FREE RADIOLOGY AND STUDY GAMES ABOUT

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FREE RADIOLOGY AND STUDY GAMES ABOUT

RADIOGRAPHY FORMULAS EXAM QUESTIONS

Actual Qs and Ans Expert-Verified Explanation

This Exam contains:

-Guarantee passing score -29 Questions and Answers -format set of multiple-choice -Expert-Verified Explanation

Question 1: What is the formula for the Magnification Factor?

Answer:

MF = Image Size/Object Size Question 2: What are the annual occupation limits for Effective Dose? How many mSv are in each rem? What are the limits in mSv? What is the occupational yearly dose limit for students under 18 years of age?

Answer:

• rem for the whole body, 50 rem for the skin & extremities, 15 rem for the lens of the eye. 1 rem = 10

mSv. 50 mSv for whole body. 500 mSv for skin/extrmities & 150 mSv for lens of the eye. 0.1 rem (100 mrem or 1 mSv) in given year for students under 18.

Question 3: What is the Grid Frequency?

Answer:

The # of Pb (lead) strips per inch.

Question 4: In digital imaging, how is pixel size determined?

Answer:

By dividing the field of view (FOV) by the matrix. Pixel size = FV/Matrix

Question 5: What is the Grid Ratio?

Answer:

GR = H/D (GR = Grid Ratio, H = Height of Pb stip, D = Distance of the interspace material between the Pb strips).

Question 6: What is the inverse square law?

Answer:

Old Intensity/New Intensity = New distance squared/Old Distance squared.Question 7: How much kVp increase in technical factors for each increase of 1cm tissue thickness?

Answer:

For each 1cm increase of tissue thickness an increase of 2 kVp to compensate.Question 8: What formula is used when converting from one grid ratio to another?

Answer:

mAs original/mAs new = GCF original/GCF new Question 9: What are the GCF for the following Grid ratios........No grid, 5:1 grid, 6:1 grid, 8:1 grid, 12:1 grid, 16:1 grid?

Answer:

No grid = 1x the original mAs, 5:1 grid = 2x original mAs, 6:1 grid = 3x original mAs, 8:1 grid = 4x original mAs, 10:1 or 12:1 grid = 5x original mAs, 16:1 grid = 6x original mAs Question 10: What is the 15% rule? How will I apply it, if repeating & wanting to keep the same the density?

Answer:

A 15% increase of kV is equivalent to increasing mAs by 50%. A 15% decrease in kVp is equivalent to a 50% decrease in mAs. If repeating & wanting the same density, increase my kVp 15% & decrease my mAs by 50%.

Question 11: For every 1" of OID, how much compensation in SID is required?

Answer:

For every 1" OID, an increase of 7" in SID is required.Question 12: What is the formula used to determine the amount of image magnification?

Answer:

Image size/Object Size = SID/OID Question 13: Can excessive radiographic density be attributed to over-development? Why?

Answer:

Yes. Overdevelopment can be caused by the developer temp being too high, which results in chemical fog.Question 14: What is the formula for Density (Incident light & transmitted light)?

Answer:

Density = log x incident light intensity/transmitted light intensity Question 15: What is the qualitative factor (weighting factor) of the following radiations.....fast neutrons, alpha particles, protons, Dx x-rays & gamma rays? What is the ranking of Relative Biological Effectiveness (RBE) from least damaging to most?

Answer:

Dx x-ray & gamma rays 1, protons 5, fast neutrons 10, alpha particles 20.Question 16: What are the mAs correction factors when changing from single phase to 3 phase

• pulse & 3 phase 12 pulse?

Answer:

2/3 X for 3 phase 6 pulse & 1/2 X for 3 phase 12 pulse (X = single phase mass).Question 17: How does an decrease in kV affect exposure latitude? What does this mean?

Answer:

An decrease in kV also decreases exposure latitude. There is less margin for error in lower kV ranges.Question 18: What is the formula for Heat Units (HU) for single phase? What are the correction factors used for 3 phase 6 pulse & 3 phase 12 pulse? What % increase is the intensity of the beam?

Answer:

HU = mA x Sec x kV. 3 phase 6 pulse 1.35 (35%) & 3 phase 12 pulse 1.41 (41%).

Question 19: How can the SID be determined with the OID & SOD? How can the SOD be determined with the SID & OID? How can the OID be determined with the SID & SOD?

Answer:

SID = OID + SOD. SOD = SID - OID. OID = SID - SOD.

Question 20: What is the gestational dose equivalent limit for the embryo/fetus of a pregnant radiographer? What is the limit per month?

Answer:

• mSv (.5 rem) for the gestational period & not to exceed .5 mSv per month (.005 rem, or 5 mrem).

Question 21: What is the density maintenance formula?

Answer:

Old Intensity/New Intensity = Old Distance squared/New Distance squared Question 22: What is the Cumulative Effective Dose? What is the radiation unit? How would it be determined?

Answer:

The Collective Effective Dose describes low doses of ionizing radiation exposure of a population or a group. The person-seivert. The # of people x the average effective dose.Question 23: what are the screen speed conversion factors for the following screen speeds mAs conversion factors, 50, 100, 200, 400, 800?

Answer:

screen spped 50=4, 100=2, 200=1, 400=0.5 & 800=0.25.Question 24: What is the transformer law? What formula is used to determine the voltage & current?

Answer:

Vs/Vp = Ns/Np (V=voltage & N=number of turns). to determine current...Ns/Np=Ip/Is (N=number of turns & I=current).

Question 25: What is the formula to calculate Equivalent Dose?

Answer:

EqD = D x Wr. (D) dose, (Wr) Radiation weghting factor.