Medical imaging is the process of creating visual representations of the body’s interior for diagnostic and treatment purposes. It encompasses various techniques that allow healthcare professionals to examine organs, tissues, and structures non-invasively.
Computed tomography (CT) and X-ray are both techniques that rely on ionizing radiation for imaging. However, key differences exist in use, resolution, image detail, and radiation exposure. Comparing the differences between CT and X-ray techniques highlights their unique strengths, helping patients understand why one modality may be preferred over the other in specific clinical situations.
A CT scan is a diagnostic imaging technique that uses X-rays and computer algorithms to generate detailed cross-sectional images of the body. The technology behind CT scans involves a rotating X-ray source and detectors that capture the attenuation of X-rays as they pass through various tissues1. These measurements are processed using advanced tomographic reconstruction techniques to produce virtual slices of the body for detailed analysis.
A CT scanner includes a motorized table that moves the patient through a circular device known as a gantry2. Within the gantry, the X-ray source and detectors rotate around the patient, often completing a full rotation in under a second. The detectors capture X-ray data from multiple angles, and a computer processes this data to construct cross-sectional images of internal structures.
.jpeg)
Skeletal Imaging
CT scans provide high-resolution images of the skeletal system, making them invaluable for2:
Acute Hemorrhage Detection
In cases of suspected internal bleeding, CT scans are the diagnostic tool of choice due to their rapid imaging capabilities3. They:
Thoracic Imaging
CT scans are highly effective for examining the lungs and chest, offering detailed imaging for4:
Oncological Uses
CT scans are critical in cancer diagnosis and treatment, particularly for5:
Additionally, CT scans are important for evaluating gastrointestinal bleeding. Techniques such as CT angiography and multiphase CT enterography are especially effective for diagnosing both active bleeding and other bowel conditions6,7.
X-rays are a form of high-energy electromagnetic radiation with wavelengths shorter than ultraviolet rays and longer than gamma rays8.
X-rays are produced when high-energy electrons interact with matter, converting their kinetic energy into electromagnetic radiation8,10. They have wavelengths ranging from 10 nanometers to 10 picometers. X-rays can penetrate many solid substances, including living tissue, which makes them valuable for imaging purposes.
The basic principle of X-ray imaging relies on the differential absorption of X-rays by various tissues in the body. Dense materials like bones absorb more X-rays and appear white on the image, while softer tissues absorb less and appear in shades of grey11.
X-rays have a wide range of applications:
Diagnostic imaging: X-rays are commonly used to detect bone fractures, examine chest conditions like pneumonia, and perform mammograms for breast cancer screening12.
Orthopedics: X-rays help diagnose and monitor arthritis progression in joints over time14.
Cancer detection and treatment: X-rays are used to identify bone tumors and guide radiation therapy for cancer treatment15.
Gastrointestinal studies: Barium X-rays are used to examine the digestive tract and identify issues like ulcers or tumors17.
Monitoring treatment progress: X-rays help healthcare providers track the effectiveness of treatments for various conditions over time.
While CT scans and X-rays are both important medical imaging techniques, they differ significantly in several aspects:
As previously mentioned, CT scans use multiple X-ray beams at different angles around the body, combining the images using a computer to create 3D cross-sectional views. X-ray imaging, however, uses a single beam of radiation to produce a 2D image of bones and some soft tissues.
CT scans provide significantly more detailed images compared to X-rays:
CT scans offer superior imaging capabilities, producing detailed 3D images that allow healthcare professionals to visualize internal structures from different angles4. They can detect subtle abnormalities and provide precise information about the size, shape, and location of tumors, lesions, and other conditions.
X-rays primarily provide 2D images suitable for bone-related conditions. They effectively diagnose fractures, dental issues, and lung infections but have limited capabilities in visualizing soft tissues and organs8.
Both CT scans and X-rays involve exposure to ionizing radiation, but the levels differ.
