Advanced Calculator

Advanced Bone Density Calculator

This calculator is intended for use by advanced bone densitometritsts only.
It may be considered for special clinical practice situations and for clinical research.
Please note that the ISCD recommends expressing precision as RMS SD, and LSC at the the 95% confidence level.
Using this calculator, you may:

Calculate precision error with as many as 50 patients.
Express precision error as RMS SD (absolute value in g/cm2), CV, or %CV.
Express LSC (Least Significant Change) with a choice of confidence levels.

Instructions: Enter BMD measurements to 3 decimal places for at least 15 patients scanned 3 times each, or 30 patients scanned 2 times each.

Precision and LSC must be calculated separately for each skeletal site and ROI (L1-L4, total proximal femur, femoral neck, etc.).
BMD results from as many as 50 patients may be entered. The calculator does the rest.

#	Scan 1	Scan 2	Scan 3	SD	SD sq	CV	CV sq
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Skeletal Site / ROI Tested:

n =	0	(Number of Patients)
Sum =	0.00000	(Sum of SD sq)
Sum / n =	N/A	(Sum of SD sq / n)
SqRT =	N/A	(Square Root of above)
RMS SD =	N/A	(Root Mean Square SD)
CV =	N/A	(Coefficient of Variation)
%CV =	N/A	(% Coefficient of Variation)

LSC based on at least 15 patients with triplicate scans:

LSC with Different Levels of Confidence

Precision	95%	90%	85%	80%	Units
RMS SD	N/A	N/A	N/A	N/A	g/cm²
CV	N/A	N/A	N/A	N/A
% CV	N/A	N/A	N/A	N/A	%

LSC based on at least 30 patients with duplicate scans:

LSC with Different Levels of Confidence

Precision	95%	90%	85%	80%	Units
RMS SD	N/A	N/A	N/A	N/A	g/cm²
CV	N/A	N/A	N/A	N/A
% CV	N/A	N/A	N/A	N/A	%