Fluke Biomedical 84-350 - Manual (Page 8)

Nuclear Associates 84-350
Operators Manual
1-4
Figure 1- 5.
Assessment of Resolution
These measurements should be done at several sensitivities and depth levels to facilitate a thorough
evaluation. As defined by the AIUM standards committee, lateral resolution "at specified control settings
and range is the minimum lateral distance between two identical reflectors or scattering volumes at which
separate registrations can be clearly distinguished on the display." A simple measurement can be taken
at a depth of 1.5 cm using the lateral resolution target. A more thorough evaluation can be done using the
vertical plane target (refer to section on beam width measurement). Closer positioning of the transducer's
focal point to each target group should result in better resolution. Assessment of vertical resolution should
be done in the same manner as assessment of lateral resolution using the vertical resolution target that is
located approximately 30 mm from the scanning surface.
Depth Calibration
This measurement should be performed using the vertical plane targets. This group of wires should be
scanned linearly and to the target plane. All wires should be displayed simultaneously. Measure the
distance between two targets using the display markers and plot the values as a function of true distance
that is known to be 20 mm. Or, more simply, align the echoes to the display markers for comparison.
Beam Width Measurement
A linear scan should be performed perpendicular to the vertical plane target. Some of the monofilament
wires are displayed as lines rather than points. The determined length of these displayed lines
demonstrates beam width as a function of depth in 1 cm increments.
Anechoic Mass Detectability