Don't you need (0028,0030) to be able to convert from pixel values to cm?

[confused]

Did a dump of some GE Logiq 700 US data and was surprised to find this
missing. Looked at their conformance and sure enough they don't
support
it. Most of their other scanners do.

Isn't this group/element required if you want to make an image
measurement
tool that automatically converts pixel values to cm?

[Erik Fabricius Simonsen]

It could be discribed in the "US frame of refference" module.

--
Erik Fabricius Simonsen, Biomedical Engineer, B.Sc.E.E.
Dept. of Biomedical Engineering, County of Aarhus
Skejby University Hospital, DK-8200 Aarhus N, Denmark
http://www.aaa.dk/mta/ e-mail:es...@mta.auh.dk

[David Clunie]

Hi

Attribute (0028,0030) Pixel Spacing is contained in the Image Plane
module, which is used only in CT, MR and PET images. It refers to
the physical pixel spacing within a patient, and there for is only
applicable to cross sectional images with homogeneous pixel spacing.

In CR, XA, XRF and DX objects, Imager Pixel Spacing (0018,1164)
describes the spacing of the pixels at the front of the image
receptor in recognition of the fact that geometric magnification
is occurring due to the diverging x-ray beam.

In ultrasound, since the "images" may consistent of multiple
"regions" on the screen (e.g. a static image, a color doppler
velocity calibration bar, a waveform, etc.), the (optional) US
Region Calibration Module provides a mechanism to describe
these regions, and if appropriate the pixel spacing for regions
that are actually cross-sections, i.e. Physical Units X/Y Direction
(0018,6024/6026) describes the units (e.g. cm) and Physical Delta
X/Y (0018,602C/602E) describes the distance.

According to the Logiq 700 Conformance Statement at:

ftp://ftp.med.ge.com/pub/DICOM/CONFSTMT/US/L700/

the US Region Calibration Module is supported, and distance is
one of the features supported. I have not checked to see if
sample images from the Logiq 700 actually contain this module.

david

confused <no-...@ix.netcom.com-no-spammers> wrote:
>
> Did a dump of some GE Logiq 700 US data and was surprised to find this
> missing. Looked at their conformance and sure enough they don't
> support
> it. Most of their other scanners do.
>
> Isn't this group/element required if you want to make an image
> measurement
> tool that automatically converts pixel values to cm?

--
David A. Clunie mailto:dcl...@idt.net
Director, Medical Imaging Technologies http://idt.net/~dclunie/
Quintiles Intelligent Imaging http://www.i2image.com/
521 Plymouth Rd #115 Work 610-238-0572 Fax -0578
Plymouth Meeting PA 19462 Home 570-897-7123 Fax -5117