I'IFIITIIBIFI UNIVERSITY OF SCIEI'ICE RITD TECHNOLOGY FACULTY OF HEALTH AND APPLIED SCIENCES DEPARTMENT OF NATURAL AND APPLIED SCIENCES QUALIFICATION: BACHELOR OF SCIENCE (MAJOR AND MINOR) QUALIFICATION CODE: 07BSC LEVEL: 7 COURSE CODE: BPH7OZS SESSION: NOVEMBER 2017 COURSE NAME: BIOMEDICAL PHYSICS PAPER: THEORY DURATION: 3 HOURS MARKS: 100 FIRST OPPORTUNITY EXAMINATION PAPER EXAMINER(S) MR. VAINO INDONGO MODERATOR: MRS. NDESHIHAFELA VERA UUSHONA INSTRUCTIONS 1. Write all your answers in the answer booklet provided. 2. Read the whole question before answering. 3. Begin each question on a new page. PERMISSIBLE MATERIALS Scientific Calculator THIS EXAMINATION PAPER CONSISTS OF 6 PAGES (INCLUDING THIS FRONT PAGE) 1 Page
QUESTION 1: [40] Answer all questions. Each correct answer weighs two marks. 1.1 A gamma camera (y-camera), also called an Anger camera, is a device used to image gamma radiation emitting radioisotopes, a technique known as... A. Positron emission computed tomography B. Scintigraphy C. Electrocardiography D Nuclear medicine imaging 1.2 The first processing layer of a gamma camera that encounter photons from radioactive source, and which restricts the gamma rays from the source so that each point in the image corresponds to a unique point in the source is called... A. Sodium iodide crystal B. Collimator C. Photomultiplier tube D. Multichannel analyser 1.3 Sievert is a unit of: A. Exposure B. Equivalent dose C. Dose rate D. Activity 1.4 Which of the following is/are CORRECT in the gamma camera? A. Each photon interacting with scintilator crystal gives a light flash. B. The total signal amplitudes depend on the energy of a gamma photon. C. Compton scattering energy events are rejected. D. All of the above 1.5 The attenuation of photons in matter is a function of: A. photon energy and Z number B. linear energy transfer C. photon energy and conversion electrons D. mode of decay 1.6 If you received a 40 mci dose of FDG at 6:00 AM and inject a patient at noon, how much activity would there be at the time of injection? A. 40 mci B. 20 mci C. 10 mci D. 5 mci Note: fluorine has a half-life of 110 minutes. 1.7 The Mo-99/Tc-99m generator is an example of which theory of equilibrium? A. First order B Secular C. Specific D Transient 2 Page
1.8 Which of the following types of radiation has the greatest linear energy transfer (LET)? A. Alpha B. Beta C. Positron D. Gamma 1.9 Which of the following types of radiation has the greatest penetration in human tissue? A. Alpha B. Beta C. Positron D. Gamma 1.10 Which component of an ultrasound system is made of lead zirconate titanate (PZT)?.005»? transducer's matching layer transducer's active element transducer's damping material scan converter's computer chips 1.11 The impedance of a transducer's matching layer is 2.6 MRayls and the impedance of the piezoelectric crystal is 3.4 MRayls. If this is assumed to be a good imaging system, what is the best estimate for the impedance of the skin? A. 1.5M Rayls B. 3.8 MRays C. 3.4 MRayls D. 5.1 MRayls 1.12 Which of the following lists orders the impedance from highest to lowest? A. skin, gel, matching layer, PZT B. PZT, gel, matching layer, skin C. gel, PZT, matching layer, skin D. PZT, matching layer, gel, skin 1.13 An ultrasonic pulse is traveling in soft tissue. Which of the following is most important in the determination of the frequency of the sound? A. The propagation speed of the ultrasound transducer's matching layer B the thickness of the transducer's backing material C. the impedance of the transducer's matching layer D the propagation speed of the transducer's active element 1.14 What is the region from the transducer to the smallest cross sectional area of a sound beam called? A. Focus B half-value layer thickness C. near zone D Fraunhofer zone 1.15 The area that starts at the ultrasound beam's smallest diameter and extends deeper is; A. the distant zone B the Fresnel zone C. the Fraunhofer zone D the depth of penetration 3 Page
