RAD 205

Scoliosis Problem Set

9/23/13

In RAD 205 you will be provided with an example calculation of the organ dose to a patient’s liver for one PA projections for scoliosis. The example assumes the exposure was made with 50 mAs at 90 kVp. For this Problem Set, recalculate the organ dose assuming the exposure was made with 20 mAs at 90 kVp. This assignment is organized into a series of problems. Each problem is worth 3 points (one point for correct equation, one for correct work, and one for the final answer). The example problem below illustrates what is expected. This example problem would earn 3 of 3 possible points. Example problem: If an exposure is measured at 25 milliRoentgen, what is the exposure in units of Roentgen? Equation(s):

Show your work:

State your answer:

The problems that you are to solve are listed below. Refer to the class handout titled “RAD 205 Effective Dose to Patients in Diagnostic Radiography” as you work through these problems.

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RAD 205

Scoliosis Problem Set

9/23/13

Problem 1. What is the Entrance Skin Exposure? Refer to page 3 of the handout and show your work on the nomogram at right. Equation(s): none for this problem. Use the nomogram instead of an equation.

Show your work: Use a straight edge to draw a line starting at 90 kVp on the axis at the far right and ending at approximately 20 mAs at the axis on the left. Find the point at which your line crosses the axis in the middle (ESE). Read the approximate ESE off of the axis in the middle to find your answer. Notice that each axis uses a logarithmic scale.

State your answer:

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RAD 205

Scoliosis Problem Set

9/23/13

Problem 2. What is the ESE after correcting for SOD? Refer to page 4 of the handout. Equation(s):

Show your work:

State your answer: ____________________________________________________________________________ Problem 3. What is the exposure at the center of the liver? Refer to page 6 of the handout. Equation(s):

Show your work:

State your answer:

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RAD 205

Scoliosis Problem Set

9/23/13

Problem 4. What is the absorbed dose for the liver tissue? Refer to page 6 of the handout. Equation(s):

Show your work:

State your answer:

Problem 5. What is the organ dose (Effective dose) for the liver? Refer to page 7 of the handout. Equation(s):

Show your work:

State your answer:

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