Week 2: Chest Procedures

Anatomy: Body Habitus

• Body habitus influences the shape, position, and movement of internal organs.
• There are four body habitus types shown in a diagram.

Anatomy: Thoracic Cavity

• The thoracic cavity is bounded by the walls of the thorax.
• It extends from the superior to the inferior thoracic aperture.
• The diaphragm separates the thoracic cavity from the abdominal cavity.
• This cavity contains the lungs and heart, respiratory, cardiovascular, and lymphatic organs, the inferior esophagus, and the thymus gland.
• There are three separate chambers: pericardial, right pleural, and left pleural cavities.
• The mediastinum separates the pleural cavities and contains all thoracic structures except the lungs and pleurae.

Anatomy: Respiratory System

• Consists of the pharynx, trachea, bronchi, and two lungs.

Anatomy: Trachea

• This is a fibrous, muscular tube supported by 16 to 20 C-shaped cartilaginous rings.
• The diameter is approximately 0.5 inches (1.3 cm).
• The length is 4.5 inches (11 cm).
• It lies in the midline, anterior to the esophagus, with a flat posterior aspect.
• The carina is a hooklike process on the last cartilage where the trachea bifurcates.
• Each primary bronchus enters its corresponding lung.

Anatomy: Bronchi

• The right primary bronchus is shorter, wider, and more vertical than the left.
• Its position and size make it easier for foreign bodies to enter the right bronchus.
• The bronchial tree subdivisions include primary, secondary, and tertiary bronchi, bronchioles, and terminal bronchioles.
• Terminals connect with alveolar ducts.

Anatomy: Alveoli

• Alveolar ducts terminate in alveolar sacs, the walls of which are lined with alveoli.
• Oxygen and carbon dioxide are exchanged by diffusion in the alveoli.
• Each lung has millions of alveoli.

Anatomy: Lungs

• Lungs facilitate respiration.
• The superior portion is the apex, which extends above the clavicles.
• The inferior portion is the base, resting obliquely on the diaphragm and lower in the back and sides than in the front.
• The sides are the costophrenic angles, and the medial border is the hilum.
• The right lung is shorter because of the liver's presence and broader than the left.
• Lungs move inferiorly during inspiration and superiorly during expiration.
• Each lung is enclosed in a double-walled serous membrane sac called the pleura.
• The inner layer of the pleura is the visceral pleura and the outer layer is the parietal pleura.
• The right lung has three lobes, while the left has two lobes.

Anatomy: Neck

• Divided into posterior and anterior portions.
• The anterior portion consists of:
  • Thyroid
  • Parathyroid glands
  • Larger part of the submandibular glands

Anatomy: Thyroid Gland

• The thyroid gland consists of two lateral lobes.
• Each lobe measures approximately 2 inches (5 cm) long, 1 1/4 inches (3.2 cm) wide, and 3/4 inch (1.9 cm) thick.
• The thyroid extends from the lower third of the thyroid cartilage to the level of the first thoracic vertebra.
• The lobes are connected at their lower thirds by a narrow median portion called the isthmus.
• The isthmus lies in front of the upper part of the trachea.

Anatomy: Parathyroid Glands

• These are small ovoid bodies, two on each side (superior and inferior).
• They are situated one above the other on the posterior aspect of the adjacent lobe of the thyroid gland.

Anatomy: Pharynx

• This is a musculomembranous, tubular structure approximately 5 inches (13 cm) in length.
• It serves as a passageway for air and food.
• It is located in front of the vertebrae and behind the nose, mouth, and larynx.
• The pharyngeal cavity is subdivided into nasal, oral, and laryngeal portions.
• The oropharynx extends from the soft palate to the level of the hyoid bone; the base of the tongue forms the anterior wall of the oropharynx.
• The laryngeal pharynx lies posterior to the larynx, extends inferiorly, is continuous with the esophagus, and the posterior surface of the larynx forms the anterior wall.

Anatomy: Larynx

• This is a movable, tubular structure approximately 1.5 inches (3.8 cm) in length.
• It is located below the root of the tongue and in front of the laryngeal pharynx.
• Suspended from the hyoid bone at the level of the superior margin of the fourth cervical vertebra to its junction with the trachea at the level of the inferior margin of the sixth cervical vertebra.
• The larynx is guarded superiorly and anteriorly by the epiglottis, and laterally and posteriorly by folds of mucous membrane.
• The epiglottis acts as a trap to prevent leakage into the larynx during swallowing.

