1. Principles of X-ray and CT
X-rays and CT (computed tomography) are both medical imaging techniques used for diagnosis and treatment. Their principles are as follows:
How X-rays Work: X-rays are electromagnetic radiation similar to visible light but with higher energy. As X-rays pass through a human body or object, it is absorbed, scattered or transmitted by different tissues and structures. By detecting and measuring the intensity of X-rays passing through the body, a two-dimensional image can be generated showing the internal structure of the object under test.
How CT works: CT is a special imaging technique that uses X-rays. It scans around the object under test by rotating the X light source and the detector to generate a series of sliced images. CT uses computer algorithms to combine these sliced images to produce an accurate three-dimensional image. The principle of CT scanning is to generate images with different densities according to the different degrees of absorption of X-rays by tissues and structures.
CT is an upgraded version of X, X from all angles, and finally uses computer technology to reconstruct the three-dimensional image in 3D.
Summary: Both X-ray and CT use X-ray radiation to obtain images of the inside of a human body or object. X-rays generate two-dimensional images by measuring the intensity of X-rays passing through an object, while CT scans by rotating the X-ray source and detector to generate a series of sliced images, which are combined by computer algorithms to create a three-dimensional image. These imaging techniques play an important role in medical diagnosis and treatment.
Radiography is the process of using X-rays to create images. The principle is as follows:
X-ray emission: X-rays are generated by an X-ray generator, which consists of a cathode and an anode. When a high-voltage current is passed through the cathode, electrons are accelerated and hit the anode, producing X-rays.
X-rays passing through an object: When X-rays pass through an object to be inspected (such as a human body), different interactions occur. Soft tissue absorbs more X-rays, while bone tissue absorbs less X-rays. Therefore, X-rays are absorbed, scattered or transmitted.
X-ray sensor reception: On the other side of the detected object, there is an X-ray sensor (such as X-ray film or digital detector) for receiving X-rays transmitted through the object.
X-ray imaging: The transmitted X-rays leave traces on the sensor, forming an image. This image shows shadows inside the inspected object, where darker areas represent areas that absorb more X-rays (such as bones) and brighter areas represent areas that absorb less X-rays (such as soft tissue).
Interpretation and Diagnosis: Doctors interpret and diagnose a patient's condition based on the shadows on the X-ray image. They can observe bone deformities, injuries, tumors, etc., and make treatment plans accordingly.
Summary: X-ray photography is the process of using X-rays to form images on the sensor through the X-rays that pass through the object. According to the absorption ability of different tissues to X-rays, X-ray images show the shadow inside the detected object, thus helping doctors to diagnose and treat.
"The principle of X-ray imaging can be simply understood as that X-rays can be absorbed by the tissue after passing through human tissue with a certain thickness and density, and the amount of radiation reaching the fluorescent screen is reduced, and the change of radiation amount can produce black and white contrast. .When some tissue is lesioned, its density and thickness will change, so the amount of absorbed X-rays will change, and when the equivalent reaches a certain level, there will be a change in black-and-white contrast.”
2.MRI
The change of the magnetic field when there is something and nothing, to model
MRI, or magnetic resonance imaging, is an imaging technique based on the principle of nuclear magnetic resonance (NMR). It performs specific excitation and detection of atomic nuclei in the human body or objects, acquires their signals and constructs images for inspection and diagnosis.
The underlying logic and principles of MRI can be briefly summarized as follows:
The spin of the nucleus: the nucleus has a spin, which is similar to the concept of the earth's rotation. In the absence of external disturbances, the spin orientations of atomic nuclei are randomly distributed.
Magnetic field: MRI uses a strong constant magnetic field, usually a uniform field created by a strong magnet. This magnetic field can make the spin orientation of the nucleus align according to the spin quantum number.
Excitation: By introducing specific radio frequency pulses into a human body or object, the spins of atomic nuclei can be deviated from an equilibrium state. The frequency of this pulse usually matches the resonant frequency of the hydrogen nuclei in the water molecules.
Relaxation: Once the excitation pulse stops, the spins of the nuclei gradually return to equilibrium, releasing energy. This process is called relaxation.
Signal detection: When an atomic nucleus relaxes, a specific electromagnetic signal is emitted. These signals are captured by receiving coils and converted into electrical signals.
Image reconstruction: By processing and analyzing the received signal, an image of the tissue can be reconstructed. Different tissue types correspond to different signal intensities and characteristics, thereby forming an image.
To sum up, MRI uses strong magnetic fields and radio frequency pulses to excite and detect atomic nuclei, and finally forms images by acquiring and processing the signals of atomic nuclei. This process involves the spin of the nucleus, magnetic field, excitation, relaxation, signal detection and image reconstruction.
3. Color ultrasound and B-ultrasound
Both color Doppler ultrasound and B-ultrasound are medical equipment, which are used to perform imaging examinations of organs or tissues in the body. Their principles and functions are different.
Color Doppler ultrasound, the full name of color Doppler ultrasonography, is a method of examining blood flow velocity using ultrasound imaging technology and the Doppler effect. Color Doppler ultrasound sends ultrasonic waves to human body parts and receives the reflected beams, which are processed by a computer to form a color image, which can visually display the shape and structure of organs or tissues, and at the same time display the speed and direction of blood flow. Color Doppler ultrasound is widely used in examinations in various fields such as gynecology, obstetrics, cardiovascular, liver, gallbladder, and urinary system.
B-ultrasound, the full name of ultrasonic tomography, is to use the high-frequency vibration of ultrasonic waves to generate different echo signals through different densities and acoustic impedances of human tissues, and form images after computer processing. B-ultrasound can clearly display the internal organs and tissue structure of the human body, and is used to check the lesions in the abdomen, chest cavity, pelvic cavity, thyroid gland, breast and other parts. B-ultrasound does not involve the measurement of blood flow velocity, but only shows the internal structure through the reflection and attenuation of sound waves.
Therefore, color Doppler ultrasound is mainly used to check the morphological structure of organs and blood flow velocity and direction, while B-ultrasound is mainly used to display the structure of organs and tissues, and does not involve the measurement of blood flow velocity. The application scope and purpose of the two are slightly different, but both are non-invasive, safe and reliable means of inspection.
It belongs to ultrasonic information data to model. relatively easy to understand
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