The most commonly used reconstruction algorithms for electronics are based on the Feldkamp method (aka Feldkamp, Davis & Kress, or FDK, cone beam CT or circular scan
The RNFL is measured in the peripapillary area with a circular scan
centred on the optic nerve head.
To assess RNFL thickness, a circular scan
concentric to the ONH is performed.
Their algorithm seems effective and robust for 5 basic ASTs: circular scan
, sector scan, raster scan, helical scan, and conical scan.
The ground-based search radar antenna will typically rotate 360 degrees in azimuth, a circular scan
. This causes an EW receiver to see evenly spaced main beams as shown in Figure 4.
A 3.46mm circular scan
is placed automatically around the optic disc and the information about peripapillary RNFL thickness is obtained.
In addition, depending on the size of the optic disc, the distance from the circular scan
to the disc margin varies, and the RNFL becomes thinner as it gets away from the disc margin, which may result with some errors when measuring the thickness.
The Palmer scan is a circular scan
that is moved linearly, as shown in Figure 3.
RNFL thickness was measured by scanning three consecutive 360 [degrees] circular scans
with a diameter of 3.4 mm centered on the optic disc.
As previously described, infrared reflection images ([lambda] = 820 nm) and OCT B-scans ([lambda] = 870nm, 40,000 Ascans/s) of the dual-laser scanning systems of the Spectralis OCT were acquired simultaneously; 3.4mm-wide circular scans
were taken (768 A-scans) around the optic disc.
(19) Three circular scans
each of 2.4, 2.8 and 3.2 mm were taken 4 mm around optic disc in normal pupil size without dilatation.