A CT (computed tomography) scan, also called a CAT (computed axial tomography) scan, is a diagnostic exam used to detect tumors, determine the stage and location of a cancer, check the effectiveness of cancer treatment, or guide a biopsy (the removal of a small amount of tissue for examination).
Listen as Peter Loud, MD walks you through a typical day for patients and what you can expect when undergoing a CT scan.
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What to Expect When Getting a CT Scan
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Learn more about Peter Loud, MD
Peter Loud, MD
Peter Loud, MD, is the Vice Chair of Diagnostic Radiology and Director of Body Imaging at Roswell Park Comprehensive Cancer Center.Learn more about Peter Loud, MD
Transcription:
What to Expect When Getting a CT Scan
Bill Klaproth (Host): A CT scan is often used for examining the head, chest, abdomen and pelvis. It is also used in detecting different types of cancer and patients with severe injuries. So, if you need a CT scan, what should you expect? With us is Dr. Peter Loud of Roswell Park Comprehensive Cancer Center. Dr. Loud, thanks for your time. So, first off, how is a CT scan different from an x-ray?
Dr. Loud (Guest): Well, it’s good to be with you. A CT scan is an x-ray study but it’s done in a different way than, say, a chest X-ray or a picture of your arm or your leg if you have trauma. This is done as a cross-sectional study and CAT scans are a very commonly performed study, one of many imaging tests used in radiology. The name CAT scan has nothing to do with cats; it goes back to the original acronym of the study which is “computed axial tomography”. What’s involved with a CAT scan, basically, you will come in and lay on a table and as the table moves through the CAT scanner, the scanner spins around your body and creates a cross-sectional image, kind of like you’re slicing your body like a loaf of bread. These can be reconstructed into three-dimensional images and can allow a very accurate evaluation of organs and disease in the body.
Bill: So, it really gives you a better view of what’s going on inside because you are able to look at it from different angles and kind of get a cross-sectional diagram of what’s happening inside the body?
Dr. Loud: Yes, it’s an excellent study and it’s actually increased tremendously in its use over the last couple of decades. I’m sure many of your listeners have either had a CAT scan or have a friend or relative who’s had a CAT scan. But it’s a very important test and, as you mentioned, there are many uses for a CAT scan. Certainly, it can be using it in the emergency room, in patients with trauma or some acute chest or abdominal injury or neurologic problems, but it’s also very important in oncology which is my area of interest. CAT scans are frequently performed both for diagnosis but also for follow-up with patients during and after their treatment.
Bill: So, afterwards you’ll do a CT scan to see if the procedure taken or if there is a cancer in the body to see if the cancer is being reduced, et cetera, so you kind of use it as a follow-up as well.
Dr. Loud: Right. Yes. So, if you’ve had surgery, you want to make sure that there’s no recurrence of disease, or if you’re having an oncology treatment like chemotherapy or radiation, you want to see that that’s having an effect in shrinking the tumor; if there’s growth, then you might change your treatment strategy.
Bill: Dr. Loud, you mentioned that the patient does get scanned in a tube, but this tube isn’t as large as an MRI tube, correct?
Dr. Loud: Yes. I wouldn’t describe it as a tube at all. The scanner is probably about a foot and a half wide with a large hole that the patient moves through, so it’s not as confining as a typical MRI that your patients may be aware of. That is more of a tube arrangement and uses a very different type of physics. Whereas CAT scanners use X-rays, MRI uses a very powerful magnet which aligns the molecules in your body and a radio signal is sent into the body which then can create data which is analyzed back into a cross-sectional image.
Bill: And, is there anything in general that a person may find uncomfortable with a CT scan?
Dr. Loud: Well, there is a variable preparation. So, if someone is just having a scan maybe in the ER for trauma they’ll go right on to the scanner, but if you’re having an elective study that your doctor may order, there may be different preparation. So, if you’re having a CAT scan of your abdomen or pelvis, you’ll typically have to drink some material and that can take about 45 minutes or an hour to work its way through your GI tract. Many CTs utilize an IV contrast agent which is injected during the scan, so you’ll have to come in a little earlier to get an IV placed, but generally the scan itself is quite quick.
