What is the Difference Between CT Scan and Ultrasound

CT scan and ultrasound are two different medical imaging techniques. Medical imaging techniques allow medical professionals to visualize the inside of the body.

The key difference between CT scan and ultrasound is their technique. CT scan utilizes X-rays and computer technology to create cross-sectional images of the human body while ultrasound utilizes high-recurrence sound waves to make pictures of designs inside the human body.

CONTENTS

1. Overview and Key Difference
2. What is a CT Scan  
3. What is an Ultrasound
4. Similarities – CT Scan and Ultrasound
5. CT Scan vs Ultrasound in Tabular Form
6. Summary – CT Scan vs Ultrasound
7. FAQ: CT Scan and Ultrasound

What is CT Scan?

CT scan stands for Computerized Tomography Scan. It uses X-rays and computer technology to create cross-sectional images of the human body. During a CT scan, the patient lies down on a table. This table slowly slides through the gantry, which is the circular part of the CT machine. Beams of X-rays that flow through the gantry are aimed at the human body. These beams rotate axially as the scan moves down the patient’s body. Ultimately, these signals are sent to the machine’s computer, and this generates cross-sectional images of the human body.

Figure 01: CT Scan

Furthermore, CT scans offer the advantage of a short study time while producing high-quality images. However, the disadvantages of this technique include the need for radiation exposure and the use of contrast dye, which is unsuitable for patients with significant kidney problems.

What is Ultrasound?

Ultrasound uses high-recurrence sound waves to create pictures inside the human body. There are two categories of ultrasound: diagnostic and therapeutic. Diagnostic ultrasound uses sound waves to create images of the body while therapeutic ultrasound uses sound waves to modify or destroy tissue. Transducers, or ultrasound probes in the ultrasound produce sound waves that cannot be heard by human ears. During an ultrasound procedure, a gel is applied to the skin. Later, the ultrasound waves move from the transducer, through the gel, into the human body.

Figure 02: Ultrasound

Moreover, the advantages of ultrasound are that it does not use ionizing radiation and makes high-quality images. However, ultrasound is not effective at getting images of body parts that have gas in them or are hidden by bone, such as lungs or the head.

Similarities Between CT scan and Ultrasound

1. CT scan and ultrasound are two different medical imaging techniques.
2. Both techniques are only available in hospitals.
3. These techniques are only used by medical professionals.
4. Both techniques have pros and cons.

Difference Between CT scan and Ultrasound

Definition

1. CT scan uses X-ray to create cross-sectional images of the human body.
2. Ultrasound uses high-recurrence sound waves to make pictures inside the human body.

Usage

1. CT scans are used to image soft tissue, bone, and blood vessels.
2. Ultrasounds are used to diagnose internal organs and in prenatal care and therapeutics.

Time Taken

1. CT scan takes less time (5 minutes).
2. Ultrasound takes a comparatively longer time (15 minutes).

Cost

1. CT scans cost more.
2. Ultrasounds cost less.

Risk of Radiation

1. CT scan has a high risk of radiation.
2. Ultrasound has no risk of radiation as there is no usage of radiation.

Advantages

1. CT scan provides more detailed images and can detect very small abnormalities.
2. Ultrasound has no risk of radiation as there is no usage of radiation, and it is comparatively cheap.

Disadvantages

1. 1. CT scan has a risk of radiation, and it also uses a contrast dye material, which is unsuitable for patients with significant kidney problems.
   2. Ultrasound takes comparatively longer time to complete the procedure and it is not effective at getting images of body parts that have gas in them or are hidden by bone, such lungs or head.

Summary – CT scan vs Ultrasound

The medical imaging technique is a type of test that makes detailed pictures of areas inside the body. CT scan and ultrasound are two different medical imaging techniques. CT scan uses X-ray to make detailed pictures of areas inside the body, while ultrasound uses sound waves to make detailed pictures of areas inside the body. CT scans provide more detailed images and can detect very small abnormalities, whereas ultrasound creates clear images with quick turnaround, has no risk, and is often a lower-cost technique. This summarizes the difference between CT scan and ultrasound.

FAQ: CT scan and Ultrasound

1. What does a CT scan test for?

1. 1. • CT scans or computerized tomography scans can be used to identify disease or injury within various regions of the human body. For example it is very useful in screening possible tumors or lesions within the abdomen. Moreover, a CT scan of the heart may be ordered when various types of heart disease or abnormalities are suspected.

2. What diseases can a CT scan detect?

1. 1. • A CT scan can be used to diagnose various diseases such as heart disease, blood clots, and bowel disorders like appendicitis, diverticulitis, blockages, Crohn’s disease, and kidney stones.

3. What are the side effects of CT scan?

1. 1. • There are complications of a CT scan. Some people who have an injection of iodinated contrast material may feel nauseous for a short time afterwards. On rare occasions, a person may have an allergic reaction to this substance. Further, CT scan also have risk of radiation exposure as well.

4. What are the main uses of ultrasound?

1. 1. • The ultrasound is used for many reasons which including, view the uterus and ovaries during pregnancy and monitor the health of developing baby, diagnose gallbladder disease, evaluate blood flow, guide a needle for biopsy or tumor therapy, examine a breast lump, check the thyroid gland, find the problems of genital and prostrate and assess joint inflammation.

5. What are the negative effects of ultrasound?

1. 1. • Unlike some other scans, such as CT scans, ultrasound scans don’t involve exposure to radiation. However, some studies have reported effects of exposure to diagnostic ultrasound during pregnancy, such as low birth weight, delayed speech, dyslexia, and non–right-handedness.

Reference:

1. “CT Scan.” Mayo Clinic, Mayo Foundation for Medical Education and Research.
2. “Ultrasound Scan.” NHS Choices, NHS.

Image Courtesy:

1. “CT-scan-4th-and-3rd-ventricles” By Aceofhearts1968 – Own work (CC BY 3.0) via Commons Wikimedia
2. “Abdominal Ultrasound Full Exam 20” By Ptrump16 – Own work (CC BY-SA 4.0) via Commons Wikimedia

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