1.	The simplified diagram shows a modern X-ray tube.

(a)	For each of the labelled parts, state what it is and explain its purpose.
A	name .................................................................................................................
purpose .............................................................................................................
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B	name .................................................................................................................
purpose .............................................................................................................
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C	name .................................................................................................................
purpose .............................................................................................................
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D	name .................................................................................................................
purpose .............................................................................................................
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(8)

(b)	On the diagram draw and label
(i)	the direction of the electron beam,
(ii)	the direction of the useful X-ray beam.
(2)
(Total 10 marks)

2.	The X-ray spectrum, produced by an X-ray tube used to produce diagnostic images, has the features on the diagram.

(a)	Explain why the spectrum has
(i)	a maximum photon energy and state the circumstances in which a photon of this energy is produced,
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(ii)	two lines, P and Q.
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(4)
 
(b)	(i)	From the graph, estimate the accelerating voltage of the tube.
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(ii)	Calculate the frequency of the line Q.
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(3)
 
(c)	On the X-ray spectrum draw an intensity curve which shows the output you would expect from the same tube when operated at 55 kV.
(3)

(d)	For diagnostic purposes it is important to minimise the X-ray dose which patients receive. State two steps taken to reduce the dose and briefly explain how each is effective in reducing patient dose.
step1 ...........................................................................................................................
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step 2 ..........................................................................................................................
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(4)
(Total 14 marks)

3.	When using an X-ray source to produce an image of part of a patient a lead grid is sometimes placed between the patient and the photographic film, as shown in the diagram. The channels in the grid diverge from the X-ray source.

(a)	(i)	Why is the grid made of lead? .........................................................................
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(ii)	By drawing the paths of about 10 rays from the X-ray source to illustrate your answer, explain how the use of the grid improves the clarity of the X-ray image.
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(5)
 
(b)	Explain why it is important to use a point source of X-rays for imaging purposes.
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(1)
(Total 6 marks)

4.	(a)	The diagram shows a rotating-anode X-ray tube. Complete the labelling of the three numbered arrows in the diagram.

(3)
 
(b)	Explain why the anode
(i)	is rotated,
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(ii)	has a bevelled edge.
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(3)

(c)	Define for a material,
(i)	the linear attenuation coefficient, m,
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(ii)	the half-value thickness.
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(2)
 
(d)	A monochromatic X-ray beam of intensity 6.0 W m–2 is incident on an aluminium sheet of thickness 2.0 mm. For these X-rays, the half-value thickness of aluminium is 3.2 mm. Calculate the intensity of the transmitted beam.
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(3)
(Total 11 marks)

5.	Diagnostic X-rays are produced using a rotating anode X-ray tube. 
(a)	(i)	State two methods which can be used to increase the intensity of the X-ray beam produced by the tube.
method 1 .......................................................................................................
method 2 .......................................................................................................
 
(ii)	For each method of increasing intensity, state the effect on the maximum X-ray photon energy.
method 1 .......................................................................................................
method 2 .......................................................................................................
(3)
 
(b)	Before taking an X-ray photograph, the X-ray beam emerging from the tube is passed through an aluminium filter. State and explain the reason for filtering the X-rays.
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(3)
(Total 6 marks)

6.	(a)	When an X-ray image is obtained of certain organs, image contrast enhancement is necessary. Explain why image contrast enhancement is needed and describe how this might be achieved.
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(3)

(b)	A monochromatic X-ray beam of intensity 3.2 × 10–2 W m–2 is incident on an aluminium sheet. Calculate the thickness of aluminium required to reduce the intensity of the X-ray beam to 1.2 × 10–2 W m–2.
	mass attenuation coefficient of aluminium, µm = 0.012 m2 kg–1
	density of aluminium, r = 2700 kg m–3
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(3)
(Total 6 marks)

7.	In the course of diagnosis and treatment of a child’s broken arm, several images of the arm are required. Similarly, to check the progress of a woman’s pregnancy, several images of the foetus are required. In each case, state which imaging technique would probably be used and give two reasons for the choice.
	Broken arm:
technique used ........................................................
reason 1 ................................................................................................................…………
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reason 2 ................................................................................................................…………
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Foetus:
technique used ........................................................
reason 1 .................................................................................................................…………
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reason 2 ................................................................................................................…………
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(Total 4 marks)

8.	(i)	Explain what is meant by the half-value thickness of lead for X-rays.
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(ii)	Calculate the linear attenuation coefficient of lead for 90 keV X-ray photons.
half value thickness of lead for 90 keV X-ray photons = 12mm.
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(iii)	Calculate the thickness of lead needed to reduce the intensity of a beam of 
90 keV X-ray photons to 5.0 % of the intensity incident on the lead.
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(Total 6 marks)

9.	The figure below shows the design of an X-ray image intensifier.

	The main components are labelled A to D. Name each component and state its purpose in the process of image intensification.
	You may be awarded additional marks to those shown in brackets for the quality of written communication in your answer.
A............................................................................................................................................
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B............................................................................................................................................
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C............................................................................................................................................
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D............................................................................................................................................
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(Total 8 marks)

10.	(a)	The diagram shows a rotating-anode X-ray tube. Complete the labelling of the three numbered arrows in the diagram.

(3)
 
(b)	Explain why the anode
(i)	is rotated,
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...........................................................................................................................
...........................................................................................................................
(ii)	has a bevelled edge.
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(3)

(c)	Define for a material,
(i)	the linear attenuation coefficient, μ,
...........................................................................................................................
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(ii)	the half thickness.
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(2)
 
(d)	A monochromatic X-ray beam of intensity 6.0 Wm–2 is incident on an aluminium sheet of thickness 2.0 mm. For these X-rays, the half-value thickness of aluminium is 3.2 mm.
Calculate the intensity of the transmitted beam.

Intensity = ....................................
(3)
(Total 11 marks)