On Wed, 20 Aug 2008 00:23:03 -0700 (PDT), vasmvr@yahoo.com wrote:

This is becoming confusing, me answering at the top and you at the
bottom

So, this time my answer is at bottom.

>On 15 Ago, 17:10, Yves Martel wrote:
>> Bonjour Vasmvr,
>>
>> The tag (0020,0037) has 6 float values. The first 3 values define the
>> horizontal axis (going from the top left pixel to the top right
>> pixel), and the last 3 define the vertical axis (going from top left
>> to bottom left).
>>
>> These axis are expressed in the patient coord. system, with the X axis
>> going from the patient right to the patient left, the Y axis going
>> from the patient front to the patient back and the Z axis going from
>> the patient feet to the patient head.
>>
>> So, for a standard axial image you may have (0020,0037) = 1/0/0 /
>> 0/1/0. In this case, you can place R on the left portion of the
>> image and L on the right portion of the image. But if you have a
>> pilot, a sagittal image or if the patient is on his side you may have
>> to place different labels on the left and right of the image. If the
>> image is at an angle, you may want to place more than one label on
>> each side...
>>
>> Here's one way to do it:
>>
>> - Look for the biggest component of the vector horizontal vector
>> (compare absolute values of the first 3 values of (0020,0037))
>> - if it is in X
>> - if it is > 0
>> Label on the left is "Right", on the right is "Left"
>> - if it is < 0
>> Label on the left is "Left", on the right is "Right"
>> - if it is in Y
>> - if it is > 0
>> Label on the left is "Front", on the right is "Back"
>> - if it is < 0
>> Label on the left is "Back", on the right is "Front"
>> - if it is in Z
>> - if it is > 0
>> Label on the left is "Feet", on the right is "Head"
>> - if it is < 0
>> Label on the left is "Head", on the right is "Feet"
>>
>> - Look for the second biggest component of the vector
>> - if it is not 0, then you may want to add a second label using the
>> same algo...
>>
>> You can also use the same technique for the top and bottom labels
>> using the last 3 values of (0020,0037).
>>
>> And for the DICOMDIR, the standard specify that there can only be one
>> DICOMDIR per media. So if for example you have a CD with 20 studies
>> from 10 patients, then the DIMDIR will have information on all 20
>> studies. It will contain a tree with 10 patients at the root, each
>> patient will have links to its studies, each study links to its series
>> and each series link to its individual images, and finally, in each
>> image description you will have the path of the filename for the
>> image. All of this inside one DICOMDIR file.
>>
>> Hope this help...
>>
>> Yves
>>
>> On Thu, 14 Aug 2008 06:05:42 -0700 (PDT), vas...@yahoo.com wrote:
>> >On 13 Ago, 14:51, Yves Martel wrote:
>> >> Bonjour Vasmvr,
>>
>> >> Your first idea of a fixed R-L view is incorrect
>>
>> >> Instead, DICOM define 2 vectors for the horizontal and vertical axis
>> >> of the image (0020,0037). These vectors give the 3D orientation of
>> >> the image in relation to the patient. Add to this the slice origin
>> >> (0020,0032) and you are able to get the 3D position of any pixels in a
>> >> dataset.
>>
>> >> As for the DICOMDIR, you have one DICOMDIR per media, not per patient.
>> >> So if you have multiple patient/studies on a media, they should all be
>> >> referred by the DICOMDIR.
>>
>> >> Yves
>>
>> >> On Mon, 11 Aug 2008 06:45:13 -0700 (PDT), vas...@yahoo.com wrote:
>> >> >Hi all,
>> >> >I'm new in Dicom, and I'd like to know if there is a rule which
>> >> >specifies the left and the right that axial image (MEDIA STORAGE SOP
