15% rule-KVP-Pt Dose-Technique rules Flashcards
What is the 15% rule?
Increasing kVp by 15% increases the receptor exposure by 100% (2x)
What is the relationship between kVp and exposure?
Exponential
How much does a 15% increase in kVp increase patient dose?
By 25-40%
If you need to cur dose in half how should kVP be adjusted?
Decrease kVp by 15%
How do the 4cm rule and 15% rule coincide?
For every 4 cm change in thickness you need to increase exposure by 2X, which can be achieved by increasing KVP 15%
Which technical factor should be increased to save patient dose?
kVp
Which interaction yields most of the patient dose?
Photoelectic interaction
How does doubling mAs affect dose?
Dose will also be doubled
What is the minimum kVP?
lowest kVp that still provides some degree of penetration through all tissues of interest
What amount of mAs can account for a low kVp?
No amount of mAs can account for lower kVp