How to encode table movements in DICOM Structured Dose Reports

[Stefan Allers]

Hi DICOM experts,

I would like to correctly encode the table movements during FLUORO in the DICOM Dose Report. In TID 10003C (Irradiation Event X-Ray Mechanical Data) under DCID 10008 "Dose Related Distance Measurements" there are these two possibilities:

"Table Longitudinal Position" (Code Value 113751) and "Table Longitudinal End Position" (Code Value 113759).

It is defined like this:

"Table Longitudinal Position with respect to an arbitrary​ chosen reference by the equipment. Table motion​ towards LAO is positive assuming that the patient is​ positioned supine and its head is in normal position."

So unfortunately the position values are dependent on how the patient lies on the table. However for changing the "longitudinal" position I would have expected that the motion is described towards heat/feet and not LAO position.

Is this just mixed up with the decription for "Table Lateral Position" or do I misunderstand it completely wrong?

Thanks,
Stefan

[Francisco Sureda]

Hi Stefan,

Thank you for your question.

The directions and signs of the "Table longitudinal" and "Table lateral" positions in the DICOM Dose Report TID 10003C (codes 113751 and 113752) were defined to be consistent with the definitions of the DICOM Part 3, C.8.7.4.1 “X-Ray Table Attribute Descriptions”.
The table position values are not dependent on how the patient lies on the table. The mention to the patient position on the table in these definitions was to provide a referential to which the direction and sign conventions are determined.

For more clarity please refer to the figures C.8-9a and C.8-9b of Part 3, as well as the note in C.8.7.4.1.3: The terms "longitudinal" and "lateral" are relative to an operator standing tableside, and facing the patient. Thus lateral movement is to the left and right of the operator, and longitudinal movement is towards or away from the operator.
In order to give more clarity to the definitions of the codes 113751 and 113752 of the DICOM Part 16, a new CP-2219 has been proposed to include a reference to “X-Ray Table Attribute Descriptions” in PS3.3.

Best regards,
Francisco Sureda (DICOM WG-02)