Positioning Unit 2

Chest or Thorax

Upper portion of the trunk, in between the neck and abdomen

What are the three sections of the chest?

Bony thorax, respiratory system, and mediastinum

Bony thorax function

To protect throacic viscera - lungs, heart, blood vessels

Bony thorax consists of:

Sternum, 2 Clavicles, 2 Scapulae, 12 pairs of ribs, and 12 thoracic vertebrae

Three divisions of the sternum

Manubrium, body, and xiphoid process

What makes up the shoulder girdle?

Clavicle and scapula

Topographic Landmarks definition

Parts of the body that are easy to locate and used to ensure correct centering

Palpate definition

The process of applying light pressure with fingertips directly on the patient to locate positioning landmarks

What are the 2 bony landmarks used for chest positioning?

Vertebra prominens C7 and jugular notch

Two other names for the jugular notch

Manubrial notch and suprasternal notch

What is the carina and where is it located?

Where the trachea bifurcates into left and right primary bronchi, Level of T4-T5

What is the diaphragm?

A dome shaped muscle that separates the thorax and abdominal cavities, the primary muscle of inspiration

Costophrenic angles

Where the diaphragm meets the ribs

Hilum region

Central area of the lungs, where the bronchi, blood and lymph vessels, and nerves enter and leave the lungs

Cardiac angles

When the heart and diaphragm meet

What is the mediastinum?

The medial portion of the thoracic cavity

What are the 4 structures of the mediastinum?

Thymus gland, trachea, esophagus, and heart and great vessels

Hypersthenic body type

Chest is broad and deep (not obese), diaphragm is high, lungs are short/wide

Sthenic body type

Average build

Hyposthenic/ Asthenic

Slender/ Very slender

Low diaphragm, long, narrow lungs

What are the 2 reasons chests are taken on full inspiration?

1. To demonstrate the lungs fully expanded

2. Prevent motion - blurring

During inspiration, the thoracic cavity expands in what 3 dimensions?

Vertical, transverse, and anteroposterior

How do you measure the degree of inspiration? (it’s good)

10 posterior ribs seen above the diaphragm

What are 2 reasons a chest x-ray could be performed on expiration instead?

Possible pneumothorax (collapsed lung) or to determine if an opacity is on the lung or rib

What are 3 reasons chest x-rays should ideally be done erect?

1. Better inspiration- diaphragm moves down farther, abdomimal organs drop

2. Visualize air-fluid levels

3. Prevent engorgement and hyperemia or pulmonary vessels

Why is the SID 72 inches for chest x-ray?

To prevent magnification of the heart

What are 3 ways to prevent giving excess radiation to patients?

Collimation, gonadal shielding, minimizing repeats

What is the kV range for chest x-rays?

110-125

Short exposure time minimizes motion; what are the two types of motion?

Voluntary: pt moving, breathing

Involuntary: heart motion

What are the criteria for good technique on a chest x-ray?

• Can visualize lungs markings

• Apices to costophrenic angles

• No motion

• No rotation- Sternoclavicular joints symmetrical

• 10-8 ribs

• See faint outlines of thoracic vertebrae through heart shadow

• Good technique (kV and mAs)

Why is a left lateral done?

It bests demonstrates the heart region

How can motion be determined on a lateral chest x-ray?

Blurring of spine or heart

How can tilt be seen on a lateral chest?

Closed disk spaces of the thoracic vertebrae

Why is it important to raise the arms on a lateral chest?

To prevent superimposition on the upper chest and to get soft tissue of arms out of the way

What are the 7 patient history questions to ask?

1. Chest pains?

2. Any heart, lung, or breast surgery?

3. Cough?

4. Shortness of breath?

5. Fever?

6. Ever been diagnosed with cancer?

7. Do you smoke or have you ever?

What anatomy is best demonstrated on a PA/AP chest?

Both lungs: apices to costophrenic angles, hilum region, heart and great vessels, and bony thorax

What size focal spot is used on chest x-rays? why?

Small, for better detail

What is the degree of angle and direction on a supine chest?

3-5 degrees caudal

How should the CR be in relation to the sternum on an AP semi-erect chest?

Perpendicular

If the CR angle on a semi-erect chest is correct, where should the clavicles be?

Below apices (3 posterior ribs seen above them)

What is the minimum SID on a supine or semi-erect chest?

40 inches

What should be placed under the patient during a lateral decubitius? Why?

A radiolucent sponge to get the patient off the bed and the mattress out of the image

What does the downside pleural space demonstrate on a lateral decubitus? The upside pleural space?

Down: Fluid Up: Air

What is the degree for the anterior oblique?

45

What is best demonstrated on an RAO?

The left lung

What is best demonstrated on an LAO?

The right lung

If a 60 degree LAO chest is performed, what is best demonstrated?

Air-filled trachea, great vessels, and heart