Compression force in mammography makes GE based assumptions

[Ed McDonagh]

On reading image header for compression force, the extractor code assumes the unit is dN as it is for the GE Senographe DS (though the DICOM conformance statement says N).

This is likely to not be true for other manufacturers - and even possibly later GE models.

@dplatten, @jacole - do you know what unit is used for Compression Force on other mammo units?

[David Platten]

GE Senographe Essential: N

Siemens Mammomat Inspiration: N

Hologic Selenia Dimensions: N

[Ed McDonagh]

Added in if statement to check if modality is Senograph DS, on the assumption that all other units are correct. Refs #135. Won't affect existing imports, needs testing.

→ <<cset 582e7e8c95c6>>

[Ed McDonagh]

Changed variable name to reflect that the model name and not the manufacturer are being tested. Refs #135

→ <<cset 53cf37573531>>

[Ed McDonagh]

Fixes #135. Now tests for model name containing 'senograph ds' and if so assumes that the compression force is in dN instead of N. Otherwise the value in the Compression Force field is taken as is. Will need to document as this will change behaviour from current for existing users.

→ <<cset a528a6b7b42a>>

[Ed McDonagh]

Added mammography compression force issue to the changes list and wrote about it in the release notes. Refs #135.

→ <<cset 35bbe1b18963>>

[Ed McDonagh]

Not sure if this was ever right... GE Senographe DS images today have compression force in N. Either way, the code treats the unit as though it were dN, when if it were anything it would be daN!

[Ed McDonagh]

Removed compression conversion for GE Senographe DS that is not required (and incorrect). Documented in changes/CHANGES and release notes. Fixes #135, again!

→ <<cset e8f520f52659>>

[Ed McDonagh]

Refs #135

→ <<cset 5250332084cd>>