Advantages and Disadvantages of High Kilovoltage Photography

The advantages and disadvantages of high-kilovolt photography are as follows:

1. Low-contrast, rich-layered X-ray photos can be obtained.

2. It can improve the uneven optical density distribution caused by different tissue densities.

3. Increasing the tube voltage value and shortening the exposure time can reduce limb movement distortion.

4. Selecting high kilovolts can reduce the tube current and use more small focus points, which can improve the photo image quality, reduce the heat generated by the X-ray tube and extend the life of the X-ray tube.

5. High-kilovolt photography produces more scattered rays and the quality of X-ray films is poor.

6. During high-kilovolt photography, the amount of X-rays is reduced, and the dose absorbed by tissues is reduced, which is beneficial to patient protection.

7. High-kilovolt photography loses photo contrast, so appropriate exposure conditions should be selected.

High-kilovolt photography is a photography method that uses X-rays with high energy generated by tube voltages above 120kV to obtain X-ray images that display rich layers in a smaller density range.

When high-energy X-rays pass through the limbs, the way they are absorbed and attenuated and the absorption coefficient are different from those of general-energy X-rays, resulting in contrast changes that are different from those of general X-ray photography. Line photography different effects. The X-rays produced by diagnostic X-ray machines are continuous spectra. Under a certain nominal tube voltage, photoelectric absorption and Compton-Wu Youxun absorption each account for a certain percentage.

In the photon energy range of 10 to 100keV, as the photon energy increases, the absorption of X-rays by the limbs is: the photoelectric absorption decreases, and the Compton-Wu Youxun absorption increases. When the photon energy is 10keV, the photoelectric absorption is more than 95%, and the Compton-Wu Youxun absorption is 5%. When the photon energy increases to 100keV, the Compton-Wu Youxun absorption is more than 95%.

Technical conditions for high dry volt photography:

1. High kilovolt photography X-ray machines can be used for high kilovolt photography within the tube voltage range of 120-150kV.

2. It will produce more scattered rays, so a high grid ratio grid is selected to improve the contrast of X-ray photos. A commonly used gate ratio is 12 to 1.

3. When the limb-sheet distance is 20cm, the air gap effect can replace the function of the grid.

4. The film should use a high contrast coefficient to improve the contrast of the photo.

5. Pay attention to replacing the filter plate when taking high dry voltage photography. 3mm aluminum and 0.3mm copper are used for 80~120kV to improve the absorption of long-wave X-rays and enhance patient protection.