Question 1

A radiographer in a hospital directs a parallel beam of X-rays at the leg bone of a patient. The attenuation (absorption) coefficient of bone is 0.7 cm-1.

The answers below are given to one significant figure. 

What is the percentage intensity of X-rays transmitted through bone of thickness 9.7 cm?

  A  

0 %

  B  

40 %

  C  

50 %

  D  

60 %

0

/

1

Question 2

The Doppler effect is used to measure the speed of blood flow in arteries. 

What medical diagnostic method uses this technique?

  A  

barium scan

  B  

CAT scan

  C  

PET scan

  D  

ultrasound scan

0

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1

Question 3

Ultrasound is reflected at a boundary between two materials. 

Which property of the materials governs the intensity of the ultrasound reflected at the boundary?

  A  

density

  B  

decay constant

  C  

acoustic impedance

  D  

attenuation coefficient 

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Question 4

A contrast material is used while taking an X-ray image of a patient. 

Which statement is correct?

  A  

Iodine is a contrast material.

  B  

Technetium is a contrast material.

  C  

A contrast material must have a short half-life.

  D  

A contrast material is used for acoustic matching. 

0

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Question 5

There are four important attenuation mechanisms by which X-ray photons may interact when they pass through matter.

In which mechanism is the X-ray photon scattered with a longer wavelength? 

  A  

simple scattering

  B  

Compton effect

  C  

pair production

  D  

photoelectric effect

0

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1

Question 6

The acoustic impedance Z of a material in the shape of a cube can be determined using the equation Z=L3Mc​


Where M is the mass of the material, L is the length of each side of the cube and c is the speed of ultrasound in the material. 

The percentage uncertainty in L is 1.2 % and the percentage uncertainty in c is 1.8 %. The percentage uncertainty in M is negligible. 

What is the percentage uncertainty in Z?

  A  

2.2 %

  B  

3.0 %

  C  

4.2 %

  D  

5.4 %

0

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Question 7

The potential difference across the cathode and anode of an X-ray tube is V. The minimum wavelength of the X-ray photons emitted from the tube is λ0​.

Which of the following statements is / are correct?


  1. λ0​ is halved when V is doubled. 
  2. λ0​ is unchanged when the temperature of the cathode is increased. 
  3. λ0​ is independent of the cathode material. 
  A  

1,2 and 3

  B  

Only 2 and 3

  C  

Only 1 and 2

  D  

Only 2

0

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Question 8

Which is not a component used in a gamma camera?

  A  

X-ray tube

  B  

collimator

  C  

computer

  D  

photomultiplier tubes

0

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Question 9

A beam of ultrasound is incident normally at a boundary between two tissues F and G. 

The table shows some data on the two tissues. 

Tissue FTissue G
Density of tissueρ\rho1.2ρ\rho
Speed of ultrasound in tissuec1.5c

What percentage of the intensity of the ultrasound is reflected at the boundary?

  A  

0.83 %

  B  

8.2 %

  C  

9.1 %

  D  

29 %

0

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1

Question 10

What is the SI unit for acoustic impedance?

  A  

kg s

  B  

kg m-2 s-1

  C  

kg m-3 s-1

  D  

kg m-2 s-2

0

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1