WEBVTT
Kind: captions
Language: en

00:00:13.800 --> 00:00:23.680
This flow chart is the Image analytical and automated segmentation algorithm.

00:00:23.680 --> 00:00:30.480
We developed an automated (i.e., unsupervised) clustering algorithm using FCM

00:00:30.480 --> 00:00:38.860
that is capable of analyzing T2w images of the radiation exposure region

00:00:38.860 --> 00:00:46.020
of the brain that had been delineated in the GKRS plan.

00:00:46.020 --> 00:00:49.280
Step 1. Interpolation.

00:00:49.280 --> 00:00:57.160
The dose intensity distribution from the dose map is converted into corresponding spatial positions

00:00:57.180 --> 00:01:05.460
on the T2w images using linear interpolation, and the Dose Grid Scaling factor

00:01:05.460 --> 00:01:10.920
is extracted from the header information of the dose data.

00:01:10.920 --> 00:01:19.120
The dose intensity distribution at the various voxel positions in the T2w image

00:01:19.120 --> 00:01:28.180
are then multiplied by the Dose Grid Scaling factor to obtain the radiation dose intensity distribution

00:01:28.180 --> 00:01:32.220
in centigrays (cGys).

00:01:32.220 --> 00:01:39.600
Step 2 is the Selection of prescription isodose region.

00:01:39.600 --> 00:01:45.820
After selecting a prescribed peripheral radiation dose intensity,

00:01:45.820 --> 00:01:55.180
the selected radiation exposure region included the entire area in the T2w images

00:01:55.180 --> 00:02:06.080
that received radiation dose intensity equal to or greater than the prescription dose intensity.

00:02:06.080 --> 00:02:11.700
Next, Step 3 is about Registration, the TOF.

00:02:11.700 --> 00:02:20.500
The TOF is registered to the corresponding T2w image via 3-D voxel registration

00:02:20.580 --> 00:02:24.200
using the normalized mutual information
method

00:02:24.200 --> 00:02:29.940
to correct for differences resulting from head movement.

00:02:29.940 --> 00:02:35.180
Next step is how to extract brain mask.

00:02:35.180 --> 00:02:42.520
A brain mask is extracted from the registered TOF based on estimates of the inner

00:02:42.520 --> 00:02:45.540
and outer skull surfaces

00:02:45.540 --> 00:02:48.680
using BET (Brain Extraction Tool),

00:02:48.680 --> 00:02:57.720
a software package developed at the FMRIB Centre, University of Oxford, Oxford, United Kingdom.

00:02:57.720 --> 00:03:01.920
Next step is ROI definition.

00:03:01.920 --> 00:03:08.700
The ROI is identified using a logical and operation

00:03:08.700 --> 00:03:14.920
applied to the selected radiation exposure region and brain mask.

00:03:14.920 --> 00:03:20.600
Step 6. Fuzzy c-means classification.

00:03:20.600 --> 00:03:29.180
The voxels in the ROI of a T2w image are classified as the nidus,

00:03:29.180 --> 00:03:32.460
brain tissue, or CSF,

00:03:32.460 --> 00:03:40.620
according to differences in voxel intensity between the various forms of tissue.

00:03:40.660 --> 00:03:47.340
Finale step is the volumes or percentages

00:03:47.340 --> 00:03:55.560
of the nidus, brain tissue, and CSF within the ROI are calculated.