Midterm: X-Ray Tube and Parts PDF

MIDTERM. INTRODUCTION X-RAY TUBE AND PARTS The art and science of radiography Radiographic imaging can be described as an art and as a science. The term "art" refers to the production of something that is very well done. Radiography -- requires skill in performance. Radiography also requires st...

MIDTERM. INTRODUCTION X-RAY TUBE AND PARTS The art and science of radiography Radiographic imaging can be described as an art and as a science. The term "art" refers to the production of something that is very well done. Radiography -- requires skill in performance. Radiography also requires study of natural phenomena. Radiography- is an art and science acquired by study and practice in the use of x-rays to produce images. The art is in the use of x-ray equipment and accessories, such as film, cassettes, and protection devices, to produce images of the body. In as much as radiography includes the use of x-rays, the "artist" radiographer be able to understand characteristics of x-radiation, how x-rays are produced, and how x-rays are used in producing images of the human body. The full name of the medical specialty is radiology. Within the medical specialty of radiology, there are two groups of professionals; radiologists and radiologic technologist. Radiologists are medical doctors (M. D's) who are board certified to practice radiology. Many radiologists choose to specialize in such areas within radiology a neuroradiology, cardiovascular radiology, computed tomography, magnetic resonance imaging, nuclear medicine, radiation therapy, and sonography, some of which may require additional board certification. RADIOLOGIC TECHNOLOGISTS- are graduated of education programs usually ranging in length from 2-4 years; they are certified to practice the profession by assisting physicians in the diagnosis of disease. Radiologic technologist are trained professionals who are skilled in the used of x-rays, radioactive materials, and or ultrasonic sound waves to produce images of the human body for diagnosis and treatment of disease. RADIOLOGIC TECHNOLOGIST -- are professionals who are skilled in the use of x-rays and radiation for the production of images of the human body. Radiographers- are professionals who are responsible for producing high quality images using x-radiation. To become a radiographer, one must complete an educational program that requires a minimum of 2 years of training and supervised practice. Radiographers are certified by the successful completion of an examination given by the American Registry of Radiologic Technologist (ARRT) The variety of roles available to a radiographer is great. NUCLEAR MEDICINE TECHNOLOGIST- are technical personnel (often radiographers) trained in the used of radioactive drugs that are administered to patients for the purpose of evaluating and treating diseases. RADIATION THERAPY TECHNOLOGIST- are also specially trained personnel who assist physicians in the set up and dose calculation for physicians in the set and dose calculation for patients who receive radiation for the treatment of cancer. SONOGRAPHERS- are specially trained personnel who use high- frequency soundwaves (ultrasonography) to produce images of the human body. RADIOGRAPHY- Is defined as the use of ionizing radiation to produce a recorded image on photosensitive material. The image produced using x-radiation is called radiograph. A radiograph represents the image recorded on photosensitive material, which is usually called ray film. Radiography is the use of ionizing radiation to produce a recorded image. Radiograph is the image produced using x-radiation. CHARACTERISTICS OF A RADIOGRAPH \- The responsibility of the radiographer must include a review of each radiograph of the following Characteristic: Expose factors are adequate There has been adequate penetration of the part of interest. Sufficient radiographic density and contrast are present. Field size selection is appropriate Motion is eliminated during exposure The anatomic part is properly positioned. Proper accessories have been selected. CHAPTER 2. XRAY TUBE One of the primary responsibilities for a radiographer is to understand how x-rays are produced. A key factor in understanding this process is knowledge of x-ray tube and its parts. Tube housing X-ray tube is inside a heavy, lead-lined protective housing. When x-rays are produced by x-ray tube, x-rays are emitted in all directions. The housing serves as a protective device, preventing x-rays