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BPH702S-BIOMEDICAL PHYSICS- JAN 2020 |
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NAMIBIA UNIVERSITY
OF SCIENCE AND TECHNOLOGY
FACULTY OF HEALTH AND APPLIED SCIENCES
DEPARTMENT OF NATURAL AND APPLIED SCIENCES
QUALIFICATION: BACHELOR OF SCIENCE (MAJOR AND MINOR)
QUALIFICATION CODE: 07BOSC
LEVEL: 7
COURSE NAME: BIOMEDICAL PHYSICS | COURSE CODE: BPH702S
SESSION: JANUARY 2020
PAPER: THEORY
DURATION: 3 HOURS
MARKS: 100
SUPPLEMENTARY/SECOND OPPORTUNITY EXAMINATION PAPER
EXAMINER(S)
MR VAINO INDONGO
MODERATOR:
DR ROSWITA HAMUNYELA
INSTRUCTIONS
dee
Write all your answers in the answer booklet provided.
2.
Read the whole question before answering.
3.
Begin each question on a new page.
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PERMISSIBLE MATERIALS
Scientific Calculator
ATTACHMENTS
None
THIS EXAMINATION PAPER CONSISTS OF 5 PAGES
(INCLUDING THIS FRONT PAGE)
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QUESTION 1
[20]
1.1 Identify and discuss the principles of any two (2) imaging techniques used in diagnostic
nuclear medicine.
(6)
1.2 A concentration of blood passing through a vein within a human body has a diffusion
constant, D = 1.4 x 10 m2/s. The radius and length of the vein are given as 0.08 m and 0.15
m respectively. Hint: (Ks = 1.3806 x 103 m2.kg.s*.K4, T = 343 K).
(a) Compute the gradient of concentration given that C2 = 20 kg/m? and Ci = 70 kg/m?.
(4)
(b) Estimate the coefficient of viscosity of blood.
(4)
1.3 In medical physics profession, scientists apply physics concepts, theories and methods to
healthcare. State four (4) physical applications applied to life sciences in medical imaging
techniques.
(4)
1.4 What are the two applications of biomechanics?
(2)
QUESTION 2
[20]
2.1 Estimate the specific ionization resulting from the passage of a 0.20-MeV beta particle
through standard air, given that the mean ionization for air is 34 eV/ip. The equation
“ddExi 2Enqm* BN2Z((e3x1xe11.00e~°66))*2 { 1E2mm(4EE-,KBBB??) |-7}=Mcemv
:is used to compute the l:inear energy
loss of a particle, where q is the charge on the electron, 1.6x 1071°C, N is the number of
absorber atoms per cm?, NZ is of absorber electrons per cm? = 3.88 x 102° for air at 0° and
76cm Hg, Em is the energy equivalent of the electron mass, 0.51 MeV, E;, is the kinetic
energy of the beta particle in MeV, £ is the speed of the ionization particle/speed of light,
B = "/¢, I is the mean ionization and excitation potential of absorbing atoms (MeV), J =
8.6 x 107° for air, and J = 1.35 x 10~5Z for the substance.
(14)
2.2 State and discuss how the two types of x-rays are generated in the x-ray tube.
(6)
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QUESTION 3
[20]
3.1 Derive Bernoulli’s equation.
(6)
3.2 A pipe has one end/side positioned on level (hz) and the other is tilted upward at a height hz.
The pressure values of fluid within this pipe, both on level and up, are measured as P: and
P2, respectively. If the fluid flow is kept at steady flow, show that the height of the fluid on
the tilted end of pipe is given by h, = P1—P72 Which pressure is greater?
(8)
3.3 Study the diagram below (figure 1). The liquid in a container behaves like the ideal fluid. The
pressure of still fluid inside the container and pressure of flowing fluid are the same as
atmospheric pressure. A small hole is at level (2) at height y2 and the water level at (1) drops
slowly from height y1 (vi = 0). Prove that v. = ./2gh.
(6)
(1) Point on surface of liquid
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‘ Ky V>=? m.st
(2) Point just outside hole
Figure 1
QUESTION 4
[20]
4.1 State any two applications of medical ultrasound.
(2)
4.2 The average velocity of ultrasound in soft tissue is 1540 m/s. Is the value higher, smaller or
similar to velocity values in bone and in lung or air? Justify your answers.
(4)
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4.3 A continuous pulse of ultrasound beam with frequency of 20 MHz was used on the patient
to measure the size of a fetus. Assumption is that the patient’s organ (fetus) is a soft tissue
(9 = 1.000 9/__3).
(i) Estimate the wavelength (A) of the beam and acoustic impedance (Z)
(4)
(ii) The distance from the ultrasound probe and the fetus is 5 cm. Compute the pulse-echo
time.
(4)
4.4 State the two sources of attenuation on the ultrasound beam.
(2)
4.5 Provide reasons for applying the gel in ultrasound medical imaging.
(2)
4.6 Define the term piezoelectric effect and state the function of the piezoelectric transducer?
(2)
QUESTION 5
[20]
5.1 Define the following terms:
(i) Effective dose
(2)
(ii) Linear Energy Transfer
(2)
5.2 Given that the activity of a radionuclide is A = -dN/dt = AN and decay constant is
A = |In2/Ti2, prove that the mean life, t= Show all steps.
(5)
5.3 Many magnetic resonance imagers operate at a magnetic field strength of 1.5 Tesla. What is
the resonance frequency of a deuterium nucleus in a magnetic field?
(1)
Note that for 4H: y = 42.58 MHz/T, and *H:y = 6.54 MHz/T.
5.4 A sample has a T2 of 70 ms. The net magnetization is rotated into the xy-plane and allowed
to decay to 50%. Estimate the time elapsed to reach transverse magnetization.
(5)
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5.5 Asample has a T: of 0.9 seconds. The net magnetization from the sample set equal to zero
and then allowed to recover towards its equilibrium value. After 1.5 seconds, what fraction
of the equilibrium magnetization value will be present?
(5)
END OF EXAMINATION QUESTIONS
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