X-rays
	CAT Scan
	MRI
	Myelogram
	Bone Scan
	DEXA Scan
	EMG

What is it?
Radiography-based bone densitometry is a test that uses X-rays to determine the density of bone. The test utilizes enhanced X-ray technology called dual-energy X-ray absorptiometry (DEXA). This technology has created a new standard for measuring bone mineral density or BMD. During this test, a beam of X-rays is transmitted through a patient's bones using two energy streams. The energy peaks of these two streams are absorbed differently by soft tissue and bone. The amount absorbed by the soft tissue is subtracted from the total amount to determine the bone mineral density.

Why is it done?
A DEXA Scan is most commonly performed to detect and diagnose osteoporosis, which involves the gradual loss of calcium resulting in thinner, more fragile bones that are more likely to break. Bone mineral density most commonly becomes a concern in women past menopause, as osteoporosis can deteriorate the spine and hips leaving patients susceptible to fractures. The use of DEXA Scan in early detection is critical, as a treatment plan can be developed to help prevent factures before they occur.

What does it involve?
The equipment used to perform a DEXA scan of the spine and hips typically consists of a large, flat table with an X-ray generator mounted below it. A detector is positioned overhead using an apparatus that allows it to be moved across the entire length of the table. Depending on the part of the body to be scanned, the test takes approximately 10 to 30 minutes. During that time, the patient is asked to lie on the table while the detector is slowly passed over the part of the body that is being tested.

Two scores are tabulated based on the results of the test: a T score and a Z score. The T score compares the amount of bone the patient has to that of a young adult with peak bone mass. A T score between -1.0 and -2.5 indicates osteopenia, the first stage of bone loss, whereas a score below -2.5 indicates osteoporosis. A score greater than -1.0 is normal. The Z score compares the amount of bone the patient has to that of people who are same gender, size, and age. If found unusually high or low, the Z score is used to gauge whether further testing should be done.

How should I prepare for it?
Because a DEXA scan is a non-invasive test, it does not require much preparation on the part of the patient. Do not take any calcium supplements for at least 24 hours prior to the test. Make sure to inform your doctor if you have recently undergone a barium examination, computer-aided tomography (CAT) scan, radioisotope scan, or have been injected with a contrast material as part of another test. You may have to wait 10 to 14 days before you can undergo a DEXA scan. It is important to note that radiation exposure can pose a serious threat to a developing fetus. Before receiving a bone scan, inform your doctor if you are pregnant (or even suspect that you are).

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