Essential Physics Of Medical Imaging: The

shifts the focus from the electron cloud to the atomic nucleus. It leverages the quantum spin of hydrogen protons, which are abundant in human water and fat. When placed in a powerful magnetic field, these protons align. By applying a specific Radio Frequency (RF) pulse , the protons are knocked out of alignment; as they "relax" back to their original state, they emit signals. The rate of this relaxation (

Unlike X-ray or MRI, uses mechanical energy rather than electromagnetic radiation. It relies on the piezoelectric effect , where crystals in a transducer convert electrical energy into high-frequency sound waves. These waves reflect off internal boundaries (acoustic impedance). By measuring the time-of-flight of the echoes and applying the Doppler Effect , physics allows us to visualize not just static anatomy, but the real-time velocity of blood flow. Nuclear Medicine: PET and SPECT The Essential Physics of Medical Imaging

evolves this concept by rotating the X-ray source around the patient. This uses the Radon transform , a mathematical principle that reconstructs 2D projections into 3D cross-sectional slices, allowing for much higher spatial resolution and the ability to distinguish between varying densities of soft tissue. Nuclear Magnetic Resonance: MRI shifts the focus from the electron cloud to