Radiology is a
medical specialty that focuses on the use of imaging techniques in the
diagnosis and treatment of disease. Traditionally, this medical specialty dealt
predominantly with imaging by x-rays. There has been an explosion in many
fields of radiology in the past 10-15 years and radiologists now also use other
imaging methods such as ultrasound, CT scan, MRI, PET and nuclear medicine
techniques. Radiologists also use imaging to perform procedures (interventional
What is a diagnostic
radiologist / radiation oncologist (therapeutic radiologist) / interventional
radiologist / nuclear medicine physician / radiographer?
radiologists are medical doctors who obtain and interpret diagnostic
images, review requests for imaging scans [e.g. x-ray, ultrasound, CT, MRI,
PET, nuclear medicine and other diagnostic imaging procedures], and determine
the applicability of requested procedures. Diagnostic radiologists differ from
interventional radiologists in that they generally do not perform complex
Interventional radiologists are medical doctors who
have specialized in doing medical procedures that involve radiology. They are
specially trained to diagnose and treat illness using miniature tools and
imaging guidance. Typically, the interventional radiologist performs procedures
through a very small nick in the skin, about the size of a pencil tip.
Interventional radiology treatments are generally easier for the patient than
routine surgery because they involve no large surgical incisions, less pain and
shorter hospital stays. Examples of procedures done by interventional
radiologists include percutaneous biopsies, angioplasty, vascular stenting and
insertion of catheters.
known as Therapeutic Radiologists) are medical doctors
who have received special training regarding the treatment of cancers with
different types of radiation. These medical specialists may also use radiation
to treat diseases other than cancer.
Physicians are medical doctors who specialize in a branch of
medicine that uses radioactive substances in diagnosis and treatment of
disease. These substances consist of radioisotopes or pharmaceuticals labelled
with radioisotopes (radiopharmaceuticals).
personnel who are specially trained in the technique of taking medical images.
Radiographers work in multidisciplinary teams led by radiologists to achieve
diagnosis and treatment.
What is an
x-ray/fluoroscopy / US / CT / MRI / PET scan?
is a test that uses small doses of radiation to produce a picture of the inside
of the body. Images are produced by sending a beam of x-rays (high energy
electromagnetic radiation) through the body. Different tissues in the body have
different densities and deflect x-rays differently. The resulting image can be
captured either on photographic film or digitally. Typically, bones are well-seen
with x-ray imaging.
technique where a portion of the body is exposed to a continuous beam of x-ray
radiation to generate a movie-like image which is viewed on a TV monitor. This
technique is helpful for the evaluation of motion of bones within joint,
swallowing and gastro-intestinal studies, and evaluation of lung and diaphragm
abnormalities. Fluoroscopy is also used for accurate placement of needles for
Ultrasound is a
non-invasive diagnostic technique which provides pictures of organs and
structures inside the body. It works like the sonar used by submarines,
bouncing sound waves off an object and using a computer to interpret the sound
returned. The interpretation of an ultrasound is very dependent upon body
structure, the amount of body fat, and the skill of the operator. Ultrasonography
does not involve the use of radiation.
for computed tomography. This is a sophisticated diagnostic imaging procedure
that uses a computer and x-rays to produce a series of detailed pictures of
areas inside the body taken from different angles. This technique is also
sometimes called computerized tomography and computerized axial tomography
(CAT) scanning. Modern CT scanners are able to generate three-dimensional
images of the body and internal organs from a large series of two-dimensional images.
Sometimes, injection of contrast medium (“dye”) is done during the scan to
enhance the image quality and assist with diagnosis.
for Magnetic Resonance Imaging. This is a non-invasive imaging technique that
uses a combination of a large powerful magnet, radiofrequencies, and a computer
to produce very detailed images of the organs and structures inside the body.
This technique does not involve the use of radiation. Sometimes, injection of
contrast medium (“dye”) is done during the scan to enhance the image quality
and assist with diagnosis. Because of the powerful magnetic field used, MRI can
affect electrical devices like pacemakers and hearing aids.
for Positron Emission Tomography. This is a type of imaging that is typically used
to help distinguish cancer from benign (non-cancerous) tissue, and assess the
response of cancer to treatment. The patient is injected with a tiny amount of
radioactive material that is combined with sugar. The test works on the
principle that tumours metabolise (use up) more sugar than normal tissue.
Do I need
to prepare myself specially before undergoing a radiological scan or
investigations require you to fast or take certain medications before the scan.
