The phenomenon of nuclear magnetic resonance was discovered by scientists in 1946. Initially, it was used primarily by chemists and physicists to study the structure of molecules. Since the 1970s, nuclear magnetic resonance imaging technology has been combined with image reconstruction technology to form nuclear magnetic resonance imaging technology. Because it can detect objects without damaging it, it is known as the key to detecting some unopenable "black boxes".
A patient felt numbness in his right hand and leg and went to the hospital for treatment. The doctor said, you need to do an MRI. The patient arrives in the exam room and lies on a plastic bed. The doctor pressed the button, and he was slowly moved into the cylindrical space of a giant magnet. The doctor started the machine and heard a "pop" sound. The sound is caused by the computer changing the strength of the magnetic field. After about 20 minutes, he was removed again. By this time the doctor had obtained more than ten photos. From the photos, the doctor could clearly see the layers inside his brain.
How were these photos obtained? In fact, each point on the photo represents the magnetic strength of the hydrogen atom nuclei in the water molecules in the brain. These hydrogen nuclei are like natural probes placed in the human body by nature. People used magnetic resonance imaging to obtain the detection results of these hydrogen nuclei, and obtained images of the internal structure of the brain.
We are no strangers to magnetism. The compass, one of the four great inventions in ancient my country, is the result of ancient people's understanding and utilization of magnetism. The magnetic needle of a compass has a magnetic south pole and a magnetic north pole. The earth we live on is also a huge magnet, and it also has a magnetic south pole and a magnetic north pole. The magnetic south pole of the compass attracts the magnetic north pole of the earth, and the magnetic north pole of the compass attracts the magnetic south pole of the earth, so the compass always indicates the direction of north and south. Research shows that the protons and neutrons that make up the atomic nucleus also have magnetic south poles and magnetic north poles. The magnetic south poles and magnetic north poles are always together and inseparable.
Scientists call the whole set of a magnetic south pole and a magnetic north pole a magnetic moment. The proton magnetic moment has two orientations, one is parallel to the magnetic field, and the other is anti-parallel to the magnetic field. The energies of the two protons are different, and the difference in energy is proportional to the strength of the magnetic field. Irradiate these protons with a beam of electromagnetic waves. When the energy of the electromagnetic wave is exactly equal to the difference in energy between the two protons, the proton with low energy (the proton with a magnetic moment parallel to the magnetic field) will absorb the energy of the electromagnetic wave and become a proton with high energy ( Protons whose magnetic moment is antiparallel to the magnetic field), this phenomenon is called nuclear magnetic resonance.
At the end of 1945, Purcell's group successfully observed the vibrational absorption of hydrogen nuclei in solid paraffin. Almost at the same time, Bloch's group also successfully observed the vibrational absorption of hydrogen nuclei in water. Vibrate. After the successful observation of condensed matter NMR, many scientists immediately felt keenly that it might play an important role in chemical analysis and might bring huge commercial benefits. As a result, the first patent on nuclear magnetic resonance was quickly registered. This began a period of great development in NMR research and application. In 1949, the first commercial NMR spectrometer came out.
Since the early 1970s, nuclear magnetic resonance imaging technology has been combined with image reconstruction technology to form nuclear magnetic resonance imaging technology. Magnetic resonance imaging technology can provide information about the molecular structure and biochemical pathology of the human body, breaking the limitation that X-ray imaging technology can only provide information about the tomographic anatomical structure of tissues. This imaging technology is now being used in clinical diagnosis and research in other medical fields.