X-ray generation and characteristics
On November 8, 1895, Roentgen discovered the X-ray.
Ultrasound imaging (USG) in the 1950s and 1960s
From the 70s to the 80s, DSA, CT, MRI, ECT, SPECT, PET, intervention
Since the 1990s, CR, DR, PACS, etc. have appeared one after another.
1. Penetrating imaging basis
2. Fluorescence effect perspective basis
3. Photography effect photography imaging foundation
4. Ionization effect radiotherapy and protection basis
Basic principle of X-ray imaging
Three basic conditions:
1. Penetration (this is the main reason for X-ray examination to diagnose diseases)
2. The density of the penetrated tissue is thick and thick
3. The remaining X-rays are invisible and need to be imaged to obtain X-ray images.
Due to the different density of the human body, when the X-ray penetrates various tissue structures of the human body, the order of penetration from strong to weak is: gas-containing tissue, fat, soft tissue (including liquid), bone
X-ray image features
The X-ray image is composed of images of different gray scales from black to white, and is the sum of projections of different density and thickness of the X-ray beam penetrating a certain part, and is an image in which the respective structure images on the penetration path are superimposed on each other. .
X-ray inspection technology
(1) Ordinary inspection
The utility model has the advantages that the operation is simple, convenient, fast, economical and practical; the body position can be rotated at any angle to observe; the dynamic change of the organ can be understood.
The disadvantage is that there is no objective record; contrast, poor definition, subtle structure can not be identified; diagnostic results are directly related to operator responsibility and level.
2. X-ray photography: The
data can be stored for a long time, and the contrast and clarity are good. The cost is high and you can't watch the dynamic changes.
(2) Special inspection
Definition: It is a method of photography that takes tissue at a certain level of the human body.
The basic principle: when the projection is made, the X-ray tube and the X-ray film move in opposite directions along a certain pivot point, so that a selected layer is clearly displayed, and the selected layer is blurred.
2. Zoom in photography
CT check advantages:
1. The density resolution is high, and the tissues with different densities can be distinguished and displayed, and the CT values of various tissues can be measured.
2. The CT image is clear and the anatomical relationship is clear.
CT check defects:
1, has certain limitations, it is difficult to find the functional changes of organ structure.
2, the lesion density and the normal tissue density of the lesions, flat scan is easy to miss diagnosis, must be enhanced scanning.