What Are X-Ray Markers? A New Student's Guide
What are lead letters?
Lead letters are small radiopaque markers that are used when taking x-rays to identify the side of the body being imaged. Radiopaque means they come up bright white on x-rays. There are two main letters, L and R, which stand for the left and right side of the body. They are usually placed immediately lateral to the area of interest.
Lead letters and x-ray markers mean the same thing. Other names you may come across are radiography markers, side markers, lead markers and more. You will notice I use lead letters and markers interchangeably on this site, they all mean the same thing.
Why do we use them?
Lead letters are a legal requirement of x-rays. They can be annotated on the image after they've been taken, but it is very important to build good habits around lead letter usage as a student. You should always do your best to ensure you use physical letters rather than post annotating them.
What are AP and PA markers?
You may have come across these terms in your studies. When starting placement, it is generally recommended to purchase one AP and one PA set of markers. AP markers are used when the x-ray beam hits the anterior (front) of the patient first, eg abdomen x-rays where the patient lies supine on the table and the detector is under the patient. PA markers are used when the beam hits the posterior (back) of the patient first, eg in chest x-rays where the patient stands facing the bucky, and the x-ray tube is behind them. PA markers are usually used in lateral x-rays, eg lateral chest or spine images, but this varies depending on the clinical site.
The easiest way to tell AP and PA markers apart is to see whether the letter appears the right way around when looking at the marker. AP markers look like normal letters. PA markers are back to front, so the L and R are backwards like this: ⅃ and Я. PA markers still show up the right way around on the actual image. You can use AP markers as PA markers and vice versa simply by flipping the marker, as all lead letters are inherently reversible. Most universities recommend getting a pair of each for less confusion and in case you lose one. Depending on your clinical site, you can use blue tack to stick the markers on the detector or patient.
It's important to use physical lead letters as a student. Get used to carrying your markers with you and using them for every image. You will start establishing a workflow for each patient, and it's easier to build good habits from the start rather than later.