B-K Medical Pro Focus 2202, User Manual

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Urology Pro Package 237
The value of the PSA factor is 1.00.
Accuracy of Calculations
Factors Affecting Accuracy
The accuracy of each calculation is influenced by a number of factors:
•
the accuracy of the measured input parameters (see the General Transducer
Information (BB0555))
• the accuracy of the estimation methods
• the accuracy of the calculations
The error introduced in the calculations by the finite resolution of the floating point
numbers is insignificant compared to that introduced by the other factors listed
above. Hence, it is not taken into consideration.
The accuracy formulas in Table 16-8 are to be used as a guide to evaluating the total
expected accuracy for the calculation methods. In the table, A = accuracy.
Table 16-8. Accuracy of urology calculation methods.
References
[1] Littrup PJ, Williams CR, Egglin TK, Kane RA. Determination of prostate volume with tran-
srectal US for cancer screening. Part II. Accuracy of in vitro and in vivo techniques. Radi-
ology, 179:49-53, 1991.
Calculation Accuracy Assumptions
HWL A = A(H) + A(W) + A(L)
= 3 x A(B-mode distance) Formula used to calculate
volume.
Planimetry A = A(stepsize) + A(area) Both area measurements made
on same equipment
The accuracy of clinical
planimetry measurements on the
prostate was found to be ±7%
with 95% confidence interval [1].
Note: This method should only
be used on organs which are
approximately “cigar-shaped”.
Empirical Less than 15% on average. See ref.
2. This only applies when the
method is used for measuring the
bladder.
PSAD A = A(area) = 4% The formula used for calculating
PSAD. The method is described
in ref [4].