Calculators

Only for use in Diagnostic Physics exams

In recent years, candidates taking the physics exam for radiology residents have not had a calculator available. This year the content of the exam will not change and any calculations may still be done by hand and would not require a calculator. However for the convenience of the candidates, the standard Microsoft windows calculator will be available. The number and type of questions that require calculations will not change.

Pictured below is the Microsoft calculator provided by the ABR for candidates taking the computer-based exam. The pictures show both the Standard View and the Scientific View of the calculator. To change the calculator from one View to another, you must click on the View menu. The Microsoft calculator is included in all versions of the Windows Operating System.

Standard View

Scientific View

Sample Problems:

1.) A radiographic room has a source image distance of 100 cm. An object is 10 cm from the receptor. The magnification of the object is:

0.75
B) 1.0
C) 1.1
D) 1.4
E) 2.0

Answer C
Magnification = Source Receptor Distance/ (Source Receptor Distance - Object Receptor Distance)Magnification = 100/ (100 -10) = 1.11________________________________

2.) A CT scan has 512 x 512 matrix with 2 bytes per pixel. How much storage is required to store 128 of these CT images?

32 Mbyte
B) 64 Mbyte
C) 128 Mbyte
D) 256 Mbyte
E) 512 Mbyte

Answer B
Number of Bytes = 512 x 512 x 2 x 128 = 67108864Number of Mbytes = Number of Bytes/ (1024 x 1024) = 64 Mbyte

3.) The field of view of a gamma camera is 36 cm. If a 128 x 128 matrix is used to for imaging, what will the width of a pixel be?

1.3 mm
B) 1.8 mm
C) 2.1 mm
D) 2.8 mm

Answer D
Pixel size = Field of View / Number of pixels across Field of View = 360 mm/128 = 2.81 mm