Experimental spatial sampling study of the real-time ultrasonic pulse-echo BAI-mode imaging technique.
The ultrasonic pulse-echo backscattered amplitude integral (BAI)-mode imaging technique has been developed to inspect the seal integrity of hermetically sealed, flexible food packages. With a focused 17.3-MHz transducer acquiring radio frequency (RF) echo data in a static rectilinear stop-and-go pattern, this technique was able to reliably detect channel defects as small as 38 microm in diameter and occasionally detect 6-microm-diameter channels. This contribution presents our experimental spatial sampling study of the BAI-mode imaging technique with a continuous zigzag scanning protocol that simulates a real-time production line inspection method in continuous motion. Two transducers (f/2 17.3 MHz and f/3 20.3 MHz) were used to acquire RF echo data in a zigzag raster pattern from plastic film samples bearing rectilinear point reflector arrays of varying grid spacings. The average BAI-value difference (deltaBAI) between defective and intact regions and the contrast-to-noise ratio (CNR) were used to assess image quality as a function of three spatial sampling variables: transducer spatial scanning step size, array sample grid spacing, and transducer -6-dB pulse-echo focal beam spot size. For a given grid size, the deltaBAI and CNR degraded as scanning step size in each spatial dimension increased. There is an engineering trade-off between the BAI-mode image quality and the transducer spatial sampling. The optimal spatial sampling step size has been identified to be between one and two times the -6-dB pulse-echo focal beam lateral diameter.
Bioacoustics Research Laboratory, Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
Xiangtao
X
Yin
Scott A
SA
Morris
William D
WD
O'Brien
D000465:Algorithms; D003257:Consumer Product Safety; D004867:Equipment Design; D019544:Equipment Failure Analysis / Q000295:instrumentation / Q000379:methods; D005506:Food Contamination / Q000517:prevention & control*; D018857:Food Packaging; D007089:Image Enhancement / Q000379:methods*; D011786:Quality Control; D018401:Sample Size; D012680:Sensitivity and Specificity; D014159:Transducers; D018617:Ultrasonography, Doppler, Pulsed / Q000295:instrumentation* / Q000379:methods*