
| Back up time of most AECs is set | longer than the anticipated manual exposure time |
| When mAs is reduced, the Photoelectric to Compton ratio will | remain the same |
| As more photons pass through the irradiated material unaffected, the resulting image receptor exposure has | greater level of exposure to the IR |
| Volume of the irradiated tissue increases as | radiation field size increases patient thickness increases |
| The shutters of a collimator will | Reduce field size Reduce penumbra Reduce off-focus radiation |
| As collimation increases,patient dose _____ and image contrast ______ | decreases, increases |
| Exposure factors used for an AP KUB with a 14x17 cassette will not be sufficient for a bladder image on an 8x10 cassette. Exposure factors must be changed to compensate for the reduction in field size by | increasing mAs 20-50% |
| Increased collimation refers to a smaller radiation field | True |
| Scattered photons will strike an area of he cassette unrelated to the anatomical area from which they were produced/created | True |
| The most common phosphor used for CR imaging plates is | barium flurohalide bromides |
| The latent image in CR imaging is created by energy transfer involving | Photoelectric interaction |
| When the CR imaging plate is scanned by the laser the phosphors release energy in the form of | light |
| A photostimulable imaging plate includes | A phosphor layer, a conductor layer and a protective layer |
| During CR imaging plate processing, the laser frees trapped electrons,allowing them to return to a lower energy state. This process is known as | Photostimulated luminescence |
| During image acquisition, laser light scans the IP in a raster pattern which means | line by line |
| As increased collimation is used with a digital image, the image contrast will | increase |
| Which phosphor shape produces more light diffusion, thereby reducing spatial resolution of the digital image? | Turbid or powder phosphor |
| Translation refers to | the laser scan across the imaging plate multiple times |
| Erasure light bulbs diminish in the level of output over time | True |
| What is NOT a determining factor of spatial resolution? | Conductive layer thickness |
| Spatial resolution is associated with contrast of the image. Another name for contrast resolution is | dynamic range |
| Which form of digital data is classified as "noise" | Scattering energy |
| Speed class of an imaging plate is determined by the amount of photostimulable luminescence or PSL during the laser scan | True |
| Upon laser beam scanning of the imaging plate, the emitted light is detected by the _______device that amplifies the light. | photomultiplier |
| It takes longer for the AEC to shut of the exposure on a thicker body part because the | quantity of radiation is reduced |
| During an AEC exposure, the sensors activated should be covered by the ______ anatomy | thickest |
| It is acceptable to override an automatic collimator (PBL) in order to | collimate tighter to reduce patient dose |
| You have produced an incorrect level of exposure to the IR while in AEC mode. Name two reasons why this could result | Used all of the energy available Panel not set correctly |
| Define averaging in relation to AEC exposure technique | averaging has to do with the 3 sensors and the energy produced from each one that is converted into a digital image |
| Using kVp as the correction factor, increase image density/level of exposure by 100%. Use original factors of 10mAs @75kVp | 5 mAs @ 85kVp |
| Maintain image density/level of exposure. INcrease kVp by 15% and state the new factors. Use the original factors of 40 mAs @ 80kVp | 20mAs at 90 kVp |
| Maintain image density/level of exposure. Double the mAs value and state the new factors. Use the original factors of 30mAs at 70kVp | 60mAs @ 60kVp |
| xray quality is numerically represented by | GSD |
| Which one of these would display the most subject contrast? | A muscular patient |
| How many half-value layers must be added to the primary beam to reduce the intensity to less than 20 percent of its original value? | 3 |
| Aluminum has an atomic number of | 13 |
| What results when longer wavelength photons interact with anatomy | Short or high scale contrast |
| As kVp is increased, the primary beam is composed of | higher frequency and shorter wavelengths |
| What will approximately double the exposure to the IR/film density? | Increasing kVp by 15% |
| An adjustment from 70 to 80 kVp wil produce | Wider exposure latitude, less patient absorption, shorter wavelengths |
| If the original radiograph shows good quality and kVp is increased by 15% | Density/exposure to the IR increases, contrast decreases |
| Which interaction involves the production of secondary radiation? | Photoelectric |
| If the original radiograph shows good quality and the mAs is increased by a factor of 2 | density/exposure to IR remains the same, contrast increases |
| Increasing the kVp on the control panel will cause an ______across the xray tube | increase in the speed of the electrons |
| How does high kVp, such as used with upright chest exams, affect radiographic contrast? | Produces longer or low scale contrast |
| As kVp increases, ______ mAs will be needed to produce an image of equal exposure | less |
| In lower kVp range, a 15% change has a greater impact on xray emission than at higher kVp values. Consider the example 50kVp vs 100kVp. | True |
| What is NOT TRUE about optimal kVp? | It determines total quantity of primary radiation |
| Higher kVp correlates with wider exposure latitude? | True |
| Which patient would produce the most scattered radiation? | 26cm abdomen |
| Increased scatter radiation in the exit or remnant beam will cause an increase in | IR exposure |
| What happens to patient absorption of energy, as kVp increases? | It decreases |
| The initial rad image exhibits underexposure. If kVp is increased as the correction it will affect | more than one but not all |
| Long scale contrast is defined as | black to many gray shades to white |
| Secondary radiation continues in a diverging direction, scatter is changed in direction of travel. | True |