from " leaking" to expose the patient and technical personnel unnecessarily. WHEN X-RAYS ARE PRODUCE BY THE X-RAY TUBE, XRAYS ARE EMITTED IN ALL DIRECTIONS. The housing also serves as a support for x-rays tube and protects it from rough handling or the possible damage. THE TUBE HOUSING SERVES AS SUPPORT FOR THE XRAY TUBEAND PROTECTS FROM ELECTRIZAL HAZARDS. THE GLASS ENVELOPE - Is located inside the tube housing. The tube consists of two electrodes inside a glass envelope. The glass envelope is usually made of heat produced during x-ray production. The x-ray tube is a special vacuum tube so that small quantities of gas, which might be found in a non-vacuum tube, will not interfere with the production of x-rays. THE XRAY TUBE IS LOCATED INSIDE THE TUBE HOUSING, ENCLOSED IN A GLASS ENVELOPE. The window of the glass envelope is small area in the Pyrex glass that is usually made thinner so x-rays photons pass through the window with minimum absorption of the photons. THE XRAY TUBE Is sometimes referred to as a diode tube, meaning it has two electrodes. The two electrodes found in the x-ray tube are the cathodes and anode, which are designed to produce x-rays. THE CATHODE -- is negatively charged electrode; it consists of these major parts: the large filament, the small filament, and the filament cup, or focusing cup. The cathode is negatively charged electrode. The filaments serve a vital function for the source of electrons in the production of x- rays. The filaments are small coils of tungsten wire about 1 to 2cm in length. The longer coil of tungsten is the large filament, and the shorter coil is the small filament. Tungsten is the metal of choice because it is able to withstand the tremendous amounts of heat that are present at the time x-rays are produced and because it provides a good source of electrons, through the process known as THERMIONIC EMISSION. THE CATHODE FILAMENT IS THE SOURCE OF ELECTRONS FOR THE PRODUCTION OF XRAYS. Thermionic emissions occurs when a current is applied to the filament, the coil of wire becomes very hot, negatively charged electrons break away from the wire to form a cloud. This cloud of electrons is called a space charge and becomes the source of electrons for producing x-rays. Thermionic emission occurs when the negatively charged electrons break away from the hot filament to form a space charge. The filament cup or focusing cup, encases the two filaments. This cup serves to focus the space charge to a target area on the anode at the time of exposure. The anode is the positive electrode in the x-ray tube. In radiology, there are two types of anodes found in x-ray tube: rotating and stationary. The rotating anode consists of three components: rotating target, stem and rotor. The rotor is a shaft -like structure made primarily of copper. It serves as the rotation device that turns the stem and target area. The stem usually made of copper, attaches the rotating target area to the rotor. Copper is the metal of choice because it is an excellent conductor and it's facilitates the conduction of heat away from the target area. The rotating target is a circular, disk like structure with a slanted or beveled edge. It serves as the target for receiving electrons as they move from the cathode to anode. The target area is made of tungsten to withstand the stress of heat when struck by the space charge. THE ROTATING ANODE TARGET RECEIVES THE ELECTRONS AS THEY MOVE FROM THE CATHODE TO ANODE. Angles on the edge of the rotating target may vary from 8 to 20 degree. Most rotating anodes turn at approximately 3000 revolutions per minute RPM with higher speed rotating anodes turning at 10,000 RPM. THE COPPER STEM AND ROTOR SERVES AS CONDUCTORS TO HELP CONDUCT HEAT AWAY FROM THE ROTATING TARGET. Line focus principle- the design of an anode target area which is angled, is known as the line-focus principle. THE LINE FOCUS PRINCIPLE RESULTS IN A SMALLER EFFECTIVE FOCAL SPOT SIZE. THE STATIONARY ANODE TUBES- are designed in a similar fashion to rotating anodes but without rotation capacity. Stationary anodes resemble a long shaft made of copper with a tungsten target area embedded on a slanted surface. The slanted surface establishes the line focus principle, allowing for a larger area to be hit by electrons. This allows for a smaller effective focal spot to be projected toward the patient. these type of x-ray tubes are usually found in dental units and some mobile radiographs unit as a result of the reduced output of these x-ray