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The x-ray tube should always be positioned so that the central ray is pointed at the center line on the grid. Grid cut-off is produced with the x-ray tube is moved across the grid lines, or perpendicular to the way the grid lines run in the grid.
- Overview of Technical Parameters
- MA
- KVP
- Sid
- Bucky Factor
- Golden Equation
As a technologist you are often faced with the situation where you need to make a change to a protocol but want to keep the exposure on the detector the same. In this scenario it is really important to understand the technical parameters and their influence the exposure, so that when changing parameters you do not end up under-exposing or over-expo...
The tube current and time in the x-ray exam are the parameters that are most frequently changed and you should consider this as your first go-to adjustment in order to change the x-ray exposure without impacting the quality of the exam in other ways. Increasing the tube current is actually just providing more electrons that with smash into the x-ra...
The kVp is the most important technical parameter as it has a very strong dependence on the x-ray exposure (kVp5). This strong dependence on the kVp for the exposure at the image receptor is because of the higher flux and stronger penetration of higher kVp imaging. Additionally, the kVp also changes the inherent contrast in the x-ray images. Since ...
The Source to Image Distance (SID) affects the exposure at the image receptor since the x-ray beam is divergent (i.e. spreading out as it gets further from the x-ray tube). Since the x-rays are spreading out the exposure depends on the SID as 1/SID2 . In our post on the basic x-ray properties we demonstrate how the divergent beam leads to the 1/R2d...
Finally, the Bucky factor is a unitless quantity which is the ratio of the x-ray exposure reaching the grid to the x-ray exposure reaching the image receptor. If no grid is used this definition will lead to a Bucky factor of 1.0. The Bucky factor for grids is dependent upon the grid ratio (grid height: grid spacing) and the kVp. It typically ranges...
Now that we have all pieces we can put these 5 simple relationshipstogether to make what we call the golden equation. You can give it your own cool name too. We just call it the golden equation since it has all of the factors that you need to consider so that as you change one factor you can compensate to keep your exposure constant. Also this is j...
This formula, called the exposure maintenance formula, or the direct square law, allows the radiographer to calculate the new exposure factors to be used when the distance between the x-ray tube and the image receptor changes.
On the basis of not deviating from the center line of the X-ray grid, the X-ray center line can be inclined at a certain angle according to the inclination direction of the lead rod, so that the X-ray radiation direction is consistent with the lead.
Antiscatter grids improve the X-ray image contrast at a cost of patient radiation doses. The choice of appropriate grid or its removal requires a good knowledge of grid characteristics, especially for pediatric digital imaging. The aim of this work ...
X-ray scatter depends on several physical factors including: body habitus (increases with increased habitus), kVp, collimation (increases with increased kVp), air gap (decreases with increased air gap), and anti-scatter grids (decreases with increased grid ratio).
People also ask
What does the center line on a X ray grid mean?
Where should the X-ray tube be positioned?
How does a grid reduce X-ray scatter?
What causes grid cut-off in X rays?
How does grid ratio affect X-ray image quality?
What is a crossed X ray grid?
These are established by the formulas: where: = grid width f0 = focalizing distance f1 = lower applicative distance film f2 = higher applicative distance film. = grid ratio V1= peripheric primary radiation loss at f1 limit V2= peripheric primary radiation loss at f2 limit.
