What is a DEXA (Dual Energy X-ray Absorptiometry) scan?
A DEXA Scan (Dual Energy X Ray Absorptiometry) scan is a special non invasive form of imaging that measures bone density and loss. In general the denser the bone, the stronger it is and therefore the less likely it is to break.
A DEXA scan uses low energy x-rays. The amount of x-rays that comes through the bone from the x ray source is measured by a detector. The computer then assesses this information and applies a score for the average density of bone in the area scanned. A low score indicates that the bone is less dense than it should be and is more prone to fracture.
It is important to note that a DEXA scan does not produce images comparable to conventional x rays (for example a hip or spine x-ray). DEXA scans are more often used to diagnose osteoporosis.
Why should I have a DEXA scan?
Some of the reasons why your doctor may suggest that you should have a DEXA scan are:
- Perimenopause/Post Menopause
- Personal or family history of fractures (in particular hip)
- Medications that are known to contribute to bone loss
- Have a personal or family history of osteoporosis, coeliac disease, diabetes, liver, thyroid and renal disease
- Loss of height due to vertebral fractures
- Change in hormones whether age related or medication induced
What are the risks associated with having a DEXA scan?
- A DEXA scan involves a very low dose of X-rays (a form of radiation) passed across the body. The associated risks are minimal and are similar in strength to other sources of background natural radiation that people are exposed to everyday without even realising it. The approximate radiation exposure is 0.001 mSv which is roughly equivalent to 3 hours of natural background radiation exposure (by way of comparison, a CT scan of chest is roughly equivalent to 2 years of natural background radiation exposure or a return transatlantic flight exposes an individual to 0.1 mSv).
Are there reasons why I can not have a DEXA Scan?
- Recent contrast X-ray e.g. Barium meal or swallow or CT with oral contrast prep
- If you are unable to remain motionless for the duration of the measurement
- It is very important that you inform the nurse if you are, or suspect that you may be pregnant. Your scan may need to be delayed or rescheduled.
If you are immobile and cannot weight-bear or require a hoist transfer, please contact the Unit, so we can make the appropriate arrangements for your attendance.
How can I prepare for a DEXA scan?
In general, it is ideal that you wear loose comfortable clothing without metal objects (buttons and zips, jeans/girdles) over your lower abdomen and hips that will interfere with the scan. You are also asked not to take calcium and Vitamin D supplementation on the morning of your scan.
Giving my consent (permission)
The information contained on this website is intended to provide you with an overview of the examination that you are to receive. Prior to any medical imaging procedure being carried out, the densitometerist conducting the procedure will describe the nature of the examination you are to receive. The densitometerist will ask you if you are happy for the examination to go ahead. This is a form of verbal consent and may only involve the densitometerist checking your ID and if you are booked for the correct examination.
It is your right to be given sufficient information to be able to make an informed decision as to whether you wish to continue with the examination or to refuse to undergo the procedure. Please ask the densitometerist any questions you may have. You can change your mind at any time and your wishes will be respected. However, not having the DEXA may delay your diagnosis as the doctors may not have all the needed information.
What happens during a DEXA scan?
Prior to attending for your first DEXA scan you will be asked to complete a questionnaire (paper or online) and get it to us prior to your attendance. The densitometerist will then escort you to the DEXA room.
It is standard practice at our Units to scan both hips and your lower back. We may also carry out an LVA (Lateral Vertebral Assessment) also known as morphometry.
The x ray detector or scanner will move slowly over you – it is important that you remain still as movement reduces the quality of the scan.
The scan takes approximately 10-15 minutes.
On completion you can get dressed and leave the department.
When will I get the results?
A Consultant will interpret the data and a report is forwarded to the doctor who referred you for the DEXA scan (GP or hospital doctor). This will take approximately 5-7 working days. Please contact your doctor’s office for results if you have not heard from them within 14 days.