>> >> >CLASS UID 1.2.840.10008.5.1.4.1.1.2) must have . I know that in
>> >> >radiology the image must be always like that:
>> >> >________________
>> >> >|R L |
>> >> >| |
>> >> >| |
>> >> >| |
>> >> >| |
>> >> >| |
>> >> >|_______________|
>>
>> >> >So i'd like to know if it is correct to assume for every DICOM image
>> >> >that I load and display, Left and Right like the picture below :
>> >> >________________
>> >> >|R L |
>> >> >| |
>> >> >| |
>> >> >| |
>> >> >| |
>> >> >| |
>> >> >|_______________|
>>
>> >> >In this case when a dicom image is created means that who create the
>> >> >dicom image must create like below:
>> >> >________________
>> >> >|R L |
>> >> >| |
>> >> >| |
>> >> >| |
>> >> >| |
>> >> >| |
>> >> >|_______________|
>> >> >is it correct?
>>
>> >> >Another question is about DicomDir:
>> >> >I'd like to know if a DicomDir must be referred only to one data-set
>> >> >or if is possible to have dicomdir that are related to more than a
>> >> >patient e/o study e/o serie.
>>
>> >> >Thank in advance for your help
>>
>> >> >vasmvr
>>
>> >> >| |
>> >> >| |
>> >> >| |
>> >> >| |
>> >> >|_______________|
>>
>> >> >In this case when a dicom image is created means that who create the
>> >> >dicom image must create like below:
>> >> >________________
>> >> >|R L |
>> >> >| |
>> >> >| |
>> >> >| |
>> >> >| |
>> >> >| |
>> >> >|_______________|
>> >> >is it correct?
>>
>> >> >Another question is about DicomDir:
>> >> >I'd like to know if a DicomDir must be referred only to one data-set
>> >> >or if is possible to have dicomdir that are related to more than a
>> >> >patient e/o study e/o serie.
>>
>> >> >Thank in advance for your help
>>
>> >> >vasmvr
>>
>> >Thank you for your answer Yves,
>>
>> >so you mean that who generate a Dicom Image must not generate it like
>> >this:
>>
>> >________________
>> >|R L |
>> >| |
>> >| |
>> >| |
>> >| |
>> >| |
>> >|_______________|
>>
>> >but can generate it like this
>>
>> >________________
>> >|L R |
>> >| |
>> >| |
>> >| |
>> >| |
>> >| |
>> >|_______________|
>> > or
>> > _______________
>> >|R |
>> >| |
>> >| |
>> >| |
>> >| |
>> >| L |
>> >|_______________|
>>
>> >or
>>
>> >|L |
>> >| |
>> >| |
>> >| |
>> >| |
>> >| R |
>> >|_______________|
>>
>> >Right?
>>
>> >I explain you my problem: i have to import dicom data set of axial CT
>> >(MEDIA STORAGE SOP
>> >CLASS UID 1.2.840.10008.5.1.4.1.1.2) so I'd like to know if i can only
>> >open the image and SET R_____L to the image.
>>
>> >With the (0020,0037) and (0020,0032) how can i understand the position
>> >R and L of the image, sorry but i'm new in Dicom. Which combination
>> >are there? Can you give me some example?
>>
>> >About DicomDir
>>
>> >you mean that one data-set = one dicomdir (one patient, one study ,
>> >one serie) ?
>>
>> >Thanks in advance for your help
>
>Hi Yves,
>
>thanks again for your help, now I understand the tag 0020,0037
>but I have another question: the value of the float value must be -1
>or 0 or 1 or the can have a floating point value (esample 0.6)
>and is it possible to have some value different from 0 esample
>0.6/-0.5/0.2 0.5/0.8/1 or it works as a switch and a can have only one
>value different from 0 in each axis? Example 1/0/0/0/1/0?
>
>Thanks again for your help.
>
>Vasmvr

The tag is composed of 2 3D vectors. They can have any values! For
example if you have an axial image with a 30 deg. gantry tilt, you
will have:
1/0/0 / 0/0.866/0.5

Any float values are permitted. Though since these should be normed
vectors, the sqrt( x*x + y*y + z*z ) should be == 1. But even that I
don't believe it is required by the specs (somebody correct me if I'm
wrong...)

Yves