Radiology 101: Medical Imaging and The Different Types

There are a lot of medical treatments when it comes to diseases. One of the most useful ones is radiology. Radiology is a medical branch in which medical imaging is used. It is used to diagnose and treat different types of diseases. The diseases are usually located within the body of patients – hence can’t be seen with the naked eye. This is where medical imaging is used.

Medical imaging refers to the techniques and processes used to create images. The images created are images of various parts of the human body. This image is created for diagnostic and treatment purposes. Medical imaging and scans assist doctors and help them treat patients. It usually helps them in trying to diagnose diseases or complaints that patients may have.

The Role of Medical Imaging in Diagnosis and Prevention

Medical imaging aims to reveal internal structures hidden by the skins or bones. It also establishes a database of normal anatomy and physiology. This makes it possible to identify any abnormalities within the patient.

The diagnosis of cancer for example, is often done with the use of medical imaging. Medical imaging is the first step used in trying to prevent the spread of cancer through early detection. After it has been diagnosed, medical imaging is then again used to follow the course of the cancer treatment. It monitors the growth and remission (disappearance of the signs of cancer). Medical imaging can then allow doctors to give the right radiation treatment of cancer.

Medical imaging is also a useful resource for musculoskeletal conditions. It is also a useful tool for physical therapists. Not only towards diseases, medical imaging also facilitates accurate diagnosis, prognosis, intervention and a general assessment of injuries or dysfunctions. These injuries might take the form of a fractured/broken bone or a ripped muscle.

Different types of medical imaging are used in different circumstances. For example, radiography is often used when doctors try to look for images of bone structures. This image of the bone structure can then be used to look for any fractured or broken bone. Another form of medical imaging is the MRI scanner. MRI scanners are often used to capture images of the brain or other internal tissues. When it comes down to this, high-resolution images are required. Nuclear medicine, also another form of medical imaging, uses radioactive materials. It aims to get images of the digestive or circulatory systems and is useful to look for blockages. To look at the fetuses in the womb, doctors use ultrasound. This gives the image of the little baby that is inside its mother’s stomach.

Different Types of Medical Imaging and Scans

As stated above, there are different types of medical imaging and scans. These are utilized differently based on which circumstances it is needed. Some types of imaging and scans uses radiation. Some other use sound waves, radio waves, or magnets. It is important to know which kind of imaging you need so that the doctor can treat you accordingly. Here are the different types of medical imaging and scans and how it works.


One of the most popular forms of imaging, the X-Ray is the pioneer of medical scans. X-Rays have been used in the healthcare sector for more than 120 years. X-Rays are useful in looking for images of the bone structure. This can then indicate whether someone has a fractured or broken bone. Other than that, the X-Ray is useful in finding problems in certain types of tissues. An example of this would be pneumonia in the lungs.

X-Ray scans works by passing a type of energy beam. It is passed through the desired part of the body that wants to be scanned. The bones or other parts of the body will block some of the X-Ray beams that pass through. This makes their shapes appear on the detectors used to capture the beams. The detectors then convert the X-Rays into a digital image. This is then used by the doctors to determine what kind of injury the patient has.

The beams from X-Ray scans uses radiation. Radiation is energy that is released as invisible particles or waves. Modern X-Ray scanners now use a very small dose of radiation to minimize the risks and harm of radiation.

CT Scans

Much like the X-Ray, CT scans also use X-Ray beams. However, the way it functions is quite different to that of the X-Ray. The beams operated will rotate around your entire body. It will then conceive a 3D image. The images created is comprised of more information than a regular X-Ray image. The scan can also be done in less than a minute. This is why CT Scans is very useful in places like the emergency department. This gives doctors the chance to immediately diagnose if a patient has a life-threatening condition.

However, CT Scans use more X-Ray beams than a normal X-Ray. This means that the CT Scans often deliver a higher dose of medical imaging radiation. However, it is not harmful as medical specialists always have way in trying to calculate the smallest radiation dose needed.

CT Scans allows images to be reconstructed as slices (often known as tomographs) of the human tissue. The most common CT scan is to scan a patient’s chest, abdomen and pelvis. This is often used to identify the spread of cancer.


Unlike X-Rays and CT Scans, MRI works in a much rather different way. Instead of using beams and radiation, it utilizes strong magnets and radio waves. The magnet and radio waves would then affect atoms in the water molecules within one’s body tissues. When the radio waves are turned off, the atoms release energy that will then be detected by the MRI machine.

The atoms in different tissue types go back to normal at different speed. It will also then release different amounts of energy. MRI software then uses the information gathered to construct a 3D image. This 3D image shows the different types of tissues.

MRI is best used when trying to identify diseases that involve the soft tissue. The soft tissue includes parts such as the muscles, tendons and blood vessels. Among the few are stroke, spinal cord injuries and brain tumor. It can also help doctors in finding small blockages or defects in one’s heart.