Anatomy: Mediastinum

• This is the area of the thorax bounded by the sternum anteriorly, the spine posteriorly, and the lungs laterally.
• Structures associated include:
  • Heart
  • Great vessels
  • Trachea
  • Esophagus
  • Thymus
  • Lymphatics
  • Nerves
  • Fibrous tissue
  • Fat

Radiography: Soft Tissue Neck

• Soft tissue neck structures shown can include:
  • Cervical spine
  • Soft tissues of the anterior neck
  • Foreign bodies
  • Swelling (especially epiglottitis)
  • Masses (intrinsic and extrinsic to the airway)
  • Fractures of the larynx and hyoid bone

Radiography: AP Soft Tissue Neck

• The radiation field size is 12 inches (30 cm) lengthwise and 1 inch (2.5 cm) beyond the skin line on the sides, but not more than 10 inches (24 cm).
• The patient position is upright or supine.
• Part position includes centering MSP perpendicular to the grid midline, adjusting the patient's shoulders to lie in the same transverse plane, and extending the patient’s neck slightly.
• The central ray (CR) is perpendicular through the MSP at the level of the laryngeal prominence (upper airway) or manubrium.
• Exposure is made during slow inspiration to ensure the trachea is filled with air.
• The image should have proper collimation, an air-filled upper airway from the pharynx to the proximal trachea, and no rotation so spinous processes should be equidistant to the pedicles and aligned with the midline of the cervical bodies.

Radiography: Lateral Soft Tissue Neck

• The radiation field size is 12 inches (30 cm) lengthwise and 1 inch (2.5 cm) beyond the skin line of the anterior and posterior surfaces, but not greater than 10 inches (24 cm).
• The patient position is seated or standing.
• Part position includes centering MSP parallel to the grid midline, clasping the hands behind the body, rotating the shoulders posteriorly to keep the shadow of the arms from obscuring the superior mediastinum, and extending the neck slightly.
• The central ray (CR) is horizontal through MCP at the level of the laryngeal prominence or at the level of the jugular notch, through a point midway between the jugular notch and the MCP for the trachea and superior mediastinum.
• Exposure is made during slow inspiration to ensure the trachea is filled with air.
• Images should have proper collimation, an air-filled upper airway, and no rotation or tilt of the cervical spine, as evidenced by superimposed zygapophyseal joints, open intervertebral joints, and nearly superimposed mandibular rami.

General Positioning Considerations for the Chest: Procedural Guidelines

• Patient preparation involves removing artifacts from the anatomy of interest, such as long earrings, necklaces, and clothing artifacts, and securing all patient possessions.
• General patient position:
  • Ambulatory patients: upright or seated erect
  • Nonambulatory patients: Determine whether air-fluid levels are critical to diagnosis; if the patient cannot sit upright, substitute a decubitus position.
• Textbook guidelines are available for image receptor (IR)/collimation size.
• The smallest IR that will demonstrate anatomy should be used.
• Radiation field size should be collimated to the anatomy of interest.
• The recommended source-to-image receptor distance (SID) for chest radiography is at least 72 inches (183 cm) to minimize magnification of the heart and increase recorded detail.
• Right or left side markers must be included on each image, without using digital annotation.
• The side marker should be placed in the collimated exposure field clear of the anatomy of interest.
• Radiation protection involves placing a lead shield between the x-ray tube and the patient's pelvis and shielding patients of reproductive age and pediatric patients per guidelines in Chapter 1.
• Ensure close collimation, proper lead shielding placement without compromising the area of interest and optimum technique factors.

Patient Instructions

• Explain and demonstrate positions when possible.
• Explain that respiration instructions are critical to image lung aeration.
• Exposures are usually made after the second deep inspiration.
• Two separate radiographs may be taken, one on inspiration and one on expiration, to demonstrate pneumothorax, diaphragm movement, the presence of a foreign body, or atelectasis.

Radiographic Procedures: Essential Projections of the Chest, Lungs, and Pleurae

• Essential projections include:
  • Posteroanterior (PA)
  • Lateral
  • PA oblique
  • Anteroposterior (AP) oblique
  • AP
  • AP axial
• All utilize the same collimated radiation field size: 14 x 17 inches (35 x 43 cm).
• Adjust the radiation field to 17 inches (43 cm) lengthwise and 1 inch (2.5 cm) beyond the lateral shadows, less than 14 inches (35 cm).
• The opposite dimensions are used for a crosswise IR.
• The vertical dimension may be less for smaller patients.

Radiographic Procedures: PA Chest

• Patient position: upright either standing or seated, if possible, to demonstrate air or fluid levels and allow the diaphragm to move to its lowest position, with the top of IR 1 1/2 to 2 inches (3.8 to 5 cm) above the shoulders.
• Part position: patient faces the vertical grid device, with the midsagittal plane (MSP) centered perpendicular to the IR; weight equally distributed on both feet; elbows flexed and back of hands resting low on the hips; shoulders depressed into same transverse plane; shoulders rolled forward.
• Central Ray (CR): perpendicular to the center of the IR, entering at MSP and the level of T7.
• The exposure should be made at the end of the second deep inspiration.
• Must show, evidence of proper collimation, entire lung fields from the apices to the costophrenic angles, no rotation with clavicles equidistant from vertebral column and trachea visible in the midline, and equal distance from the vertebral column to the lateral border of ribs on each side.
• Proper scapulae rotation is shown with the scapulae projected outside the lung fields.
• Proper Inspiration requires ten posterior ribs.
• In addition, sharp outlines of the heart and diaphragm should be seen, faint shadows of the ribs and superior thoracic vertebrae should be visible through the heart shadow, and lung markings should be visible from the hilum to the periphery of the lungs from the hilum to the periphery of the lungs.

