a special program of the National Emergency Medicine Association (NEMA)
Transcripts: 502-1 to 502-4
Week: 502.1 Guest: Pat Sauer, B.S., R.T. (R,CT). Topic: CAT Scans- Part One Host: Richard Roeder Producer: Ed Graham
NEMA: This is a four part series on CT scans and what to expect if you're having one. My guest is CT Technologist Pat Sauer.
NEMA: Pat, what does the CT in the term CAT scan stand for and what is the difference between a CT scan and a CAT scan?
SAUER: There's absolutely no difference at all. CAT which was the original term stands for Computerized Axial Tomography. Tomography means x-rays while the x-ray tube is in motion, computerized - obviously they use x-rays in conjunction with a computer, and axial referred to the plane in the body. There's three planes in the body and it referred to the axial plane and that's how they took their slices, their images. As CT became more advanced and able to do more and more things, it also became able to image patients in other planes in the body so the powers that be decided for authenticity to sort of drop the "A," the axial plane because things are now done in multiple planes, tangential, axial, coronal and sagittal.
NEMA: You just made a very interesting distinction about the x-ray tube being in motion. That obviously differs from conventional x-rays. How does this machine function and why is it important to have that in motion?
SAUER: Tomography's been in use in x-ray for years. There are special x-rays they still use called tomograms and they are x-rays taken while the x-ray tube moves back and forth or in some sort of circular motion to blur our planes above and below so CT borrowed that name from conventional radiography. CT basically works with an x-ray tube that travels in a circle around the body emitting a very fine beam the entire time and that beam traverses the body and hits a detector, one of many detectors on the opposite side. Then those detectors take that analog, that x-ray radiation information translated into digital or computer talk, put it into a computer and the computer puts together all those little bits of information while the tube has traveled the whole way around and gives you a computer image out on a screen and if you imagine whatever part of your body is going to be scanned as a loaf of bread, just kind of think of the trunk of your body as being a loaf of bread, we create slices and sort of pull out using the computer each slice and look at it and then pull out the next one so it gives you a cross-sectional image.
NEMA: There's a term that is actually, compared to many decades ago, it's very rarely heard anymore and that term is exploratory surgery. Things like CT scans had a lot to do with that, didn't it?
SAUER: It sure did. One of the things you had before was very limited ability to see what was going on especially inside the abdomen. You've got all the organs and everything just kind of mushed in there together and what we're doing now is looking inside for them and we're giving them a clear picture of the anatomy one slice at a time.
NEMA: Join me for part two on CT scans with Pat Sauer.
Week: 502.2 Guest: Pat Sauer, B.S., R.T. (R,CT). Topic: CAT Scans- Part Two Host: Richard Roeder Producer: Ed Graham
NEMA: This is part two in a four part series on CT scans and what to expect if you're having one. My guest is CT Technologist Pat Sauer.
NEMA: What are some of the medical conditions that CT scanning seems to be most appropriate in diagnosing?
SAUER: You name it. We'll scan for it and probably do it very well. One of the most often used acute reasons or emergent reasons is in patients who have had strokes. By the doctor's exam, the patient appears to have had a stroke. A number of things could have happened that will appear the same way. The patient could have a blood vessel rupture or a tumor in their head or a stroke which is basically when a blood vessel blocks off and the brain can't get blood anymore and they all appear the same way but they're treated very very differently and the biggest thing is if a patient appears to have had a stroke, have they had a bleeding-type stroke where the brain is not getting the blood because the blood's just bleeding out or have they had what's known as an embolic stroke where the blood vessel blocks off. They're going to be treated exactly opposite. One you might give blood thinners. One you might do surgery or certainly wouldn't give blood thinners if a patient's bleeding and CT can answer that question very rapidly. Very easy, quickly with virtually no trauma to the patient at all. So we're used quite extensively right off the bat on patients who come in with symptoms of a stroke. Probably second on the list would be looking at things in the abdomen. Whether it's from trauma and they want to see if an organ has ruptured or a patient's just having abdominal pain or vague symptoms, we're used extensively for the abdomen. Metastatic workup - a patient has a known cancer. Before they decide to treat this patient and need to know how to treat this patient, they need to know exactly how far that cancer has gone both in the primary site or has it spread to other organs.
NEMA: How much detail, when you mention something like metastatic use, how much detail can you determine in terms of cancer showing up in a different area? How small can that cancer be or is that entirely dependent on the location? Is it on the surface of the liver? Is it inside the liver, etc. or can you be extremely accurate about spotting very small masses?
SAUER: Yes and no. A lot of it is dependent not only on size but on the type of cancers. Some cancers show up better - as I'm sure you know different cancers go to different places. It depends on where they go. It depends on what kind of cancer it is. If it's a lesion amenable to be seen on CT, we can see them as small as a couple millimeters. They use CT a lot in chest cancer, lung cancer looking for small lesions, looking for spread to the medius thynum which is where all the great vessels in the heart are located. We look a lot in the liver looking for different lesions in the liver and we can pick up very very small lesions.
NEMA: Join me for part three on CT scans with Pat Sauer.
Week: 502.3 Guest: Pat Sauer, B.S., R.T. (R,CT). Topic: CAT Scans- Part Three Host: Richard Roeder Producer: Ed Graham
NEMA: This is part three in a four part series on CT scans. My guest is CT Technologist Pat Sauer.
