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Glossary
Glossary
| ISCD | International Society for Clinical Densitometry This non-profit medical society dedicated to high quality in the field of bone densitometry. |
| DXA | Dual Energy X-ray Absorptiometry This is the most common technology for measuring BMD of the spine, hip, or forearm. |
| ROI | Region of Interest A portion of the skeletal site selected for BMD measurement, such as femoral neck or trochanter. |
| BMD | Bone Mineral Density Expressed as g/cm2 when measured by DXA. |
| SD | Standard Deviation This is calculated for the BMD values of each patient. |
| SD sq | Sum of SD sq Values The total of SD sq values for 15 patients tested 3 times each, or 30 patients tested 2 times each. |
| N | Number of Patients This is usually15 or 30 for precision testing. |
| Sum/n | Sum of SD sq Values Divided by the Number of Patients Tested |
| SqRT | Square Root of Sum/n |
| PE | Precision Error This may be expressed as RMS SD, CV, or %CV. RMS SD is recommended. |
| RMS SD | Root Mean Square Standard Deviation The standard deviation of the group, and the preferred method of expressing precision error, in g/cm2. |
| CV | Coefficient of Variation SD divided by the mean BMD. Not advised for expressing precision error. |
| %CV | Percent Coefficient of Variation CVx100%. Not advised for expressing precision error. |
| CL | Confidence Level The ISCD recommends a 95% confidence level for establishing statistical significances for serial BMD testing. |
| LSC | Least Significant Change This value is calculated by multiplying the precision error by 2.77 for a 95% confidence level. For a BMD change to be considered statistically significant, it must equal or exceed the LSC. LSC should be calculated with a new DXA instrument, and whenever it is moved to a new room or location. |
| FAQ | Frequently Asked Questions Click this link to view commonly asked questions about precision assessment and the precision calculator. |
