Chapter two final
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| Kilovoltage(kV) | controls the energy(penetrating power) of the x-ray beam
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| Milliamperage(mA) | controls the quantity or number of x-ray produced
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| Exposure time (ms) | controls duration of the exposure usually expressed in milliseconds
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| Image quality factors for radiograph images | Density, Contrast, Resolution and Distortion
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| Density | amount of "blackness" on the produced radiograph
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| Controlling Factors of Density | mA's are main and SID is second
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| Adjusting Film density | mA's of 25% to 30% to make visual change
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| Anode Heel affect | cathode end to thicker part of patient except in chest xrays
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| Contrast | the difference in density between adjacent areas of radio graphic image
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| Controlling Factors of Contrast | kV higher kV produces lower contrast (less shades of grey) 15% increase in kV will increase film density similar to doubling mA's
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| Grids | used for body parts 10 com or more
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| off center grid | the CR is not centered along the center of the axis of the grid
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| Off level grid | CR and grid are not in equal angles
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| off focus grid | must be used a certain SID to prevent grid cut off
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| Up side down grid | grid put in up side down
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| Resolution | recorded sharpness on the image
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| Controlling Factors | focal spot size, SID and object image receptor distance
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| Distortion | misrepresentation of object size or shape
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| Controlling Factors for distortion | SID,OID object image receptor alignment and Central ray alignment
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| Digital Imaging | a numeric representation of the x-ray intensities that are transmitted to the patient
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| Exposure Factors for Digital Imaging | mA's, kV's
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| Image Quality Factors for Digital | Brightness, Contrast, Resolution, Distortion,Exposure index, Noise
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| Brightness | the intensity of a light that represents the individual images on a monitor =(similar to density)
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| Contrast in DI | the difference in brightness light and dark areas of an image
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| Contrast Resolution | ability of an imaging system to distinguish between similar tissue
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| Controlling Factors for Brightness | the screen
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| pixels | a single shade of grey
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| bit depth | the greater the contrast resolution the greater the bit depth
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| Pixel size | acquisition pixel size-minimum size (important one) display pixel size-minimum that can be displayed on monitor
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| Resolution in DI | the recorded sharpness or details of a structure
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| Controlling Factors of Resolution in DI | display matrix, pixel size
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| Distortion | misrepresentation of object size or shape as projected onto radiographic recording media
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| Exposure index | a numeric value that is Representative of the exposure that the IR has received
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| "s" number | inversely proportional to radiation that strikes the IR
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| exposure index | is directly proportional to the radiation that strikes the IR
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| Noise | a random disturbance that obscures or reduces clarity
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| SNR | Signal-to-noise ratio high good low bad
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| Computed Radiology | similar to conventional film screen but using digital
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| Collimation | used to reduce patient dose and scatter
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| 30% Rule | at least 30% of IR must be exposed
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| PACS | picture archiving communication systems
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| DICOM | Digital imaging Communication in Medicine
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| ALARA | As low as reasonably achievable
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| Roentgen (R) | radiation exposure in the air
measured on rem( radiation protection) rads (patient dose)
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| Rads | patient dose of radiation
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| occupational recommendations | 5 rem (50 mSv) of whole body effective dose per year
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| general public | *frequent exposure*.1 ren (1 mSv) per year not frequent .5 rem (5mSv)
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| Pregnant technologist | .05 rem (.5 mSv) per month
.5 rem (5 mSv) for gestation period
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| ALARA principles | Always wear protection, restraining devices, collimation, proper technique *time distance and shielding*
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| SEE | Skin entrance exposure
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| Effective dose high | male-AP unshielded hip
Female-AP thoracic spin w/o breast shields
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| Floro limit | 10 R/min
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| Accurate Collimation | limiting the size and shape of the x-ray beam to only clinical intrest
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