CT scans generally expose patients to higher levels of radiation. A CT scan may expose the patient to the radiation equivalent of 100-800 chest X-rays18. At Ezra, we use low-dose CT (LDCT) scans in our Full Body Plus scans. This improves safety while still being more effective than an X-ray19. Studies show that a small proportion of patients have high cumulative rates of multiple or repeat imaging, leading to a potentially heightened risk of developing cancer20.
X-rays use a lower level of radiation that is generally considered safe for most people. However, the cumulative radiation dose from multiple X-rays should not be ignored, especially in children with malignancies21.
The diagnostic capabilities of CT scans and X-rays vary based on their imaging characteristics.
CT scans are versatile and can capture images of various body parts, including soft tissues and organs. They are useful in evaluating complex conditions and providing valuable insights for treatment planning. CT scans are particularly effective for diagnosing conditions such as blood clots, brain injuries, cancer, internal bleeding, lung problems, and spinal cord injuries22.
X-rays are most suitable for bone-related conditions, pneumonia, and some chest conditions. They are commonly used to diagnose bone fractures, joint problems, pneumonia, and certain types of cancer23.
X-rays offer several significant benefits in medical imaging.
X-ray imaging is quick and widely available, making it a highly accessible diagnostic tool24:
X-rays are generally more affordable compared to other imaging modalities25.
X-rays provide clear images of dense structures like bones, making them ideal for diagnosing bone fractures and breaks, assessing joint problems and dislocations, and evaluating bone degeneration. Chest X-rays are also typically the first choice when evaluating the lungs and heart due to their speed and effectiveness26.
CT scans can provide a comprehensive view of internal structures of the body, imaging bone, soft tissue, and blood vessels simultaneously27. CT scans can also simultaneously image various body parts and structures with high precision, including bones, soft tissues, and blood vessels28. The ability to identify small abnormalities makes CT particularly effective for early cancer detection, especially in lung cancer screening.
Compared to conventional X-rays, CT scans offer superior detail, producing 3D cross-sectional images that eliminate overlapping structures. These detailed images allow for the precise identification of abnormalities and their exact location.
There are several reasons why CT might be preferred over an X-ray:
Choosing the right imaging technique between X-ray and CT scan depends on several factors.
X-ray is useful for imaging bone-related conditions like fractures, dislocations, and dental issues. It is also suitable for initial screening of chest conditions like pneumonia. CT scans are recommended for complex injuries, soft tissue damage, and conditions requiring detailed visualization of internal structures. CT is particularly useful for diagnosing cancer, cardiovascular diseases, neurological disorders, and abdominal conditions.
CT scans are often used in severe trauma cases as they can quickly asses internal injuries and detect internal bleeding. X-rays, however, expose patients to lower radiation doses compared to CT scans, making them more suitable for children or patients requiring frequent imaging.
CT scans provide more comprehensive images, allowing visualization of organs, blood vessels, and soft tissues. X-rays offer 2D images suitable for less complex diagnostic needs. X-rays provide faster results, making them ideal for initial screenings or situations requiring quick diagnosis.
The choice between CT and X-ray scans should be made in consultation with healthcare providers, taking into account the specific medical condition, patient factors, and diagnostic requirements.
A routine head CT scan delivers approximately 20 times more radiation than a chest X-ray. and a multiphase abdomen and pelvis CT scan can deliver about 310 times more radiation than a chest X-ray31.
LDCT significantly reduces this exposure by around 37%32,33! We use LDCT in our Full-Body Plus Scans to image your lungs. This allows us to use the best imaging method for your lungs while still maintaining safety.
CT scans provide significantly more detailed 3D images than X-rays, offering superior diagnostic capabilities by revealing internal structures with greater clarity. Unlike X-rays, CT scans can detect subtle findings such as blood clots, organ injuries, and bone fractures that might be invisible on traditional radiographs. CT technology creates 360-degree computerized views of the body's structures, making it ideal for emergency situations and providing physicians with rapid, comprehensive diagnostic information.
