Positioning Terminology - Chapter 1

Body habitus

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

Four general types of Habitus

sthenic
hyposthenic
hypersthenic
asthenic

sthenic

about 50% of population'
average

hyposthenic

thin, more slender than sthenic
about 35% of population

hypersthenic

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

asthenic

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

impact of body habitus on radiographic positioning

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

radiographic positioning

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

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

radiography

the process and procedure of producing a radiograph

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

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

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

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

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

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

Portable Digital Radiography

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

Fluoroscopic screen

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

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 contro

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.

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.

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.

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

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.

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

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

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.

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 p

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.

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.

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

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

Cephalad

refers to parts toward the head of the body

Caudad

refers to parts away from the head of the body

Superior

refers to nearer the head or situated above

inferior

refers to nearer the feet or situated below

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

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

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

ipsilateral

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

contralateral

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

Positioning terminology

Projection
Position
View
Method

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. t

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

AP projection of the foot

AKA dorsoplantar projection

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

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 a

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

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 p

Transthoracic lateral projection

unique projection used for shoulder radiography

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

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 a

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

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

Right Anterior Oblique position RAO

Right anterior body surface is in contact with the radiographic table

Left anterior oblique position LAO

left anterior body surface is in contact with the radiographic table

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 te

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)
Ven