Piezo-electric Crystal: A piezo-electric crystal generates an e.m.f. when its shape changes and changes shape when a p.d. is applied across it.
Ultrasound Waves: Ultrasound waves are generated and detected by a piezoelectric transducer.
Reflection of Ultrasound: Reflection of ultrasound at boundaries between tissues can be used to obtain diagnostic information about internal structures.
The specific acoustic impedance of a medium is Z = ρc, where c is the speed of sound in the medium.
Intensity Reflection Coefficient: IR / I0 = (Z1 – Z2)2 /(Z1 + Z2)2 is used for the intensity reflection coefficient of a boundary between two media.
Ultrasound Attenuation: Ultrasound is attenuated as it passes through matter and I = I0e(–μx) is used to describe this attenuation.
X-ray Production: X-rays are produced by electron bombardment of a metal target, and the minimum wavelength of X-rays produced from the accelerating p.d. can be calculated.
X-ray Imaging: X-rays are used in imaging internal body structures, including X-ray imaging, and contrast can be used to improve image quality.
X-ray Attenuation: I = I0e(–μx) is used to describe the attenuation of X-rays in matter.
CT Scanning: CT scanning produces a 3D image of an internal structure by combining multiple X-ray images taken in the same section from different angles to obtain a 2D image of the section, then repeating this process along an axis and combining 2D images of multiple sections.
Tracer Substance: A tracer is a substance containing radioactive nuclei that can be introduced into the body and is then absorbed by the tissue being studied.
PET Scanning: A tracer that decays by β+ decay is used in positron emission tomography (PET scanning).
Annihilation Process: Annihilation occurs when a particle interacts with its antiparticle, and mass-energy and momentum are conserved in the process.
Annihilation in PET Scanning: In PET scanning, positrons emitted by the decay of the tracer annihilate when they interact with electrons in the tissue, producing a pair of gamma-ray photons traveling in opposite directions.
Energy of Gamma-ray Photons: The energy of the gamma-ray photons emitted during the annihilation of an electron-positron pair can be calculated.
Image Creation in PET Scanning: The gamma-ray photons from an annihilation event travel outside the body and can be detected, and an image of the tracer concentration in the tissue can be created by processing the arrival times of the gamma-ray photons.