Computed Tomography Scan

What is the meaning of CT?

CT Scan – CT is the abbreviated form of computed tomography. It is the diagnostic imaging technique which works on the principle of the X-ray diffraction mechanism. 

The working mechanism of CT scan

In a CT scan, ionizing radiations are directed at the target internal organ of the body through different angles. The signals are detected with a built-in electronic detector which measures the resulting pattern of densities along a series of linear paths and transmits these signals to produce images. This technique involves scanning a particular organ or tissue of the body; hence, it is called a CT scan or computerised axial tomography.

Instrumentation of a CT Scan

A CT scan device consists of a scanner, a table on which the patient is laid down, an X-ray machine, and a computer workstation to which the main CT is connected.

1. 1. CT Scanner- large doughnut-shaped structure in which a patient’s table goes in and out for scanning. 
2. 2. Patient table- It is a bed on which a patient is laid down, and this table moves inside the scanner. 
3. 3. X-ray tube – The X-ray tube converts electrical energy into photons. The X-ray beams are directed at the patient’s body while the tube is rotated around the table accordingly, targeting a particular tissue or organ.
4. 4. Detector – It is a built-in device of a CT scanner located at the lower half of the scanner. It captures the reflected X-rays from the patient’s body.
5. 5. Computer system- The signals are transmitted to the computer and converted into readable black and white pictures. Each image obtained in a CT scan represents a series of slices of the targeted tissue’s anatomy.
6.  

Why does your doctor recommend you have a CT Scan?

A physician may recommend a CT scan due to following reasons:

1. 1. To diagnose bones or muscle disorders like fractures or bone tumours.
2. 2. To guide– While carrying out surgeries, radiation therapies or biopsies, it is mandatory to take out the CT scans beforehand for the target tissues or organs.
3. 3. To detect– If a person complains of an accident or internal discomfort, the doctor recommends a CT scan to detect internal bleeding or injuries.
4. 4. To monitor– Patients undergoing chemotherapies or other surgical treatments for cancer are required to get a CT scan repeatedly after every therapy to check the effectiveness of the treatment. 
5. 5. To track– a CT scan helps in monitoring various heart diseases, liver masses or lung nodules
6. 6. To identify– for pinpointing the site of infection, blood clotting or tumour, a CT scan is carried out.
7.  

Contrast material- Contrast material is a special dye. Certain patients are asked to drink it before the test, and it can be inserted into the rectum before the procedure or injected into veins according to the part examined. 

Is undergoing a CT scan risky? Or does it cause any pain?

A computed tomography procedure is not a painful diagnostic test. However, it may be risky for some people or under some conditions. 

1. 1. Risk to unborn babies: Although the radiations of CT scans are of a very low dose, that does not harm humans. However, if a woman is pregnant, she might inform her doctor of her so that her doctor can recommend alternative diagnostic techniques like magnetic resonance imaging or ultrasound because ionizing radiations are more harmful to unborn babies than magnetic radiations and ultrasonic waves.

2. 2. Exposure to radiations: CT scan imaging involves brief exposure to ionizing radiations. In a CT scan, detailed information about a target tissue is obtained from different angles. Therefore, CT involves a comparatively high dose of ionizing radiation than normal X- rays. Since your body is exposed to a high dose of ionizing radiation, frequent CT scans may lead to cancer.
3.  

Experts in this field chose a minimal radiation dose to get information about the target tissue. 

You can discuss possible risk factors of a CT scan with your doctor. 

3. 3. Reactions to contrast material: In certain cases, your doctor may recommend that you receive a special dye called contrast material. Contrast material is a special dye. Certain patients are asked to drink it before the CT scan, and it can be inserted into the rectum before the procedure or injected into veins according to the part examined. 
4.  

Prepare yourself before you go for a CT scan

Patients are asked to do the following things:

1. 1. To remove metal objects
2. 2. Stop eating/drinking 
3. 3. Remove personal clothing
4.  

To remove metal objects: Patients are asked to remove metallic things like jewellery, eyeglasses, belt, etc.

Stop eating/drinking: People must have an empty stomach before a CT scan.

Remove personal clothing: Depending on the region to be examined, people need to wear hospital gowns instead of their personal clothing.

Frequently Asked Questions

What do you mean by a CT scan?

CT is the abbreviated form of computed tomography. It is the diagnostic imaging technique which works on the principle of the X-ray diffraction mechanism. 

What is the principle behind a CT scan?

In a CT scan, ionising radiations are directed at the target internal organ of the body through different angles. The signals are detected with a built-in electronic detector which measures the resulting pattern of densities along a series of linear paths and transmits these signals to produce images. This technique involves scanning a particular organ or tissue of the body; hence, it is called a CT scan or computerised axial tomography.

What is the instrumentation involved in a CT scan?

Instrumentation of a CT Scan

A CT scan device consists of a scanner, a table on which the patient is laid down, an X-ray machine, and a computer workstation to which the main CT is connected.

1. 1. CT Scanner- large doughnut-shaped structure in which a patient’s table goes in and out for scanning. 
2. 2. Patient table- It is a bed on which a patient is laid down, and this table moves inside the scanner. 
3. 3. X-ray tube – The X-ray tube converts electrical energy into photons. The X-ray beams are directed at the patient’s body while the tube is rotated around the table accordingly, targeting a particular tissue or organ.
4. 4. Detector – It is a built-in device of a CT scanner located at the lower half of the scanner. It captures the reflected X-rays from the patient’s body.
5. 5. Computer system- The signals are transmitted to the computer and converted into readable black and white pictures. Each image obtained in a CT scan represents a series of slices of the targeted tissue’s anatomy.
6.  

Why does your doctor recommend you have a CT Scan?

A physician may recommend a CT scan due to following reasons:

1. 1. To diagnose 
2. 2. To guide
3. 3. To detect
4. 4. To monitor
5. 5. To track
6. 6. To identify
7.  

Risks associated with a CT scan test?

A computed tomography procedure is not a painful diagnostic test. However, it may be risky for some people or under some conditions. 

1. 1. Risk to unborn babies: If a woman is pregnant, she might inform her doctor of her so that her doctor can recommend alternative diagnostic techniques like magnetic resonance imaging or ultrasound because ionising radiations are more harmful to unborn babies than magnetic radiations and ultrasonic waves.

2. 2. Exposure to radiations: CT scan imaging involves brief exposure to ionising radiations. In a CT scan, detailed information about a target tissue is obtained from different angles. Therefore, CT involves a comparatively high dose of ionising radiation than normal X- rays. Since your body is exposed to a high dose of ionising radiation, frequent CT scans may lead to cancer.
3.  

Experts in this field chose a minimal radiation dose to get information about the target tissue. 

You can discuss possible risk factors of a CT scan with your doctor. 

3. Reactions to contrast material: In certain cases, your doctor may recommend that you receive a special dye called contrast material. Contrast material is a special dye. Certain patients are asked to drink it before the CT scan, and it can be inserted into the rectum before the procedure or injected into veins according to the part examined.

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