DICOM FAQ

DICOM (Digital Imaging and Communications in Medicine) is the international standard for handling, storing, printing, and transmitting information in medical imaging. It serves as both a file format and network protocol specifically designed for healthcare, ensuring medical images can be shared across any DICOM-compliant device regardless of manufacturer.

DICOM is maintained by the DICOM Standards Committee and is used by virtually every medical imaging system worldwide.

Yes and no. A DICOM file contains image data, but it also includes a vast amount of metadata about the patient, the study, and the equipment. While it serves a similar purpose to JPEG for pictures, it is a much more complex and information-rich format designed specifically for medical use.

Key differences from standard image formats:

• Metadata-rich: Contains patient demographics, study details, and equipment information
• Multi-frame: Can store multiple images (e.g., an entire CT series) in a single file
• Standardized encoding: Uses specific transfer syntaxes for consistent interpretation
• Privacy-aware: Supports de-identification for research use

DICOM is the standard or protocol that defines the format of the images and how they are communicated. PACS (Picture Archiving and Communication System) is the system or technology that uses the DICOM standard to store, retrieve, and manage those images.

In short, PACS is the archive, and DICOM is the language it speaks.

• DICOM = the standard (file format + network protocol)
• PACS = the system (servers, storage, viewing workstations)

You cannot open a DICOM file with a standard image viewer like Windows Photos or macOS Preview. You need a specialized DICOM viewer, which is software designed to interpret the file’s metadata and display the image correctly.

Popular free DICOM viewers include:

• 3D Slicer (open source, advanced 3D visualization)
• Horos (macOS, open source)
• MicroDicom (Windows, free for personal use)
• RadiAnt (Windows, free trial)

Virtually all modern medical imaging equipment supports DICOM, including:

• CT — Computed Tomography
• MRI — Magnetic Resonance Imaging
• US — Ultrasound
• DR/DX — Digital Radiography
• MG — Mammography
• PET — Positron Emission Tomography
• NM — Nuclear Medicine
• XA — Angiography
• RF — Radiofluoroscopy
• SC — Secondary Capture (scanned documents and screen captures)

DICOM devices communicate over TCP/IP networks using specific service classes:

Each device is identified by an Application Entity Title (AE Title), and communication begins with an association negotiation where devices agree on which services and transfer syntaxes to use.

DICOM files contain extensive metadata organized into groups:

• Patient Information: Name, ID, birth date, sex
• Study Details: Date, time, description, referring physician
• Series Information: Modality, body part examined, acquisition parameters
• Image Data: Pixel data, dimensions, bit depth, window/level settings
• Equipment Info: Manufacturer, model name, software version

This metadata is stored as data elements identified by standardized tags (e.g., (0010,0010) for Patient’s Name). See our DICOM Specifications page for a detailed tag reference.

The DICOM standard itself includes security features like encryption profiles and audit trail requirements. When implemented correctly within a secure network infrastructure, a DICOM-based system is a key component of a facility’s overall HIPAA compliance strategy.

However, proper implementation and network security are crucial. The standard provides the tools, but the organization must ensure they are correctly configured and maintained.

Key DICOM security profiles include:

• Basic TLS Secure Transport — encrypted network communication
• Audit Trail Message Format — standardized logging
• Attribute Level Confidentiality — data element encryption

DICOM includes several privacy protection mechanisms:

• Data Encryption: Support for encrypted data transmission using TLS
• Access Controls: Integration with authentication systems and AE Title-based access
• Audit Trails: Logging of all access and modifications to imaging data
• De-identification: Standardized tools and profiles to remove patient identifiers for research, teaching, and secondary use

• Use encrypted connections (TLS/SSL) for all DICOM communications
• Implement strong authentication and access controls for all DICOM nodes
• Conduct regular security audits and monitoring of DICOM network traffic
• Keep DICOM software and systems updated with the latest security patches
• Follow organizational HIPAA and privacy policies for all imaging workflows
• Segment DICOM traffic on isolated network VLANs where possible
• Review and restrict AE Title access lists regularly

See our guide on configuring DICOM over TLS with Mirth Connect for a practical implementation walkthrough.

