Medical imaging techniques: principles and applications
Scientific Disciplinary Sector (SSD)
FIS/07 - APPLIED PHYSICS
Secondo semestre dal Mar 7, 2022 al Jun 10, 2022.
Aim of the course is to provide students with an introduction to modern medical imaging methods. Knowledge and understanding. At the end of the course, the student will be able to describe the physical principles behind the different imaging techniques (ultrasounds, X-rays, nuclear medicine, magnetic resonance and optical imaging). Applying knowledge and understanding. Specifically, the student will be able to demonstrate an understanding of the principles underlying image quality and contrast, spatial resolution and time resolution, and get awareness of their main clinical/biological applications. Making judgements. The student shall demonstrate to be able to plan and realize a simple project whose goal is to acquire data with real acquisition equipment, e.g., magnetic resonance scanner, to reconstruct the images from the raw data and to properly visualize/inspect them. Communication. The student will demonstrate to be able to properly present to a qualified audience the knowledge acquired during the course. Lifelong learning skills. The student will have the basic knowledge that will allow him to read and understand scientific papers in the field, and present the main findings.
- Ultrasound Imaging
Mechanical and electromagnetic waves. Reflection and refraction of waves: total reflection. Mechanical waves: sound waves, intensity, impedance, Doppler effect. Ultrasounds (US). Production and detection of US: Piezoelectric materials, Transducers. Propagation speed. Interaction of US with matter: reflection, refraction, scattering. Attenuation of ultrasounds. The dB. Block diagram of an ultrasound system. Properties of the ultrasound beam. Spatial resolution. Operation in A mode and B mode. Diagnostic use of the Doppler effect. Contrast Agents for US. Advanced applications.
- X-rays Imaging
Electromagnetic waves, em spectrum. Production of X-rays. X-ray spectrum, Bremsstrahlung effect, continuous spectrum and characteristic spectrum. Radiation-matter interaction: scattering Rayleigh, scattering Compton, photoelectric effect, pairs production. X-ray attenuation. Linear attenuation coefficient of biological tissues. Formation of Radiological image. Contrast. Tomographic reconstruction (back projection reconstruction). Computed tomography (CT) 1st, 2nd, 3rd generation machines. 4th generation machines and spiral computed tomography (Spiral CT). Block diagram of CT equipment. The detector of X-rays: photographic plates, ionization chambers, scintillators, photomultipliers. Contrast Agents for X-Rays Imaging. Advanced applications.
- Nuclear Medicine
Introduction to physics of the nucleus. Properties of the nucleus. Stable and radioactive atoms. Radioactive decay. Alpha decay. Beta-decay. Radiopharmaceuticals. G-Camera, collimators. SPECT and PET. Block diagram of the experimental apparatus. Applications.
-Magnetic Resonance Imaging
Spin and nuclear magnetism. Nuclear magnetic resonance. Energy levels of a spin system in a magnetic field and transitions. The population of energy levels. Magnetization vector and Bloch equations. Precession motion of magnetization. Rotating reference system. T1 and T2 relaxation. The effect of a radiofrequency pulse on the magnetization: rotation of the magnetization. Soft and hard pulses. Free induction decay. Spin-echo. The introduction of the gradient to obtain spatial information. The imaging sequences. Block diagram of a Magnetic Resonance Tomograph. Diffusion-weighted techniques: the Stejskal and Tanner sequence. Diffusion tensor imaging. Contrast agents in MRI. Perfusion Imaging with intrinsic and exogenous contrast. Arterial Spin Labeling. Applications.
Propagation of light in biological tissues: absorption and scattering. Law of Lambert-Beer. Absorption coefficient. Optical characteristics of biological tissues. The window of tissue transparency. Elastic scattering in the Rayleigh and Mie approximation. Fluorescence and bioluminescence emission.
Guided laboratory sessions will be provided in order to practice firsthand some of the techniques introduced in the theory.
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Oral talk in which students will demonstrate that they understand a scientific article in the field and present its main results.