This is an important topic that I feel we need to cover before moving any further in our chest X-ray series. I wish I had more time to learn from radiologic technologists (RT), the real pros. Here is my quick and dirty assessment of the image.
Rest In Peace. Don’t die, but just enjoy a relaxing moment today and marvel at how wonderful and amazing life has been. RIP for the rest of this talk will be used to remind us of rotation, inspiration, and penetration. I’m not sure this is coming out right.
Rotation refers to patient alignment for the exam. Is the patient centered? The easiest way radiologists are first taught is to look at the clavicles. They should appear relatively symmetric. We look at the clavicular heads which is the bump where it connects to the bone in the center of your chest/sternum.
While this patient may be rotated, it is entirely acceptable. This is a good exam. Reshooting an X-ray to correct for this degree of “rotation” would be inappropriate.
Inspiration reflects the patient’s lung expansion and breath hold capability. Remember chest X-rays can be done in the radiology department with a standard PA view or portably. The portable view generally does not enable a patient to have as good an inspiratory effort. Take a deep breath slouched in your couch. Now with good posture standing up straight and tall. Your chest can get much larger with your ribs elevating up and out as your lungs fully expand. As a resident I was taught being able to visualize 8-10 ribs was considered a good inspiration. Since your ribs curve they are higher posteriorly where they join to your spine and lower anteriorly near your front where they connect through cartilage to your sternum. Eight anterior ribs and/or ten posterior well-visualized ribs is the goal.
We already talked about how the heart will appear larger in size/cardiomegaly on portable chest X-rays. Well the blood vessels in the lungs look different too! With a small inspiration the vessels appear larger, more closely packed and crowded, and can seem a little more hazy overall. To inexperienced readers this gives the appearance of increased fluid in the lungs, so called pulmonary edema. So a portable chest can make the heart look bigger and the lungs appear to have more fluid. We’ve just described the findings of congestive heart failure (CHF), cardiomegaly with pulmonary edema.
So how can you tell the difference between CHF and a low inspiration? Well, I try to cheat as much as possible. I’m either stupid or smart, but I use whatever information I can obtain to help me out. If I am perplexed I grab my cell phone and text or call my colleague to discuss the case, but it usually doesn’t come to this. RTs can make or break a radiologist. We are a team. They always see the patient and I don’t get to see patient’s enough. I read every single RT note. They will often let me know if the patient has a history of CHF. In fact many outstanding technologists will relay pertinent clinical information that is extremely valuable to the appropriate interpretation of most X-rays, whichever body part.
Penetration refers to the appearance of the film. Is it too dark and burned out looking blackened? This is called overpenetrated. Is it too bright and the heart and mediastinum are all a bright white and it’s hard to separate the two? This is called underpenetrated.
The goal is to be able to see the lung markings/blood vessels well. But you must also be able to “see through” the heart following the contour of the aorta and able to detect the subtle behind the heart/retrocardiac pneumonia.
This is part of the art of radiography. Sure there are autotimers and preset technique settings for different body parts, but everyone is different. A bigger patient has more soft tissue which stops X-rays from getting to the plate/detector (used to be film) in which case the image will appear bright. So larger people require more radiation exposure/dose to obtain a similar appearing image to a smaller patient. Do not freak out. You probably had more radiation exposure on your last airplane flight than this small dose adjustment, seriously.
Radiologists can use their computers to adjust the brightness and contrast of an image, but you can only adjust the source material so much. So again, it is up to the radiologic technologist to ultimately acquire the best possible images. We work together as a team. As a patient, please be kind and do your best to work with the technologist when they adjust your position and ask you to TAKE IN A GOOD BREATH AND HOLD IT. They care about you and are trying to provide you the best healthcare possible.