CT scans and X-rays are both indispensable tools in medical imaging, each offering unique advantages. While CT scans provide detailed 3D images for complex diagnoses, X-rays are quick, accessible, and cost-effective for simpler conditions. Choosing the right technique depends on the patient’s condition, the complexity of the issue, and the diagnostic requirements. Both methods play critical roles in modern healthcare, helping physicians deliver accurate diagnoses and effective treatment.
If you want to be proactive about your health, why not book an Ezra Full-Body Plus? We combine MRI with LDCT to catch abnormalities earlier, leveraging AI through the screening process to make it more efficient, affordable, and faster.
1. CT scan - Mayo Clinic. Accessed December 9, 2024. https://www.mayoclinic.org/tests-procedures/ct-scan/about/pac-20393675
2. Computed Tomography (CT). National Institute of Biomedical Imaging and Bioengineering. Accessed December 9, 2024. https://www.nibib.nih.gov/science-education/science-topics/computed-tomography-ct
3. Siddiqui FM, Bekker SV, Qureshi AI. Neuroimaging of Hemorrhage and Vascular Defects. Neurotherapeutics. 2011;8(1):28-38. doi:10.1007/s13311-010-0009-x
4. Bhalla AS, Das A, Naranje P, Irodi A, Raj V, Goyal A. Imaging protocols for CT chest: A recommendation. Indian J Radiol Imaging. 2019;29(3):236-246. doi:10.4103/ijri.IJRI_34_19
5. Computed Tomography (CT) Scans and Cancer Fact Sheet - NCI. January 3, 2024. Accessed July 16, 2024. https://www.cancer.gov/about-cancer/diagnosis-staging/ct-scans-fact-sheet
6. Wortman JR, Landman W, Fulwadhva UP, Viscomi SG, Sodickson AD. CT angiography for acute gastrointestinal bleeding: what the radiologist needs to know. Br J Radiol. 90(1075):20170076. doi:10.1259/bjr.20170076
7. Ilangovan R, Burling D, George A, Gupta A, Marshall M, Taylor SA. CT enterography: review of technique and practical tips. Br J Radiol. 2012;85(1015):876-886. doi:10.1259/bjr/27973476
8. X-rays. National Institute of Biomedical Imaging and Bioengineering. Accessed December 9, 2024. https://www.nibib.nih.gov/science-education/science-topics/x-rays
9. Babic RR, Stankovic Babic G, Babic SR, Babic NR. 120 YEARS SINCE THE DISCOVERY OF X-RAYS. Med Pregl. 2016;69(9-10):323-330. doi:10.2298/mpns1610323b
10. Short Wavelength X-Rays - an overview | ScienceDirect Topics. Accessed December 9, 2024. https://www.sciencedirect.com/topics/engineering/short-wavelength-x-rays
11. Mowery ML, Singh V. X-ray Production Technical Evaluation. In: StatPearls. StatPearls Publishing; 2024. Accessed December 12, 2024. http://www.ncbi.nlm.nih.gov/books/NBK564332/
12. X-ray. nhs.uk. October 18, 2017. Accessed December 12, 2024. https://www.nhs.uk/conditions/x-ray/
13. Radiology (ACR) RS of NA (RSNA) and AC of. Panoramic Dental X-ray. Radiologyinfo.org. Accessed December 12, 2024. https://www.radiologyinfo.org/en/info/panoramic-xray
14. Branch NSC and O. Rheumatoid Arthritis. National Institute of Arthritis and Musculoskeletal and Skin Diseases. April 20, 2017. Accessed December 12, 2024. https://www.niams.nih.gov/health-topics/rheumatoid-arthritis
15. Bone cancer and X-rays: Appearance and next steps. February 24, 2023. Accessed December 12, 2024. https://www.medicalnewstoday.com/articles/bone-cancer-xray
16. CDC. Facts About Fluoroscopy. Radiation and Your Health. February 27, 2024. Accessed December 12, 2024. https://www.cdc.gov/radiation-health/data-research/facts-stats/fluoroscopy.html
