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ExposuresEdna
Exposures Help
| Question | Answer |
|---|---|
| Who discovered x-rays? | Wilhelm Conrad Roentgen |
| When were x-rays discovered? | November 8, 1895 |
| What was the name of the first x-ray tube? | Crooke's Tube |
| What were the problems with Crooke's tube? | It was not a vacuum and it was not focused. |
| What was the name of the 2nd x-ray tube? | Jackson Focus Tube |
| What were the differences between the Crooke's Tube and the Jackson Focus Tube? | If focued the beam and had an inclined anode. |
| What was the 3rd x-ray tube? | Coolidge Hot Cathode Ray Tube |
| What were the advantages of the Coolidge Hot Cathode Ray Tube? | Consistant source of x-rays that could be duplicated. It was vacuum sealed. |
| What is the cathode made of? | A spiral incandescent filament of tungsten wire. |
| Is the cathode negative or positive? | Negative |
| How many filaments are in the cathode? | 2. Small and Large |
| What does incandescent mean? | Gives light. |
| What heats the filament? | Electrical current |
| What determines the electrons that are sent to the filament and controls heat? | mA- milliamperes |
| Is the anode positive or negative? | positive |
| Where does x-ray production happen? | Anode |
| What are x-rays? | Striaking of matter by high speed electrons (bombarding of electrons) They are electromagnetic energy. |
| What are the differences between x-rays and light? | X-rays have short wavelengths and can penetrate. Light has long wavelengths and can't penetrate. |
| What is wavelength? | KVp |
| If you increase KVp what happens to wavelength? | It becomes shorter. (more power) |
| Can x-rays penetrate material? | yes |
| Do x-rays cause objects to flouresce (give light)? | yes |
| Are x-rays visible? | no |
| Do x-rays produce biological changes? | yes. They stimulate or retard growth |
| Are x-rays ionized gas? | yes (removing electrons from atoms forms ions) |
| Do x-rays travel in straight lines? | yes |
| Is energy changed from on ion to another in an x-ray? | yes |
| What is the normal light that we expect to see? | Luminescent (good) |
| What is phosflourescent? | After glow (bad) |
| What is the anode made of? | Tungsten Atomic #74 |
| How fast does the anode spin? | 10,000 revolutions per min |
| Spinning anode goes from a focal spot to a ? | focal track |
| Does a stationary anode have a focal spot or a focal track? | focal spot |
| What sends electrons to the spiral filament on the cathode and warms the anode by spinning it? | Rotor button |
| What sends the electrons to the anode? | Exposure switch |
| What controls the amount of radiation produced? | mAs milliamperes per second |
| If you increase mA what happens to heat? | Increases |
| If you increase mA what happens to x-rays? | Increases |
| If you increase s (seconds) what happens to heat? | Increases |
| If you increase s (seconds) what happens to x-rays? | Increases |
| What is power? | KVp |
| What is tube current? | KVp |
| What does Bremsstrahlung mean? | Breaking radiation |
| Where does Bremsstrahlung occur? | The anode |
| What is boiling off of electrons from around the filament? | Thermeonic Emission |
| Some x-rays are totally absorbed by the anode? True or False | true |
| Anode slows tube current to form x-rays. What is this called? | Bremsstrahlung |
| Which is stronger? Bremsstrahlung or Characteristic? | Bremsstrahlung |
| Where are Bremsstrahlung and Characteristic created? | In the tube |
| How many x-rays make it out of the tube? | 1/3 |
| How many x-rays go away as heat? | 95% 5% give x-rays |
| Which interactions happen closer to the nucleus? | Bremsstrahlung interactions |
| Which type usually does not make it out of the tube? | Charactaristic Radiation |
| Which type makes it to the patient? | Bremsstrahlung |
| X-rays are polyenergenic. True or False | True (they have many energies) |
| How much inherant filtration is in the x-ray tube? | 1-1.5 mm |
| What accounts for inherant filtration? | glass envelope oil in the tube |
| How much filtration is added by the manufacturer? | 1-1.5 mm |
| What is added filtration made out of? | aluminum |
| How much total aluminum filtration should there be? | 2.5 mm (1-1.5 inherant + 1-1.5 added) |
| Added and inherant filtration get rid of what type of radiation? | Characteristic |
| What type of radiation come out of the anode and directly down to the top of the patient? | Primary radiation |
| What is it called before it interacts with the patient? | Primary radiation |
| What type of radiation goes from the patient to the IR | Remnant Radiation |
| What is it called after it interacts with the patient? | Remnant Radiation |
| What passes through the patient unaffected? | Primary beam |
| Rays that interact within the patient emit what type of radiation? | Secondary and Scattered |
| What percent of the primary beam goes to the IR and interacts with nothing? | 5% |
| What percent of the primary beam comes out as secondary radiation? | 15% |
| What percent of the primary beam gets absorbed by the patient? | 80% |
