Positioning Terminology - Chapter 1

Body surfaces and parts: Posterior or dorsal

Refers to the back half of the patient, or that part of the body seen when viewing person from the back; includes the bottom of the feet and the back of the hands as seen in the anatomical position.

Right Anterior Oblique position RAO

Right anterior body surface is in contact with the radiographic table

Body habitus

build, physique and general shape of human body Impacts positioning of specific regions

radiography

the process and procedure of producing a radiograph

Fluoroscopic screen

X-rays strike a fluoroscopic screen and image is formed image is transmitted to a TV monitor "Real time" device

Oblique Plane

a longitudinal or transverse plane that is at an angle or slant and not parallel to the sagittal, coronal or horizontal planes An oblique plane can pass through a body part at any angle between the sagittal, coronal and horizontal plane.

radiograph

an image of a patient's anatomic part (s) produced by the action of x-rays on an image receptor. Film screen digital technology

In Diagnostic Radiography, the IR will be one of these devices:

1 Cassette with film 2 Image Plate (IP) Photostimulable storage phosphate PSP IP 3 Solid State detectors 4 Portable Digital Radiography 5 Fluoroscopic image receptor

Midcoronal Plane

A specific coronal plane that passes through the midline of the body, dividing it into equal anterior and posterior halves. Sometimes called "midaxillary" plane

Midsagittal Plane

A specific sagittal plane that passes through the midline of the body and divides it into equal right and left halves. Sometimes called "median" plane

AP projection of the foot

AKA dorsoplantar projection

Oblique positions

Always named according to the side of the patient that is placed closest to the IR An oblique radiographic position is achieved when the entire body or body part is rotated so that the coronal plane is NOT parallel with the radiographic table or IR. The angle of oblique rotation varies with the examination and structures to be demonstrated EG rotated 45 degrees from the supine position) The relationship between oblique position and oblique projection: posterior oblique positions (RPO and LPO) result in AP oblique projections.

Medial or lateral rotation

An AP or PA oblique projection of the upper or lower limbs must also include a qualifying term indicating which way it is rotated such as medial or lateral position (from AP or PA as based on anatomical position) For oblique positions of the limbs, the terms medial rotation and lateral rotation have been standardized to designate the direction in which the limbs have been turned from the anatomic position

AP projection

Anteroposterior Projection A perpendicular central ray enters the anterior body surface and exits the posterior body surface. Projection of the CR from Anterior to Posterior In a true AP projection without rotation, the CR is perpendicular to the coronal plane and parallel to the sagittal plane assumes a true AP without rotation unless some qualifying oblique or rotational term is used to indicate otherwise Ex. When the CR enters anywhere in the front (anterior) surface of the body and exits the back (posterior), an anteroposterior (AP) projection is obtained regardless of the body position (e.g. supine or upright)

Sagittal Plane

Any longitudinal plane that divides the entire body or body part into right and left segments. The plane passes vertically through the body from front to back.

Distal

Away from the source or beginning parts farthest from the point of attachment, point of reference, origin, or beginning; away from the center of body

Coronal Plane

Divides the entire body or a body part into anterior and posterior segments. The plane passes through the body vertically from one side to the other.

Body surfaces and parts: Hands

Dorsal - refers tot he back or posterior aspect of the hand Palmar - refers to the palm of hand; in the anatomical position, the same as the anterior or ventral surface of hand

projection

PATH OF THE CENTRAL RAY as it exits the x-ray tube and goes through the patient to the IR. Most projections are defined by the entrance and exit points in the body and are based on the anatomic position. Position can be used in two ways in radiology: 1. to refer to the specific placement of the body part in relation to the table/IR during imagining 2. to identify the overall posture of the patient or the general body position

Horizontal (axial) Plane

Plane that passes crosswise through the body or body part at right angles to the longitudinal plane, dividing the body into superior and inferior portions. Also referred to as "transverse" or "axial" plane

Planes

Planes are used in radiographic positioning to center a body part to the IR or CR and to ensure body part is properly oriented and aligned with IR. EX. MSP may be centered and perpendicular to the IR EX. CR for AP projection passes through the body part parallel to the sagittal plane and perpendicular to the coronal plane Body planes are used in CT, MRI and US to identify the orientation of anatomic cuts or slices demonstrated in the procedure

Body surfaces and parts: Feet

Plantar: refers to the sole or posterior surface of the foot Dorsum: refers to the anterior surface (top) of foot

PA Projection

Posteroanterior Projection A perpendicular central ray enters the posterior surface of the body and exits the anterior body surface A true PA without rotation requires the CR to be perpendicular to the coronal plane and parallel to the sagittal plane

Positioning terminology

Projection Position View Method

Body planes, sections and lines

The human body as viewed in the anatomic position can be subdivided through the use of imaginary body planes. There are 4 fundamental body planes referred to in medical imaging.

Left posterior oblique position LPO

The patients left posterior surface is in contact with the radiographic table LPO radiographic position of the chest results in an AP oblique projection

Lateral Projection

a perpendicular CR enters one side of the body or body part, passes transversely along the coronal plane, and exits the opposite side Lateral projections can enter from either side of body or body part as needed for examination This can be determined by patient condition, ordered by physician or departmental protocol When a lateral projection is used for Head, Chest, or Abdominal radiography, the direction of the CR is described with reference to the associated radiographic position. A left lateral position or right lateral position specifies the side of the body closest to the IR and corresponds with the side exited by the CR. Ex. lateral projection with right lateral position The right side of the chest is touching the IR. The CR enters the left side of the body. Lateral position with right lateral projection. lateral radiographic positions are always named according to side of the patient that is closest to the IR. The specific side selected depends on the condition of the patient, the anatomic structure of clinical interest, and the purpose of the exam. Lateral projections of the limbs are further clarified by the terms lateromedial or mediolateral to indicate the sides entered and exited by the CR.