Bill: And when you say quite quick, how long is that, generally? How long does a CT scan take?
Dr. Loud: Right. Well, patients are typically done with the scan itself in under five minutes. As I said, the preparation may take some time, but once you’re on the table, given instructions, you’ll typically be done in a minute or less. Scanners have become very quick over recent years, as well as being more accurate and having a lower radiation dose, as well.
Bill: And, how soon should a patient expect to see results from their CT scan?
Dr. Loud: Well, the CAT scan images are transmitted electronically right to a radiologist’s workstation and they’ll be interpreted there. Depending on how much time it may take to correlate with prior studies and with clinical history, the report will generally be interpreted within an hour or so and then sent electronically to the referring physician.
Bill: So, Dr. Loud, what’s the difference between an MRI and a CT scan? As I think there is some confusion.
Dr. Loud: Yes, as I said, there are many imaging techniques in radiology. CAT scan, MRI are common ones you think of, but other things like ultrasound have different utilities. So, if you’re looking for a gall stone, for instance, or looking at the ovaries in a female patient, ultrasound would be a great test for that. MRI is particularly useful in imaging the brain and spine but has other uses for musculoskeletal system and the chest or abdomen. CAT scan is the most widespread imaging study for looking at the internal organs just because it’s very commonly available; the quality is excellent these days; and, as I said, it’s a quick scan, and gives very excellent results.
Bill: And, is there any danger from radiation or anything like that?
Dr. Loud: Well, like with an x-ray study, there is radiation involved. And, as CAT scans have increased in frequency, there is more radiation to the public and that’s certainly been a concern. I think patients should generally be comforted that if the study is ordered for appropriate reasons, then the benefits far, far outweigh the minimal risks of radiation that’s involved. Obviously, you don’t want to have a test that’s unnecessary, and if there’s concern about radiation, your doctor yourself can speak with the radiologist and try and determine the best study for the particular problem that your doctor is concerned about.
Bill: Dr. Loud, thanks for your time today. For more information about a CT scan, visit www.Roswellpark.org. That’s www.Roswellpark.org. You’re listening to Roswell Park Cancer Talk. I’m Bill Klaproth. Thanks for listening.
What to Expect When Getting a CT Scan
Bill Klaproth (Host): A CT scan is often used for examining the head, chest, abdomen and pelvis. It is also used in detecting different types of cancer and patients with severe injuries. So, if you need a CT scan, what should you expect? With us is Dr. Peter Loud of Roswell Park Comprehensive Cancer Center. Dr. Loud, thanks for your time. So, first off, how is a CT scan different from an x-ray?
Dr. Loud (Guest): Well, it’s good to be with you. A CT scan is an x-ray study but it’s done in a different way than, say, a chest X-ray or a picture of your arm or your leg if you have trauma. This is done as a cross-sectional study and CAT scans are a very commonly performed study, one of many imaging tests used in radiology. The name CAT scan has nothing to do with cats; it goes back to the original acronym of the study which is “computed axial tomography”. What’s involved with a CAT scan, basically, you will come in and lay on a table and as the table moves through the CAT scanner, the scanner spins around your body and creates a cross-sectional image, kind of like you’re slicing your body like a loaf of bread. These can be reconstructed into three-dimensional images and can allow a very accurate evaluation of organs and disease in the body.
Bill: So, it really gives you a better view of what’s going on inside because you are able to look at it from different angles and kind of get a cross-sectional diagram of what’s happening inside the body?
Dr. Loud: Yes, it’s an excellent study and it’s actually increased tremendously in its use over the last couple of decades. I’m sure many of your listeners have either had a CAT scan or have a friend or relative who’s had a CAT scan. But it’s a very important test and, as you mentioned, there are many uses for a CAT scan. Certainly, it can be using it in the emergency room, in patients with trauma or some acute chest or abdominal injury or neurologic problems, but it’s also very important in oncology which is my area of interest. CAT scans are frequently performed both for diagnosis but also for follow-up with patients during and after their treatment.