| From the 20% of the Remnant Radiation (after it interacts with the patient) how much of the beam exposes the film? | 20% |
| What type of radiation most closely follows the direction of the original beam? | Secondary Radiation (good) |
| What type of radiation has rays that go in all directions? | Scatter radiation (bad) |
| What type of radiation gives color (density) that is not useful? | scatter radiation (veil of density) |
| What is partial absorption of the x-ray beam? | attenuation |
| What is it called when the beam is totally absorbed? | absorption |
| What color will total absorption be on an x-ray? | white |
| Why is an an x-ray beam that is absorbed white on the film? | Because it does not make it to the IR. |
| What color is attenuation on the film? | any where from gray to black |
| Greater absorption give greater subject contrast or lesser subject contrast? | Greater |
| What is subject contrast? | Subject contrast represents the differences in x-ray absorption in the body. |
| Is contrast the differences in the film or the patient? | Film |
| Is subject contrast the differences in the film or the patient? | patient |
| What gives lighter gray on the film? Higher attenuation or lower attenuation | Higher |
| Is low contrast a long or short gray scale? | long |
| Is high contrast a long or short grey scale? | short |
| What is used to center your body part? | Central Ray |
| What does SID mean? | Source to Image Distance |
| What are other ways to say SID? | TID- Target to Image Distance FID- Focal to Image Distance |
| What does OID mean? | Object to Image Distance |
| How else can you say OID? | OFD- object to film distance TFD- target to film distance FFD- focal to film distance |
| What is the primary unit used for the quantity of x-rays? | R- roentgen |
| What is the exposure to the patient? | RAD- radiation absorbed dose |
| What does RAD mean? | Radiation absorbed does. |
| What is exposure to technologist? | REM- radiation equivilent man |
| What does REM mean? | radiation equivalent man |
| What are the exposure factors? | mA, S, KVp |
| If you increase mAs, what happens to density? | Increases |
| If you increase mAs, what happens to color? | Increases |
| If you increase mAs, what happens to gray scale? | nothing |
| If you increase mAs, what happens to contrast? | nothing |
| If you increase mAs, what happens to quantity of x-rays? | Increase |
| If you increase mAs, what happens to recorded detail? | nothing |
| What protects the x-ray film? | the cassette |
| Where do you put the film? | Inside the screen |
| What kind of crystals are in the film? | silver bromide crystals |
| What are the silver bromide crystals suspended in? | gelatin |
| What is the most functional part of the film? | emulsion |
| What do the silver bromide crystals give on the film? | density |
| What does the blue tint in the gelatin do? | helps with contrast on the final image |
| What protects the emulsion? | T-coat (tough coat) |
| What attacks the silver bromide crystals that are fractured? | Developer |
| What washes away the silver bromide crystals that are unfractured? | Fixer |
| What washes away off all the chemicals? | Wash tanks.. water |
| What is the last step to film processing? | drying |
| What do x-rays do to the silver bromide crystals that they hit? | fracture them |
| What type of film has emulsion on one side? | Single emulsion |
| What type of film has emulsion on both sides? | Double emulsion |
| Does double or single emulsion film have better detail? | Single |
| On single emulsion film, what is the other side made from? | polyesther plastic |
| Is the emulsion side of the film shiny or dull? | dull |
| What is the image before processing film called? | Latent Image (invisible) |
| What is the imnage after processing film? | Manifest Image (visible) |
| What are x-rays that you can hold called? | Static x-rays |
| Do you get more or less fractured crystals with thicker body tissue? | Less |
| Does thicker body tissue result in more or less density on the film? | Less |
| What are the layers of film? | Base- supports the film Emulsion- silver bromide crystals gelatin blue tint Tough coat- on top of emulsion (t-coat) Adhesive layer- connects the layers |
| What are other names for focal spot? | focal point focal track target |
| Where is the focal spot located? | on the anode |
| How big is the focal spot? | 1/2" square |
| How fast does the anode rotate? | 10,000 revolutions per min |
| What is the focal spot called on a rotating anode? | Focal track |
| Name the 2 types of anodes | Stationary and Rotating |
| What is the anode made out of? | Tungsten |
| Why is the anode made of Tungsten? | High atomic # (74) high melting point good conductor of heat efficient producer of x-rays |
| Where is the filament mounted on the cathode? | in the focusing cup |
| Is mAs quality or quantity? | quantity |
| If you increase quantity, what happens to density? | Increases |
| If you increase quantity, what happens to contrast? | Nothing |
