Where is the CT Department?
There are currently 4 CT scanners at Ashford and St Peter's NHS Trust, two on each site.
The scanners at St Peter's hospital provide emergency support 24/7, whilst Ashford hospital scanners (one of which is on loan from NHSE) are operational Monday to Friday 9am -5pm (though this service is flexed to match demand, therefore we may send out appointments for the early evening or weekend).
The CT Scanning Team
In-patients and specialist out-patients (vascular and cardiac) are primarily scanned at St Peter's. Ashford mainly scans urgent and routine out-patients.
Please note it is likely that your out-patient CT scan will be scheduled at Ashford hospital.
Who is who in the CT department?
Radiographers are specially trained healthcare professionals who operate x-ray equipment. It will be the radiographer who performs your scan. The radiographer may also cannulate you should your scan require you have contrast media injected (see the contrast media section for more information).
More information about radiographers can be found at www.sor.org/about-radiography/patient-information.
RDAs (Radiology Department Assistants) assist with the daily running of the CT department. You might see them when you are booking in for your scan.
Radiologists are specialist doctors who have trained in interpreting x-ray images and scans. They are the people who report on the images taken for your CT scan. Radiologists also perform interventional procedures in CT [biopsies for example]. You will probably not meet a radiologist during your visit to the CT department.
How does CT work?
CT uses x-rays and a computer to produce cross sectional slices of the body. Standard x-rays produce a flat picture of a body part but CT produces cross sectional slices which can be reconstructed to make 3D images.
Plain x-ray of an ankle
3D reconstructed CT scan of the same ankle
CT uses x-rays in a rotational or helical form. A patient lies on the CT couch which moves into the middle of the scanner and the x-ray rotates around the patient. This x-ray is continuously taking pictures and each time a rotation is made, a cross section image or slice is produced. These slices allow us to look inside the body. A good way of explaining how CT images are taken in the body can be likened to a sliced loaf of bread. The CT scanner takes very thin images (0.25 - 10 mm in thickness) of an area which is then viewed on a computer screen.
A CT cross-sectional image
What should I wear for my scan?
You can wear your normal clothes. The department does ask that you try to avoid wearing metal [under-wired bras, braces, tops with zips, etc] and clothes that have diamante detail. You may be asked to pull your trousers to your knees for some examinations (this removes the metal zip of the trousers from the area being scanned) however you will be covered and your dignity will be maintained at all times. Occasionally, you may be asked to change into a hospital gown for your CT examination.
How long will my procedure take?
Some CT scans require you to drink some fluid before we take you into the scanner. You will be asked to drink the fluid for between 30 and 60 minutes [see the section entitled Are there any preparations for my scan? for more information]. Once you enter the scanning room CT scans take between 5 and 15 minutes on average depending on what procedure you are having.
Do I need to bring someone with me whilst I'm having my CT?
You can bring someone with you while you are having your scan if you wish but it is not essential. Both CT departments' have waiting areas so anyone accompanying you can wait there whilst you are having your scan.
Are there any preparations for my CT scan?
Some CT scans require you to be nil by mouth for 2 or 4 hours before coming for your appointment. CT scans of the chest/abdomen require you to be nil by mouth for 2 hours before your appointment time. CT scans of chest/abdomen/pelvis, abdomen/pelvis require you to be nil by mouth for 4 hours before coming for your scan. More detailed information can be found on your appointment letter for the procedures.
For certain scans you will be asked to drink some water or an oral contrast which has an aniseed taste before you have your scan. The drink helps to give your stomach and bowel better definition.
If you are a taking a medicine called Metformin [normally taken for type 2 diabetes or poly-cystic ovarian syndrome] and are having an injection, you will need to stop taking your tablets 24hours before and 48 hours after your appointment. Please contact the department if you have any questions.
Will I have an injection?
Some CT scans require you to be injected with an iodine based contrast media. The radiographer will explain the procedure to you when you come into the scanning room. They will also ask you some questions to make sure you are suitable to have the contrast media.
The radiographer will usually insert a cannula into your arm. The injection allows for the contrast media to be injected into your body. The contrast media shows the blood vessels and helps to enhance the organs inside your body.
When the contrast media enters your body you might get a warm flush, a metallic taste in your mouth and you may feel as though you have passed urine.
Contrast media produces better images and helps to make the diagnosis. The contrast media will be passed through your kidneys and will pass naturally in the urine. The contrast media is not radioactive and it won't turn you or your urine a different colour.
How will I find out the results?
The radiologists need to view your images and formulate a report. The results will then go to the doctor who sent you for the scan. In most cases this will be your hospital doctor, not your GP. If you are an in-patient, most scan results will be available the same day.
Appointments for urgent CT appointments will be sent to you directly. For routine appointments the department operates a "choose and book" system. This means a letter will be sent to you at home asking you to phone our appointments centre to arrange your appointment.
If you are an in-patient, you can expect your scan to be performed within 3 days of your doctor sending a request.
Areas of the body examined by CT
This is a relatively new and evolving technique utilising the speed of the latest generation of CT scanners which can scan almost the whole body within a matter of seconds. An injection of a contrast dye can be given into a vein in the arm to highlight blood vessels and the scan timed to coincide with when all the arteries are filled with dye and show up as white. The images are then processed by a powerful computer which can then display the arteries clear of the soft tissues around them to give an accurate diagnosis of any disease of the arteries.
The advantages are that it is non-invasive, needing only a simple intravenous injection. It is quick – the scan lasting only 5-10 minutes in total. As a bonus the other organs are also scanned and other unexpected disease may be diagnosed at an early stage. The walls of the arteries are also seen (unlike catheter angiography and Magnetic Resonance Angiography), which can lead to more sensitive diagnosis of earlier stage arterial disease.
A CT (computed tomography) scan is a special type of x-ray which takes pictures of the inside of the body using a narrow rotating beam of x-rays focused on a specific part of the body, together with sophisticated x-ray detectors and a computer. It is a non-invasive technique, and modern scanners use multiple rows of detectors (multi-slice or multi-detector CT) to rapidly scan and produce thin high-resolution cross-sectional images of the body.
Most scans can be performed in less than a minute, and the information acquired is then processed by a computer to construct images which can be displayed in different planes, and sometimes as 3-dimensional images.
Any part of the body can be scanned, and the scanner displays a range of tissue densities from air in the lungs to dense calcification and bone. It can be used to examine the brain and spine, neck, chest, abdomen and pelvis and any bones. The more modern multi-detector scanners are useful to evaluate the heart and blood vessels.
PET/CT is a unique imaging technique that combines structural and functional information to produce a fused picture of the body showing anatomy and metabolic activity.
PET (Positron Emission Tomography) uses a small dose of radioactivity coupled to glucose (FluoroDeoxyGlucose, FDG) to detect areas of increased metabolism in the body. Many cancers show significantly increased glucose uptake over normal surrounding tissues and this can be detected by a special camera placed around the body.