Medical Physics Course 2024-2025 PDF

17-01-2025 Medical Physics Course 2024/2025 Classroom: Tacciuolo 14:00-16:00 Resistors in series and in Parallel Series Parallel  Resistors in series The electric current is the same through all components, including any resistors in th...

17-01-2025 Medical Physics Course 2024/2025 Classroom: Tacciuolo 14:00-16:00 Resistors in series and in Parallel Series Parallel  Resistors in series The electric current is the same through all components, including any resistors in the circuit. This means the same amount of current flows through each resistor, regardless of their resistance. This uniformity is because, in a series circuit, there is only one path for the current to flow. Resistors in parallel The voltage across each component is the same, but the current can vary. The total current flowing into the parallel circuit is divided among the parallel branches according to the resistance of each branch.  Problem 1 Determine the electric current flowing through the given circuit: Reflection and image formation Reflection and image formation nearsighted  Myopia Presbyopia Astigmatism  Problem 2 A beam of flashlight traveling in air incident on a surface of a thin glass at an angle of 38 ̊ with the normal. The index of refraction of the glass is 1.56 What is the angle of refraction? Θr= 23.2 ̊ Lorentz Force This equation demonstrates that the Lorentz force is the vector sum of two components: the electric force (qE) and the magnetic force (qv × B). The electric force acts in the direction of the electric field, while the magnetic force is always perpendicular to the velocity of the charged particle and the magnetic field.  Electric & Magnetic Fields + + + + + + + + + +       B      Fnet = 0  FB = FE  E        qvB = qE  v =       B v       -       q, m       E         - - - - - - - - - - - Applications in Medical Physics Oxygen saturation is the fraction of oxygen-saturated hemoglobin relative to total hemoglobin (unsaturated + saturated) in the blood. The human body requires and regulates a very precise and specific balance of oxygen in the blood. Normal Blood oxygen levels: 95% Blood oxygen levels below 80 percent may compromise organ function, such as the brain and heart, and should be promptly addressed. Absorption spectra of oxygenated hemoglobin (HbO2) and deoxygenated hemoglobin (Hb) for red and infrared wavelengths  Pulse Oximetry Light source Pulse Rate Light -sensors 82 bpm Picture credit: Shutterstock  Blood oxygen saturation Red blood cells Haemoglobin Saturation Signal 75 % Red IR Picture credit: Shutterstock  LASER Light Amplification by Stimulated Emission of Radiation Interaction of radiation with atoms Quantized energy: electrons can possess only certain discrete energy values  Atomic transition 2. Atomic transition  Inversion of energy level 3 energy levels (He-Ne) Stimulated emission N2>>N1 Elements of a laser Radio Waves: Mobile Phones Mobile phones use microwave energy. We know that microwaves can cook food – can a mobile phone cause heating? Radio Waves: Mobile Phones 0.2C temperature rise  x-ray tube head X-rays/Gamma rays Ultraviolet Visible Infrared Radio waves Increasing wavelength High voltage Cathode + Anode Evacuated glass tube electrons X-rays  Radiography X-ray machine X-rays absorbed by dense parts of patients body Photographic plate or digital detector Radiograph White indicates dense parts of body Grey indicates less dense regions Patient image used with permission of Jens Langner, adapted from: http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-23509 LINAC-Linear Accelerator Radiation therapy  Motion of a Charge in a Magnetic Field Acceleration voltage Thermionic emission  LINAC-Linear Accelerator linear accelerator blades X-ray profile TrueBeam Varian