| What determines the size of your focal spot? | quantity of beam |
| Which focal spot gives better detail? Small or Large? | Small |
| Which focal spot can hold more electrons? Small or Large? | Large |
| What is the only thing that focal spot size affects? | DETAIL..... only detail |
| What does intensity mean in x-ray? | DENSITY... |
| Does the x-ray beam increase or decrease toward the anode? | decrease |
| Does the x-ray beam increase or decrease toward the cathode? | increase |
| If you increase the focal spot what happens to detail? | decreases |
| Do you get better detail with a small or large focal spot? | small |
| The distinction between lines is? | sharpness |
| What is the spreading of the edges of the image? | penumbra |
| Which is the good part of the image umbra or penumbra? | umbra |
| Do you want to minimize umbra or penumbra? | penumbra |
| Do you get more penumbra with a large or small focal spot? | Large |
| How does penumbra grow? | Inward and outward... invading the spaces of the umbral image |
| Does OFD cause more or less penumbra? | more.. OFD is same as OID |
| What is sharpness of detail? | Penumbra and umbra |
| What is the size of a large focal spot? | 1 mm to 2 mm |
| What is the size of a small focal spot? | .05 mm to 1 mm |
| What has to grow to get magnification? | penumbra and umbra |
| How does focal spot affect magnification? | Not at all.. only affects detail |
| Is focal spot an electrical or geometrical factor? | geometrical |
| What is the line focus principal? | the actual stream of electrons is considerably wider than the projected focal spot |
| What does the actual focal spot determine? | how many electrons |
| What does the projected focal spot determine? | Sharpness |
| What is the angle of the anode bevel? | 15 to 17 degrees |
| What gives better detail? an anode bevel of 17 degrees or an anode bevel of 45 degrees? | 17 degrees.. the more toward vertical, the better the sharpness |
| Can the technologist change the anode bevel? | no |
| A variation in x-ray intensity output along the longitudinal tube axis is called? | Anode heel effect |
| With the anode heel effect, does the larger part go toward the anode or the cathode? | cathode... (fat-cat) |
| In normal x-ray procedures do we put the head toward the anode or the cathode? | anode |
| What reasons do we use the anode heel effect? | 1. differences in body thickness 2. large focal spot 3. Short SID 4. larger film size |
| What body parts do we use the anode heel effect for? | 1. T-spine 2. femur 3. feet 4. humerus |
| Do you have more or less divergence if you increase SID? | less |
| What is the only portion of the beam that goes straight down? | Central ray |
| Do you have more divergence at 40" or 72"? | 40" |
| What is the Star Pattern Template Method used for? | to determine focal spot deterioration |
| What is the Wisconsin Focal Spot Test Tool? | It is similar to pentrometer and is used to evaluate where you see sharp lines. |
| What happens if you increase exposure time? | density increase |
| What happens to contast if you increase mA? | nothing |
| What are the primary factors for a good radiograph? | mA s (time) KVp SID |
| What are the elctical factors? | mAs KVp noise |
| What are the goemetrical factors? | Shape distortion Size distortion Sharpness |
| Anything that we do are used is called? | Technical factors |
| What gives the electical current in the beam? | mA milliamperes |
| If you increase mA, what happens to the electrical current? | increases |
| How does the intensity of the beam affect contrast? | Intensity is density... Never affects contrast |
| If the quantity of the beam increases, what happens to the quality? | nothing... quantity is density, quality is KVp |
| What does mAs directly affect? | density |
| What does KVp directly affect? | contrast |
| The use of many different combinations of mA and s to keep the same mAs, and maintain the same radiographic density refers to what law? | The Reciprosity Law |
| What controls the intensity of the total exposure? | total mAs |
| What does Quantum Mottle look like on an x-ray? | salt and pepper |
| What causes Quantum Mottle? | lack of density from too low mAs |
| What is the only way to compensate for Quantum Mottle? | Increase mAs |
| What is responsible for bringing mAs to the film? | KVp |
| Does detail come from electrical or geometrical factors? | geometrical |
| Contrast cannot change unless what happens? | The absorption rate between tissues change |
| If a film is overexposed, what should you adjust? | cut back on mAs |
| What does scatter create on a film? | fog |
| How much do you need to adjust mAs to compensate for an underexposed film that is not penetrated? | you don't adjust mAs. underexposure caused from no penetration is due to KVp |
| When you have structural lines on the film do you have penetration? | yes |
| Do you always want to use the longest time or the shortest time when taking an exposure? | shortest |
| Why do you want to use the shortest time when taking an exposure? | to reduce motion from the patient |
