How to Measure distance between 2 points from JPEG Ultrasound images converted from DICOM?

[Elisa Italy]

Hi Guys!

I would like your opinion about how to get a distance measured between two points in a ultrasound image converted from DICOM to JPEG.

I have no idea which algorithm is used to convert the DICOM :-(

Anyway let's assumed that our DICOM images has:

- number of rows: NR

- number of columns: NC

- Physical Delta X: PDx

-  Physical Delta Y: PDy

The JPEG image has a new size:

- JPEG number of rows: JPEG_NR

- JPEG number of columns JPEG_NC

I compute two conversion factors to take in account the new dimension of the JPEG image and how the space occupied by each pixel change :

RX_FACTOR =  PDx / JPEG_NR

RY_FACTOR =  PDy / JPEG_NC

Finally I compute the distance between two point A(XA,YA) and B(XB,YB) in the JPEG image as:

d = sqrt((XA-XB)^2*RX_FACTOR^2+(YA-YB)^2*RY_FACTOR^2)

  

I've done some distance measurement and it's seems correct.

Do you think is it the right way to proceed?

Thanks!!!

[Chris Horn]

yep get SequenceOfUltrasoundRegions DicomSequence
get the PhysicalDeltaX and PhysicalDeltaY values
confirm that PhysicalUnitsXDirection = 3 and PhysicalUnitsYDirection = 3 (this is cm * cm) so dont foget to convert to mm

the PhysicalUnit values are :
NoneOrNotApplicable,
Percent,
Db,
Cm,
Seconds,
Hertz,
DbPerSecond,
CmPerSecond,
SquareCm,
SquareCmPerSecond,
CubicCm,
CubicCmPerSecond,
Degrees

[Elisa Italy]

Thank you very much :-)