Comparing Two Ultrasound Techniques

The two imaging techniques that I would discuss in this essay is Ultrasound and X-ray. An Ultrasound is a procedure that uses sound waves to create image of the inside of the body and ultrasound uses high frequency sound that is much higher than the sound that the human ear can hear. Ultrasound frequency is 20,000 HZ and therefore objects that are smaller than this wavelength cannot be detected by the ultrasound. Higher frequencies are used to take image of the subjects that are closer to the surface, however lower frequencies are used to scan areas that are deeper down in the body. Sound waves are produced from the piezoelectric crystals from Ultrasound transducers and these piezoelectric crystals changes electrical signals to mechanical

Ultrasound is also used to look into foetuses during prenatal care. Ultrasound is used in first aid cases and trauma. High power ultrasound can break up tissues and it also speed up the effect of drug in target area. An internal Ultrasound is used to look at the internal structures of the body for instance the prostate gland and the ovaries. However for the endoscopic ultrasound a long tube is inserted into the patient's body through trough their mouth to examine different areas inside the chest. For example stomach , oesophagus and the lymph nodes. For the endoscopic procedure the patient is asked to lie on their side and swallow the endoscope and its pushed down through the stomach. Endoscope has a light and Ultrasound devise at the end once its inserted inside the body, it takes images of the body as external ultrasound. Endoscopic ultrasound is more effective than the external one, because it examine some organs in close details. It might give a little side effect such internal bleeding. Ultrasound does not go through bone and clear image of some part of the body can not produced for instance brain which is surrounded by bones. Although ultrasound is a safe technique and it doesn't use ionising radiation, but it has some limitation for example ultrasound is not useful for examining the structures that has gas on them. Another risk related to ultrasound is

X-rays has wavelength of 0.01to 10 nanometre and its wavelength is shorter than ultraviolet and longer than gamma waves. X-rays are made of photons , all photons has the same velocity and the rest mass of the photon is zero this means that photons can never be found at rest. An x-ray tube is made of two electrodes a positive anode and a negative cathode. These electrodes are located in a vacuum and when an acceleration potential is applied the electrons are pulled towards anode. When an electron reaches the anode it gives part of its energy to the atom and this energy will appear as heat energy. The electrons losses its energy in form of photon and these photons make the main part of x-ray that are being used in diagnostic imaging. In anode a major part of energy is converted to heat, the anode should have a high melting point and good heat conductivity to get a high amount of x-ray energy. A photon undergoes two process incoherent scattering and coherent scattering. coherent scattering is when photon changes its direction of motion, and when the photon energy increases the probability for photon decreases and it increases with the increase atomic number. X-rays has clinical advantages for instance in chest x-ray screening test if its negative its sufficient and x-rays