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BPH702S - BIOMEDICAL PHYSICS - 1ST OPP - NOVEMBER 2024 |
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p
nAml BIA UnlVERSITY
OF SCIEnCE AnDTECHnOLOGY
FacultyofHealthN, atural
ResourceasndApplied
Sciences
Schoool f NaturalandApplied
Sciences
Departmenot f Biology,
ChemistrayndPhysics
13JacksonKaujeuaStreet T: +264612072012
Private Bag13388
F: +264612079012
Windhoek
E: dbcp@nust.na
NAMIBIA
W: www.nust.na
QUALIFICATION: BACHELOR OF SCIENCE
QUALIFICATION CODE: 07BOSC
COURSE: BIOMEDICAL PHYSICS
DATE: NOVEMBER 2024
DURATION: 3 HOURS
LEVEL: 7
COURSE CODE: BPH702S
SESSION: 1
MARKS: 100
FIRST OPPORTUNITY: EXAMINATION QUESTION PAPER
EXAMINER: Dr Vaino Indongo
MODERATOR: Dr Vera Uushona-Mikka
INSTRUCTIONS:
1. Answer all questions on the separate answer sheet.
2. Please write neatly and legibly.
3. Do not use the left side margin of the exam paper. This must be allowed for the
examiner.
4. No books, notes and other additional aids are allowed.
5. Mark all answers clearly with their respective question numbers.
PERMISSIBLE MATERIAL:
Non-Programmable Calculator
ATTACHEMENT
None
This paper consists of 4 pages including this front page.
Biomedical Physics, First Opportunity Examination Memorandum, November 2024
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OUESTIONl
[20]
1.1 Briefly explain the terms: (i) tomography, (ii) radio-sensitivity.
(4)
1.2 State two tomographic imaging modalities whose performances are based on detections of
photons from the patient's body and the inner structures are obtained as a result of
spontaneous decays of radioisotopes.
(2)
1.3 Explain, in short, why lubrication is essential on mechanical or human machines?
(2)
1.4 A collagen of cross-sectional of 1.2 x IO - 4 m2 and mass m kg has a tensile strength of
2.3 x 10 4 Nnf 2 . Calculate the;
(i) breaking force of the collagen, and
(3)
(ii) value of its mass, g = 9.8 m/s2.
(2)
1.5 State two physical use of bones in the skeletal system.
(2)
1.6 The application of physics is an important phenomenon in observing electrical activities of
a biological material. Discuss, in short, the use for each of the following instruments:
(i) Electrocardiogram
(1)
(ii) Electroencephalogram
(1)
iii) Sphygmanometer
(1)
1.7 Discuss briefly the application of physics on a newborn baby.
(2)
OUESTION2
[20]
2.1 Define flow rate, Q, and write down its mathematical formula in terms of cross-sectional
v, area, A, of a channel and velocity, of fluid under consideration.
(3)
2.2 Given that the ultrasound frequency of 2 MHz and wavelengths of 6.5 nm was used
to take an image of a bone. Calculate the acoustic impedance of a bone if the density
of a bone is 2.2 x 103 kg/m 3.
(3)
2.3 Calculate the amplitude reflection coefficient for a fat-liver interface.
Z (fat)= 1.62 x 106 Rayls ; Z (liver)= 1.41xl0 6 Rayls.
(3)
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Biomedical Physics First Opportunity Examination Paper, November 2024
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2.4 The relative sound intensity is measured on a logarithmic scale. Calculate the
relative intensity of a sound beam when it is:
(i) reduced by a quarter.
(2)
(ii) a seven-fold increase.
(2)
2.5 What are the two main causes of attenuation of a beam of intensity?
(2)
2.6 Estimate by calculating the pulse-echo period in µs when the depth of the interface from
the ultrasound probe is 0.3 mm. Note: v = 1540 mis
(2)
OUESTION3
[20]
3.1 Define a spin state. Which nucleic particle possesses a spin? And what are the two
microscopic properties of this particle responsible for magnetic resonance imaging? (4)
3.2 Determine the total nuclear spins following atoms;
(i) Protium
(2)
It's total nuclear spin is ½fora proton.
(ii) Deuterium
(2)
3.3 Many magnetic resonance imagers operate at a magnetic field strength of 1.5 Tesla. A few
research units operate at 4.7 Tesla. What is the resonance frequency of the phosphorus
nuclei in both magnetic fields? y = 17.24 MHz/T
(2)
3.4 A group of spins was placed into a magnetic field with the number of spins in the lower
energy level of 5 and that in the upper level as 25. Given the Boltzmann's constant, k =
1.3805x10-23 J.K 1; the temperature, T = 27°C and 1 eV= 1.602x10-19J, calculate the energy
difference M between the spin states. Give your answer in e V.
(7)
3.5 A sample has a T2 of 50 ms. The net magnetization of 200 µTis rotated into the xy-plane
and allowed to decay. How much transverse magnetization will be present 22 ms after being
placed in the plane?
(3)
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Biomedical Physics First Opportunity Examination Paper, November 2024
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QUESTION4
[20]
4.1 An X-ray machine mounted in private medical centre has molybdenum (!~Mo) as a target
material. A female patient with a complain had to undergo mammography examination.
The radiologist has decided on the voltage of 20 ke V and the radiographer recommended
for 25 ke V for settings during the procedure. These two medical personnel mutually agreed
for an average potential difference to be set on the instrument. Determine the energy of X-
ray photons produced in e V.
(5)
4.2 A beam intensity of 150 µW/m 2 was focused to pass through aluminium material of half-
value thickness = t112 2.1 cm. Determine the;
(i) attenuation coefficient,µ, of the material
(3)
(ii) strength of intensity after passing through a thickness of 1.5 cm a material (3)
(iii) beam intensity after the 6th value layer.
(3)
4.3 Explain the attenuation by means of absorption and scattering of X-ray beam when passed
through a human body for imaging purposes.
(2)
4.4 The intensity of X-ray beam passing through a material decreases exponentially. Use the
equation of attenuation and derive the equation in the form ofy = mx + c.
(4)
QUESTIONS
[20]
5.1 State and discuss the law ofradioactive decay.
(4)
5.2 Explain, in short, the term biological half-life.
(2)
5.3 A radionuclide has a half-life of 5 hours.
(i) Estimate its decay constant (s-1)
(2)
(ii) Calculate the activity ofa radionuclide after 24 hours, when its initial activity is 5 mBq.
(3)
5.4 The half-life of 99mTc is 6 hours. After how much time will 1116thof the radioisotope
remain?
(5)
4.5 During radiotherapy, either radioactive or non-radioactive sources are used for efficient
treatment of cancer. Give two reasons why collimators are crucial in the gantry of a
radiotherapy equipment.
(4)
END!!!
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Biomedical Physics First Opportunity Examination Paper, November 2024