Radiographic Imaging Chapter 7
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| 4 basic requirements for the production of x-rays | 1. Vacuum (tube housing)
2. Source of electrons (filament)
3. Method to accelerate electrons rapidly (Voltage)
4. Method to stop the electrons (target)
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| Beam of x-rays, mechanically produced by passing high voltage through a cathode ray tube, transverses a patient and is partially absorbed in the process. | Basic mechanism of radiographic image production.
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| 4 Basic methods of Imaging the body: | 1. X-rays (Radiography & CT)
2. Gamma Rays (Nuclear medicine)
3. Sound waves (Ultrasound)
4. Magnetism (MRI)
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| In making x-rays, electrons are created at the ________ and accelerated to the _______? | Cathode; Anode
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| In making x-rays, the kinetic energy of the electrons is converted into what? | Heat (99%+) and X-Rays (less than 1%)
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| Electrons always move to what direction? | Toward Positive
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| Cathode is what charge? | Negative
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| Anode is what charge? | Positive
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| This is the measure of the electrical current passing through the x-ray tube. | Milliamperage
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| mAs directly controls the _________ of x-ray photons produced. | Quantity
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| What is the measure of electrical pressure (potential difference) forcing the current through the tube? | kVp (Kilovolt peak)
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| This primarily affects the quality but also the quantity of the x-ray photons produced. | kVp
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| The distance between the point of x-ray emission in the x-ray tube and the image receptor. | SID (Source to Image Distance)
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| The "C-Arm" is primarily used in this setting? | Surgery
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| Name the 3 things that make up DENSITY. | 1. Primary Radiation (radiation exiting the tube)
2. Remnant Radiation (the primary radiation that passes through the patient producing the image)
3. Scatter or Secondary Radiation (primary radiation that changes direction)
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| This radiation is the image producing radiation that passes through the patient | Remnant Radiation
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| This radiation produces bad images and makes the image look more gray. | Scatter or Secondary Radiation
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| This radiation is the primary reason for Collimation. | Scatter Radiation
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| The process by which the nature of the primary radiation is changed (partially absorbed) as it travels through the patient. | Attenuation
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| Name the 2 types of Luminescence: | 1. Fluoroscence
2. Phosphorescence
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| The emission of visible light only during stimulation of an outside force. | Fluoroscence
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| The continued emission of light after stimulation has ended. | Phosphorescence
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| Phosphorescence in an intensifying screen is called ___________ or ___________ and can be objectionable (not good) | Screen lag; Afterglow
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| 95% of the ___________ on a radiography is from light emitted from a screen. | Density
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| The invisible image inside the base of the radiographic film | Latent Image
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| A light-tight holder for the film: | Cassette
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| Remnant radiation that hits the buckie tray and bounces back: | Backscatter
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| The back of this type of cassette will have a low atomic number material to allow remnant x-rays to reach the photo-timer thus ending the exposure when the image is received: | Photo-Timed cassette
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| This type of cassette has a _______ atomic material to absorb backscatter radiation. | High
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| Cassettes should have these 2 types of characteristics: | 1. Compression device (felt or rubber to maintain a close film/screen contact)
2. Back
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| The 2 basic properties of the X-Ray Beam: | Quantity and Quality
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| Name the 4 properties of Quantity: (NIME) | 1. # of Photons
2. mAs (milliampere seconds)
3. Intensity
4. Exposure
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| Name the 3 properties of Quality: (SPH) | 1. Strength
2. Penetrating Power
3. Hardness
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| Density is the amount of _________ on the film. | Blackness
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| mAs is _______ __________ to Density. | Directly proportional (mAs = Density)
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| 60 kV = __________ volts | 60,000
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| 1 Kilo = | 1000
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| 1 millisecond is equal to? | 1/1000 of a second
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| Convert to decimal: 30milliamps | .03 amps
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| Convert to decimal: 4milliamps | .004
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| Convert to decimal: 500milliamps | .5
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| _____ = mA x time in seconds | mAs
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| Convert to milliseconds: 0.25 sec | 250milliseconds
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| Convert to milliseconds: 3/10 sec | 3/10 = 0.3 = 300milliseconds
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| Solve for mAs: 1. 100mA at 1/2 second 2. 200mA @ 0.4 second 3. 400mA @ 250millisecond | 1. 100 x 1/2 = 50mAs
2. 200 x 0.4 = 80mAs
3. 250milliseconds = .25 seconds: 400 x .25 = 100mAs
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| The controlling factor for Contrast is? | kVp
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| The controlling factor for Density is? | mAs
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| Formula in solving for Intensity and Distance: | I(original)/I(new) = Density(new)squared/Density(original)squared
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| A 15% increase in kVp will result in a DOUBLING the density and a 15% decrease in kVp will result in cutting the density in HALF | kVp 15% Rule
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| Why would increasing the SID decrease the intensity of the beam? | Divergence of the beam
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| There must be at least ___% change in distance to cause a visable change in density and require an adjustment in technique. | 20%
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| Inverse square law of SID and Density | Intensity = 1/Distance squared
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| Thin patients will have more or less density on the radiographic image? | More
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| Fat, muscle and air will have more or less density on a radiographic image? | More
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| What is the major controlling factor for Contrast? | kVp
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| An increase in kVp will increase or decrease contrast? | Decrease Contrast
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| Increasing kVp will do what to Density? | Increase Density
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| kVp in relation to Density follows what rule? | 15% rule
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| The 15% rule means what? | Increasing kVp 15% doubles Density; Decreasing kVp 15% cuts Density in half
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| How much more kVp would double the density if the original kVp was 80? | 12 more kVp would be 92kVp which would double density
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| What would be the new kVp to Half the density if the original kVp was 60? | 15% of 60 = 9, the new kVp to cut the density in half would be 51kVp
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| Intesity is measured in ______ | mR (milliRoentgen)
