Positioning 1- Chapter 10/week 5 Flashcards
Body habit us
Determines shape, position, and movement of the internal organs
Four types of body habitus
Sthenic
Hypersthenic
Asthenic
Hyposthenic
Thoracic cavity
• bounded by walls of thorax
• extends from the superior thoracic aperture to the inferior thoracic aperture
• diaphragm separates thoracic cavity from abdominal cavity
• contains the kings and heart; the organs of the respiratory, cardiovascular, and lymphatic systems; and the thymus gland
• three separate chambers
-pericardial
-right and left pleural
• mediastinum separates pleural cavities
-contains all thoracic structures, except lungs and pleurae
Respiratory system
• consists of
- pharynx
- trachea
- bronchi
- two lungs
Trachea
• fibrous, muscular tube with 16 to 20 c-shaped cartilaginous rings in its walls for strength
• measurements
-diameter= approximately 1/2 inch(1.3 cm)
-length = 4 1/2 inches (11cm)
-posterior aspect is flat
• lies in midline, anterior to esophagus
• carina is hooklike process on the last cartilage
• trachea divides, or bifurcates, at carina
-right primary bronchus
-left primary bronchus
• each primary bronchus enters the corresponding lung
Bronchi
• right primary bronchus is shorter, wider, and more vertical than left
-position and size make it easier for foreign bodies to enter the right bronchus
• subdivisions of bronchial tree
-primary bronchi
-secondary bronchi
-tertiary bronchi
-bronchioles
-terminal bronchioles
• terminals communicate with alveolar ducts
Alveoli
• alveolar ducts end in alveolar sacs
• walls of alveolar sacs lined with alveoli
-oxygen and carbon dioxide exchanged by diffusion In alveoli
• millions of alveoli in each lung
Lungs
• Organs of respiration • superior portion = apex -reaches above clavicles • inferior = base -rests obliquely on diaphragm -lower in back and sides • sides = costophrenic angles • medial border = hilum • right lung is shorter than left because of presence of liver -broader than left • move inferiorly- inspiration • move superiorly- expiration • each lung enclosed in a double walled serous membrane sac called the pleura -inner layer = visceral pleura -outer layer = parietal pleura • each lung divided into lobes -right has three lobes -left has two lobes
Mediastinum
• area of thorax bounded by sternum anteriorly, spine posteriorly, and lungs laterally • structures associated -heart -great vessels -trachea -esophagus -thymus -lymphatics -nerves -fibrous tissue -fat
Which lung has three lobes?
A. Right
B. Left
C. Neither
D. Both
A. Right
Aspirated foreign objects are more likely to lodge in the:
A. Right primary bronchus
B. Left primary bronchus
C. Carina of the trachea
D. Esophagus
A. Right primary bronchus
The level of the trachea bifurcation is the:
A. Thyroid cartilage
B. Carina
C. Larynx
D. Diaphragm
B. Carina
At the bottom of it
General procedural guidelines for thoracic viscera
- patient preparation
- general patient position
- image receptor(IR)/collimated field size
- source-image receptor distance (SID)
- identification (ID) markers
- radiation protection
- patient instructions
Patient preparation
• patient preparation for thoracic viscera procedures requires removal of artifacts from the anatomy of interest
- long earrings
- necklaces
- clothing artifacts
• secure all patient possessions in designated manner and location
General patient position
• ambulatory patients
- upright or seated erect
• nonambulatory patients
- determine wether air-fluid levels are critical to diagnosis
- may have to substitute a decubitus position if patient cannot sit upright
IR/collimated field size
- textbook gives guidelines
- use smallest IR that will demonstrate anatomy
- collimate field size to anatomy of interest
SID
- source to image receptor distance
- recommended SID for chest radiography is at least 72 inches (183 cm) to minimize magnification of heart and increase recorded detail
ID markers
- right or left side markers must be included on each image
- avoid using digital annotation to put side markers on images
- other required ID markers must be in the blocker or elsewhere on the final image
Radiation protection
• shield patients of reproductive age and pediatric patients
-refer to guidelines on pp. 33-34, volume 1
• other radiation protection measures
- close collimation
- optimum technique factors
Patient instructions
• explain and demonstrate positions, when possible
• 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
- demonstrates pneumothorax
- diaphragm movement
- presence of foreign body
- atelectasis- partial un-expanded lungs
Essential projections of the chest
- posteroanterior
- lateral
- PA oblique
- anteroposterior (AP) oblique
- AP
- AP axial
• all use same collimated field size
- 14x 17 inches (35 x43 cm)
What is the patient position for a PA chest?