| What is the direct cause of motion? | Patient movement |
| How do the electrical factors affect the geometrical factors? | They do not affect them |
| What determines tube current? | mAs |
| What is the overall blackening of the film? | Density |
| How many shades of gray can we see on a static film? | 32 |
| How many shades of gray can we see on a computerized image? | 256 |
| How much do you need to increase mAs for a visual change in density? | 30% |
| If you go from supine to prone, how much do you need to increase mAs? | 50% |
| What happens to density if you increase by a factor of 2? | it doubles |
| What is used to measure density on an x-ray? | densitometer |
| What are odu's? | Optical density units |
| How does KVp affect density? | exponentially (it increases quickly) |
| What does KVp to in order to penetrate the body? | It alters the wavelength |
| If you increase KVp, what happens to wavelength? | it decreases |
| If you increase KVp, what happens to frequency? | it increases |
| If you increase KVP, what happens to penetration? | it increases |
| What is determined by absorption and attenuation levels? | contrast |
| Does higher KVp result in higher or lower contrast? | lower contrast |
| Do you increase or decrease KVp for a larger patient? | Increase |
| What is the most important function of KVp? | penetration of the x-ray beam through the body |
| What do we want to strive for in terms of contrast? | The longest scale for the part |
| If a radiograph is overexposed and there are no whites, is it because of mAs or KVp? | KVp |
| If a radiograph is overexposed and the are whites, is it because of mAs or KVp? | mAs |
| If you increase mAs, what happens to patient dose? | It increases |
| How much mAs do you need to correct the lack of KVp? | No amount of mAs will compensate for the lack of KVp |
| What produces white on the radiograph? | Bones |
| What produces black on the radiograph? | Air |
| What is fat and other tissue cause on the radiograph? | gray scale |
| If absorption levels change what happens to contrast? | It also changes |
| Only a few x-rays are produced at peak KVp level. What is the average of the rest of the beam? | approximately 1/3 of peak KVp |
| How much do you need to alter mAs to double density? | by a factor of 2 |
| How much do you need to alter KVp to double density? | 15% |
| How much do you need to alter mAs for a visual change in density? | 30% |
| How much do you need to alter KVp for a visual change in density? | 5% |
| What kind of radiation most closely follows the direction of the original beam? | Secondary radiation |
| Does scatter give any useful information on the radiograph? | no |
| If you alter KVp do you change density or contrast? | Both |
| If you alter mAs do you change density or contrast? | density... mAs does not affect contrast |
| Do you need to increase or decrease KVp for Degenerative diseases? | decrease |
| Do you need to increase or decrease KVP for Additive diseases? | increase |
| What is the differences in intensity between one portion of the x-ray beam and another? | Subject Contrast (subject contrast is patient contrast) |
| Which is more detrimental to the finished radiograph? Short or long scale contrast? | Short (short scale is high contrast) |
| What are 3 things that affect subject contrast. | Insufficient penetration alteration of the direction of the remnant beam extreme overexposure of the film |
| What is the #1 form of noise on a radiograph? | Fog |
| What is noise? | A type of distraction on your radiograph |
| Can a film be fogged without being overexposed? | yes |
| How do you know if a film is fogged? | There will be no whites on it |
| What does ALARA mean? | As Low As Reasonably Achievable |
| What does ALARA refer to? | patient dose |
| What combination of mAs and KVp do you want to use to minimize patient dose? | High KVp and low mAs |
| What is the light we see come out of the view box is called? | Tone value (tone value is the opposite of density) |
| Does the white area on a radiograph have high or low tone value? | High |
| What is exposure latitude? | the range between minimum and maximum exposure that gives a diagnostic radiograph. The margin for error latitude=leeway |
| If you increase KVp, what happens to exposure latitude? | increase exposure latitude |
| Does high contrast give a wide or a narrow exposure lattitude? | narrow |
| If you have a long gray scale, do you have a narrow or wide exposure lattitude? | wide |
| In order to see an x-ray, you need light energies in the form of what? | photons |
| What has a shorter wavelength and higher frequency? photons or light? | photons |
| What is the differences between intensities? | Contrast |
| Does fog affect detail? | no.. only the visibility of detail |
| What type of matter can be penetrated by x-rays? | radioluscent |
| What type of matter can not be pentrated by x-rays? | radiopaque |
| Name a substance that is radiopaque | barium |
| What causes size distortion on a radiograph? | SID and OID |
| How do you minimize shape distortion? | beam-part-film alignment |
