The Radiography Instructor

We just wrapped up Week Three of the Fall semester. We spent the week learning and practicing Chest positioning. At first, chest positioning seems overwhelming, but here are a few basic rules to remember:

1. Always perform chest imaging sitting or standing, whenever possible. In an upright position the diaphragm will move farther down on inspiration, allowing the lungs to fully aerate. An upright position will also demonstrate any possible air/fluid levels in the pleural cavity.
2. For a PA projection, the central ray should enter the patient at midsagittal plane (MSP) and the seventh thoracic vertebrae (T7). You can use the hand-spread method to find T7, (place your pinky finger on C7 first, then spread your hand and your thumb should land close to T7). Double check your positioning by ensuring that the top of the image receptor and top of the light field are at least 1″ above the patient’s shoulders.
3. For a Lateral projection, the central ray should enter the patient at midcoronal plane (MCP) and T7. Raise the patients arms out of the lung fields. Don’t forget to rotate the patient slightly (roll right side anteriorly) to ensure the posterior ribs are aligned.
4. For an AP Portable projection, the central ray should enter the patient at MSP and mid-sternum. Don’t forget to add a caudal tube angle to prevent the clavicles from appearing raised, or lordotic. The angle of the tube should match the angle of the patient’s sternum. Again, don’t forget to double check that the image receptor is at least 1″ above the patient’s shoulders, and that you have light there as well.
5. For decubitus chest positions, the centering is exactly the same: MSP and T7 for a PA projection, MSP and mid-sternum for an AP projection. Remember, to rule out a pleural effusion, place the affected lung down. To rule out a pneumothorax, place the affected lung up. For example, to rule out a left pleural effusion, you should perform a left lateral decubitus. To rule out a right pneumothorax, you should also perform a left lateral decubitus. Remember to add a right or left marker, marking the lung side “up”, not the side patient is laying on.
6. Instruct the patient to raise their chin, and take in two big breaths, holding the second breath during exposure. The first breath is like a warm-up, allowing more air to be inhaled during the second breath, with less strain.

When critiquing your images, be sure you’ve included all lung anatomy from lung apices to costophrenic angles. If the patient is lateral, be sure you’ve included anterior and posterior lung tissue.

Assess for rotation by looking at the sternoclavicular joints; they should look symmetrical. If one clavicle is farther away from midline than the other, that shoulder is slightly pulled away from the image receptor. For example, if the right clavicle (at the SC joint) looks farther away from midline than the left, the right shoulder is slightly pulled away from the image receptor, and the patient is in a slight LAO.

Don’t forget to count 10 posterior ribs, indicating full inspiration.

Practice chest positioning concepts using several scenarios, and check your work using this KEY.

Keep up the great work – I believe in you!