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| When changing the kVp 15% what must you do to mAs to maintain the same exposure? | increasing kVp 15% requires you 1/2 mAs; Decreasing kVp 15% requires you to double mAs
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| What is the formula for solving for Intensity and Distance? | Inverse square law:
I(1)/I(2) = D(2)Squared/D(1)squared
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| Intensity is the ___________ of photons in the beam. | Number
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| Increases the SID does what to the intensity? | Decreases because of divergence
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| Changing the SID by _____% will cause a visible change in Density and require an adjustment in techniqe | 20%
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| When solving for distance and beam intensity what is the formula? | I=1/d squared
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| What is the intensity if the distance is 3 m? | I=1/9
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| What is the intensity if the distance is 8 m? | I=1/64
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| The filtration made possible by the glass envelope and the cooling oil which the beam must pass through is called ____________ filtration | Inherent filtration
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| Inherent plus added filtration is called __________ | Total filtration
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| A sheet of metal through which the x-rays must pass before striking the object to be examined or treated is called? | Filter
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| Tube housing (vacuum) is usually made of what substance? | Lead
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| This term describes the hardness, penetrating ability or quality of the beam. | Half Value Layer (HVL)
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| The thickness of a specified material (filter) that will reduce the original intensity of the beam to half its initial value is called? | Half Value Layer
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| The measurement of kVp is | Half value layer
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| Increasing mAs does what to Density? Contrast? | Increases Density; nothing to contrast
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| Increasing kVp does what to Density? Contrast? | Increases Density; Decreases Contrast
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| Increasing film speeds does what to density? Contrast? | Increases Density; decreases Contrast
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| Increasing film processing chemicals does what to Density? What to Contrast? | Increases Density; only a 2degree increase will increase contrast more than that will decrease contrast
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| Increasing collimation does what to density? Contrast? | Decreases Density; Increases Contrast
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| Increasing grid ratio does what to Density? Contrast? | Decreases density; Increases Contrast
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| Increasing screen speed does what to density? Contrast? | Increases Density; Increases Contrast
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| Increases in processing by 2 degrees or 2 seconds does what to contrast? | Increases contrast
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| Increases in OID does what to contrast? | Increases contrast
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| Anything that reduces scatter does what to contrast? | Increases contrast
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| Contrast media does what to contrast? | Increases contrast
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| Positive contrast media does what to Density? Contrast? | Decreases density; Increases Contrast
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| Negative contrast media does what to Density? Contrast? | Increases Density; Increases contrast
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| These factors have no effect on contrast: | mAs; time; FSS; SID
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| Detail/Distortion is also referred to as? | Resolution
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| The sharpness of structural line or minute details on the radiograph | Detail
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| The 2 parts to detail are: | Visibility of Detail (can be seen but not measured); Geometric (can be measured)
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| 4 ways to reduce motion: | Short exposure techniques; Immobilization; Suspension of respiration; COMMUNICATION
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| The image proper or true image is known as: | umbra
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| The light hazy area surrunding the true image | penumbra
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| 3 factors that affect Geometric Detail: | SID (Increases in SID reduces penumbra)
OID (Increasing OID increases penumbra)
FSS (Increasing FSS increases penumbra)
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| Best Detail in Radiographs have these geometric qualities: | Longest possible SID;
Shortest possible OID;
Smalles possible FSS
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| Misrepresentation of the true size and or shape of the object is known as: | Distortion
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| 2 types of distortion: | Size (true distortion) Shape (false distortion)
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| Magnification: If OID must be increased what should be done to SID to compensate for the loss of Detail and increase in magnification? | Increase SID
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| Foreshortening happens when the object is not __________ with the film | Parallel
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| _________ happens when the tube is angled. | elongation
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| This type of imaging is dynamic in nature. | Fluoroscopic Imaging
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| What is caused by the misalignment of the tube? | Shape distortion
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| This is part of the electromagnetic spectrum and is used in imaging techniques in the form of x-rays-for conventional radiography & computed tomography-or gamma rays for imaging in nuclear medicine. | Ionizing Radiation
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| This is the forming part of the beam: | Remnant Radiation
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| Negative contrast media will do what to the image? | Darken (lessen the atomic number)
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| Positive contrast media will do what to your image? What is the change in atomic number? | Lighten the image (Increases the atomic number)
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| Which would have higher contrast Regular speed screen or an extremity cassette? | Regular speed screen
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| Increasing OID does what to density and contrast? | Higher contrast (reduces scatter) and lower density
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| What 4 things have no effect on Contrast? | mAs, Time, FSS, SID
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| What 3 things give the BEST geometric detail? | Increasing SID, Decreasing OID, Small FSS
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| Thomas Edison invented this type of phosphor material: | Calcium Tungstate
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| Radiolucent material has more or less density? | More
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| What percent of density is from light emitted on a screen? | 95%
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| kVp affects what 2 things of the x-ray photon? | Wavelength and frequency
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| How does kVp affect Density? | 15% rule
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| What are automatic collimators called? | Positive Beam Limitation (PBL)
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| This is a device designed to remove as many scattered x-ray photons as possible: | Grids
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| Anything bigger than ______ should use a "Bucky" | 12cm
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| Increase in OID does what to contrast? | Increases contrast
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| Increasing screen speed does what to detail? | Decreases detail
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| An increase in screen speed does what to density; what to contrast? | Increases density; increases contrast
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| What 3 things give the best detail? | Increase SID
Short OID
Smallest FSS
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