17. Radiology (ACR) RS of NA (RSNA) and AC of. Upper GI x-ray. Radiologyinfo.org. Accessed December 12, 2024. https://www.radiologyinfo.org/en/info/uppergi
18. US EPA O. Frequent Questions: Radiation in Medicine. December 4, 2023. Accessed December 12, 2024. https://www.epa.gov/radiation/frequent-questions-radiation-medicine
19. Kubo T, Ohno Y, Takenaka D, et al. Standard-dose vs. low-dose CT protocols in the evaluation of localized lung lesions: Capability for lesion characterization—iLEAD study. European Journal of Radiology Open. 2016;3:67. doi:10.1016/j.ejro.2016.03.002
20. Griffey RT, Sodickson A. Cumulative radiation exposure and cancer risk estimates in emergency department patients undergoing repeat or multiple CT. AJR Am J Roentgenol. 2009;192(4):887-892. doi:10.2214/AJR.08.1351
21. Radiology (ACR) RS of NA (RSNA) and AC of. Radiation Dose. Radiologyinfo.org. Accessed December 12, 2024. https://www.radiologyinfo.org/en/info/safety-xray
22. Radiology (ACR) RS of NA (RSNA) and AC of. Body CT. Radiologyinfo.org. Accessed December 9, 2024. https://www.radiologyinfo.org/en/info/bodyct
23. Mujoomdar M, Russell E, Dionne F, et al. Diagnosis of Fracture. In: Optimizing Health System Use of Medical Isotopes and Other Imaging Modalities [Internet]. Canadian Agency for Drugs and Technologies in Health; 2012. Accessed December 13, 2024. https://www.ncbi.nlm.nih.gov/books/NBK174863/
24. Phelan A, Broughan J, McCombe G, et al. Impact of enhancing GP access to diagnostic imaging: A scoping review. PLoS One. 2023;18(3):e0281461. doi:10.1371/journal.pone.0281461
25. Flores JP, Moreno-Koehler A, Finkelman M, Caro J, Strauss G. MA03.05 Cost Effectiveness Analysis of CT vs Chest X-Ray (CXR) vs No Screening for Lung Cancer (LC) in the PLCO and NLST Randomized Population Trials (RPTs). Journal of Thoracic Oncology. 2017;12(1):S354-S355. doi:10.1016/j.jtho.2016.11.392
26. Broder J. Imaging the Chest. Diagnostic Imaging for the Emergency Physician. Published online 2011:185-296. doi:10.1016/B978-1-4160-6113-7.10005-5
27. Singh R, Szczykutowicz TP, Homayounieh F, et al. Radiation Dose for Multiregion CT Protocols: Challenges and Limitations. AJR Am J Roentgenol. 2019;213(5):1100-1106. doi:10.2214/AJR.19.21201
28. Singh R, Szczykutowicz TP, Homayounieh F, et al. Radiation Dose for Multiregion CT Protocols: Challenges and Limitations. AJR Am J Roentgenol. 2019;213(5):1100-1106. doi:10.2214/AJR.19.21201
29. Radiology (ACR) RS of NA (RSNA) and AC of. Computed Tomography (CT) - Head. Radiologyinfo.org. Accessed December 9, 2024. https://www.radiologyinfo.org/en/info/headct
30. Clark RA, Towbin R. Abscess drainage with CT and ultrasound guidance. Radiol Clin North Am. 1983;21(3):445-459.
31. Smith-Bindman R, Lipson J, Marcus R. Radiation Dose Associated With Common Computed Tomography Examinations and the Associated Lifetime Attributable Risk of Cancer. JAMA Internal Medicine. 2009;169(22):2078-2086. doi:10.1001/archinternmed.2009.427
32. Shi HM, Sun ZC, Ju FH. Understanding the harm of low-dose computed tomography radiation to the body (Review). Exp Ther Med. 2022;24(2):534. doi:10.3892/etm.2022.11461
33. Simmons C, Milburn J. Impact of Low-Dose Computed Tomography on Computed Tomography Orders and Scan Length. Ochsner J. 2019;19(4):303-308. doi:10.31486/toj.19.0008
