This data was
collected in order to assess acoustic field aberrations and transmission loss
induced by human skulls in the context of focused ultrasound stimulation of the
primary visual cortex (V1) region of the brain.
A 2 element spherically
focusing annular array ultrasound transducer (H115, driven at 270 kHz, Sonic
Concepts) was used to generate an acoustic field. Measurements were performed
with a 0.2 mm PVDF needle hydrophone (Precision Acoustics) with right angle
connector to reduce its length so it could be accommodated within the skull
cavity. The transducer was driven under quasi continuous wave conditions at low
drive level to produce a linear field. The transducer was held in a fixed
position, the skull was positioned to obtain the correct focal alignment and
the hydrophone was held in a 3D printed mount with manual alignment in the
axial direction and automated scanning in the lateral directions.
Measurements
were performed inside 3 human skulls which had previously had the superior
section of the parietal and frontal bones removed. Measurements were made with
the transducer positioned at two
locations for each skull corresponding to the focal region intersecting with
the positions of the left and right V1 regions of the brain, with a 1 cm
separation between source and skull. For each position, the hydrophone was
aligned with the focus inside the skull, then a planar scan was performed
covering the largest possible area while avoiding collision of the hydrophone
with the skull bone. The skull was then removed and a 2nd scan was
performed in water as a reference, the axial position was determined from time
of flight in free field during these reference water scans.
The
study consists of 6 datasets, each of which contains a planar scan made within
the skull cavity, and a reference planar scan in water after the skull was
removed, preserving the coordinates.
File 1:
skull 2120, left V1
File 2:
skull 2120, right V1
File 3:
skull 2150, left V1
File 4:
skull 2150, right V1
File 5:
skull 2125, left V1
File 6: skull 2125,
right V1
; Wright, Olivia; Treeby, Bradley