QUANTITY and QUALITY Radiolologic PHYSICS LAB Qestions

1. 1.    What happens to the energy of the electron beam striking the tube target as kV is increased?.

Higher kV X-rays are less likely to intact with tissue, that is more penetrating. kV is the voltage applied across an X-ray tube. It determines the kinetic energy of the electrons accelerated in the X-ray tube and the peak energy of the X-ray emission spectrum. Every body part (in our experience the Al plate) contains a certain type of cellular arrangement which requires an x-ray beam with a certain kVp to go through it. Since the energy of the stream of electrons in the x-ray tube increases and the electron beam striking the tube target, the additional likely the x-ray photons formed from those electrons will penetrate the cells of the body and achieve the image receptor, resulting in increased radiographic density. Nevertheless, “scatter radiation” as well contributes to increased radiographic density; So, the higher the kVp of the beam, the more scatter will be produced.

 

1. 2.    What happens to the energy of the electron beam striking the tube target as mAs is increased?.

mAs is the primary controlling cause of radiographic density, Increasing mAs results more photons of the particular kVp energy, to be formed. This is beneficial when bigger parts are imaged, because they require more photons. The extra photons we can get to exceed through a tissue type will result in a statistically enlarged amount of photons reaching the image receptor. The more photons that pass through a part, and reach the image receptor the more useful the density is created on the resulting image. On the other hand, lesser mAs creates fewer photons, which will reduce density, however is helpful while we image lesser parts.

 

 

1. 3.    Define quantity and quality as it applies to an X-ray beam.

The quality of the x-ray beam is controlled by the amount of voltage. Voltage results contrast to the IR. Increased voltage provides less contrast. However, the beam has more penetrating power. Decreased voltage, on the other hand, results more contrast. Though, there is fewer penetrating force in the small voltage exposure. The x-ray beam quantity is controlled by the mA. The more x-rays in the x-ray beam, the denser the x-ray negative becomes. By increasing the mA, we increase the number of electrons at the cathode. When electrons impact on the anode, a larger number of x-rays are also produced. The more x-rays that are available to penetrate an object, the denser is the x-ray negative.

 

1. 4.    What effect does changing kV have on quantity and quality of an X-ray beam? Support your answer with your experimental data..

 

An alteration in voltage influences the amplitude and the position of the x-ray emission spectrum. As we vary the kVp the quantity and quality of the x-rays raises.

As quality of an x-ray beam’s increases the penetrating ability of X ray increased. In our lab experience we had next cheques:

 

mAs	kVp	mR
50	70	720
50	90	1062
50	120	1362

 

As shown on table with increasing kV, the mR is increased and for reaching to HVL we needed more sheet of Al.

 

 

1. 5.    What effect does changing mAs have on quantity and quality of an X ray beam? Support your answer with your experimental data.

 

A change in mAs results in a proportional change in the amplitude of the x-ray emission spectrum at all energies. mA controls density by controlling the quantity of radiation that the film absorbs. In our lab experience we had next cheques:

 

mAs	kVp	mR
40	90	1006
50	90	1260
63	90	1596

 

It shows the higher is the mA, the higher is the density.