They are often used as an initial screening to rule out anything obvious before an advanced modality is used such as CT or MR. It offers lower dosage compared to CT, and certain studies are performed relatively quickly (Chest X-rays). The biggest advantage with plain film X-rays is the amount of radiation involved. These receptors are placed behind the patient to capture the x-ray photons that are transmitted through the patient and ultimately form the image. With technological advancements, many instutions will be using a cassette receptor or if newer technology is available, a digital plate receptor may be used instead. Traditionally, radiographic film was used known as double emulsion film containing silver nitrate. These X-rays then travel through a focusing cup, focusing and accelerating the photons towards the area of the body to be imaged. Energy levels of the X-ray photon will vary and can be adjusted when selecting a parameter known as kVP or kilovolts peak. One of these interactions causes electrons to be expelled from the outer orbits of the atoms releasing a X-ray photon. When the electrons collide with the tungsten, several interactions occur at the atomic level. The electrons emitted by the cathode rush towards the anode, which holds a disc made of tungsten. This process is known as thermionic emission. These electrons are emitted from a filament on the cathode and rush towards a target material known as the anode. This causes electrons to “boil-off” from the cathode end of an X-ray tube assembly. The radiation is created when an electric current is generated from a high voltage generator. Ability to detect the radiation once it has passed through the patient.Ability to focus the radiation on a particular area.Ability to create to the electromagnetic radiation at the wavelength required.There are three criteria that must be met to allow electromagnetic radiation to be used for imaging purposes: X-rays are a type of electromagnetic radiation (just like visible light).
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