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Surname Other Names For Examiner's Use


Centre Number Candidate Number

Candidate Signature




General Certificate of Education
January 2007
Advanced Level Examination

APPLIED SCIENCE SC08
Unit 8 Medical Physics

Tuesday 23 January 2007 9.00 am to 10.30 am


For this paper you must have: For Examiner's Use
! a pencil and…

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Answer all questions in the spaces provided.



1 A medical technician is using an EEG machine to study a patient's brain activity.
To do this, she attaches electrodes to the patient's skin.

(a) How does the technician ensure that there is good electrical contact between the…

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(ii) When do beta waves normally occur?

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(1 mark)

(iii) When do delta waves normally occur?

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(1 mark)
____
6



Turn over for the next question




Turn over!
M/Jan07/SC08

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2 Radiographers use X-rays to help diagnose many medical conditions.

(a) A diagram of an X-ray machine is shown below.




(i) Add the correct label to each part indicated in the diagram above.
(4 marks)

(ii) Explain how the anode is prevented from overheating.

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(iii) State one medical problem or condition that can be caused by over exposure to
X-rays.

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(1 mark)

(iv) The terms stochastic and somatic can be used to describe the types of damage
caused by X-rays.
State what each term means.

Stochastic ..................................................................................................................

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3 Radiologists use radioisotopes for both diagnosis and therapy.
The choice of radioisotope to be used for a particular task often depends on its half-life.

(a) (i) What does the term half-life mean?

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(1 mark)

(ii) Radioisotope A has a half-life of 6 hours.…

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Activity
(counts per
minute)




Time (months)
(ii) Use your graph to find an accurate value for the half-life of radioisotope B.

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half-life =........................months

(2 marks)

(c) (i) Give two reasons why radioisotope B has a suitable half-life for use as a tracer.

Reason 1 ....................................................................................................................…

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(ii) Both radioisotopes A and B are believed to emit gamma radiation only.
Design an experiment you could carry out to test whether a radioisotope emits
only gamma radiation.

Explain what you would do and how the results of your experiment would tell
you whether the…

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(d) Radioisotopes used as tracers must emit gamma radiation and should emit little or no
alpha or beta radiation.
Explain why.

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(4 marks)

(e) Radioisotope A has a suitable half-life and emits only gamma radiation. However, a
medical…

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4 Manufacturers of optical instruments know that endoscopes must be made from glass fibres
with a high refractive index. A technician is testing a new type of glass to find out if its
refractive index would make it suitable to use in an endoscope.

He found…

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