1.16 All of the following are true of the focus except: A. It is at the end of the near zone B. It is at the beginning of the Fraunhofer zone C. it has the highest spatial peak intensity l2) D. it is at the start of the Fresnel zone 1.17 The lateral resolution of an ultrasound system is primarily determined by the. A. width of the sound pole B. length of the ultrasound pulse C. duration of the sound pulse D. none of the above 1.18 In the presence of a uniform magnetic field, hydrogen protons; A. Line up along the field and rotate around its axis B. Line up along the field and precess around its axis C. Remain oriented mostly randomly and precess D. Are not affected by the magnetic field around the field axis 1.19 MRI measures hydrogen magnetization; A. Along the main magnetic field B Perpendicular to the main magnetic field C. At inclined angle with the main magnetic field. D When magnetic field is set to zero 1.20 A spin echo is formed by; A. Reversing the direction of B0 B. Flipping proton direction by a radiofrequency pulse C. Applying a negative magnetic field gradient D. None of the above QUESTION 2: [20] 2.1 Define the radiation protection term ALARA and discuss this principle in terms of: (i) time, (ii) distance and (iii) shielding. (7) 2.2 A M099m/Tc99m Generator is in transient equilibrium. The radioactivity of Mo-99m at time to is 16 GBq, (i) find the time (t) elapsed when the activity of Mo-99m turns to be 3.2 GBq later if no milking took place during this time interval? (ii) Estimate the activity ofthe daughter nuclide after time t found in (i). Note: Mo-99m Tm: 67 hours and Tc-99m T1,; = 6 hours. (10) 4 Page
... 2.3 A previously fit and healthy 52 year old woman presents with diarrhoea and weight loss. At the hospital, diagnostic imaging reveals a mass in the head of the pancreas. Biopsy confirms adenocarcinoma. Discuss radiation therapy or control measures taken in the management of patients with pancreatic cancer in general. (3) QUESTION 3 [19] 3.1 A collagen of cross-sectional of 1.2 x 10 7 m2 and mass m kg has a tensile strength of 5.0 x 107 Nm z. Calculate the breaking force of the collagen and the value of mass m. (4) 3.2 In medical physics profession, scientists apply physics concepts, theories and methods to healthcare. Discuss four (4) physical applications applied to life sciences on each of the following: (i) Medical imaging techniques. (4) (ii) Medical research using electrical activities in the human body. (4) 3.3 Discuss the similarities and differences between x-rays and gamma rays (5) 3.4 Discuss how bremsstrahlung radiations are produced QUESTION 4 [21] 4.1 Estimate the relative sound intensity on the logarithmic scale corresponding to a (i) 2 fold increase and (ii) 70% decrease in intensity. (4) 4.2 Given that the ultrasound frequency of 5 MHz and wavelengths of 5.9 nm was used in taking an image of a bone. Determine the acoustic impedance of a bone if the density of a bone is 7.2 x 103 kg/ma. 4.3 Resonant frequency is the natural frequency of oscillation in the piezoelectric crystal. Suppose the crystal of diameter 0.94 mm and a volume of 3.2 x 10 '5 m3 has been used in medical imaging department. The third patient attended had to be diagnosed by ultrasound and the velocity of the organ under study was 2050 m/s. approximate the value of frequency of the crystal. (6) = 4.4 if the intensity of reflected ultrasound is R, (22 31) 2 1 transmitted ultrasound wave IS given by T _[Zl+Zz]2' _ 42122 _ 2 show that the intensity for (5) 5 Page
4.5 Explain the following terms: (4) (i) Radiography (ii) Fluoroscopy END!!!llllllllllllllllllllll 6 Page