How can I achieve the DICOM Alignment

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votes

The question is quite simple, we have many DICOM serial images, for same patient for sure. I need figure out the image of the same location in the body in different serials and compare them. Let's assume the image parameters like pixel spacing, slice thickness, etc. are the same. But the patient may moved after each scan.

How can I achieve the image alignment?

Actually I got a parameter "slice location", I heard its a DICOM3 attribute, let's say we always have this one. Is the image with same slice location means the same position on the body? I heard the coordinate system is based on patient's body, how can we define the origin point on patient's body? I believe the origin point should on the scan machine, which called world coordinate, isn't it?

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imagealignmentdicom
DICOM location tags are relative to the scanner. There are no coordinates relative to the body - they wouldn't be useful in general, because the body is deformable. Aligning two scans requires deformable image registration, although if you are only interested in aligning a particular rigid part of the anatomy then a rigid transformation might suffice. Image registration is a big area of research; it's not a simple problem. – Tom

1 Answers

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Alignment between series is more than just image position.

See http://dicom.nema.org/medical/dicom/current/output/html/part03.html#sect_C.7.6.2 for the relevant part of the DICOM image standard.

See http://www.dclunie.com/medical-image-faq/html/part2.html for information about drawing appropriate scout lines in images, which may help to clarify the information.

If the patient physically moved within the scanner between series (or they are different studies), then you have to use some image registration algorithms using the mutual information in the images.

There is a lot of information on the web and stackoverflow relating to this.