What happens when you increase kVp?

The higher the kVp, the more likely the x-ray beam will be able to penetrate through thicker or more dense material. Low kVp photons are weak and easily absorbed by body tissues or filters that have been placed.

How does the photoelectric effect affect contrast?

The proportion of interactions via the photoelectric effect is higher for X-ray beams containing more low-energy photons (30 keV-50 keV), and so the image contrast is better. However, the greater absorption of energy through the photoelectric effect reduces the proportion of X-rays that is transmitted through the body.

What happens in the tube when the kVp and mAs of an x-ray machine are increased?

The increase in x-ray tube voltage increases the amount of radiation coming out of the x-ray tube, as well as the average photon energy (i.e., increased penetration). Accordingly, the tube current exposure time product value (mAs) is reduced to 36 mAs; whereas at 60 kV, the value was much higher (141 mAs).

Why does increasing kVp decrease contrast?

A higher kVp will make the x-ray beam more penetrating. This will result in less difference in attenuation between the different parts of the subject, leading to lower contrast.

Does mA effect contrast?

Increasing the mA will improve image quality by reducing noise, but will not affect contrast.

Why photoelectric effect is predominant in lower energies?

The energy range overlaps with the photoelectric energy range. With very low photon energies, the photoelectric effect is dominant, but becomes less common with increasing photon energy. The Compton effect begins slowly at low levels of energy and becomes dominant from 0.1 to 0.15 MeV and onwards, see Fig.

Does photoelectric effect increase with atomic number?

Here Z is the atomic number and n is a number which varies between 4 and 5. The photoelectric effect rapidly decreases in significance in the gamma-ray region of the spectrum, with increasing photon energy. It is also more likely from elements with high atomic number.

How does kVp affect radiograph?

Kilovoltage peak (kVp) is the peak potential applied to the x-ray tube, which accelerates electrons from the cathode to the anode in radiography or computed tomography. Tube voltage, in turn, determines the quantity and quality of the photons generated.