What is the relationship between intensity of light and distance?
There is an inverse relationship between distance and light intensity – as the distance increases, light intensity decreases. This is because as the distance away from a light source increases, photons of light become spread over a wider area.
What is the inverse square law graph?
Inverse Square Law Graph i.e. x = kR-1/2-c. Hence a plot of x against R-1/2 turns out to be a straight line if the inverse square law has been verified.
What happens when kVp is increased?
The higher the kVp, the more likely the x-ray beam will be able to penetrate through thicker or more dense material. Low kVp photons are weak and easily absorbed by body tissues or filters that have been placed.
What are the factors that affect image quality?
Image Quality Factors are also called Key Performance Indicators (KPIs).
- Sharpness.
- Noise.
- Dynamic-Range.
- Color Accuracy.
- Distortion.
- Uniformity.
- Chromatic Aberration.
- Flare.
What is the reason for decreasing mAs when kVp is increased?
For example, an increase from 100 to 120 kVp would increase CT dose index by more than 50% if other parameters were held constant. In reality, so as to not increase dose unnecessarily, the mAs setting is typically adjusted down to compensate for the increased photon quantity caused by increasing kVp.
What are the four image quality factors of a radiograph?
The quality of a medical image is determined by the imaging method, the characteristics of the equipment, and the imaging variables selected by the operator. Image quality is not a single factor but is a composite of at least five factors: contrast, blur, noise, artifacts, and distortion, as shown above.
What is an ideal radiograph?
DEFINITION • An Ideal Radiograph is one that provides a great deal of information, the image exhibits proper density and contrast, have sharp outlines and are of the same shape and size as the object being radiographed.
How can I improve image quality in radiology?
From the equations above we can see contrast can be improved by:
- Decreasing the energy (tube potential kV)
- Increasing the difference in Z (atomic number) (e.g. use of iodine or barium as a contrast medium against soft tissue)
- Increasing the difference in ρ (density) (e.g. use of barium or gas as a contrast medium)
How is image quality measured?
Measure Of Image Quality Resolution is determined by the ratio of pixels in proportion to image size. This is measured in PPI (Pixels Per Inch). A high resolution image will usually have more pixels to every square inch in an image.
What is image quality in xray?
The important components of the radiographic image quality include contrast, dynamic range, spatial resolution, noise, and artifacts. The detectors with wide dynamic range will show very low or very high exposure values in an image, and viewers can view the range of different visible intensities.
How does distance affect image quality in the radiograph?
Source–Image Receptor Distance (SID) Affects the density and intensity of the x-ray beam. Each dimension of the radiation field is proportional to the SID. Therefore the field area is proportional to the square of the SID and the radiation intensity is inversely proportional to the square of the SID.
Does magnification increase or decrease with distance?
Increasing object to film distance only will result in an increase in magnification of the radiographic image. Decreasing object to film distance only will result in a decrease in magnification of the radiographic image (Figure 8).
What is source image distance?
About. The Source-to-Image Distance (SID) is the distance measured between the focal spot target on an x-ray tube to the image receptor of a x-ray cassette.
What is the formula for the magnification factor?
Review
| Question | Answer |
|---|---|
| How can the size of a particular structure or image can be calculated? | Image size/Object size = SID/SOD |
| What is SOD the difference of? | SOD = SID – OID |
| What is the formula for the Magnification Factor? | MF = Image Size/Object Size |
How does Sid affect density?
SID and Density: As SID increases, intensity of the beam decreases. A 20% change in SID will cause a visible difference in density. We use the inverse square law to calculate the difference between distance and density. When SID is doubled, the density will decrease by a factor of 4 (will be 1/4 the original).