The Image Sets Sequence (0072,0020) within a Hanging Protocol Instance serves to identify the type of image or other object sets to which the Hanging Protocol is intended to apply. Multiple types of image sets may be identified for a Hanging Protocol, to combine, for example, multiple imaging studies for a specific anatomy, or multiple imaging studies performed over a period of time, to monitor the progress of a condition. All image sets shall be for the same patient.
The images to be included in an Image Set may be specified directly by matching attribute values within the images, or indirectly through Key Object Selection Documents or Presentation States by matching their attribute values.
Key Object Selection Documents shall be matched by their SOP Class UID. The available Key Object Selection Documents may be further matched on the values of their other attributes (e.g., Concept Name Code Sequence, Coding Scheme Designator = “DCM” and Code Value = “113003”, which has a code meaning of “For Surgery”). When the Hanging Protocol Instance is applied, the image object instances referenced by the matching Key Object Selection Document instances comprise the image set.
Presentation States shall be matched by their SOP Class UID. The available Presentation States may be further matched on the values of their other attributes (e.g., Content Label). When the Hanging Protocol Instance is applied, the image object instances referenced by the matching Presentation State instances comprise the image set.
Note: Image Sets Sequence (0072,0020) allows other objects such as waveforms and SR documents to be identified. However, Hanging Protocol Display module operations such as filtering, reformatting, and sorting are defined only for image objects. The only expectation for non-image objects is to associate the objects with a position on a screen.
Each sequence item in the Image Sets Sequence (0072,0020) shall follow these rules:
Each sequence item in the Time Based Image Sets Sequence (0072,0030) shall identify one image set, based on time criteria.
The Items of the Image Set Selector Sequence (0072,0022) shall collectively identify one type of image set.
One instance of time based criteria combined with the Items of the Image Set Selector Sequence (0072,0022) shall identify one image set.
Notes: 1. The identification of a current image set is established by the application prior to selection of a Hanging Protocol Instance. The current image set is not necessarily from a single study.
2. In mammography screening, for example, the Hanging Protocol defines the current image set plus the screening image set for the patient from the year prior. There would be one sequence item in the Image Sets Sequence (0072,0020). Within this sequence item, the Items of the Image Set Selector Sequence (0072,0022) would identify a mammography screening image set type. The Time Based Image Sets Sequence (0072,0030) would have two sequence items, one to identify the current, and one to identify the prior.