| Secondary radiation is lowered in intensity from the primary beam, as is scatter | True |
| What is NOT TRUE concerning the relationship between image density and contrast? | mAs is a quality factor and affects image density |
| Which set of factors produces a rad with the highest scale of contrast? | 30mAs @50kvP |
| The 15% rule states that | Density may be halved by decreasing kVp by 15% Density may be doubled by increasing kVp by 15% |
| Name 3 true statements about scattered radiation | It has less energy than primary It contributes to density on the image It travels in a different direction than primary |
| Increasing energy of an incident electron results in the production of an xray photon with | greater energy |
| As kVp _____ a ______ range of photon energies is produced | increases, wider |
| High contrast is directly related to | number of photoelectric interactions |
| The 10kvp guideline for kilovoltage is true in the range of | 60-80kVp |
| An image contrast decreases, the number of densities in the image | increase with more gray tones/densities |
| Wide exposure latitude shows long scale of contrast, creating a greater margin for error | true |
| the relationship between kVp and density is described as | direct, but not proportional |
| The original technique is 30mA @ 80kVp. What will produce a rad with twice the IR exposure/film density. | 30mas @90 kvp 60mas @ 80kvp |
| How does kvp influence rad density? | Sets penetrability of the photons in the beam |
| Low kvp creates ____ contrast | increased |
| Low kvp creates ____ shades of gray | few |
| Name a set of exposure factors that would provide an image with higher contrast than that produced by 12mas @92kvp but maintains the original density/level of exposure? | 24mAs@78kvp |
| The usage of high kVp techniques would result in | lower patient dose, decreased contrast and less scatter fog |
| What effect does beam penetration have on rad contrast? | Increased kvp will decrease contrast |
| Image density is a product of intensity x duration of exposure is a definition of | reciprocity law |
| The relationship of mA and time to maintain image density is directly proportional | false |
| A disadvantage or limitation of high mA exposure is | usage of a large focal spot |
| mAs affects visibility of detail | False |
| What happens to patient doseage as the mAs increases? | Increases |
| The relationship between kVp and contrast is | inverse |
| What interaction produces a longer scale of contrast due to a high level of scatter from increased beam penetration? | Compton |
| What definition describes body habitus? | Variations in the shape of the human body |
| The relationship of mAs and kVp to maintain the level of exposure/film density is | Inverse |
| Low kVp results in ____ kinetic energy of electrons | reduced |
| The NCRP recommends a minimum total filtration value of ______ mm Al/Eq for imaging at 70kVp or greater | 2.5 |
| What influences the production of scattering radiation? | Level of kvp, tissue thickness, field size of radiation |
| Compton becomes the dominant interaction at ____kvp | 80 |
| Which cast material of normal thickness requires only a doubling of mAs? | Dry plaster |
| An increase in kilovoltage applied to the xray tube increases the | exposure rate |
| Name an example of a compensating filter | Wedge filter |
| Identify the purpose of a compensating filter | Creates uniform image density |
| The standard protective filter material used in diagnostic radiology is | aluminum |
| A long leg exam is ordered and the wedge filter is routinely used. The thin portion is placed at the | proximal or hip end |
| What effect does the addition of protective filtering have on the average energy of photons in the primary beam | Increases the average energy |
| Photons emerging from a properly filtered diagnostic unit are homogenous since they have the same energy level | false |
| Which material requires a 2 times increase in mAs and an increase in kVp? | wet plaster |
| Whether a fiberglass or plaster cast is applied, image contrast | decreases |
| Filtration is the process of filtering undesirable _______by the insertion of absorbing material into the primary beam | low energy xray photons |
| Filtration at the required diagnostic (>70kVp) minimum removes a portion of the useful beam | True |
| Which is the following is affected by half-value layer? | Patient exposure |
| total filtration is equal to the sum of _______filtration | inherent and added |
| Name one factor which would require the technologist to change AEC sensor selection | disease |
| Digitizing the light signal from the photomultiplier tube means assigning a numerical value to each light photon | True |
| In CR imaging, images have increased contrast resolution along with increased spatial resolution | True |
| Grid ratio determines the maximum angle by which a scattered photon can pass through the lead strips | True |
| What artifact may be prevented by substituting a multi-hole grid for the standard linear grid when digital imaging is utilized? | Grid lines |
| A low ratio grid compared to a high ratio grid will | absorb less scatter radiation, produce a longer scale of contrast, require less exposure for a given density |
| the efficiency of a grid is its ability to remove scattered radiation which is based on | grid ration and grid frequency |
| Using an out of range SId with a linear focused grid results in | a loss of image density on the outer edges |
| Angulation of the beam with a linear, focused grid may be done | with the long axis |
| Grid movement during the exposure serves what purpose? | blurs grid lines |
| If an image taken with a 12:1 linear focused grid with 100 lpi exhibits a loss of density at the internal edges. It is because the | grid is upside down |
| the majority of scattering energy is produced in the | patient |
| the patient has an imapact on all the properties that affect a balanced image, such as IR exposure/density, contrast/dynamic range, resolution and distortion | True |
| The ____ the body part, the _____ the primary beams attenuation | thicker, greater |
| Bone produces |
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