Masking is used for digital subtraction and you can use our CombineCommand, AddCommand (for
averaging multiple frame before subtracting), DigitalSubtractCommand to implement this.
Please see DICOM Standard Part 3 section C.7.6.10 for more information.
You will need to create a REST service that will perform the mask subtraction on the web server
and will return the processed image to client. On server side you will load the DICOM file and look for appropriate attributes related to mask module and apply the mask accordingly.
Following information is from the DICOM standard:
Mask Subtraction Sequence (0028,6100): Defines a sequence that describes mask subtraction
operations for a Multiframe Image
Mask Sub-pixel Shift (0028,6114):
A pair of floating point numbers specifying the fractional vertical [adjacent row spacing] and horizontal [adjacent column spacing] pixel shift applied to the mask before subtracting it from the
contrast frame.
The row offset results in a shift of the pixels along the column axis.
The column offset results in a shift of the pixels along the row axis.
A positive row offset is a shift toward the pixels of the lower row of the pixel plane.
A positive column offset is a shift toward the pixels of the left hand side column of the pixel plane.
You can use DicomTag.MaskSubPixelShift to access the tag.
Mask Frame Numbers(0028,6110):
Specifies the frame numbers of the pixel data used to generate this mask. Frames in a Multi-frame
Image are specified by sequentially increasing number values beginning with 1. Required if the Mask Operation (0028,6101) is AVG_SUB.
You can use DicomTag.MaskFrameNumbers to access the tag.
Mask Operation (0028,6101):
Defined term identifying the type of mask operation to be performed.
Possible values:
- AVG_SUB:
(Average Subtraction) The frames specified by the Mask Frame Numbers
(0028,6110) are averaged together, shifted by the amount specified in the Mask
Sub-pixel Shift (0028,6114), then subtracted from the contrast frames in the
range specified in the Applicable Frame Range (0028,6102) . Contrast Frame
Averaging (0028,6112) number of frames starting with the current frame are
averaged together before the subtraction. If the Applicable Frame Range is not
present in this sequence item, the Applicable Frame Range is assumed to end at
the last frame number of the image minus Contrast Frame Averaging (0028,6112) plus one;
- TID:
(Time Interval Differencing) The mask for each frame within the Applicable
Frame Range (0028,6102) is selected by subtracting TID Offset (0028,6120)
from the respective frame number. If the Applicable Frame Range is not present
in this sequence item, the Applicable Frame Range is assumed to be a range
where TID offset subtracted from any frame number with the range results in a
valid frame number within the Multi-frame image.
- REV_TID:
(Reversed Time Interval Differencing) The number of the mask frame for each
contrast frame within the Applicable Frame Range (0028,6102) is calculated by
subtracting the TID Offset (0028,6120) from the first frame within the Applicable
Frame Range, the TID Offset (0028,6120) +2 from the second frame within the
Applicable Frame Range, the TID Offset (0028,6120) +4 from the third frame and
so on. The Applicable Frame Range (0028,6102) shall be present.
When multiple pairs of frame numbers are specified in the Applicable Frame
Range attribute, the beginning frame numbers (i.e. the first frame number in each
pair) shall be in increasing order.