Samsung SONOACE R3 Instrukcja Użytkownika Pobierz pdf (Strona 46)

Operation Manual

1-28

Liver .43

Muscle .55

l = skin line to measurement depth (cm)

f = Center frequency of the transducer/system/mode combination(MHz)

Since the ultrasonic path during an examination is likely to pass through varying lengths and types of

tissue, it is dicult to estimate the true In Situ intensity. An attenuation factor of 0.3 is used for general

reporting purpose; therefore, the In Situ value which is commonly reported uses the formula:

In Situ (derated) = Water [

-(0.069 lf)

]

Since this value is not the true In Situ intensity, the term “derated” is used.

The maximum derated and the maximum water values do not always occur at the same operating

condition; therefore, the reported maximum water and derated values may not be related to the In

Situ (derated) formula. Take for example a multi-zone array transducer that has maximum water value

intensities in its deepest zone: the same transducer may have its largest derated intensity in one if its

shallowest focal zones.

Acoustic Output and Measurement

The terms and symbols used in the acoustic output tables are dened in the following paragraphs.

ISPTA.3 The derated spatial-peak temporal-average intensity (milliwatts per square centimeter).

ISPPA.3 The derated spatial-peak pulse-average intensity (watts per square centimeter). The value of

IPA.3 at the position of global maximum MI (IPA.3@MI) may be reported instead of ISPPA.3 if the

global maximum MI is reported.

MI The Mechanical Index. The value of MI at the position of ISPPA.3, (MI@ISPPA.3) may be reported

instead of MI (global maximum value) if ISPPA.3 is 190W/cm

Pr.3 The derated peak rarefactional pressure (megapascals) associated with the transmit pattern

giving rise to the reported MI value.

WO The ultrasonic power (milliwatts). For the operating condition giving rise to ISPTA.3, WO is the

total time-average power;. For operating conditions subject to reporting under ISPPA.3, WO

is the ultrasonic power associated with the transmit pattern giving rise to the value reported

under ISPPA.3

Fc The center frequency (MHz). For MI and ISPPA.3, Fc is the center frequency associated with

the transmit pattern giving rise to the global maximum value of the respective parameter. For

ISPTA.3, for combined modes involving beam types of unequal center frequency, Fc is dened

as the overall range of center frequencies of the respective transmit patterns.

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Samsung SONOACE R3 Instrukcja Użytkownika Strona 46