Introduction To Technology And Positioning PDF

## Introduction To Technology And Positioning **X-Ray:** is artificial electromagnetic waves that are produced by X-ray machine. X-Ray was discovered in November 1895 by the German scientist Roentgen, and he has got the nobel prize in physics at 1901. **X-Ray machine:** is the machine that produce...

## Introduction To Technology And Positioning **X-Ray:** is artificial electromagnetic waves that are produced by X-ray machine. X-Ray was discovered in November 1895 by the German scientist Roentgen, and he has got the nobel prize in physics at 1901. **X-Ray machine:** is the machine that produces the x ray, Conventional X-ray machine is the machine used for general X-ray examinations as chest x-ray, abdomen, extremities... It consists of: - Generator: - It transforms the usual current to high voltage current. - X-Ray tube: (fig. 1) - It transforms the high voltage current to X-ray, which emerge from the x-ray tube. The X-ray unit is called the photon. - The X-ray coming out of the tube is called **primary beam** (1ry beam). - Diaphragm (collimator): placed in contact with the x ray tube through which the x-ray pass through. Its function is to collimate the x-ray beam according to the size of the part to be examined, to prevent unnecessary exposure to other parts of the body. The diaphragm contains light source which helps us to control the size of the emerging x-ray. - X-Ray filter: is a metal sheet present in the diaphragm immediately below the x ray tube. It absorbs the weak X-ray waves, to avoid its absorption by the human body. It is usually made of aluminum sheet 2 mm, other material may be used. **How Image is Formed on the X-Ray Film?** In a simple form, when the 1ry X-ray beam pass through the body several events occurs. Most of the X-ray photons pass through the body to reach the X-ray film or image receptor. While passing through the body, the X-ray photons are attenuated according to the structure of each part of the body e.g. while passing through air as the lung less attenuation occurs, i.e more X ray reach the X-ray film so this part will appear black. Another example, when x - ray photons pass through bones or any structure of high molecular weight it absorb more X-ray photons so in this case less or no X-ray photons reach the x ray film, so this part appear white or light gray. Our last example will be on soft tissues as muscles or abdomen, in the case while X-ray photons pass, attenuation of the X-ray photons occur according to the differential structure of this part, so this part appear grey, light gray if more x ray absorbed and dark grey if less x ray absorbed. Some X-ray photons are scattered to the surrounding, called scatter radiation (or 2ry X-ray). For more details, please refer to physics book. ## X - Ray Table: (Conventional X-Ray Machine; Fig.2) - It's the table where the patient lies down during examination. it allows passage of the X- ray through it. The X-ray table may be stationary (not moving). Or moving (called floating table moving in all directions). ## Grid, OR Bucky: - The grid is plate of special material, it, s present in the table, just below the table top or in the stand bucky. - Function; it filters the X-ray beam and prevent scatter radiation from reaching the X-ray film or the image receptor. So it allows only the 1ry beam passing in a straight line to reach the film. - Generally the grid is not used while examining peripheral thin parts (hands, feet), due to less scatter radiation in this case. And the grid should be used in thick parts (hip, obese knee, abdomen, chest...) with more scatter radiation. - Figure; 3, show the difference between bucky and non bucky x ray pelvis. ## Bucky stand: - It is a metal stand at the wall, it has a bucky buit in. It s used during X-ray examination for the patients while standing. It is sometimes called chest stand, usually used for x- ray examination of the chest, erect abdomen or any other examination while standing. - For pregnant females;. Review the indication with the referring doctor. During radiological examination protect the abdomen by lead apron. - Strict to 10 or 28 days rule: any married female (during her reproductive life) can be exposed to x-ray only during the 1st 10 days of her menstrual cycle. ## Radiological staff:- - Never expose your hands to direct X-ray. - Do not stand close to the x- ray table without protection. - During exposure you should stand behind lead partition. - Careful technique to avoid repetition. - You should strict to ALARA (as low as reasonably achievable) - You should use film badge. - The walls and doors in the x ray department should be isolated by lead sheets or by special materials. # While doing radiographic examination the following items should be fulfilled :- 1. Position of the patient or body part to be examined on the X-ray table or while standing beside the stand bucky. 