Global Worklist
Select a patient to open their jacket
| Patient Name | ID | Last Study |
|---|
DICOM Objects
In the previous lesson, we used the ID of the image called the SOP instance UID of 1.2.840.10008.5.1.4.1.1.2.1.12345 to identify the image that we sent to PACS.
A SOP Instance UID (Unique Identifier) is a globally unique identifier assigned to a specific instance of a DICOM object, such as an image or report, ensuring it can be distinctly identified within a PACS or other medical imaging systems.
DICOM Hierarchy
Patient Level:
- Represents the individual patient.
- Example: John Doe.
- In PACS, all imaging studies and related data are stored under the patient’s profile.
- The patient is identified by demographic information like name or medical record number.
Study/Exam Level (Study Instance UID):
- Refers to a specific medical exam or study the patient underwent.
- Example: CT of the Head.
- In PACS, each study has a unique identifier called the Study Instance UID. This UID distinguishes one study from another, even if they are from the same patient.
- Study Instance UID: Ensures that every exam (e.g., multiple CT scans) can be uniquely tracked across systems.
Series Level (Series Instance UID):
- Each study is divided into multiple series of images or sequences.
- Example: Axial, Coronal, and Sagittal views in a CT scan.
- In PACS, a series of images is uniquely identified by a Series Instance UID, which organizes the specific group of images within a study.
- Series Instance UID: Ensures that individual groups of images, such as different views or phases of an exam, are uniquely identifiable.
Image Level (SOP Instance UID):
- The lowest level, representing each individual image within a series.
- Example: Axial slice of a CT scan.
- Each image in PACS has its own unique identifier called the SOP Instance UID. This UID is crucial because it ensures everysingle image, even within the same series, is uniquely identifiable and traceable.
- SOP Instance UID: Provides a globally unique ID for each image in the system.
Example Flow
Patient → Study → Series → Image (SOP Instance)
- John Doe (Patient)
- CT of the Head (Study Instance UID)
- Axial View (Series Instance UID)
- Individual Image (SOP Instance UID)
This hierarchy ensures that every level of data in a DICOM system is uniquely identifiable, allowing precise organization, retrieval, and tracking of medical images and related information.
A PACS administrator can search the PACS database for these specific UIDs saving time and finding the accurate DICOM object.
DICOM Hierarchy Chart
Let's visualize the data. For example, in the Ultrasound test study, there was only one test image.
Okay but what if there are two series with a total of three images? And what if the first series only had one image and the rest were in the second series?
An image is also referred to as an instance or an object. The instance can also be another single DICOM object such as a SR (structured report) file or any other non-image DICOM file.
Make sense now? But what's up with the numbers in parenthesis? Those are DICOM tags. Let's get into those in the next lesson.