Body positioning in x-ray studies

Encyclopedia of Nursing and Allied Health, 20050229 by MBA/TM Elaine R. Proseus, BSRT, RT(R)

Definition

Body positions in x-ray exams are based on body part, suspected defect or disease, and condition of the patient. The radiographer, also known as the x-ray tech or more formally as the radiologic technologist, uses standardized body positions in performing an x-ray exam. Positions are learned by the radiographer according to body part in relation to body habitus, anatomical position and bisecting planes, and relationship of the body to the x-ray equipment.

Purpose

Since many body parts overlay other internal structures, the radiographer uses positioning of the body part as well as specific positions of the x-ray equipment to obtain clearer views of the overlapping structures. X-ray exams usually consist of two or more radiographs, taken in orthogonal planes or variations to the relationship of body part and x-ray equipment. Exams require radiographs to be taken at 90 degrees to each other where anatomy is superimposed over important structures, where alignment of fracture ends is questioned, or for localization of foreign bodies. Exams require a minimum of three radiographs when joints or articulations are in the area of interest, although some referring physicians may ask for only two. This allows for evaluation of the bones and well as the joints.

Precautions

The radiographer applies principles of immobilization in performing the exam. The use of immobilization has two purposes. First, the patient's safety is of primary importance to the radiographer. Second, immobilization assists the patient in maintaining the applied body position during the exam. Some x-ray exams require the patient to suspend breathing during the exposure such as for chest x rays. Suspension of breathing is a method of immobilization that the patient voluntarily performs. In other cases, the radiographer assists the patient in maintaining a position with the use of radiolucent sponges or other positioning aids.

Radiation protection is used to reduce or prohibit x-ray exposure to areas of the body that are biologically sensitive. The determinants of x-ray exposure include time spent under irradiation, distance of x-ray unit, and shielding practices. The most common practice of radiation protection is to protect the reproductive organs, especially in children and young adults. It is standard practice to question women of childbearing age if there is a possibility of pregnancy. Radiographic exams are not usually performed on pregnant women as the developing fetus is biologically sensitive to radiation.

Description

The use of body positioning requires an understanding of terminology that refers to the relationship of the body to the x-ray equipment and to anatomical references. All body positions and exam requirements are expressed in terms of projection, position, and view. A projection refers to the path the x rays take through the body, from entrance to exit. Position describes the body and its relationship to the x-ray film device (film cassette, image intensifier, image receptor). View is not a positioning term but instead is used in discussion the radiograph. For example, the physician orders an upright chest x ray with two views of an ambulatory patient. The standard positions are P. A. (back to front) and lateral (from the side). The radiographer positions the patient standing at the x-ray image receptor for a posterior-anterior projection (the x rays pass from the patient's back to the front) and a left lateral projection (patient's left side closest to image receptor and x-rays pass from the patient's right to left). Body positioning may also require adjacent areas be addressed, i.e., moving the arms out of the way.

Anatomical position

Anatomical position is the fundamental term used in body positioning. In this position, the patient is standing and facing front. The arms are down at the sides and the palms are turned forward so that you can see them. Feet are pointed straight ahead and the toes are lying down on the floor. The surface of the body that is facing front is known as the anterior, or ventral, surface. Any anatomical structure located in the half of the body that is adjacent to the anterior surface is considered to be anterior within the body. The surface of the body facing the rear is the posterior, or dorsal, surface. Any anatomical structure located in the half of the body that is adjacent to the posterior surface is considered to be posterior within the body. The body is also discussed in right and left sides using an imaginary line dividing the sides through the body's center.

Posture and relationship to x-ray equipment

X-ray exams are performed with either stationary or mobile equipment. Stationary equipment may be specialized for upright exams such as a chest x-ray unit or panoramic chair unit. Some stationary equipment only allows for the patient to lie down on a table for the exam. Other stationary equipment has a rotating table that allows for upright exams in addition to having the patient lie on the table. Mobile, or portable, x-ray equipment can accommodate a variety of patient positions. Regardless of the equipment used, the same principles and terminology of positioning are applicable.