2. Examination technique including: - Exposure Parameters: exposure factors: kilovoltage (kvp), Milliampere Seconds (MAS), (Milliampere x Seconds), - Focal Film Distance (FFD): is the distance between the focus (or central part of the x- ray tube (anode) and x ray film. The usual distance is 100 cm, except the chest 150-180 cm to avoid magnification. - Object Film Distance; is the distance between the part to examined (object) and the X-ray film. The examined part should be in contact and parallel to the cassette. (If the object film distance increased, the examined part will be magnified). (e.g. if you want to magnify any part, you have to increase the object film distance) 3. Central Ray (CR): Is the center of the X-ray beam, and it should be in the center of the examined part e.g. in X-ray elbow (AP view) the center should be in the center of the elbow. Also, the central ray should be in the center of he film. 4. Image receptor:- is the medium which receives the X-ray photons passed through the examined part The image may be produced either on X-ray film or through a digital system on a computer:: - Film Screen Cassette: Where an X-ray film is put in a cassette. After exposure to X-ray, the film is put in special chemicals (processing), to get the final X-ray image. Size of the film should be suitable to the part to be examined. (For more detail, please refer to the dark room book). - The Digital Image: the X-ray fall on a special phosphorous plate (which is put either in a digital cassette or the plate put within the x-ray table ). In case of digital cassette, After exposure of the plate to X-ray the plate is put is a special machine to read the image and transfer it to a computer, and the plate becomes ready to receive another x- ray exposure. In case of a table built in plate" called direct radiography OR DR", after exposure of the plate to X-ray, the image is transferred directly to the computer system so this is called direct radiography. ## Common Film sizes: In inches: 14 x17 & 14x14 & 12 x 15 & 10x 12 & 8x 10.INCHES In centimeter: 30x40 & 24 x 30 & 18 x 24. CM ## Respiration: Instruction to the patient to stop breathing during X-Ray exposure. Generally in chest x ray, stop respiration after deep inspiration, and in abdominal examination stop respiration after deep expiration .In extremity studies, no need to stop breathing. ## ANATOMIC POSITIONS The normal anatomic position: is the standard standing position with the person facing forward, and both hands forward. Anterior surface, (ventral surface) refers to the front of the body or any part of the body when seen from anterior e.g. front of the chest is the anterior of the chest, front of the hand is the palmer aspect of the hand. (fig. 4) Posterior surface (dorsal surface), is the back of the body or any part, when seen from the back e.g. back of the chest is the posterior of the chest, dorsal aspect of the hand is the posterior of the hand or finger. ## Body Planes, Sections, and Lines **Common planes :- (fig. 5)** **Sagittal Plane:** longitudinal plane that divide the body into right and left parts, if in the midline its called midsagittal plane, and it divides the body into two equal parts. If not in the midline (paramidline) called parasagittal (right parasagittal to the right of the midline or left parasagittal to the left of the midline). **Coronal Planes:** longitudinal plane that divide the body into anterior and posterior parts **Axial Plane:** transverse plane (at right angle to the above two planes) passing through any body part, dividing it to superior and inferior parts. ## SECTION: "CUT" OR "SLICE" IMAGE OF BODY PART:- Cut or slice of any part of the body: this produces images of the part according to its direction (axial cut or axial slice similarly coronal or sagittal cut or slice). The thickness of the cut or slice vary, e.g. 1mm, or more, according to the part or protocol of examination, In Computed tomography (CT) examination the cuts are axial, from these axial cuts sagittal or coronal or oblique planes can be reconstructed. In magnetic resonance imaging (MRI), the slices or cuts are axial, coronal and sagitta) (fig.6). ## Important lines: 1. Midline; longitudinal line, passing the mid sagittal plane 2. Midclavicular line; passing through the middle of the clavicle, i.e right midclavicular line, & left midclavicular line. 3. Midaxillary line, passing through the center or apex of the axilla. 4. Anterior or posterior axillary line passing through the anterior or posterior axillary folds 5. Epigastric line, passing one inch below the xiphoid process of the sternum. ## Terms used for the hands: - **Palmer surface:** is the anterior or frontal surface of the hand or fingers; - **Dorsal surface:** is the posterior surface of the hand or fingers. FIG. 7. ## Terms used for the foot: - **Planter surface:** refers to the sole of the foot. - **Dorsal surface,** is the anterior surface of the foot. ## RADIOGRAPHIC POSITION It is the position of the patient or examined part during X-ray examination. ## Common positioning terms ### BASIC POSITIONS: OR BASIC VIEWS; This is the basic position that should be done to the part under question. Always two perpendicular views e.g. when X-ray wrist is requested, this means that you will do PA ar AP and lateral views. ### ADDITIONAL, OPTIONAL OR SPECIAL VIEWS, are the views done in addition to the basic views to add more information, and will be more helpful for diagnosis..for example an important special view of the wrist i.e. PA with ulnar deviation will be done to answer a specific question or to add more data to the diagnosis. You should always remember that the part of interest should be close or in contact with the film. e.g. we do chest x ray left lateral view if the problem in the heart or left lung, on the other hand we do chest x ray right lateral if the patient has right sided lung lesion. Also, remember that the part to be examined should be close and parallel to the film,e.g during X-ray the elbow (AP view), the posterior surface of the elbow in contact with the cassette, at the same