Bill: So, afterwards you’ll do a CT scan to see if the procedure taken or if there is a cancer in the body to see if the cancer is being reduced, et cetera, so you kind of use it as a follow-up as well.
Dr. Loud: Right. Yes. So, if you’ve had surgery, you want to make sure that there’s no recurrence of disease, or if you’re having an oncology treatment like chemotherapy or radiation, you want to see that that’s having an effect in shrinking the tumor; if there’s growth, then you might change your treatment strategy.
Bill: Dr. Loud, you mentioned that the patient does get scanned in a tube, but this tube isn’t as large as an MRI tube, correct?
Dr. Loud: Yes. I wouldn’t describe it as a tube at all. The scanner is probably about a foot and a half wide with a large hole that the patient moves through, so it’s not as confining as a typical MRI that your patients may be aware of. That is more of a tube arrangement and uses a very different type of physics. Whereas CAT scanners use X-rays, MRI uses a very powerful magnet which aligns the molecules in your body and a radio signal is sent into the body which then can create data which is analyzed back into a cross-sectional image.
Bill: And, is there anything in general that a person may find uncomfortable with a CT scan?
Dr. Loud: Well, there is a variable preparation. So, if someone is just having a scan maybe in the ER for trauma they’ll go right on to the scanner, but if you’re having an elective study that your doctor may order, there may be different preparation. So, if you’re having a CAT scan of your abdomen or pelvis, you’ll typically have to drink some material and that can take about 45 minutes or an hour to work its way through your GI tract. Many CTs utilize an IV contrast agent which is injected during the scan, so you’ll have to come in a little earlier to get an IV placed, but generally the scan itself is quite quick.
Bill: And when you say quite quick, how long is that, generally? How long does a CT scan take?
Dr. Loud: Right. Well, patients are typically done with the scan itself in under five minutes. As I said, the preparation may take some time, but once you’re on the table, given instructions, you’ll typically be done in a minute or less. Scanners have become very quick over recent years, as well as being more accurate and having a lower radiation dose, as well.
Bill: And, how soon should a patient expect to see results from their CT scan?
Dr. Loud: Well, the CAT scan images are transmitted electronically right to a radiologist’s workstation and they’ll be interpreted there. Depending on how much time it may take to correlate with prior studies and with clinical history, the report will generally be interpreted within an hour or so and then sent electronically to the referring physician.
Bill: So, Dr. Loud, what’s the difference between an MRI and a CT scan? As I think there is some confusion.
Dr. Loud: Yes, as I said, there are many imaging techniques in radiology. CAT scan, MRI are common ones you think of, but other things like ultrasound have different utilities. So, if you’re looking for a gall stone, for instance, or looking at the ovaries in a female patient, ultrasound would be a great test for that. MRI is particularly useful in imaging the brain and spine but has other uses for musculoskeletal system and the chest or abdomen. CAT scan is the most widespread imaging study for looking at the internal organs just because it’s very commonly available; the quality is excellent these days; and, as I said, it’s a quick scan, and gives very excellent results.
Bill: And, is there any danger from radiation or anything like that?
Dr. Loud: Well, like with an x-ray study, there is radiation involved. And, as CAT scans have increased in frequency, there is more radiation to the public and that’s certainly been a concern. I think patients should generally be comforted that if the study is ordered for appropriate reasons, then the benefits far, far outweigh the minimal risks of radiation that’s involved. Obviously, you don’t want to have a test that’s unnecessary, and if there’s concern about radiation, your doctor yourself can speak with the radiologist and try and determine the best study for the particular problem that your doctor is concerned about.
Bill: Dr. Loud, thanks for your time today. For more information about a CT scan, visit www.Roswellpark.org. That’s www.Roswellpark.org. You’re listening to Roswell Park Cancer Talk. I’m Bill Klaproth. Thanks for listening.