In recent months, several of my patients have asked for my opinion as a diagnostic radiographer regarding the benefits of having a CT scan, what to expect and preparation.
Of course, I already had an opinion on the subject. But I also conducted in-depth research to provide them with the most accurate and objective information.
You will find the links to the scientific publications I rely on at the end of the article!
Happy reading 🙂! Any comments, additional information or questions are welcome in the comments section!
▶️What does a CT scan stand for and what does it do?
A computed tomography (CT) scan, commonly referred to as a CT, is a radiological imaging study we use every day to detect diseases.
CT refers to a computerized x-ray imaging procedure in which a narrow beam of x-rays is aimed at a patient and quickly around the body, producing signals that are processed by the machine’s computer to generate cross sectional images.
The machine was developed by physicist Allan MacLeod Cormack and electrical engineer Godfrey Hounsfield (Petrik,2006)
The first scanners were installed in 1974. Since then, technological advances and math have allowed single images to be computed into two-dimensional informative images.
Image of a CT scan x-ray showing the whole CT scanning and control rooms. (source Huang
The CT scan is essentially an X-ray study, where a series of rays are rotated around a specified body part, and computer-generated cross-sectional images are produced
▶️What can CT scans detect that a mere plain x-ray could not detect: advantages
I always hear patients ask why a CT scan is better than a plan file x-ray.
🟠A CT (Computed Tomography) scan is often considered “better” than a standard 2D X-ray because it provides a much higher level of detail and a 3D perspective of the body’s internal structures
While a standard X-ray takes a single flat “shadow gram” where organs and bones are superimposed (meaning they overlap on top of each other), a CT scan captures a series of X-rays from many different angles
Here are some of the differences between a CT scan and a plain x-ray.
| CT scan | Plan X-ray |
| ⚫combines multiple X-ray images to create detailed cross-sectional views, or “slices,” of the body. | ⚫A standard X-ray takes a single flat “shadow gram” where organs and bones are superimposed |
| ⚫CT scans eliminate this overlap, making the exact size, shape, and position of abnormalities much clearer. | ⚫In a regular X-ray, dense bones (like ribs) can hide or obscure softer tissues (like the lungs). |
| ⚫CT scans can accurately image internal organs, muscles, and blood vessels all at once. | ⚫Standard X-rays are excellent for seeing clear bone fractures, but they struggle to differentiate between various soft tissues. |
| ⚫CT scans are vital in trauma situations, such as car accidents | ⚫X-ray can miss threatening issues such as internal bleeding, organ damage, or blood clots. |
| ⚫A CT scan can detect small “hairline” or complex fractures-such as those in the spine or facial bones | ⚫X-ray can fail to detect small fractures like in the spine . |
▶️Why can a CT scan be better for your diagnosis?
🟣With multiple x-ray images the doctor can look at internal organs layer-by-layer, just like looking at slices of a cake, rather than seeing everything flattened together.
🟣CT scans are vital in trauma situations, such as car accidents, because they can rapidly pinpoint life-threatening issues that an X-ray might miss, such as internal bleeding, organ damage, or blood clots.
🟣Contain detailed information about a specified area in cross-section, eliminating the superimposition of images, which provides a tremendous advantage over plain films.
🟣CT scans provide excellent clinicopathological correlation for a suspected illness
▶️In which situations would a doctor request for a CT scan
CT scans can be used to identify disease or injury within various regions of the body.
I have seen doctors request for CT scans in these situations:
♦️To help detect possible tumours or lesions within the abdomen.
♦️A CT scan of the heart may be ordered when various types of heart disease or abnormalities are suspected.
♦️Used to image the head to locate injuries, tumours, clots leading to stroke, haemorrhage, and other conditions.
♦️Image the lungs to reveal the presence of tumours, pulmonary embolisms (blood clots), excess fluid, and other conditions such as emphysema or pneumonia.
♦️Imaging complex bone fractures, severely eroded joints, or bone tumours since it usually produces more detail than would be possible with a plane x-ray.