PACS (Picture Archiving and Communication System) is the technology healthcare organizations use to store, retrieve, and distribute medical images electronically. Instead of physical film archives, PACS provides digital access to imaging studies from any connected workstation.

A PACS typically includes four key components:

• Archive server: Central database and storage for all imaging data
• Viewing workstations: Software for radiologists and clinicians to display and interpret images
• Network infrastructure: Connections between imaging devices, the archive, and workstations
• Acquisition gateways: Interfaces that receive images from modalities (CT, MRI, X-ray) via DICOM

PACS relies on the DICOM standard for all communication between components. Modern alternatives include cloud PACS (hosted storage and viewing) and vendor neutral archives (VNA), which store images in a standardized format independent of any single PACS vendor.

Consider these factors when selecting a PACS:

• Scalability: Current and future storage needs — plan for 3-5 years of growth
• Integration: Compatibility with existing EHR, RIS, and imaging equipment
• Performance: Speed of image retrieval and display, especially for large studies
• Vendor Support: Training, maintenance, updates, and response time SLAs
• Cost: Initial investment, ongoing licensing, storage, and maintenance expenses
• Compliance: HIPAA, state regulations, and any specialty-specific requirements
• Disaster Recovery: Backup, redundancy, and business continuity capabilities

Storage requirements vary significantly by modality:

Common challenges include:

• Interoperability: Ensuring different vendors’ equipment works together despite variations in DICOM conformance
• Network Performance: Managing large image files (CT/MRI studies can exceed 500 MB) over hospital networks
• Storage Management: Handling massive and continuously growing volumes of imaging data
• User Training: Teaching clinical and IT staff to use new PACS and imaging systems effectively
• Data Migration: Moving existing images and studies from legacy systems to new platforms without data loss

Common connectivity issues include:

• Network Configuration: Incorrect IP addresses or ports
• Firewall Settings: Blocked DICOM ports (typically port 104 or 11112)
• Service Class Mismatch: Incompatible DICOM services between sender and receiver
• Authentication Issues: Incorrect AE titles or credentials not configured on both ends
• Transfer Syntax: Unsupported image compression formats between devices

Start troubleshooting with a C-ECHO test to verify basic connectivity, then check AE Title configurations and conformance statements.

Use these methods to test DICOM connections:

• C-ECHO: Basic connectivity test (DICOM “ping”) — the first thing to try
• DICOM Ping Tools: Specialized testing software like DCMTK’s echoscu
• Log Analysis: Review DICOM service logs on both the SCU and SCP for error details
• Test Images: Send sample DICOM files to verify end-to-end transfer
• Vendor Tools: Use manufacturer-provided diagnostic utilities for device-specific troubleshooting

If DICOM images display incorrectly:

1. Verify the transfer syntax is supported by the receiving application
2. Check for network transmission errors (dropped packets, timeouts)
3. Validate DICOM file integrity using tools like DCMTK’s dcmftest
4. Review window/level settings — incorrect values can make images appear blank or washed out
5. Test with a different DICOM viewer to rule out viewer-specific rendering issues
6. Contact the sending device manufacturer if the issue persists

• DICOM Standard: Complete official documentation and standard browser
• NEMA Publications: Standard downloads and updates
• IHE Profiles: Integration profiles and testing frameworks
• Professional Training: DICOM certification courses from organizations like SIIM and RSNA
• Vendor Documentation: Equipment-specific implementation guides from your device manufacturers

Consider expert assistance for:

• Complex Integrations: Multi-vendor environments with diverse imaging equipment
• Performance Issues: Slow image transfer, display lag, or network bottlenecks
• Security Implementation: HIPAA compliance, TLS configuration, audit trail setup
• System Migrations: Moving to new PACS, VNA, or cloud-based imaging platforms
• Custom Development: Specialized DICOM applications, workflow automation, or AI integration

Our team at Saga IT specializes in medical imaging integration across all major PACS platforms and imaging modalities. Contact us to discuss your project.