| What happens if you angle the x-ray beam? | elongation |
| What happens if you angle the anatomy? | foreshortening |
| What happens if you angle the film? | elongation |
| If you increase SID, do you get more or less magnification? | less |
| If you increase OID, do you get more or less magnification? | more |
| If you increase SID, do you get elongation or foreshortening | neither... SID does not affect shape distortion |
| What is shape distortion? | The difference between the shape of the real object and its projected image. |
| What ranges of density are diagnostically acceptable? | .25odu's to 2.5 odu's |
| What is the most common artifact on an x-ray? | Static (caused by friction) |
| What is the most common form of static? | Tree Static |
| What are some forms of static on a x-ray? | Tree Static Smudge Crescent Moon |
| What are all statics forms of? | Artifacts |
| What is nthing that does not represent the true anatomy called? | False image |
| What is the remnant beam called? | Exit radiation |
| What is exit radiation composed of? | Secondary and scatter radiation |
| How is a radiographic image created? | By passing an x-ray beam through the patient and the interactions that occur within the IR |
| What is any radiation that goes through the patient without any interactions called? | Transmission radiation |
| What color is transmission radiation on the film? | black |
| What are the 3 aspects of tissue that determine attenuation and absortion, resulting in subject contrast? | tissue thickness tissue density tissue atomic # |
| What interactions are complete absorption? | Photoelectric Interactions |
| Which interactions occur with inner shell electrons? | Photoelectric interactions and Thompson Interactions |
| Which interactions occur with outer shell electrons? | Compton Interactions |
| What percent of scatter are Compton Interactions responsible for? | 99% |
| What are other names for Compton Interactions? | Incoherant and Modified |
| Which interactions have a slightly higher energy than binding? | Photoelectric |
| Which interactions have a greatley larger energy than binding? | Compton Interactions |
| Which interactions have less energy than binding? | Thompson Interactions |
| What percent of scatter radiation comes form Thompson Interactions? | 1% |
| What are the other names for Thompson Inter, actions? | Coherant, unmodified and classical |
| What percent of remnant radiation is scatter? | 75% |
| Is all scatter secondary radiation? | yes |
| Is all secondary scatter radiation? | no |
| What is the degree of blackness or darkness in an area of the image, determined by the amount of silver deposited on the film in that area? | Density |
| What is the amount of light that is able to penetrate through an area on the film, or the area's translucency. The opposite of density. | Tone value |
| What is the ratio of differences between two adjacent densities in the image? | Contrast |
| What is the range or number of different densities in present in the image? The opposite of contrast. | Gray scale |
| What is any unwanted, useless information recorded in the image which obscures the visibility of the desired image details. It includes fog, static and artifacts. | Noise |
| A form of noise. A veil of useless density covering portions of the desired image. It is caused by randomly scattering radiation which carries no useful signal or image. | Fog |
| What is the abruptness with which the edges of an image stop. More precisely, the lack of penumbra shadows at the edge of an image. | Sharpness of recorded detail |
| What is the presence of penumbra, or the lack of sharpness, at the edges of an image. | Blur |
| What is the partial shadow at the edges of an image, whereby its transition into the adjacent. | Penumbra |
| What is the differences between the size of a real object being radiographed and the size of it projected umbral image (measured in all directions) | Magnification |
| What is the differences between the shape of a real object being radiographed and the shape of its projected image, consisting of either elongation or foreshortening of the image? | Shape distortion |
| What are those image qualities which directly affect the ability to see an image. They include density or tone value, contrast or gray scale and noise including fog? | Visibility factors |
| What are those geometrical image qualities which directly affect the ability to discern the nature of the real object being projected onto the image. These include sharpness of detail, magnification and shape distortion. | Recognizability factors |
| What is the ability to distinguish small adjacent details in the image as being separate from each other. It is controlled by both visibility and recognizability factors. | Resolution |
| What is the total amount of diagnostically useful information resolved in an image. It is controlled by the combination of all visibility and recognizability factors. | Radiographic Image Quality |
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