Etc ……and so many other conditions, these are the ones I see every day in radiology.
▶️How long does a CT scan take
What you should know a CT scan (Computed Tomography scan) typically involves two timeframes:
1️⃣The actual imaging.
2️⃣The overall appointment
♦️Most CT scans we do typically take 10 to 30 minutes for the entire appointment.
♦️The actual imaging process is very fast, often taking less than 1 minute on modern machines. The total time you spend inside the scanner is usually between 5 and 15 minutes.
The actual imaging process usually takes less than 1 minute to only a few minutes.
However, the total time in the radiology department can extend to 1-2 hours if contrast dye is used, requiring prep and post-scan observation.
▶️Factors That Can Change the Duration of your scan to 1 to 2 hours
♦️If your scan requires contrast dye (a special “dye” to make images clearer), you may need to arrive early to drink it or receive it through an IV. Afterward, you might be asked to wait for 15–30 minutes to ensure you don’t have an allergic reaction.
♦️Depending on which body part is being scanned, larger areas or more complex regions (like a full abdominal or pelvic scan) naturally take longer to image than a simple head scan.
♦️Some scans may require your preparation like fasting for several hours or drinking oral contrast over a period of 60 minutes before the scan begins.
Here is an estimated total appointment times by area
| Scan type | Estimated total time. |
| Kopf / Gehirn | 10-15 minutes |
| chest | 15-20 minutes |
| Abdominal or pelvis | 20-30 minutes. |
| With oral contrast | 60-75 minutes |
That being said, most hospitals often prioritise emergency cases, so your appointment might be delayed if urgent trauma patients arrive.
▶️What will a CT scan detect?
CT scan is particularly effective at showing bones, internal organs, and blood vessels all at once.
Here are some of the diagnoses that I normally see being detected on a CT scan.
♐ Internal Organs:
A CT scan can detect diseases, tumours, cysts, infections, and inflammation in the liver, spleen, kidneys, pancreas, and intestines.
♐Bones:
For fractures such spine and tumours that cannot be detected on x-ray can be visualized on a CT scan with high detail.
♐ Blood Vessels & Heart:
CT scan can Identify coronary artery disease, blood clots, aneurysms, and plaque buildup.
♐ Brain & Head:
Can show bleeding (haemorrhages), skull fractures, strokes, tumours, and fluid build up.
♐Soft Tissues & Lungs: Identifies infections, injuries to organs, and lung disease
▶️Benefits of having a CT scan
🟤 Scans take only a few minutes, allowing doctors to rapidly assess life-threatening conditions like internal bleeding, stroke, or organ injury after trauma.
🟤Reduced Need for Surgery: By providing a precise look inside, CT scans often eliminate the need for exploratory surgery or invasive surgical biopsies.
🟤They help doctors pinpoint the exact location and size of tumours, which is critical for planning precise surgeries, radiation therapy, or monitoring how well cancer treatments are working.
🟤CT scans are a primary tool for monitoring how well treatments like chemotherapy are working by tracking changes in tumour size over time
So, when you are offered a CT scan do not hesitate to have one, this will make your treatment quicker.
▶️What should you not do before a CT scan?
Preparation varies depending on the type of scan (especially if it involves contrast dye), so always follow the specific instructions in your appointment letter
Here are some of the instructions we give patients when they come for a CT scan.
Eating and Drinking Restrictions:
🔴Do not eat solid foods for typically 2-4 hours before a scan if contrast dye is being used.
🔴Avoid caffeinated beverages (coffee, energy drinks) specifically before a cardiac CT scan, as caffeine can raise your heart rate and blur images.
🔴Do not have fizzy drinks if requested, as they can interfere with abdominal imaging
Check if you need to fast; scans without contrast often don’t require it. Unless told otherwise, drink plenty of water to help your kidneys process contrast dye later.
Metal and Clothing:
🔴Do not wear jewellery or clothing with metal (zips, snaps, underwired bras, or metallic buttons). Metal causes “streaking” on images, which can make them difficult for doctors to read.
