Samsung SONOACE R3 Manuel d'utilisateur télécharger pdf (Page 37)

Chapter 1 Safety

1-19

Applying ALARA

The system-imaging mode used depends upon the information needed. 2D-mode and M-mode imaging

provide anatomical information, while Doppler, Power, and Color imaging provide information about

blood flow. Scanned modes, like 2D-mode, Power, or Color, disperse or scatter the ultrasonic energy

over an area, while an unscanned mode, like M-mode or Doppler, concentrates ultrasonic energy.

Understanding the nature of the imaging mode being used allows the sonographer to apply the ALARA

principle with informed judgment. The probe frequency, system set-up values, scanning techniques, and

operator experience aid the sonographer in meeting the denition of the ALARA principle.

The decision as to the amount of acoustic output is, in the nal analysis, up to the system operator. This

decision must be based on the following factors: type of patient, type of exam, patient history, ease or

diculty of obtaining diagnostically useful information, and the potential localized heating of the patient

due to probe surface temperatures. Prudent use of the system occurs when patient exposure is limited

to the lowest index reading for the shortest amount of time necessary to achieve acceptable diagnostic

results.

Although a high index reading does not mean that a bioeect is actually occurring, a high index reading

should be taken seriously. Every effort should be made to reduce the possible effects of a high index

reading. Limiting exposure time is an eective way to accomplish this goal.

There are several system controls that the operator can use to adjust the image quality and limit the

acoustic intensity. These controls are related to the techniques that an operator might use to implement

ALARA. These controls can be divided into three categories: direct, indirect, and receiver control.

Direct Controls

Application selection and the output intensity control directly aect acoustic intensity. There are dierent

ranges of allowable intensity or output based on your selection. Selecting the correct range of acoustic

intensity for the application is one of the rst things required during any exam. For example, peripheral

vascular intensity levels are not recommended for fetal exams. Some systems automatically select the

proper range for a particular procedure, while others require manual selection. Ultimately, the user bears

the responsibility for proper clinical use. The Samsung Medison system provides both automatic and user-

denable settings.

Output has direct impact on acoustic intensity. Once the application has been established, the output

control can be used to increase or decrease the intensity output. The output control allows you to select

intensity levels less than the dened maximum. Prudent use dictates that you select the lowest output

intensity consistent with good image quality.

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Samsung SONOACE R3 Manuel d'utilisateur Page 37