Issue saving ImageOrientationPatient

[Jeremy Donaghue]

I'm trying to flip around the cooridantes for the ImagePositionPatient
and ImageOrientationPatient tags, but when I save the file, the
changes do not get saved.

I have tried (abridged)

plan=dicom.read_file(filename)
plan.ImageOrientationPatient[0]=-1*plan.ImageOrientationPatient[0]
plan.save_as(filename)

If you print the tag out after the change, it shows appropriately, but
the data is not getting written to the saved dicom file.

Thanks for the help.

Jeremy

[Darcy Mason]

The current version of pydicom stores the original string version of
some VR types (like "DS") so they can be written back exactly.
Unfortunately when one item in a list like this is changed, it doesn't
recognize that and writes the original string out.

The work-around is to set the entire list rather than a sub-item, so
something like this should work for your case:
orient = plan.ImageOrientationPatient
orient[0] = -1 * orient[0]
plan.ImageOrientationPatient = orient

The key is the last line which sets the list itself, forcing pydicom
to recognize the change.

This problem should go away with a change to using python's Decimal
type, which is on the issues list for a near future version.

Hope that helps,
Darcy

[Lei Qiu]

HI Man,

My code works!! I am searching the forum trying to directly write the RTstructure into a dicom file. I will email you