Radiographic Procedures: Lateral Chest

• Patient position: Upright, if possible (same reasons as stated for PA).
• The side placed closer to IR is the side demonstrated in the image.
• Left lateral is routinely used to minimize magnification of the heart.
• Top of IR: 1 1/2 to 2 inches (3.8 to 5 cm) above the shoulders.
• Part Position: true lateral position, MSP parallel with IR, midcoronal plane (MCP) perpendicular to IR, the shoulder in contact with the grid, arms extended over head, elbows flexed and forearms resting on head.
• The patient is not leaning sideways or bending forward and must be provided with IV stands, as needed, to hold onto.
• Central Ray: Directed perpendicular to IR; enters patient on MCP at level of T7.
• Exposure is made at the end of second deep inspiration.
• Evidenced by proper collimation, no superimposition by the arm, costophrenic angles and apices of lungs shown and the superimposition of the ribs posterior to the veterbral column.
• The lateral sternum should show no rotation, with intervertebral spaces open (unless the have scoliosis), with field penetration of the lungs/heart and sharp outlines of the heart/diaphragm.

Radiographic Procedures: PA Oblique Chest

• Patient position: upright, standing, or seated, with the top of the IR 1 1/2 to 2 inches (3.8 to 5 cm) above the vertebra prominens.
• Part position: 45-degree left anterior oblique (LAO) or right anterior oblique (RAO), with the side of interest farther from the IR (elevated side), shoulders in the same transverse plane, and arms positioned out of the radiation field.
• The central ray (CR) is perpendicular to the IR and enters at the level of T7.
• Exposure is made after the second full inspiration.
• Shown by both lungs in their entirety, trachea filled with air, visible identification markers, heart and mediastinal structures within the lung field of the elevated side in oblique images of 45 degrees, The maximum area of the right lung on LAO and the maximum area of the left lung on RAO

Radiographic Procedures: AP Oblique Chest

• Patient Position: Upright or recumbent, with a top of IR 1½ to 2 inches (3.8 to 5 cm) above vertebra prominens.
• Part Position: 45-degree left posterior oblique (LPO) or right posterior oblique (RPO), with the side of interest closer to IR, (dependent side), Arms out of field and shoulders in same transverse plane.
• CR: Perpendicular to IR center, with beam entered 3 inches (7.6 cm) below jugular notch.
• Exposure made on second full inspiration
• Shown be evidence of collimation,trachea, identification and lungs with field structure and the maximixed area of lung ( left on LPO, right on RPO)

Radiographic Procedures: AP Chest

• Patient Position: Supine or seated upright in wheelchair or stretcher; used when patient is too ill to stand.
• Top of IR: 1 1/2 to 2 inches (3.8 to 5 cm) above shoulders.
• Part position: Center MSP to IR; if patient condition perimits, flex elbows, pronate hands, and place hands on hips to draw scapula laterally with shoulders adjusted into the same transverse plane.
• CR: Perpendicular to long axis of sternum and center of IR with point of entry, 3 inches (7.6 cm) below jugular notch.
• Exposure made after second full inspiration
• Shown by collimation, angles, sterum and trachea alignment and equal distance between the vertebral column to lateral border of ribs.
• Clavicles lying more horizontally, obscuring the apices than in PA projection as well as the field penetration into heart space allowing for faint visibility, and vascular markings.

Radiographic Procedures: AP Axial Chest Lordotic Position

• Patient Position: Upright, facing tube, with a proximately 1 foot (30.5 cm) in front of grid and top of IR placed 3 inches (7.6 cm) above shoulders
• Part Position: MSP centered to midline of grid with and assistance provided to patient to lean backward until shoulders rest on grid
• CR: Perpendicular to IR. and Enters MSP at midsternum 3 to 4 inches (7.5 to 10 cm) below jugular notch.
• Exposure made after second full inspiration
• View shown by collimation, appropriate lung portion, alignment of sternun and overlapping of clavicles with 1st and 2nd ribs,

Radiographic Procedures: Lungs and Pleurae

• Two types include AP/PA and lateral
• They utilized collimated radiation, sized 14 × 17 inches (35 × 43 cm)

Radiographic Procedures: AP/PA Lateral Decubitus Position

• Patient position requires decubitus on right or left side, with fluid to settle in that position or air to rise in unaffected position. ( requires 5 minutes for each) with IR set at 1/2 to 2 inches (3.8 to 5 cm) beyond shoulders.
• Next, elevation to 2 to 3 inches (5 to 8 cm) needs to exist in body along with true lateral ,extending arms over head and surface set against device.
• Enter horizontally at enter medially 3 in at AP, at TP7 on PA, both to take exposure on 2nd inhalation.
• Position allows proper display to occur if proper adjustment, vascular marking and arm placement happen.

Radiographic Procedures: Decubitus Positions

• Set to either prone or supine depending (fluid/no obstruction) then elevation to 2 to 3, level IR set at thyroid cartilage point all in place within true side/over arm. Also set to expose on 2nd true breath after the full duration.
• This should appear with T8 positioned, the arms well set alongside it.