Image Production · Equipment, AEC and QC2 min read5-question check
Informatics: PACS, DICOM and Security
DICOM moves images, HL7 moves text, and every login, logoff and password choice protects patient information.
The systems
Several connected systems handle imaging data. The hospital information system (HIS) holds the whole patient record, including registration, admission, discharge and transfer, orders and billing. The radiology information system (RIS) handles the imaging side: scheduling, exam tracking, radiology reports and billing. The picture archiving and communication system (PACS) stores images, sends them to reading stations and lets clinicians view them. These systems must share data accurately or images end up on the wrong record.
The standards
DICOM (Digital Imaging and Communications in Medicine) is the standard for medical images. It sets the file format and the rules for sending images between devices. Each DICOM file has a header with the patient name, ID, accession number, exam and technique data. HL7 (Health Level Seven) is the standard for text messages between information systems, such as orders, patient data and reports. Modality worklist is a DICOM service. The modality pulls the patient and order data from the RIS, so you select the patient instead of typing.
Storage and numbers
A single DR image can be about 2,500 by 3,000 pixels at 2 bytes per pixel, roughly 15 MB. Lossless, or reversible, compression keeps every bit of data and usually reaches about 2:1 to 3:1, so that image shrinks to about 5 to 7.5 MB. Lossy, or irreversible, compression reaches higher ratios but discards data for good. PACS keeps recent studies on fast storage and older ones in a long-term archive, with backup copies off site. Teleradiology sends images over secure networks to a radiologist in another place.
Security
Images and reports are protected health information (PHI) under HIPAA. The Privacy Rule limits who may see PHI, and the Security Rule requires safeguards for electronic PHI. Use only your own login and never share passwords. Open only the records your work requires. Lock or log off a workstation before you step away, and angle monitors away from public view. Systems keep audit trails, so every access is logged. Never photograph or post patient images, even without a name.
Clinical Example
A technologist selects her patient from the modality worklist instead of typing the name. The DICOM header now carries the correct ID and accession number, and the images land on the right record in PACS. Before helping the patient off the table, she locks the workstation.
Common Mistakes
- Mixing up DICOM (images) and HL7 (text messages between systems).
- Calling PACS the place where exams are scheduled; that is the RIS.
- Thinking lossy compression can be undone; discarded data is gone.
- Leaving a workstation logged in because you will be right back.
Why It Matters
The 2027 ARRT content specifications add security, confidentiality and teleradiology to the informatics topics. Expect questions on what each system and standard does and on protecting PHI.
Key Relationships
- RIS → scheduling and reports; PACS → image storage and viewing
- DICOM → images and headers; HL7 → text messages
- Modality worklist → fewer patient ID errors
- Shared logins or open workstations → HIPAA violations