Positioning Principles

Adjustable collimator and light field

Are used to ensure the body part to be imaged, the X-ray tube, and the image receptor are lined up correctly

13.8 x 16.9 (14 x 17), 13.8 x 13.8 (14 x 14), 10 x 12, and 8 x 10

Common IR sizes for computerized radiography

17 x 19, 16 x 19, and 17 x 17

Common IR sizes for digital radiography

14 x 17, 7 x 17, 11 x 14, 10 x 12, 8 x 10, and 14 x 36

Common IR sizes for film radiography

14 x 36

IR size used for the spine with film radiography

Multiple projections on one film

Is possible on screen film radiography but not digital radiography

Pertinent anatomy

Must all be visible on a radiograph when positioning for an optimal image

Central ray

Must be at the center of the image for an optimal image when using digital imaging

Size of IR

Must be correct for the body part to be imaged for an optimal image

Position

Must be correct including proper placement of body part in relation to the IR, factors important for projection, correct centering, and collimation for an optimal image

Collimation

Must be correct to the size of the desired area to be imaged to prevent blurring of desired area for an optimal image

Anatomical side markers, patient ID, and date

Must be used to prevent wrong procedures on patients and to prevent confusion

View

Not a correct positioning term because it describes the body part as seen by the IR or other recording medium such as fluoroscopic screen

2

Number of projections when imaging a shoulder

To check for superimposition of anatomical structures, location of lesions and foreign bodies, and determination of alignment of fractures

Purpose for taking a minimum of two views of a body part

IR centering

Step four of the positioning sequence and routine

General patient positioning

Step one of the positioning sequence and routine

Part positioning

Step three of the positioning sequence and routine

Measuring part thickness

Step two of the positioning sequence and routine

3 views

The minimum number of views required when a joint is the prime interest

2 views

The minimum number of views required when imaging body parts and long bones

AP or PA, lateral, and oblique

The three most common projections used when imaging a joint

X-ray tube, IR, and the body part

The three things that must be aligned for a successful image

Coccyx

Topical landmark that is found by feeling the greater trochanter or the symphysis pubis

S1-2

Topical landmark that is the anterior superior iliac spine (ASIS)

L4-5

Topical landmark that is the iliac crest. This is the most common

L2-3

Topical landmark that is the inferior margin of the lower ribs

T2-3

Topical landmark that is the jugular or sternal notch

T1

Topical landmark that is the spinous process of c7 of the vertebrae

T4-5

Topical landmark that is the sternal angle

T9-10

Topical landmark that is the tip of the xiphoid process

Ischial tuberosity

Topical landmark that is two inches inferior to the coccyx

Floating

Type of tabletop that can maneuvered into a correct position

Fixed

Type of tabletop that cannot be maneuvered so the patient must move into the correct position

Average of the exposure

Way that an image is produced in digital radiography

Moving the upper leg

Way to find the the greater trochanter when using the coccyx as a topical landmark

Kidneys, liver, and ribs

types of x-ray exams that use the topical landmark T9-10