Do check with the radiology department about any special preparations that may
be required whenever you get your scan appointment. It is also important to
inform the personnel at the radiology department should you have any drug
allergies or medical conditions so that they can make adjustments to the type
of scan if required.
Why do I get an injection for some
sometimes given during imaging studies (e.g. CT, MRI, ultrasound etc). This
injection is typically a contrast medium (conceptually similar to a “dye”
although it is often colourless) that makes a scan more sensitive in detecting
the doctor prescribe me steroids before a CT scan?
This is often done
when a patient has a history of asthma or allergy. The steroids help to reduce
the risk of an adverse drug reaction or allergic reaction from developing as a
result of the injection of contrast medium (“dye”) that is given during the
If I have
allergies or medical conditions, do I need any special precautions prior to
undergoing scans at the radiology department?
You should always
inform the staff at the radiology department if you have any allergies or
medical conditions. This is because the type of scan may have to be changed or
you may need to take certain types of medication before the scan can be
undergo imaging tests in the radiology department if I am pregnant?
You should always
inform the staff at the radiology department if you are or suspect that you may
be pregnant. This is because many tests in the radiology department involve
radiation, which can be harmful to an unborn foetus. Certain imaging tests are
not performed in patients who are pregnant or suspected to be pregnant.
Why do I
benefit when my scans (x-ray/CT/MRI/US etc) get reported by a radiologist? Why
isn’t interpretation by my main doctor alone sufficient?
A radiologist is a
specialist medical doctor who is trained in reading X rays and other imaging
scans. The radiologist is trained to detect abnormalities, arrive at the
diagnosis and identify possible complications using the different types of
scans. A qualified radiologist undergo years of rigorous training in all
different types of scans and investigations, and is best placed to read and
interpret your scans.
As a trained medical
doctor, the radiologist is also able to understand the clinical information
provided by your referring doctor and when necessary, use results from other
relevant investigations such as blood tests to arrive at the most accurate
Very often your
referring doctor will also consult a radiologist and discuss the more complex
Are all patients suitable for Magnetic
Resonance Imaging (MRI)?
MRI is an imaging
modality that does not use ionising radiation or X-rays. For some
investigations, an injection of a contrast medium (“dye”) may be necessary.
However, because of
the use of the high magnetic fields in MRI, patients with certain implants such
as those listed below are not suitable for MRI.
4. Some older
metallic heart valves replacements
foreign body in the eye/s
documented allergy to the contrast medium
Other common implants
such as metallic plates and screws for fractures, hip and knee replacements,
spinal implants or intraocular lens implants after cataract surgery are safe
Pregnant patients in
the 1st trimester are currently considered unsuitable for MRI. MRI
for patients in the 2nd and 3rd trimesters however has
not been found to be unsafe.
If you are still
unsure of whether you are a suitable candidate for MRI, you should speak to a
radiologist. You will also be screened with a series of questions by the
technologist before you undergo the MRI scan.
Some patients may be
feel excessive discomfort and anxiety in the small enclosed space of the MRI
machine. In such cases, some form of sedation, from light sedation which lasts
only a couple of hours to even general anaesthesia may be needed for a small
number of patients with extreme claustrophobia (fear of enclosed spaces). A
written consent will be taken from you before any form of sedation is
Why does the
radiologist sometimes change the type of investigation requested by my doctor?
A radiologist is a
specialist medical doctor trained in all the different types of scans and
investigations. Also as trained medical doctor, a radiologist is able to
understand the clinical information provided by your referring doctor and when
necessary, use results from other relevant investigations such as blood tests
to decide which scans or investigations is the best to arrive at the diagnosis.
In circumstances when
another type of scan may be more suitable, the radiologist would discuss with
your referring doctor. Referring doctors also commonly consult radiologists
about which scans are more appropriate for your clinical problem before
Can I claim the bill/costs from my company/insurance/Medisave?
It is best your contact your company (e.g. HR department), insurance agent, or the Ministry of Health to confirm. However in general:
- Inpatient scans are generally included in the total inpatient bill and covered as part of the inpatient insurance (e.g. Medishield / Medisave or your private insurer)
- Outpatient scans are not covered by Medishield/Medisave, except for MRI, CT and PET scans for cancer ($600 per year from Medisave)
- Outpatient scans are generally not covered by your health insurance, unless as part of a larger payout (e.g. cancer diagnosis, followup scan after discharge from hospital, etc.)
- Outpatient scans may be covered by your employer as part of your health package.