Rapid Measurements of Intensities for Safety Assessment of Advanced Imaging Sequences

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Abstract

FDA requires that intensity and safety parameters are measured for all imaging schemes for clinical imaging. This is often cumbersome, since the scan sequence has to broken apart, measurements conducted for the individually emitted beams, and the nal intensity levels calculated by combining the intensities from the individual beams. This paper suggests a fast measurement scheme using the multi-line sampling capability of modern scanners and research systems. The hydrophone is connected to one sampling channel in the research system, and the intensity is measured for all imaging lines in one emission sequence. This makes it possible to map out the pressure eld and hence intensity level for all imaging lines in a single measurement. The approach has several advantages: the scanner does not have to be re-programmed and can use the scan sequence without modication. The measurements are orders of magnitude faster (minutes rather than hours) and the nal intensity level calculation can be made generic and reused for any kind of scan sequence by just knowing the number of imaging lines and the pulse repetition time. The scheme has been implemented on the Acoustic Intensity Measurement System AIMS III (Onda, Sunnyvale, California, USA). The research scanner SARUS is used for the experiments, where
one of the channels is used for the hydrophone signal. A 3 MHz BK 8820e (BK Medical, Herlev, Denmark) convex
array with 192 elements is used along with an Onda HFL-0400 hydrophone connected to a AH-2010 pre-amplier
(Onda Corporation, Sunnyvale, USA). A single emission sequence is employed for testing and calibrating the
approach. The measurements using the AIMS III and SARUS systems after calibration agree within a relative
standard deviation of 0.24%. A duplex B-mode and
ow sequence is also investigated. The complex intensity
map is measured and the time averaged spatial peak intensity is found. A single point measurement takes 3.43
seconds and the whole sequence can be characterized on the acoustical axis in around 6 minutes.
Original languageEnglish
Title of host publicationProceedings of the SPIE - Progress in Biomedical Optics and Imaging
Volume9040
PublisherSPIE - International Society for Optical Engineering
Publication date2014
Article number90400Z
DOIs
Publication statusPublished - 2014
EventSPIE Medical Imaging 2014 - Town & Country Resort and Convention Center, San Diego, California, United States
Duration: 15 Feb 201420 Feb 2014
http://spie.org/x12166.xml

Conference

ConferenceSPIE Medical Imaging 2014
LocationTown & Country Resort and Convention Center
CountryUnited States
CitySan Diego, California
Period15/02/201420/02/2014
Internet address

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