In the table below, gamma rays are the strongest radiation, followed by X rays. X-ray is a kind of electromagnetic radiation with short wavelength, and its wavelength is about (20 ~ 0.06) × 10 (-8) cm. X-rays have strong penetrating power and great lethality, and can penetrate many substances that are opaque to visible light, such as ink paper (such as photosensitive film wrapped in ink cartridges), wood, and not too thick brick walls. Used for human tissue detection, X-ray is the difference of transmitted light caused by different absorption of X-ray by human tissues with different densities. The spectral image obtained after imaging reflects the shape and composition information of human tissue, especially the boundary difference between muscle tissue and bone tissue can be clearly distinguished.
Nuclear magnetic resonance, in terms of energy, in the range of radio frequency waves, the energy of radio frequency waves is weaker than that of microwaves, basically in the range of radio waves in radio frequency bands. It can be considered that its harm to human body is almost negligible. Used for human tissue detection, magnetic resonance imaging is based on the principle of nuclear magnetic resonance. According to the fact that the released energy attenuates differently in different structural environments such as human body, muscles, bones, body fluids and water. The emitted electromagnetic wave can be detected by the external gradient magnetic field, so that we can know the position and type of the nucleus that constitutes this object, and draw the image of the internal structure of the object accordingly.