Medical imaging has made a revolution for medical filed, making possible to execute diagnosis without any invasion with perfect accuracy and very fast time. Medical image lead us to broaden our observation capabilities, and allow us to understand biophysical world, by applying new algorithms such as new protocols for manipulation which help to increase accuracy with intervention of artificial intelligence.
From discovery of X-Ray in 1885, medical imaging is the fast way to acquiring information from patient’s health state. During last two decades Significates advances are noticed in computerized medical imaging, two and three dimensions modalities which became more helpful for radiologists.
While in last century, Radiology imaging were the first and unique way to acquisition of images, new modalities are developed include physiological, metabolic state detection, the most know techniques are: Computed Tomography (CT), Magnetic Resonance Imagery (MRI), Positron Emission Tomography (TEP) and Ultrasound.
Today imaging medical become an essential task in medical routine, in most cases anomalies can be observed before appear of symptoms and this is a very important point. Each imaging modality has particular organ a tissue to observe, but they are completely and offer and full view for such organ from functional and structural side.
We can divide all modalities into 2 categories: structural or morphological and functional
For the first we found: X-Ray, Ultrasound, MRI, Computed tomography CT
In the second time we have multiple technologies which are used to assess tissues metabolism, like as Scintigraphy, single photon emission computerized tomography (SPECT), positron emission tomography (PET), and functional magnetic resonance imagery (fMRI). in the next section we will talk about each technology.
The X-Ray are the produced by 2 ways : the first one is that a high difference electric in X ray tube between anode an cathode, this late is associated to filament which issued electrons also they will reacted with two ways, first by Bremsstrahlung where the electron is decrease his speed and converted it to energy which is X-Ray, second is Characteristic radiation where the electron emitted by filament remove an electron of nuclei which create gap this will be occupied by the supra electron which give emitted a radiation outside the nuclei, this is X-RAY
X-Ray are used to be projected to patient body, they transverse targeted area, bones can block these Ray for that we observe them as light area, in other side soft tissue allow passage of these Rays this appear as dark area in the image.
Ultrasound imaging is the second most popular imaging modality after X-Ray, is estimated that 25% of medical process call Ultrasound Imaging(1), this modality complement other modalities such as MRI and CT. Ultrasound is based on high frequency sound waves and for that they are called Ultrasound, these late waves are used to traverse tissues and produce different echoes categorize each tissue type, however the echoes will be captured by a receiver and send to computer which transform it to screen signal.
Second, Computed Tomography or CT is a imaging technology use X(Rays for reconstruction a 3D image of patient body by capturing images in different angles, first the image is generated by a number of 2D radiographs, then we use an algorithm called Random Transfer. CT offers high contrast between soft tissue and bone, and low contrast among the soft tissue.
Now, we’ll talking about MRI technology which refer to Magnetic Resonance imaging, in this technique we use one of the most popular and important propriety of human body that its composed of about 75% water, so when its placed within a magnetic field the hydrogen nuclei will be excited, however this will make them in supra-energetic state which need to spend this extra-energy under relaxation, this late is depend on such tissue type also we can create images by using this difference. An advantage of MRI is that it not inosinate so there is no any hazard for patient. MRI is so better for soft tissue in particular brain and spinal cords imaging.