3 Questions
What is the approximate percentage change in exposure for each step on any of the step charts?
25%
How many step changes up or down are necessary to correct light or dark films?
At least three step changes
Which exposure factor must be reduced by the same number of steps as kV is increased to retain the same film density?
mAs
Study Notes
- The step system is a standardized way of manipulating exposure factors for accuracy.
- It works on step charts for kV, mAl, mAs, time, and FFD.
- Each step on any chart changes exposure by approximately 25%.
- A noticeable change in film density requires a change of at least 25%.
- Changing exposure factors by at least three steps up or down is necessary to correct light or dark films.
- Step changes can be applied to any of the step charts or split between them.
- The necessary step changes can be split up between charts if required.
- Other factors such as contrast and patient dose influence the decision of which step chart to apply changes to.
- To retain the same film density, mAs must be reduced by the same number of steps as kV is increased.
- The step system removes guesswork and makes exposure setting more accurate.
Test your knowledge of the step system, a standardized method for adjusting exposure factors in radiography. Learn about step charts for kV, mAl, mAs, time, and FFD, and how each step changes exposure by approximately 25%. Discover how to correct light or dark films by changing exposure factors by at least three steps up or down, and how to apply step changes to any of the charts or split between them. Gain insight into how contrast and patient dose influence the decision of which
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