A guide to the benefits and limits of radiology tests
Posted on 4 October 2018
Radiology plays a major role in medical care as it allows patients to be diagnosed and treated for disease and injuries without having to undergo explorative surgery just to see inside the body. Diagnostic radiologist Dr John-Henry Corbett, of Van Dyk & Partners based at Mediclinic Bloemfontein, takes us through the benefits, advancements and risks.
Most of us have had X-rays. This technology has been around for more than 100 years, but radiology contributes much more to our medical care than we may realise.
Imaging technology used in radiology, like X-rays that use electromagnetic energy to produce images of internal bones and organs, provides invaluable detail about what is happening inside the body.
Radiologists are medical doctors specialising in diagnosing and treating injuries and illness through various medical imaging techniques. These tests can help to diagnose symptoms, monitor how the body is responding to treatment and screen for diseases like cancer.
Different types of radiology
Radiology is a complex science. According to the Radiology Society of South Africa, the field includes diagnosis and treatment for all ages and because there are so many aspects to radiology, there are various subspecialties focusing on specific areas of the body or technology.
Dr Corbett says plain film (X-ray) radiology is still the most common investigation at his practice, including chest, spinal and joint X-rays as well as upper abdominal ultrasound examinations.
Diagnostic radiology helps doctors to see structures inside the body by using common procedures like X-rays, computed tomography (CT or CAT scans), magnetic resonance imaging (MRI) and mammography.
Interventional radiology involves a range of imaging procedures in order to perform, or guide, medical procedures – like inserting catheters and other small instruments into the body. Doctors also use the technology to treat conditions like blocked arteries or fibroids in the uterus, instead of a scope (camera) or open surgery.
Common radiology tests
X-rays – electromagnetic waves create pictures of inside the body which are used to diagnose bone and joint-related fractures or conditions.
Mammography – low-energy X-rays and specialised medical imaging are used to examine the human breast.
Computed tomography (CT or CAT scan) – a computer combines X-ray images to combine different angles and produce a cross-section of the body – almost ‘virtual slices’ of areas inside the body.
Magnetic resonance imaging (MRI) – powerful magnets and radio waves create three-dimensional pictures of organs and muscles that don’t appear on X-rays.
Fluoroscopy – a continuous X-ray beam in a specific body part is transmitted to a monitor to detect motion in detail.
Nuclear medicine scans – used for bone and thyroid scans, and to view how organs are functioning.
Positron emission tomography (PET scan) – nuclear medicine imaging after liquid radioactive material is injected into the body to detect cancer earlier than CT or MRI scans.
Ultrasound – high-frequency sound waves are used to create images of blood vessels, tissues and organs.
Dr Corbett says there are constant advances being made in imaging technology. Some emerging areas of interest include:
- Dual energy CT: uses normal X-ray and a less powerful X-ray to analyse ‘slice-like’ images
- 3 Tesla MRI: uses radio waves and a powerful magnet that produces better images of organs and soft tissue than normal MRI
- Breast tomography: an advanced form of three-dimensional breast imaging
The benefits of radiology
- Reduces the need for exploratory surgery.
- It may be the only special investigation that can answer clinical questions.
- Helps doctors to diagnose, manage conditions, and assess treatment and surgery options.
- Interventional radiology involves less risk and time spent in hospital, as well as shorter recovery time.
- It’s used to screen for diseases like breast cancer, which means earlier detection and lower risk of death.
What are the risks?
In terms of detecting and treating illness, experts agree the benefits far outweigh the risks of radiology.
But ionising radiation from medical imaging examinations can potentially cause cell mutations that may lead to cancer. (The most radiosensitive tissues in the body are the testes and ovaries, lymphoid tissue, bone marrow, blood and intestines.)
There is a small amount of risk involved with such exposures and this risk may increase with the amount of exposure, repeated exposures and when the patient is young.
“As a general rule we attempt to avoid ionising radiation in children and pregnant women by using alternative modalities, like ultrasound or MRI (that don’t involve any radiation),” explains Dr Corbett, adding that radiologists adhere to the “as low as reasonably achievable (ALARA) principle” as set out by the US Nuclear Regulatory Commission.