NEMA: There certainly are people listening to us who either know they're going to have a scan or know someone who is in their family. Would you walk us through just the basics, the basic procedure of receiving a CAT scan and first, what kind of preparation does the patient have to make in the days or hours leading up to the procedure?
SAUER: For most of the scans, there's virtually no preparation. For our purposes, the only thing we ask is patients that are having their abdomens scanned, we don't let them have anything to eat or drink for a couple hours prior to the scan because we don't want food in their stomach. The reason we don't want food in their stomach is we give them a lovely drink prior to the scan. That drink is usually an iodinated contrast mixed in Coke or Kool-Aid or whatever or a barium contrast to fill up their stomach and their whole G.I. tract and the reason we do that is to change the stomach and the G.I. tract so that as we scan through we can see exactly where one organ ends and where the other one begins. That's really the only test that there's going to be any preparation for.
NEMA: Now you mentioned this contrast medium. You also sometimes need to use an injectible contrast medium. Would you just briefly explain what that does and why it's important for you to have that during the procedure.
SAUER: It's an iodine contrast. It's x-ray dye. Most people are familiar with x-ray. X-ray dye has been around forever and although it's been improved, it's still basically the same dye. It's an unbound iodinated contrast. The injected dye does not replace the oral contrast, the stuff you have to drink. They don't do anything with each other. The injected dye will show us certain organs better that are very vascular organs. They show us the blood vessels themselves. They enhance certain tissues. They help us see things like the kidneys and the bladder better. There are some tests that this helps an order of magnitude to see it better but as anything with CT, it's not all or nothing. There are many patients out there who are allergic to iodine. You can still do the test without the iodine.
NEMA: Now, kind of walk us through the basics of the actual procedure. Let's take a typical environment - a non-emergency situation where someone comes in because of abdominal problems and you need to do a complete abdominal workup with the CT. What is involved? What do they do? Where do they lie down or stand up and what happens?
SAUER: Once we've given you our lovely breakfast which may consist of two or three different milkshake-size cups over a period of time, we take you in the room and it looks almost like an x-ray table that at one end will go through this giant doughnut kind of affair. It's very open. A lot of people think it's a long tunnel or a tube and are pleasantly surprised when they get there. It's very open. You lie on the table. We may or may not start an IV if we have to give you the iodine and the table moves.
NEMA: Join me for part four on CT scans with Pat Sauer. Transcripts:
Week: 502.4 Guest: Pat Sauer, B.S., R.T. (R,CT). Topic: CAT Scans- Part Four Host: Richard Roeder Producer: Ed Graham
NEMA: This is part four in a four part series on CT scans and what to expect if you're having one. My guest is CT Technologist Pat Sauer.
SAUER: It's very open. You lie on the table. We may or we may not start an IV if we have to give you the iodine and the table moves. We move the table in or out depending on where we're going to go.
NEMA: About how long, the procedure we were using hypothetically, the abdominal workup, on the average how long does that take, the total procedure, assuming everything goes smoothly the first time through?
SAUER: Depending on the scanner you have, the scanner that I use primarily, we can complete an exam in about 20 minutes. Some of them that are not quite that fast, some of the older scanners that use - I was talking about scanning time, you use two second scanning time and things like that - can take up to about 45 minutes but it shouldn't take any longer than that.
NEMA: Is a CT scanner noisy?
SAUER: No. You'll hear some whirring in the tube. You'll hear the tube move around.
NEMA: Again the distinction. When you say the "tube," you explained a minute ago there is not tube the body goes in. You mean the x-ray tube.
SAUER: The x-ray tube that's inside this big doughnut kind of affair that goes in that full circle around you. You can hear it go around so you can kind of hear the motor wind up and you hear a light whir but it's not noisy.
NEMA: It's not the famous long tunnel and the rapping noise that is MRI.
SAUER: Exactly. Exactly. Compared to that it's much quieter. It's quiet enough that you could go to sleep if it weren't for the fact that I would be hollering at you to hold your breath and breathe and hold your breath and breathe through a microphone.
NEMA: How soon after the procedure is completed can results be interpreted or does that depend on what personnel is present at the time?
SAUER: Generally what happens is once the scan is completed, the technologist then does all the imaging on film because when it's completed all you have is that computer data in the computer and they pull that computer data back out of the computer and image it off the screen one at a time. They have to develop the film. They get it ready for the doc and I mean in theory it's pretty much ready within the hour, depending on how complex. There are cases that we have to go back long after the patient's gone, like some complicated orthopedic cases and take the data that we already have and stack it back up and cut it in other directions.
NEMA: So this is something that due to the fact it's digitized information, it can be rotated and sliced into different thicknesses.
SAUER: It can be rotated. It can be cut. It can be slanted. It can be looked at it at a different angle. In fact it can even be stacked up back together and three dimensional images can be made out of it and you can then rotate it in real time which is where you're rotating it as you're looking at it and you've got it stacked up so you're actually looking at like a skeleton again.
NEMA: How much radiation exposure does a person get from receiving a CAT scan that may last 20 minutes?
SAUER: Even though it seems like a lot and the x-ray tube's on a lot and gee, it's a long time and I'm being radiated so much, you really probably on a normal scan don't get any more than you would on two views of a chest x-ray - a front view and a side view.