DICOM vs. PACS: The 9 Differences That Matter | 3DBiology.com (2023)

Some of the main areas of work in the area of ​​medical imaging are the management, distribution and analysis of medical images. Whether you're performing a CT scan, MRI or X-ray, you need to be sure that patient information is secure once the image is captured and that all major equipment can display the images correctly.

To do this, you need to work with PACS and DICOM. These are two types of software that work together and independently to provide you with optimal control over your medical images and associated data. Because they are so deeply connected, it can be difficult to understand what sets them apart.

Below are the main differences that separate the two and how these distinctions work together.

DICOM and PACS have different medical functions

Although they work together, PACS (Image Archiving and Communication System) and DICOM (Digital Imaging and Communications in Medicine) are separate software programs that perform different functions for healthcare professionals. In its simplest terms, PACS is intended to store medical images captured by hardware such as X-ray scanners and MRIs (Magnetic Resonance Imaging).

Please note that all of these images are digital as they are primarily stored (technically called "files") by photographic or recording equipment.The following features represent how PACS manages these digital images based on the acronym:

• WHENsceneryrefers to digital image data shared by medical devices.
• AN -filingrefers to the transfer process by which digital images are sent to the PACS.
• C-Communicationrepresents the system's ability to distribute these medical images to various connected devices, especially DICOM-compliant devices, healthcare IT (information technology) systems, and more.
• S-Systemof course it refers to all the components responsible for executing PACS functionality.

(Those ones:IT solutions for healthcare)

On the other hand, DICOM is a global communication.Pattern- not exactly the mechanism - by which medical professionals can manipulate, store, print and transmit medical images.It also represents the file format in which these images can be saved. Thus, DICOM has many more applications than PACS in medical practice.

Further explanation of DICOM features

As mentioned above, DICOM is a multifaceted system that offers a wide range of medical image management, manipulation, storage, and distribution capabilities. Through DICOM, medical professionals can add multiple sets of data, just as a JPEG tag can be embedded with metadata. (Source:contribution)

You can store a lot of important information in DICOM metadata, including patient ID, date of birth, and more.Due to the sensitive data in these files, DICOM has an anonymization security measure in place.

Images are not the only medical files that can be transferred between devices using DICOM. If you need to share reports and other clinically relevant documents between systems and devices, DICOM can do that too.

DICOM and PACS have different purposes for the user

DICOM is the standard way of communicating for almost everything related to the acquisition, storage and distribution of medical images. Rather, PACS is the management system itself. As they are two distinct components of medical image management, they are used very differently by the physician, radiologist, or other medical professional.

PACS systems are capable of archiving medical image files received from scanning and imaging hardware. However, you are limited to separate functions with no method to exchange these files. This is where DICOM comes in. DICOM is the communication "bridge" that allows PACS systems to transmit the information stored in them. (Source:IT solutions for healthcare)

DICOM and PACS have different functional components

PACS and DICOM contain different functional components.PACS consists of four main parts (source:Ampronix medical imaging technology):

• Imaging hardware (e.g. MRI, CT scan, X-ray, etc.)
• Secure network for sharing patient information between healthcare centers
• devices and workstations for viewing and analyzing medical images
• The process of storing and retrieving images and documents.

All of these components work together to enable the PACS to transmit medical images digitally, eliminating the need for manual document processing and handling. In addition, medical professionals can acquire, store and share film sleeves digitally within and outside their departments and organizations.

DICOM requires the following "objects"* to function properly:

• AE title: The application entity title (eg "Heart CT") is assigned to a device so that it can be identified on a network. AE is used in conjunction with IP.
• DICOM Message Service Element (DIMSE): This item allows the exchange of information between connected AEs. (Source:pynetdicom)
• Service object pair (SOP): The connection of IOD and DIMSE is the central determining factor of an SOP. It prescribes the attributes of the IOD or the rules according to which the DIMSE can perform communication services. (Source:dicom library)
• Information Object Descriptor (IOD): This is a computer model that allows AEs to display pre-exchange object information shared between DICOM devices (instead of separate displays).
• Entity Relationship (E-R): Refers to an IE (Information Entity) or computer model of a tangible object (eg, a study or an image). (Source:OTpedia)
• IP (Internet Protocol) address.
• Unique Identifier (UID): this element ensures that an object has a unique identity that uniquely distinguishes it from other objects accessed over the same DICOM network. (Source:DICOM)
• Value Representation (VR): represents the type and format of the data element. (Source:DICOM)

*Also called IODs, objects are formulations of elements that define instances of an entity such as CT, MR (magnetic resonance imaging), US (ultrasound), etc.The attributes of these objects are defined in "modules". For example, patient modules contain the patient's name and other identifying information, while study modules contain the study date, accession number, and unique identifier (UID).

DICOM and PACS have different levels of functional independence

Medical professionals can use DICOM and PACS in different capacities, each with different degrees of functional independence.

for example justDICOM ensures that files remain intact and that all metadata remains associated with the appropriate file.Depending on the type of PACS you have (ie, on-premises or in the cloud), you can access your DICOM data remotely or through a workstation. Therefore, it can be argued that DICOM is functionally more versatile than PACS.

The difference of,PACS can almost only be operated in conjunction with DICOM, as the "universal format for storing and transmitting images in PACS is DICOM".Thanks to DICOM, PACS retains its ability to transmit data. (Source:PeekMed)

DICOM also refers to the file format, usually a DCM or DCM30 (DCM3.0) file extension. While specific devices are still required for compatibility, this represents another facet of the DICOM suite of applications: it is not just a communication system and imaging tool, but also a file storage component. (Source:Medical LNB)

DICOM and PACS meet different communication requirements

As two distinct image acquisition, storage, management, and distribution components, DICOM and PACS address different facets of the file management process.

