Radiographics Positioning & Projections Terminology

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  • 0:01 Radiographic Position…
  • 0:30 Body Positioning
  • 2:50 Radiographic Projections
  • 5:05 Putting It All Together
  • 6:05 Lesson Summary
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Lesson Transcript
Instructor: Artem Cheprasov

Artem has a doctor of veterinary medicine degree.

When you have an x-ray taken, two important terms are used to describe how you are positioned and what kind of view or projection of the insides of your body is taken. This lesson introduces the basics of these two concepts.

Radiographic Position and Projection

If you stand next to a wall, you may have your side next to it, or your back, or your front next to it. This denotes your positioning relative to the wall.

If an arrow enters your body it may project from front to back, back to front, or side to side, depending on how it entered.

Remember these two examples for later as I introduce some of the core concepts of radiographic positioning and radiographic projections.

Body Positioning

Radiographic positioning refers to the way the body is placed, we call this general body position, or to the part of the body that's the closest to the image receptor, and we call this specific body position. The image receptor (IR) is a device, such as x-ray film or digital acquisition device, that captures and then helps transform the x-ray beam into a visible image. So, as I just said, radiographic positioning can refer to a general body position or a specific body position.

By general body position, I mean quite simply, it's the way the body is positioned in general! Is the person supine (lying on the back, facing up)? Or are they prone (lying on their stomach, facing downward)?

Supine and Prone Positions

Are they in a lithotomy position (lying on their back with their knees up) or in a Trendelenburg position?

Trendelenburg Position
Trendelenburg Position

But radiographic positioning can also refer to specific body positions. A specific body position describes the body part closest to the IR or the body surface on which the patient lies.

Let's pretend the IR is a wall, if you stand with your left shoulder and left hip pressed against the wall, that is known as the erect left lateral position where lateral means pertaining to a side. On the flip-side, if I say you are in the erect right lateral position, then which side of your body is nearest the wall? The right side, of course!

Okay, so that was really easy; let's build on that, then. When I say the word decubitus, I mean lying down. So, based on what you've learned, if I say the position is right lateral decubitus, what's going on?

Well, lateral means 'side' and decubitus means 'lying down.' This means the patient is lying down on the right side. We can also call this position the recumbent right lateral position, because recumbent means lying down, as well. If I say left lateral decubitus, then the patient is lying down on the left side.

Again, this terminology may indicate the body's position when the x-ray is taken or the part of the body that's closest to the x-ray film. Sometimes they're equivalent and other times they're not. I'll explain how so, after we go over radiographic projections.

Radiographic Projections

For now, what I want you to know is that not all radiographic positioning terminology has to do with body positions. Sometimes, they have to do with radiographic projections, the path the x-ray beam takes through the body. Before I go further, clinically, you may hear the word projection and position being used interchangeably but I will be delineating them for you here as separate concepts because they're not truly the same.

Position refers to the placement or the position of the body as per the last section. Projection refers to the way the x-ray beam, like an arrow, passes through the body when the person is in that position. Remember, that arrow can pass through and project front to back, back to front, side to side, and so forth.

Like that arrow, the x-ray beam can pass through your body in many different directions as well. Front to back, back to front, side to side, etc., depending on how it's aimed. We have names for these paths. If the name of the projection combines two terms into a single word, then the term that comes first is the aspect of the body the x-ray beam passes through first. The IR is located on the side where the x-ray beam exits the body.

An anteroposterior projection (AP) passes from the front (anterior) of the person and exits through the back (posterior) of the person. This means the IR is located behind the person's back.

In the posteroanterior projection (PA), the x-ray beam enters the back of the person and exits the front of the person. This means the IR is in front of the person.

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