radiographic Examination or procedure

a radiographic exam includes the following 5 general functions: 1. Positioning of body part and alignment with the IR and CR 2. Application of radiation protection measure and devices 3. selection of exposure factors (radiographic technique) on the control panel 4. Patient instructions related to respiration (breathing) and initiation (or "making") of the exposure 5. Processing of the IR

sthenic

about 50% of population' average

impact of body habitus on radiographic positioning

centering may need to be altered image receptor needs to be considered lengthwise (portrait) or crosswise (landscape)

Cassette with film

device that contains special intensifying screens that glow when struck by x-rays and imprints the x-ray image on the film requires the use of darkroom or daylight processing to develop film

Image Receptor (IR)

device that receives the energy of the x-ray beam that exits the patient and forms the image of the body part film/screen cassettes - old digital acquisition devices - CR, DR

Oblique projections

during an oblique projection the CR enters the body or body part from a side angle following an oblique plane Oblique projections may enter from either side of the body. And from anterior or posterior surfaces If the CR enters the anterior surface, it is an AP Oblique projection If the CR enters the posterior surface, it is an PA oblique projection Most oblique projections are achieved by rotating the patient with the CR perpendicular to the IR As in the lateral projection the direction of the CR for oblique projections is described with reference to the associated radiographic position A right posterior oblique position places the right posterior surface of the body closest to the IR and corresponds with the AP oblique projection. An oblique radiographic position is achieved when the entire body or body part is rotated so that the coronal planeis not parallel with the radiographic table or IR. The angle of oblique rotation varies with the examination and structures to be demonstrated. EG. rotated 45 degrees from the supine position

Axial Projection

in an axial projection, there is a longitudinal angulation of the CR with the long axis of the body OR a specific body part The angulation is based on the anatomic position and is most often produced by angling the CR cephalad or caudad The Longitudinal angle in some examinations is achieved by angling the entire body or body part while maintaining a perpendicular CR The term axial refers to all projections in which the longitudinal angulation between the CR and the long axis of the body part is 10 degrees or more When a range of CR angles, such as 5 to 15 degrees, is recommended for a given projection, the term axial is used because the angulation could exceed 10 degrees

Decubitus position

in radiographic positioning terminology, the term decubitus indicates that the patient is lying down and that the CR is horizontal and parallel with the floor. 3 primary decubitus positions: lateral decubitus (left or right) Dorsal decubitus (on back) Ventral decubitus (on front) Of these positions, the lateral decubitus positon is most often used to demonstrate the presence of air-fluid levels or free air in the chest and abdomen The patient is in the left lateral decubitus radiographic position with the back closest to IR. In this position, the horizontal CR provides an AP projection. This patient could also be placed with the front of the body (anterior surface) facing the IR. This would result in a PA projection Dorsal decubitus position - right side of the body next to the image receptor. Right dorsal decubitus radiographic positon of the abdomen results in a right lateral projection. Ventral decubitus radiographic position places a side of the body adjacent to the IR resulting in a lateral projection

Medial

in the anatomic position, it is the "inside" part closest to the medial plane or midline of the body

Lateral

in the anatomic position, it is the part away from the center, or away from the median plane or midline of the body

Left anterior oblique position LAO

left anterior body surface is in contact with the radiographic table

hypersthenic

massive body style large and broad frame as compared to sthenic about 5% of population

Tangential projection

means touching a curve or surface at only one point describes a projection that merely skims a body part to project that part into profile and away from other body structures

asthenic

more slight in stature than even hyposthenic very thin or slender compare to sthenic about 10% of population

Proximal

near the source or beginning parts nearer the point of attachment, point of reference, or origin, or beginning; toward the center of the body

contralateral

part or parts on the opposite side of the body Right knee and left hand

ipsilateral

part or parts on the same side of the body Rt. Thumb and Rt. Great Toe

Portable Digital Radiography

portable lightweight DR system can be tethered to the computer or wireless transmission

inferior

refers to nearer the feet or situated below

Superior

refers to nearer the head or situated above

Caudad

refers to parts away from the head of the body

Cephalad

refers to parts toward the head of the body

Central Ray (CR)

refers to the center most portion of the x-ray beam emitted from the x-ray tube; the portion of the x-ray beam that has the least divergence

Body surfaces and parts: Anterior or ventral

refers to the front half of the patient, or that part seen when viewed from the front; includes the tops of feet and the fronts or palms of hands in the anatomical position.

Anatomic Position

refers to the patient standing erect with the face and eyes directed forward, arm extended by sides palms of hands facing forward, heels together, and toes pointing anteriorly.

Four general types of Habitus

sthenic hyposthenic hypersthenic asthenic

radiographic positioning

study of patient positioning performed for radiographic demonstration or visualization of specific body parts on image receptors (IRs)

Right posterior oblique position RPO

the right posterior body surface is in contact with the radiographic table RPO radiographic position of the chest results in an AP oblique projection

hyposthenic

thin, more slender than sthenic about 35% of population

Transthoracic lateral projection

unique projection used for shoulder radiography

Solid State detectors

used for direct digital radiography "cassetteless" detector captures the x-ray energy that passes through the patient and converts it directly into digital format DR - digital radiography The image is viewed on a computer monitor or printed on film

Imaging Plate

used in computed radiography a special phosphorus plate is placed inside a CR cassette X-ray energy is deposited in the phosphorus particles after it passes through patient Photostimulable storage phosphor plate (PSP IP) Cassette is inserted into a reader device Reader scans the IP with a laser to release stored x-ray energy pattern as light Radiographic image is converted to digital format Digital image is viewed on a computer monitor or printed on film