• Upright, if possible, to demonstrate air or fluid levels and allow diaphragm to move to its lowest position
• part position
- patient faces vertical grid device with midsagittal plane (MSP) centered
- weight equally distributed on both feet
- top of IR 1 1/2 to 2 inches (3.8 to 5 cm) above shoulders
- flex elbows and rest back of hands low on hips
- depress shoulders into same transverse plane
- roll shoulders forward
• central Ray (CR)
- perpendicular to center of IR
- enters at MSP and level of T7
* exposure should be made at the end of second deep inspiration
Lateral chest position
• Left lateral is routinely used to minimize magnification of heart
• upright, if possible
• top of IR 1 1/2 to 2 inches (3.8 to 5 cm) above shoulders
• part position
- true lateral position
- MSP parallel with IR
- mid coronal plane (MCP) perpendicular to IR
- shoulder in contact with grid
- extend arms over head, flex elbows, and rest forearms on head
• CR
- directed perpendicular to IR
- enters patient on MCP at level of T7
• exposure made at end of second deep inspiration
Structures associated with the mediastinum
- heart
- great vessels
- trachea
- esophagus
- thymus
- lymphatics
- nerves
- fibrous tissue
- fat
What kV is used for chest x-ray?
110-130 with a grid
Up to 100 without a grid
Patient position for AP Chest
- supine or sitting upright
* used when patient is too ill for upright positions
Part position for AP chest
- Center MSP to IR
- top of IR 1 1/2 to 2 inches (3.8 to 5 cm above shoulders
- if patient condition permits, flex elbows, pronate hands, and place hands on hips to draw scapula laterally
- adjust shoulders into same transverse plane
Central ray(CR) for AP chest
- perpendicular to long axis of sternum and center of IR
* enters 3 inches (7.6 cm) below jugular notch
What is atelectasis
Collapse or part of the lung
Define COPD
Chronic obstructed bronchial airflow
Define tuberculosis
Tubercule bacillus
Define metastasis
CA transferred from one area to another
Define pleural effusion
Fluid in the pleural cavity
Define pneumonia
Acute infection
Define pneumothorax
Air in pleural cavity
Image evaluation of PA chest
• evidence of proper collimation
• entire lung fields from the apices to the costophrenic angles
• no rotation
- sternal ends of the clavicles equidistant from the vertebral column
- trachea visible in the midline
- equal distance from the vertebral column to the lateral border of the ribs on each side
• proper shoulder rotation demonstrated by scapulae projected outside the lung fields
• proper inspiration demonstrated by ten posterior ribs visible above the diaphragm. At least one less rib visible on expiration
• sharp outlines of the heart and diaphragm
• faint shadows of the ribs and superior thoracic vertebrae visible through the heart shadow
• lung markings visible from the hilum to the periphery of the lung
What cavity contains the heart and lungs?
Thoracic
Which structure separates the thoracic cavity from the abdominal cavity?
Diaphragm
Which part of the thoracic cavity contains all thoracic organs except the lungs and pleurae?
Mediastinum
Which bony structure forms the anterior border of the mediastinum?
Sternum
What mediastinal structure consists of C-shaped cartilaginous rings?
Trachea
What area of the trachea divides into two lesser tubes?
Carina
Which structures branch from the distal end of the trachea?
Primary bronchi
Which primary bronchus is shorter and wider than the other?
Right
What thoracic structures are the organs of respiration?
Lungs
What is the name of the medial aspect of each lung in which the primary bronchus enters?
Hilum
What is the name of the superior portion of each lung?
Apex
Which structures are at the terminal end of the respiratory system?
Alveoli
How many lobes are found in the right lung? Left lung?
Three in right and two in left
Which lung (right or Left) is shorter and broader than the other? Explain why.
Right, because of its close proximity to the liver and heart
With reference to the patient, where should the upper border of the IR/collimated field be placed?
About 1 1/2 to 2 inches (3.8 inches to 5 cm) above the top of the shoulders
What is the purpose of depressing the shoulders?
To keep the clavicles below the apices
Why should the shoulders be rotated forward?
To move the scapulae laterally away from the lung field
Which thoracic structures are of primary interest with the left lateral projection?
Heart and left lung
Which thoracic structure is of primary interest with the right lateral projection?
Right lung
