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FREE RADIOLOGY AND STUDY GAMES ABOUT RAD 121 -
FORMULAS EXAM QUESTIONS
Actual Qs and Ans Expert-Verified Explanation
This Exam contains:
-Guarantee passing score -14 Questions and Answers -format set of multiple-choice -Expert-Verified Explanation
Question 1: Formula to calculate geometric unsharpness.
Answer:
P = FSS - OID / SOD
Question 2: Double receptor exposure with mAs
Answer:
OLD mAs x 2 = NEW mAs Question 3: Percent of magnification based on distance:
Answer:
%M = SID - SOD / SOD x 100 Question 4: Exposure rate with changes in distance from source: Inverse Square Law
Answer:
I 1 / I 2 = SID 2 squared / SID 1 squared
Question 5: Magnification factor based on object and image:
Answer:
MF = IW / OW (which also equals SID / SOD) Question 6: Percent of magnification based on object and image:
Answer:
%M = IW - OW / OW x 100 Question 7: Magnification factor based on distances:
Answer:
MF = SID / SOD
Question 8: Finding percentage difference in mAs or kVp.
Answer:
High value - lower value; Answer divided by original value; multiply by 100 Question 9: Maintain receptor exposure with mAs for changes in SID. (mAs distance compensation formula)
Answer:
mAs 1 / mAs 2 = SID 1 squared / SID 2 squared
Question 10: mAs, mA, or Time when 2 of 3 are known.
Answer:
mAs = mA x Time; mAs/Time = mA mAs/mA = Time Question 11: Application of 15% kVp rule:
a) Double receptor exposure. AOFC
b) Halve receptor exposure. AOFC
c) Increase contrast and maintain receptor exposure.
d) Decrease contrast and maintain receptor exposure.
Answer:
a) Double receptor exp AOFC orig kVp x 1.15 = new
b) Halve receptor exp AOFC orig kVp x .85 = new
c) Increase contrast, maintain receptor exp
orig kVp x .85 and double mAs
d) Decrease contrast, maintain receptor exp
orig kVp x 1.15 and half mAs
Question 12: Maintaining receptor exposure with change in Grid Ratio.
Answer:
mAs 1 / mAs 2 = GR 1 / GR 2
Question 13: Double receptor exposure with kVp
Answer:
OLD kVp x 1.15 = NEW kVp
Question 14: Grid Ratio formula
Answer:
GR = Height of lead strips/ Distance between lead strips
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