time, the forearm and the arm should be in contact and parallel with the film by lowering down the shoulder ## Postero anterior view or projection: (PA): In this position the x-ray passes from posterior to anterior. The X-ray tube is posterior, and the cassette is anterior. i.e the X-ray pass from posterior to anterior. ## Antero posterior view (AP):- This is the position when the X-ray passes from anterior to posterior , the cassette is put posteriorly, and the x ray tube in front of the patient. ## Lateral view :- This is the position when the x ray pass from one lateral side to the other. e.g. in lateral X-ray chest when the x ray beam pass from right to left side (the cassette at the left side), this is called left lateral. On the other hand when the x-ray beam passes from left to right side (the cassette at the right side), this is called right lateral view. (this means that the right side in contact with the cassette ). ## Oblique views : In this case, The patient is positioned oblique mid way between frontal and lateral position, ie we put the patient in the lateral view then rotate 45 degree to have the oblique view. For example, if the cassette at the right side of the back, this is called right posterior oblique. On the other hand if the cassette at right side of the front of the patient this is called right anterior oblique.. Left posterior oblique when the posterior aspect of the left side closest to the cassette. We can say there is an AP oblique view (right or left), and PA oblique view (right or left), according to the side close to the film. ## BODY POSITIONS 1. **Supine:** when one lies on his back. 2. **Prone:** when one lies on the abdomen. 3. **Erect:** Standing upright. Erect AP, when the anterior surface facing the tube and the posterior surface towards the cassette. Erect PA, when posterior surface facing the tube and the anterior surface facing the cassette. 4. **Recumbent:** lying down; - Supine recumbent ; lying on his back. - Prone recumbent; lying on his abdomen. - Lateral recumbent; lying on one side (right lateral recumbent or left lateral recumbent). 5. **Trendlenberg:** lying supine recumbent, head lower than feet. 6. **Decubitus:** when patient lying down. However, its commonly used when lying on one side as mentioned in the recumbent state. In decubitus position, the X-ray beam is horizontal. - Right or left lateral decubitus: (fig.8). Right lateral decubitus, (called also, right lateral recumbent) when the right side is down i.e lying on his right side. Left lateral decubitus (called also, left lateral recumbent) when the left side is down i.e. lying on his left side. Postero anterior (PA lateral decubitus), this means that when doing lateral decubitus the X-ray come from posterior to anterior, Antero posterior (AP lateral decubitus), this means that while doing lateral decubitus the X-ray pass from anterior to posterior. 7. **Axial:**- along the long axis of the part; inferosuprior or superio inferior 8. **TANGENTIAL:** when the X-ray pass tangential to the part. ## RELATION TERMS - **Proximal versus distal:** proximal is the part close to body e.g the knee is considered proximal than the foot. Distal is the part not close or relatively remote as related to other parts e.g. the foot is considered distal to the knee, and the knee is distal to the hip joint. - **Medial versus lateral:** e.g. lateral aspect of the thigh is the outer aspect.medial aspect of the thigh is the part of the thigh towards the midline. ## CEPHALIC VERSUS CAUDAL ANGLE; - **Cephalic angulation:** when the x ray beam is angled towards the head. - **Caudal angulation:** when the x ray beam is angled towards the feet. ## Identification card: should be put on the film - Film mark should be used R or L to identify right or left side of the patient. - Patient identification I.D. should be put on the film; including patient name, date of the study, hospital number and part examined. ## MOVEMENT TERMS; - **Flexion:** flexion of a joint when the bones at both sides of the joint come close together e.g flexion of the elbow; when the forearm and the arm come close together. Flexion of the spine when you bend the spine anterior so the head become close to the knee. - **Extension:** extension of a joint to make it straight e.g. extension of the elbow to make both arm and forearms straight - **Abduction:** e.g_abduction_of the arm by moving the arm away from the body. The same apply to the legs - **Adduction:** moving the part close to the body e.g adduction of the arm by moving it close to the body. the same apply to the legs. - **Bending:** while standing the body moved to one side (right bending or left bending). ## Gonadal protection; (fig. 9 & fig. 10) Aiming to protect the gonads (testis and ovaries) from X - ray effects. The ovaries and the testis are covered by thin lead sheet. ## PATIENT PREPARATION: 1. Psyhological preparation. 2. Explanation of the technique to the patient or relatives. 3. Special care for very young, mentally unstable, unconscious or inco-operative patient. 4. All detachable artifacts, e.g, ear rings, long hair are removed from the X ray path. 5. it s important to have clean sterilized conditions: clean hands, clean X ray table, clean cassette and immobilization aids. ## RADIATION PROTECTION Radiation protection is essential for the radiological staff, and patients ## Patient protection:- (No relatives should be present in the X-ray room) - Protect the gonads. - Good technique to avoid repetition of the x-ray.