NORME INTERNATIONALE CEI IEC INTERNATIONAL STANDARD 61391 1 Première édition First edition 2006 07 Ultrasons – Scanners à impulsion et écho – Partie 1 Techniques pour l''''étalonnage des systèmes de mesu[.]
Méthodes d’essai
The following elements are essential for conducting test procedures: a) test objects that mimic fabric, featuring targets arranged at precisely specified positions; b) a test object that simulates fabric, containing a 3D object of precisely defined dimensions; c) a reservoir filled with degassed working liquid.
Les spécifications de ces dispositifs sont données en annexes.
Instruments
The equipment outlined in this section has been chosen to facilitate ultrasonic scanner testing for medical applications The described devices ensure that data collection and analysis are both objective and reproducible.
While conventional digital calipers can perform some spatial measurements, encoding ultrasonic images obtained during tests in digital form is essential for obtaining objective and reproducible data for broader applications Many modern ultrasonic imaging devices provide digital images from a frame converter, which are more representative of the displayed images and can be effectively utilized by hospital users with expertise in digital measurements For spatial measurements, this is directly applicable; however, for FDP and FDL measurements, a characteristic linear echo amplitude curve at the transducer is necessary, representing the function of the digital image values, or a sparse representation of this curve must be created using calibrated reflectors In some systems, RF scan line data is available, offering better accuracy for precision measurements where linear signal amplitude is crucial It is important to clearly indicate measurements made with RF data and document the level from which they originate For devices that do not provide digital images, an image digitizer can be used to acquire and digitize ultrasonic images, requiring adequate spatial resolution (at least 512 × 512 pixels) and sufficient grayscale (at least 256 shades) Additionally, appropriate image analysis software should be used to perform the basic measurements on the digital ultrasonic images of test objects The digitizer must exhibit linearity leading to a spatial inaccuracy of