DICOM covers five main areas of functionality related to communication and distribution:

• Transmission and storage of medical images, waveforms, structured reports and documents, each called a "whole object".
• Query and recovery of previous objects
• Perform the requested actions on these objects
• Workflow Management
• Image quality and consistency (both for digital viewing and printing)

PACS is "just part of a larger IT infrastructure at an institution".It connects all of the following systems exclusively for data transmission (source:UCSF-RORL):

• Radiology Information System, RIS for short
• Electronic Medical Record, also known as EMR0
• voice recognition software
• Primary diagnostic reading tasks
• Show business workstations
• Radiation dose engine (only in some cases)

PACS is primarily intended to simplify image management, particularly images critical to patient care and recovery. By using PACS, team members can search and retrieve data as needed. DICOM is the method that allows imaging devices to communicate with the server, allowing medical personnel to perform these actions. (Source:Advanced Systems Corporation)

DICOM and PACS interact differently with workstations

Most medical imaging devices can optionally be operated via workstations, the functions of which are listed below:

• Workstations are not connected to the Imaging Console. Thanks to the convenient and fast remote control, this allows healthcare professionals to continuously examine patients.
• Workstations can reprocess DICOM RAW data captured from imaging hardware.
• Medical professionals can remotely analyze and interpret the collected images.

So what does this have to do with PACS and DICOM? As modalities need to capture and archive images for later distribution and analysis, they must interface with PACS and DICOM.Images would primarily need to be stored in the DICOM file format to ensure smooth switching between systems.

In the context of workstations, DICOM does not face as many functional dilemmas as PACS. For example, a hospital or clinic may face challenges with PACS depending on the infrastructure. If each department has its own PACS infrastructure, images cannot be shared across all devices and systems. On the other hand, DICOM would not be limited to specific departments if all devices were DICOM compliant.

DICOM is more flexible than PACS

PACS across health departments uses DICOM to store and transmit medical images, but can be functionally hampered by infrastructure differences across departments.

DICOM works the other way around, connecting different systems together, especially when using VNAs (Vendor Independent Archives). VNAs separate PACS to provide a single rather than multiple viewing experience, regardless of the image source.

This is not possible with PACS as it must be used with DICOM. However, DICOM can be used in conjunction with VNA and PACS.It sometimes works better with VNA as vendors often agree on "DICOM image storage, a standard DICOM network interface, and administrative updates". This allows you to avoid common interoperability issues. (Source:HIT-Infrastructure)

PACS manages the DICOM workflow, but not the other way around

While DICOM has proven to be much more versatile than PACS, it could be argued that in some cases both are equally necessary. This is primarily because PACS stores DICOM-compliant images and allows you to perform functions related to these images.

To understand this better, think of PACS as the "central coordinator" that hosts and oversees the following DICOM resources:

• DICOM standard grayscale display function (allows DICOM to calibrate and optimize images for display)
• Anonymize or anonymize medical imaging and comply with HIPAA (Health Insurance Portability and Accountability Act) to protect patient safety
• Structured DICOM radiation dose reporting (a way to report dose metrics from a CT scanner)

While DICOM is "clearly the only standard for the PACS mode of communication", it still requires PACS to perform the core workflow. PACS is a facet of the DICOM workflow that enables the exchange of information between devices and systems.Without them, DICOM devices would not have access to the medical documentation they wanted.

The different workflow requirements between PACS and DICOM

PACS and DICOM also differ in another important way; Each has different workflow requirements. DICOM has more features and simpler workflow while PACS has more unique features and much more complex workflow.

PACS requires the following components to support an optimal DICOM workflow:

As DICOM is not a "coordinator" but a standard for versatile management of digital medical data, the workflow is clearer.In essence, the DICOM workflow includes the following (source:US National Library of Medicine):

DICOM allows manipulation of images while PACS does not.

DICOM workstation software allows radiologists many different imaging options that PACS cannot directly provide (source:postDICOM), such as:

• quality control: Even on the simplest DICOM viewers, compatible workstation software helps improve image quality by allowing image brightness, color and contrast to be modified.
• image editing: Medical professionals can manipulate and extract new information from medical images using advanced DICOM workstation software.
  • One of the best examples of this is multiplanar reconstruction (MPR), where three separate files can be combined to create a 3D image.
• Location of visual focus: Medical professionals can better identify anatomical abnormalities using maximum and minimum intensity projections (MIP and MINIP), respectively.
• reports: Depending on your viewer, you can create a report directly from the transferred data and export it to a word processor.

DICOM allows direct control and manipulation of the image and extracted data. These controls are not available through PACS.

Below is a nice video about DICOM and PACS:

Finally

Although closely intertwined in their functionality, DICOM and PACS are two very different technologies with separate (but related) applications in the medical field. DICOM acts as an international communication standard and file format through which PACS transmits medical imaging data while PACS controls the DICOM workflow.

DICOM also allows direct control over the image and data, while PACS is a little more convenient, only allowing the capture, storage and transfer of files to and between DICOM devices. Despite its importance, PACS is functionally much more limited than DICOM, as the latter can be used with other software such as VNS.

Click on the link below for more information on this.View DICOM on a Mac.