Medical-x-ray machine principleTime:2011-08-23 14:49:25 Edietor: admin
Basic principle of medical-x-ray machine
X-ray is found by Germany professor in 1895. This Vacuum tubes issue radiation which can penetrate object and energy is stronger than visible light on electromagnetic spectrum; Wavelength is shorter and frequency is higher; The similar radiation are Cosmic rays and X-rays.
Produces X-rays, there must be x-ray tube and x-ray tube basic structures are Cathod, Anode, Evacuated glass envelope and Power supply.
There are two ways to produce X-ray
Bremsstrahlung: After High-speed electronic slowing down suddenly, kinetic energy turn into energy and release. The energy is the X-ray and it will be different with slowdown extent.
Characteristic: High-speed electronic hit atoms and electronic of peripheral orbit and make it dissociate and release energy, it is X-ray.
Producing way proportion of diagnosis X-ray: 30% is Characteristic and 70% is Bremsstrahlung
X-ray characters: First, It can penetrate object;
Second, it is no visible light
Third, it is in electromagnetic spectrum
Fourth, Wavelength range is widely
Fifth, Linear scattering
Sixth, it runs by light speed
Seventh, it can make Fluorescent object shine
Eighth, it can make film exposure
Ninth, it will cause scattering line
When X-ray go into object, there are three conditions: Firstly, it is absorbed by object;
Secondly, it produces scattering line
There are four factors impacting Radiographic Quality
Density, Contrast, Sharpness and Distortion
X-ray wavelength is relative with contrast:
X-ray can penetrate patient and penetration rate is relative with the patient organization structure and X-Ray wavelength.
Short wavelength energy is higher and penetrating is good and it causes lower contrast on film.
Long wavelength X-ray
The energy is lower and is easy to be absorbed by people and penetrating is bad and it causes higher contrast on film.
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