🔴Do not wear makeup or lotions, if possible, as some contain microscopic metal particles that can interfere with the scan.
Wear loose, comfortable, metal-free clothes like sweatpants.
Medications and Medical History
🔴Do not stop regular medications unless explicitly told otherwise. However, certain drugs like Metformin (for diabetes) or NSAIDs may need to be paused for 48 hours if you are receiving contrast dye.
🔴Do not withhold health information: Always inform the staff if you are (or might be) pregnant, have kidney problems, or have had allergic reactions to iodine or seafood
▶️Why do doctors prefer CT scan over MRI?
Doctors typically do not “prefer” one over the other in a general sense; rather, they choose the scan that best answers a specific clinical question.
Why CT scans are Often Chosen First
🔴Speed: A CT scan is significantly faster, usually taking 5 to 10 minutes (with the actual imaging often lasting under a minute), whereas an MRI can take 30 to 60 minutes.
🔴Emergency Suitability: Due to their speed, CTs are the “gold standard” for emergencies like acute trauma, suspected strokes, or internal bleeding, where every second counts.
🔴Superior Bone Detail: CT scans provide much clearer images of complex bone fractures and skeletal structures compared to MRIs.
🔴Safety with Implants: Patients with metallic implants, pacemakers, or shrapnel often cannot have an MRI due to its powerful magnetic field, making CT the only safe option.
🔴 Lower Cost: CT scans are generally about half the price of MRIs, making them more accessible for routine screenings and diagnostic “workhorse” tasks.
🔴Patient Comfort: CT machines are typically a more open “donut” shape, which is less likely to trigger claustrophobia than the narrow, enclosed tube of an MRI.
▶️In which situations will an MRI scan be preferred?
While a doctor might start with a CT, they will often move to an MRI if they need to see
🔴Soft Tissue Detail: MRI is far superior for imaging the brain, spinal cord, nerves, ligaments, and tendons.
🔴 Cancer Differentiation: MRIs are better at distinguishing between healthy tissue and cancerous tumours
🔴 Zero Radiation: Unlike CT scans, which use X-rays, MRIs use magnetic fields and radio waves, making them safer for pregnant women and those needing frequent imaging.
……
We have come to the end of this article; hope I have made your knowledge clearer about a CT scan. Wishing you a quick recovery!🙋
📚Sources:
Petrik V, Apok V, Britton JA, Bell BA, Papadopoulos MC. Godfrey Hounsfield and the dawn of computed tomography. Neurosurgery. 2006 Apr;58(4):780-7; discussion 780-7. doi: 10.1227/01.NEU.0000204309.91666.06. PMID: 16575342.
Wu D, Wang G, Bian B, Liu Z, Li D. Benefits of Low-Dose CT Scan of Head for Patients With Intracranial Hemorrhage. Dose Response. 2020 Mar 6;19(1):1559325820909778. doi: 10.1177/1559325820909778. Erratum in: Dose Response. 2021 Mar 18;19(1):15593258211002755. doi:
Pasteur-Rousseau A, Souibri K, Fouassier D, Mehier B, Wong T, Paul JF. Le scanner thoracique injecté « triple-rule-out » a-t-il un intérêt dans le bilan des douleurs thoraciques aiguës pour éliminer le syndrome coronaire aigu, l’embolie pulmonaire et la dissection aortique ? [Benefits and drawbacks of CT scan as a triple rule-out exam in acute chest pain to exclude acute coronary syndrome, pulmonary embolism and aortic dissection]. Ann Cardiol Angeiol (Paris). 2023 Nov;72(5):101641. French. doi: 10.1016/j.ancard.2023.101641. Epub 2023 Sep 11. PMID: 37703710.
Huang Z, Zhao S, Leng Q, Hu S, Li Z, Song B. Container CT scanner: a solution for modular emergency radiology department during the COVID-19 pandemic. Diagn Interv Radiol. 2021 May;27(3):350-353. doi: 10.5152/dir.2021.20740. PMID: 33650498; PMCID: PMC8136529.