Bushong Chapter 16
Spatial resolution improves as: - answer Screen blur decreases, motion blur decreases
and geometric blur decreases
What is radiographic noise? - answer Random fluctuation in optical density of the image
What reduces quantum mottle? - answer Use of high mAs, low kVp and slower image
receptors
Radiographic quality rules: - answer1. Fast image receptors have high noise and low
spatial resolution and contrast resolution
2. High spatial resolution and contrast resolution require low noise and slow image
receptors
3. Low noise accompanies slow image receptors with high spatial resolution and
contrast resolution
What is quantum mottle? - answerrandom nature by which x-rays interact with image
receptor
Increase in Log Relative Exposure (LRE) of 0.3 results from: - answerdoubling the
radiation exposure
Optical density = - answerlog10 (Io/It)
What does higher fog density do to contrast of radiographic image? - answerReduces it
Base plus fog OD has a range of: - answer0.1-0.3
What does the reciprocity law state? - answerOD on a radiograph is proportional only to
the total energy imparted to the radiographic film
What is film contrast related to? - answerSlope of the straight-line portion of the
characteristic curve
Average gradient = - answerOD2-OD1 / LRE2-LRE1
Speed = - answer1 / exposure in roentgens to produce an OD of 1.0 plus base + fog
New image receptor speed / old image receptor speed = - answerold mAs / new mAs
How are latitude and contrast related? - answerInversely proportional
Spatial resolution improves as: - answer Screen blur decreases, motion blur decreases
and geometric blur decreases
What is radiographic noise? - answer Random fluctuation in optical density of the image
What reduces quantum mottle? - answer Use of high mAs, low kVp and slower image
receptors
Radiographic quality rules: - answer1. Fast image receptors have high noise and low
spatial resolution and contrast resolution
2. High spatial resolution and contrast resolution require low noise and slow image
receptors
3. Low noise accompanies slow image receptors with high spatial resolution and
contrast resolution
What is quantum mottle? - answerrandom nature by which x-rays interact with image
receptor
Increase in Log Relative Exposure (LRE) of 0.3 results from: - answerdoubling the
radiation exposure
Optical density = - answerlog10 (Io/It)
What does higher fog density do to contrast of radiographic image? - answerReduces it
Base plus fog OD has a range of: - answer0.1-0.3
What does the reciprocity law state? - answerOD on a radiograph is proportional only to
the total energy imparted to the radiographic film
What is film contrast related to? - answerSlope of the straight-line portion of the
characteristic curve
Average gradient = - answerOD2-OD1 / LRE2-LRE1
Speed = - answer1 / exposure in roentgens to produce an OD of 1.0 plus base + fog
New image receptor speed / old image receptor speed = - answerold mAs / new mAs
How are latitude and contrast related? - answerInversely proportional
