Projection Terminology PDF

PROJECTION TERMINOLOGY Course Instructor: Dr. Ali Hayder ALi GENERAL Objectives:  To know how hang the radiograph according to standards.  To know Projection terminology for each radiographic ,modalities. Projection terminology  The human body is a complicated structur...

PROJECTION TERMINOLOGY Course Instructor: Dr. Ali Hayder ALi GENERAL Objectives:  To know how hang the radiograph according to standards.  To know Projection terminology for each radiographic ,modalities. Projection terminology  The human body is a complicated structure, and errors in radiographic positioning or diagnosis can easily occur unless practitioners have a common set of rules that are used to describe the body and its movements. Patient aspect Anterior aspect: that seen when viewing the patient from the front. Posterior (dorsal) aspect: that seen when viewing the patient from the back. Lateral aspect: refers to any view of the patient from the side. The side of the head would therefore be the lateral aspect of the cranium. Medial aspect: refers to the side of a body part closest to the midline, e.g. the inner side of a limb is the medial aspect of that limb. Anterior aspect: Posterior (dorsal) aspect: Medial aspect: Lateral aspect: Positioning terminology:  This section describes how the patient is positioned for the various radiographic projections described as follow:  1/ Erect.  2/ Decubitus.  3/ Semi-recumbent. Erect: The projection is taken with the patient sitting or standing.  In the erect position, the patient may be standing or sitting: 1/ with the posterior aspect against the cassette; or 2/ with the anterior aspect against the cassette; or 3/ with the right or left side against the cassette. Erect: Decubitus: The patient is lying down. In the decubitus position,  the patient may be lying in any of the following positions: 1/ Supine (dorsal decubitus): lying on the back. 2/ Prone (ventral decubitus): lying face-down. 3/Lateral decubitus: lying on the side. - Right lateral decubitus –lying on the right side. - Left lateral decubitus – lying on the left side. Decubitus: Semi-recumbent:  Reclining, part way between supine and sitting erect, with the posterior aspect of the trunk against the cassette. Semi-recumbent: Antero-posterior (AP):  The central ray is incident on the anterior aspect, passes along or parallel to the median sagittal plane, and emerges from the posterior aspect of the body. AP: Postero-anterior (PA):  The central ray is incident on the posterior aspect, passes along or parallel to the median sagittal plane, and emerges from the anterior aspect of the body. PA: Lateral projection:  The central ray passes from one side of the body to the other along a coronal and transverse plane.  The projection is called a right lateral if the central ray enters the body on the left side and passes through to the image receptor positioned on the right side.  A left lateral is achieved if the central ray enters the body on the right side and passes through to the image receptor, which will be positioned parallel to the median sagittal plane on the left side of the body. LATERAL: Anterior oblique:  The central ray enters the posterior aspect, passes along a transverse plane at some angle to the median sagittal plane, and emerges from the anterior aspect.  The projection is also described by the side of the torso closest to the cassette.  In the diagram below, the left side is closest to the cassette, and therefore the projection is a described as a left anterior oblique. AO: Posterior oblique:  The central ray enters the anterior aspect, passes along a transverse plane at some angle to the median sagittal plane, and emerges from the posterior aspect.  Again, the projection is described by the side of the torso closest to the cassette.  The diagram below shows a left posterior oblique. PO: Oblique using Beam angulations:  When the median sagittal plane is at right- angles to the cassette, right and left anterior or posterior oblique projections may be obtained by angling the central ray to the median sagittal plane. Lateral oblique:  The central ray enters one lateral aspect, passes along a transverse plane at an angle to the coronal plane, and emerges from the opposite lateral aspect.  With the coronal plane at right-angles to the cassette, lateral oblique projections can also be obtained by angling the central ray to the coronal plane.  Image formation  The X-rays used in medical diagnosis are produced from a small area within the X-ray tube when an exposure is made. They diverge outwards from this area, travel in straight lines, and can be detected by a variety of devices used for medical imaging.  As the X-rays pass through the body, some will be absorbed by the organs and structures within the body whilst others will pass through to the equipment used to form the image. Image formation: Projection and view:  It is important to note that X-ray images are formed by projection, i.e. images of objects in the path of X-rays are projected on to a device for capturing the image, e.g. photographic material.  This differs from the way in which images are formed on the retina of the eye or on the photographic film in a camera, where light travels from the object to the recording median to produce an image that is a view of the object; a radiographic image is a projection of the object. Projection and view Density and contrast Density: When considering the radiographic image, the term ‘density’, as stated previously, can be defined crudely as the degree of ‘blackening’ within the image. The greater the amount of radiation that is incident upon the image detector, the greater will be the density within the image.  Contrast:  In order to detect pathology, an imaging system must be able to detect the differences in the density (patient density) of the pathology compared with that of the surrounding tissues.  This must then be translated into differences in density within the final image (image or film density) that are visible to the observer. Contrast is the difference in density between structures of interest within the image. A low-contrast image will show little difference in density between structures of interest, whereas a high-contrast image will show a larger difference in density between structures.  Hanging Radiographs I think it’s a cardiomegaly! How to hang radiograph?  Prior to evaluation, a radiograph should be correctly hung on a view box.  This section describes the proper hanging procedures for most radiographs.  Radiographs of different parts , positions , and projections should be hung as follows:  Torso , vertebral , cranial ,and hip radiographs: As if: The patient is standing in an upright position.  Fingers , wrist, and forearm radiograph: As if: The patient is hanging from the fingertips  Elbow ,and humerus radiographs As if: They are hanging from the patient’s shoulder Toe ,and AP and oblique foot radiographs As if: The patient is hanging from the toes  Lateral foot , ankle , lower leg and femur radiographs As if: They are hanging from the patient’s hip. Decubitus chest and abdomen radiograph As if: That the side of the patient that was positioned upwards when the radiograph was taken is upward on the hung radiograph  Axiolateral positions of the shoulder and hip As if: The patients anterior surface up and posterior surface down Which side (front or back) of the radiograph is placed against the view box is determined by the projection/position presented , as follow:  Anteroposterio (AP) ,Posteroanterior (PA) projections ,and oblique positions of the torso ,vertebrae , and cranium The radiographs taken in AP or PA or oblique position should be placed on the view box as if the viewer and the patient are facing each other Lateral positions of the torso , vertebrae , and cranium As if: The side of patient which was in contact with the film when radiograph was taken ,put a against the viewing box.  Extremities Extremity radiographs are hung as if the viewer’s eyes are the x-ray beam going through the radiographic image in the same manner that the photons went through the extremity when it was radiographed Are you ready for the advance part ?