Doctors would most likely use MRI often more in children. This is because MRI does not use the beams such as in X-Rays. However, MRI machines requires you to lie down, motionless, for a very long time. This can be exhausting and uncomfortable for some people. For children especially, it can also be hard.

Children are well known as active and it can be difficult for them to lie down and hold still. In the scenario that the child does not want to lie still, doctors will administer general anesthesia. It makes them unconscious and unable to move. Generally, it is very safe, but comes with some risks. An MRI researcher at Stanford University, Dr. Shreyas Vasanawala came up with a solution. He and his team created a flexible, blanket-like version of MRI hardware to use with children. This setting creates a comforting environment, making the children want to be still and calm.


An ultrasound scan uses high-frequency sound waves to capture images of the patient’s body. This is performed by firstly applying a water-based gel. The doctor would then glide a transducer (a device that generates or sense ultrasound energy) over the desired area. The transducer would then send sounds waves into the body. It will then receive the echoing waves and would then form an image.

Ultrasound scanning is often used during pregnancy – identifying the movement of the fetus in its mother’s womb. However, it can also detect and diagnose conditions that affect the body’s organs soft tissues. Other diseases that can be detected by ultrasound are liver cancer and gallstones. It can also identify breast cancer. Other than identifying diseases, ultrasound can guide procedures such as biopsies.

Often times, doctors will instruct their patients to fast before doing the ultrasound scan. The scan usually takes time between half an hour to an hour. It also does not require anesthesia or medication. Unlike X-Ray and CT scans, there are no known risks that is caused by the sound waves from ultrasound scans.

Other Scans

There are also other types of scans and medical imaging that are less popular. However, they are still used by doctors and radiologists. One of them is called nuclear imaging. This test uses a tiny amount of a radioactive substance known as “tracers”. Most of the times, tracers are injected to the body. Some others are also inhaled or swallowed. The tracers would then enter the body and release radiation that can be measured by a detector. Some of the diseases treated by nuclear imaging are hyperthyroidism, thyroid cancer and lymphomas.

Another type of medical imaging that belongs to this list is called Positron Emission Tomography (PET) scan. This scan is quite unique, as it uses a radioactive sugar. This is useful in trying to diagnose and identify different types of cancer. The radioactive sugar would first be consumed by the patient. When cancer cells take up the radioactive sugar, they will then be seen by the PET scanner.

Errors in Scanning and Medical Imaging

While medical imaging and scans is considered to be an advanced technology, it is also not free from errors. Most of the time, the errors lie in the usage and operation of the medical imaging.  Usually, the errors occur on the processing of the image. There are different types of scanning and medical imaging errors.

The first one is heel effect. Heel effect is a source of visual error related to X-Rays. This is due to the fact that the X-Rays released are not uniform. There are two ends in an X-Ray machine, a cathode end and anode end. The cathode end releases more photons compared to the anode end. This might result in an over-exposure of the image at the cathode end and under-exposure at the anode end. Technicians will usually reposition the patient on the table. The thickest portion of the body being scanned is placed nearest the cathode end. The thinner part of the body is placed near the anode end.

Another error is known as Artefact. This is an error in the perception of the visual image of the radiograph. It is usually seen as an abnormal finding. It occurs when the cassettes that contrains the X-Ray film plates get exposed to finger prints or small debris.

Movement can also cause errors in medical imaging. Simply put, this causes a blurry image because the patient being scanned moved.


Like everything in life, there is always a risk behind a benefit. This applies as well towards medical imaging and scans. Particularly on the usage of X-Ray imaging, the risks are well known. X-Ray imaging uses ionizing radiation to capture images of the body. This ionizing radiation is a form of radiation that has enough energy to possibly cause damage to DNA.

There are different types of risks when being exposed to ionizing radiation. One of them is a small increase in the possibility of developing cancer in later life. Another risk is tissue effects. This includes cataracts, skin reddening and hair loss which occurs at high levels of radiation exposure.

Another risk of developing cancer from medical imaging and scans is relatively small. It depends on a couple of things. Firstly, is the dose of radiation. There is a higher possibility of getting cancer when a larger dose of radiation is administered. Secondly, is the patient’s age. The lifetime risk of cancer is larger when a patient who receives it is at a younger age. Thirdly, is the patient’s sex. Women are prone to a higher lifetime risk than men when exposed to radiation from X-Ray or CT scans. Lastly, is the body region. Some organs are more radiosensitive compared to other organs.

However, the risks have a relatively small chance to occur. Still, patients need to be vigilant when wanting to get themselves scanned. To help reduce risk to the patient, all scans utilizing ionizing radiation should only be done to treat a disease.

Every day, scientists and doctors alike are trying to develop new types of medical imaging. The types of medical imaging and scans developed are hoped to bring with them no risks. As technology advances, there is a high possibility that scientists and doctors can invent a new type of medical imaging. One that is easy and fast to do and possesses little to no risk to the patient.