A dicom viewer as the name suggests are designed for viewing the DICOM (Digital Imaging and COmmunication in Medicine) file format. These scans are usually stored in Picture Archiving and Communications Systems (PACS) – a pacs server. PACS provide convenient access for data and dicom content such as CT images, MRIs, ultrasounds or Xrays. The specific pacs server is also linked to the dicom database which then can be viewed with the specific dicom viewer; 3Dicom. The medical imaging data that is stored in the pacs database typically follows this specific hierarchy.
Patient (patient id) – This is the highest level as all studies and series are linked to the unique patient ID (unless anonymised). A Patient is the person who is receiving, or has received, a medical imaging procedure – typically an MRI or CT Scan. For example, when analysing public dicom data, it is common for the dicom file to have patient anonymization so patient id may often be hidden or displayed as ‘anonymous’. Multiple studies and series can be attributed to a single patient and to help find a particular patient, most DICOM viewers allow for the ability to search by patient name, date of birth and other identifying attributes to narrow the search. In 3Dicom Lite, users are limited to 3 Patients so this functionality is available but shouldn’t be required.
Studies – Studies relate to a particular imaging procedure, allocated by date and imaging modality (such as CT, MRI, PET, X-Ray, Ultrasound etc.). For example, if a patient had a CT scan and MRI scan on the same day, these would be stored as two separate studies and data sets. Studies may also store information about the radiology company and who performed the medical imaging procedure or the imaging equipment used .
Series – Each study, no matter what date or imaging modality, contains at least 1 Series of images. Most Studies contain a number of series as the positioning of the patient may change, a few different scans may have been taken during the imaging session or it may contain ‘composite’ images generated from the plane of acquisition. Series may also contain the number of image files or the size of the image data.
Instance/Image – At the most basic level, each ‘slice’ of a CT/MRI/PET scan is stored as a separate DICOM image, typically in .DCM format and is normally 512×512 pixels in dimensions. Relevant information such as the space between pixels (pixel spacing) and thickness of the slice (slice thickness) are captured as meta-data for each and every image.
3Dicom provides all users with a local DICOM archive which acts as a mini-PACs system on your own device. The scan data itself is stored at whichever destination folder you first loaded from and the relevant patient, study and series data is securely processed, hashed and cached in a local database on your device. This enables users to quickly reopen the 3Dicom program and browse/load scans rather than manually browsing for scans on the device each time.
For more unique file or image types, such as NiFTi and JPEG2000 etc. which don’t always load easily or aren’t compatible with the Local DICOM Archive / Database, users have the option to “Open Other” rather than “Import DICOM” which provides more support for niche files.
Additionally, for those who use Removable Media such as CDs and USBs, the Local DICOM Archive / Database does not work as the patient metadata might be securely stored however the DICOM files themselves may be removed from the device at the end of the session. To account for this, 3Dicom has the option to “Load from CB/USB” which ensures that DICOM metadata is not stored in the Local DICOM Archive whilst in the desktop version. Furthermore, it also counters any loss of clinical data or medical data when using removable media.
For a full rundown and to see how to load in DICOMs and NII files on the desktop version, please see the video below:
Please note that this blog is purely for educational and marketing purposes and doesn’t not purport to be medical advice. 3Dicom is currently registered as a TGA Class 1 Visualisation device and is not approved for diagnostic purposes.